Category: Study Materials
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Tamarin: Description, Habitat, & Fun Facts
Continue ReadingTamarin Classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Callitrichidae
Genus: Saguinus
Species: Saguinus ursula
Tamarin Description
The tamarin is a small monkey that belongs to the genus Saguinus. The genus comprises 13 species that are native to New World. The tamarins are distributed in the jungles of the Amazon basin and other parts of Central and South America and live in the treetops.
Most of the species of tamarin are endangered in their jungle habitat. Appearance The most notorious species of tamarin include the golden lion tamarin (S. Ursula), which has an impressive golden-brown mane of fur similar to those of male lions. The tail is relatively long and its face is small, black.
Other tamarin species are black with some interesting mustache-like features. The weight of 13 species ranges from 7.8-31.7 oz and their length ranges from 5.1- 11.8, not including their weights.
Tamarin Diet and Predators
The range of tamarin occurs in tropical rainforests and lives in trees. They rest on hollow trees at night and during the day, they forage for food by climbing branch to branch. Their long fingers help them in snagging insects, fruits, and small lizards and birds.
Tamarins are small primates and have several predators such as snakes prey on them and their young and wild cats, some species of birds also feed on tamarin. To avoid predation, they move swiftly in the forest canopy at high speed. They hide in tree hollows at night to avoid predation.
Social Structure and Breeding of Tamarin
Tamarins are social animals and live in family groups of up to 40 individuals. However, a typical family group consists of about 10 members. The males are also involved in parental care and also carry their offspring around between feedings.
The gestation period of around 140 days after that the female gives birth to two young, which are usually twins. The new monkeys are raised by the males and other juveniles in the family, they often carry for them throughout the day but when required, return them to their mothers.
New tamarin starts eating solid food at the age of one month. They reach full maturity at the age of two years and become an independent member of the family. The life span of tamarin is about 18 years, although some species live closer to about 10 years.
Conservation Status of Tamarin
The Amazon rainforest basin is the major habitat of tamarin and also one of the most biodiverse areas in the world. Amazon basin is also considered as one of the most threatened areas in the world.
The tamarin and thousands of other species are continuing to strip from their natural habitats due to deforestation and the extension of agricultural land.
The IUCN red list for threatened species listed the golden lion tamarin as endangered species after the improvement from its previous critically endangered status.
Fun Facts About Tamarin
The habitat of tamarin includes one of the highly important and rare parts of the world. The area is relatively small and productive, which provided habitat to many closely related species. The tamarin show many interesting biological concepts to learn about it.
i. Difficult to Categorize
The taxonomy of tamarin is not straightforward. Originally, there are ten species in the genus Saguinus. Further, based on their unique facial hair patterns, they are divided into ‘morphotypes’.
Later, they are classified based on dental measurements and separated into two clades, and eventually, the genus consists of 15 species and no subspecies. A genetic analysis was conducted by the researcher in 2016 on the genus and other primates.
This study suggests that some members of the genus have emerged from other members about 10 million years ago. The members include the saddle-back tamarin but they emerged earlier than other monkeys and marmosets of genera Callithrix, Cebuella, and Mico thus the saddle-back tamarin was moved to genus Leontocebus.
ii. The Golden Touch
A beautiful color morph has evolved by the red-handed tamarin, which is quite interesting. The species is native to wooded areas north of the Amazon River and is well known for its conspicuous golden hair. It contains golden hair on hand which is in contrast to its black fur. The red-handed tamarin also has some gold-colored flecking on the anterior side and rump.
iii. Fierce Competition
Some species of tamarin are relocating from their natural habitat due to being threatened and global climate change, changing weather patterns in many areas. Thus due to fierce competition for remaining habitat, it can add to the demise of other tamarin species and it also causes harsh effects on the ecosystem.
For instance, the red-handed marmoset is expanding into the historical range of the pied tamarin, which is causing inter-specific competition and leading to the replacement of pied tamarin by the red-handed marmoset.
It also highlights the challenges linked with conservation efforts because the introduction of threatened species to a new range to save it, may cause harm to the native species of this range.
Tamarin Citations
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Siberian Tiger: Description, Habitat, & Fun Facts
Continue ReadingSiberian Tiger Classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Felidae
Genus: Panthera
Species: P. tigris
Siberian Tiger Description
A tiger subspecies, known as the Siberian tiger is native to far eastern Russia, China, and North Korea. Genetically, the Caspian tiger native to Central and Western Asia is extinct now and closest to Siberian Tiger.
The body of these tigers comprises notorious transverse strips all over the body with red-rust or rust-yellow colored coarse fur. In comparison with other tiger species, the ground coat of the Siberian tiger is often pale and changes between seasons and populations.
These tigers have strong legs and a long tail with relatively short and extended bodies. The length of the Siberian tiger is up to 60 inches and they weigh up to 675 lbs. historically, larger tigers were targeted by hunters, even females weighing at least 220 lbs with most remaining tigers falling short of this.
Generally, tigers are solitary animals. They are territorial animals and claim their large territories by scent-marking. They hunt any prey that falls within their territory and aggressively defends it. The large deers and boars, young of even larger animals are the prey of Siberian tigers.
On availability, they also eat rabbits and badgers. They track their prey and then camouflage to ambush it. The females give birth to two to six cubs at a time after a 3-month pregnancy. The male tigers are involved a little in the parental care of cubs.
The cubs are unable to hunt for 18 months and remain with their mother for at least two to three years and then find their territory. In some cases, the female offspring shares a part of their territory with their mother when they become adults.
Current and Historic Range of Siberian Tiger
The historical range of the Siberian tiger ranges from the Korean Peninsula, northern China, and Mongolia. In different regions, they are also known are “Amur tiger”, “Manchurian tiger”, “Korean tiger”, and “Ussurian tiger”.
Now the remaining population is found in a mountainous area in southwest Primorye Province of Russia and a part of Siberia, thus they get the name “Siberian Tiger”. Only about 350 tigers remained in wild in 2005 but currently, the population is stable since, even increasing to about 550 individuals in 2014 due to intensive conservation efforts.
Habitat loss and illegal poaching are the major threats to the viability of tigers. Now, Siberian tigers are listed as “endangered” by the IUCN.
Fun Facts About Siberian Tiger
Tigers are the most famous animals in the world. They are well known for their mysterious, elusive, dangerous, and beautiful characters. In the 20th century, 3 species from a total of 9 tiger subspecies went extinct, and even more, are endangered. So this proves that we are failing to conserve them despite the collective awareness.
i. The Great Traveler
According to various genetic studies, the Siberian tigers share common ancestors with Caspian tigers. They traveled from Eastern China via the Gansu-Silk Road corridor, colonized Central Asia, and ultimately reach Siberia.
The Siberian tigers are also known as great travelers and travel for large distances. They even travel up to 1000 km in search of prey or mates, but their range is now limited.
According to some records, the Siberian tigers travel up to 60 km per day. Thus, tiger conservation essentially requires the conservation of large areas or tracts of undisturbed wilderness.
ii. Rare Neighbors
Besides the tiger, another large feline also lives in this region. Generally, leopards live at a higher elevation than tigers but the Amur leopard’s habitat overlap with a Siberian tiger in the Changbai Mountains. The Amur leopards are one of the most evasive cats in the world. The IUCN listed these leopards as critically endangered.
iii. Not a Man-eater
The Siberian tigers look very dangerous and are often seen as a threat but opposite to this, they are very elusive and avoid humans to eat. In all cases, when they are reported becoming aggressive towards humans, it is mainly due to any injury or being ill.
Occasionally, an individual tiger does such behavior due to the dwindling population of prey species. However, there are some terrifying exceptions to this rule. John Vaillant, in this book “The Tiger”, described the story of a hunter named Vladimir Markov, a poacher in Far East Russia.
Before stealing a part of its kill, he shot and wounded a tiger. The injured tiger stalked the hunter and waited at the door for him to come home before it killed him and ate him. This rare case is an apparent act of vengeance in which the tiger waits up to two days for the hunter before killing him.
Although in India, some populations of tigers kill humans relatively regularly, this is thought to be an extraordinarily rare behavior of these tigers. The retaliation killings by people led by this, which further increase the threat to their populations.
Siberian Tiger Citations
Siberian Tiger: https://www.nationalgeographic.com/
ABOUT THE SIBERIAN TIGER https://www.rgo.ru/
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Mycology: Definition, History, & Career
Continue ReadingMycology Definition
The study of fungi is called mycology. In this branch, the relationships between fungi and other organisms and their unique biochemistry are studied. Fungi belong to a separate kingdom, most of them are eukaryotic organisms.
Earlier, it was assumed that fungi are an offshoot of the plant kingdom but with the help of DNA and biochemical analysis, it has been revealed that they belong to a separate lineage of eukaryotes. Their cell wall is the main distinguishing feature between fungi and plants.
The fungal cell wall is made of chitin and glucans. Fungi are significantly different from both plant and animal kingdoms thus mycology is considered a necessary branch of biology.
History of Mycology
Until the 1800s, fungi were assumed as a different kind of plant. Some fungal species such as Mushrooms (their reproductive bodies) are edible and also used for medicinal uses, for their hallucinogenic effects since antiquity.
Fungi were considered by many Greek philosophers and naturalists but all relate them with plants. After the invention of the microscope in the 1800s, the inner workings of fungi began to examine.
In 1836, M.J. Berkeley coined the term mycology, when fungi were recognized as their separate kingdom. However, the differences were recognized after the advent of modern biochemistry and DNA analysis. The fungal cell wall is made of chitin, instead of the cellulose cell wall found in plants.
Unlike most plants and animals, the fungal cell is multinucleated and contains special pores, which allows the cytoplasm and nucleus to flow freely between various chambers in the fungal chambers. After observation, it was revealed by scientists that most fungi spend their time as a mold or ooze.
The multicellular fungi obtain nutrition from decaying organic matter. According to scientists, fungi are also responsible for fermentation, and crop diseases. The field of mycology exploded with various discoveries.
In agricultural mycology, we focus on controlling and utilizing fungi in commercial crops. The adverse effects of fungi on other organisms were studied by toxicologists. The useful compounds of mushrooms are extracted by pharmaceutical companies. Like the field itself, the careers in this field are also diverse and complex.
Careers in Mycology
In the agricultural industry, mycology was first used and emerged as an important science and it remains until today. Various plant diseases which affect crops were studied by a phytopathologist.
For many crops, fungi are the major pests, which also show some beneficial effects by serving as a symbiont as allowing the plant to extract nutrients and water from the soil. The beneficial and harmful are distinguished with the help of mycology and it is also needed to treat crops and other infections caused by fungi.
Several fungi can kill targeted insects thus they are used as pesticides that are more natural than synthetic pesticides. After the origin of mycology in agriculture, it expanded well. After knowing the diversity of this kingdom, the roles of fungi were understood properly in society.
For instance, fungi were used in the production of cheese. The organism was classified and described in mycology, which leads to better and efficient production of cheese and other dairy products.
The other form of fungi is yeast, which is used in fermentation and the process of yeast fermentation is science itself. A person can get a bachelor’s degree in fermentation science and work in the brewing and distilling industries.
Yeast is also used in bread making and to maintain the cultures to produce enough yeast for the production, microbiologists are required.
Mycotoxicology is another specialized field of mycology in which the toxic effects of mushrooms were studied. Typically, to become a mycotoxicologist, a person needs a doctorate in biochemistry or organic chemistry or a medical doctorate with concentrations in mycology and toxins.
A variety of chemicals with toxic effects on all kinds of organisms were produced by fungi. Since the earliest hunter-gatherers, humans have eaten mushrooms, but some mushrooms are highly toxic while some species of mushrooms are beneficial and also used as medicine.
Many mycotoxicologists try to develop new drugs from these compounds and work for pharmaceutical companies. Still, more specializations are found in mycology and it is still evolving. With continuous, the kingdom is becoming more large and complex.
Researchers are focusing on special areas and interesting applications for certain fungi. For instance, radiotrophic fungi could alleviate radioactive wastes because it appears to grow in the presence of radioactivity, and fungi can convert complex organic substances into simpler molecules such as CO2.
Many of these applications have important commercial values and institutes need researchers to explore the aspects of mycology. Finally, the scientist studying the historical uses of fungi is called an ethnomycologist.
Mushroom is used in various cultures as food, medicines, hallucinogens, etc. these uses were studied by an ethnomycologist and then inform the front-line researchers about known effects of certain fungi.
Ethnomycologists also provide a critical function by sorting the helpful information which is already gathered by past cultures and societies. As these professions are pushing the boundaries of knowledge and filling the missing gap, the field of mycology is still expanding.
Mycology Citations
Mycologist: What do you do?
Welcome to Mycology Online
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Equilibrium Constant: Definition, Types, & Examples
Continue ReadingEquilibrium Constant Definition
A chemical reaction’s tendency to proceed to completion is described by an equilibrium constant, Keq, which is a variable. It means that all the reactants are converted to products. The point at which the conversion of reactants into products is equal to the conversion of products back into reactants is called equilibrium.
What is Equilibrium Constant?
When the reaction proceeds in the forward direction, from reactants to products it means a large equilibrium constant until almost all the reactants have been converted to products. When the chemical reaction favors the reactants and the reaction proceeds in the opposite direction, the Keq is less than one.
When the equilibrium constant is 1, it indicates that the reactants and products will be equal at the stage of equilibrium. The equilibrium constant is used by scientists to understand how quickly the equilibrium will be reached, and it will be in favour of reactants or products.
When the equation has reached equilibrium, the constant can be calculated using the ratio of products to reactants. The variable Keq is used to represent the equilibrium constant, and the equilibrium constant expression defines it.
Equilibrium Constant Equation for a Chemical Reaction
The concentration of products divided by the concentration of reactants describes the equilibrium constant expression when the reaction reaches equilibrium. This expression can be seen below-
Keq = [C]ceq [D]deq / [A]aeq [B]beq
In this reaction= aA +bB<=> cC +dD
The concentration of a reactant or product in the reaction is described by each term when the product C and D are produced by chemicals A and B. the number of moles of each chemical is indicated by the lowercase letters.
The brackets around a letter [A], indicate the concentration of each chemical, and the equilibrium constant determined by the concentration if each molecule is denoted by the subscript.
A famous scientist, J. Willard Gibbs studied the energy present in the reaction. He described that the equilibrium constant is directly related to the amount of free energy change that occurred during the reaction.
The free energy change is denoted by ∆G. Gibbs proved that standard free-energy change or ∆G0 occurs in every reaction. The initial concentrations of chemicals govern the total free energy change of each reaction.
Using the equilibrium constant of the equation, the following equation is used to calculate the standard free energy.
∆G0 = -RTIn (Keq)
According to this equation, the standard free energy change is another method to describe the driving forces of reaction, and which way they will proceed. However, we can know whether we will have more reactants or products at the end of a reaction by the equilibrium constant but it does not hint about the time taken to complete the reaction.
This is called the rate constant and it is denoted by a lowercase k. A variety of other equations related to the speed of the reaction are also related to the rate constant. A number of biological reactions need the equilibrium constant, as seen in the examples below.
Equilibrium Constant Examples
i. Ionization of water
Life on earth is based on water. The main reason behind this is, it is a good solvent and it can form hydrogen bonds with other non-water molecules and itself. Due to this ability, water can dissolve and diffuse solutes and also carry an electrical current.
A hydrogen bond is formed by water or H2O, in which the hydrogen is pulled away from the oxygen, and the hydrogen molecule forms hydrogen ion (H+) and hydroxide ion (OH–) by dissociation. In solution, individual hydrogen protons exist freely and immediately form bonds with the water molecules.
Due to this, hydronium ion, or H3O+ is formed. The equilibrium constant for this reaction is-
Keq= [H+]eq [OH–]eq / [H2O]eq
The electrical conductivity of water is used to measure the equilibrium constant of this reaction, which is determined by the concentration of (H3O+). An electrical signal is passed by the hydronium ion in the form of the transfer of electrons. The signal is measured by sensitive electrical equipment.
Thus, using sensitive electrical equipment, the equilibrium constant of water is measured to be 1.8 x 10-16, which means that the water has much probability of being the reactant H2O instead of becoming the hydronium ion.
ii. Cells, free energy, and the equilibrium constant
The measurement of the equilibrium is done when a reaction is at equilibrium but it does not mean that all reactions are allowed to proceed to equilibrium. Many reactions are constantly resupplied in the cell by various chemicals due to which, the reactions of the cells are kept far from equilibrium.
However, the tendency of these reactants to form products is described by the equilibrium constant. Some reactions are exergonic, which means that when they happen, they release energy and they have high equilibrium constant that describes their tendency to become products.
It is also said that these reactions have a positive change in free energy, which means that they give off energy to reactions around them. Endergonic reactions are other important reactions that requires energy for completion.
A low equilibrium constant of these reactions describes their tendency to remain as reactants. These reactions are coupled in cells and allow the endergonic reactions to takes place.
Many cellular reactions convert ATP to ADP by using the high equilibrium constant of ATP to drive endergonic reactions. The examples include the formation of fatty acids and protein
Equilibrium Constant Citations
The equilibrium constant K
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Notochord: Definition, Types, & Function
Continue ReadingNotochord Definition
An elastic rod, found in all chordate organisms, is known as the notochord. It provides rigid support to the organism. The notochord is replaced by the vertebral column in chordates, called the vertebrates. It is formed by a cartilaginous substance between vertebrae. Lancelets are one of the simplest chordates, which also contain notochord.
What is Notochord?
In anatomy, the notochord is a flexible rod formed of a material similar to cartilage. If a species has a notochord at any stage of its life cycle, it is, by definition, a chordate. The notochord lies along the anteroposterior axis (front to back), is usually closer to the dorsal than the ventral surface of the embryo, and is composed of cells derived from the mesoderm.
The length of the notochord is extended to the length of the organism, and it allows the muscles to attach. Thus, the lancelet can swim in fast bursts. The notochord is developed at some point in all chordate organisms, like lancelets, however, some organisms may lose it later in life.
For instance, some marine organisms like tunicates, live in the bottom of the ocean and filter feed. The adult form of a tunicate does not require a notochord, but in the larval stage, it helps in swimming to potential settling sites, thus they lose notochord at the adult stage.
Other species do not grow a vertebral column and retain the notochord throughout life. These animals are called invertebrate chordates. Lancelets, tunicates, and some large fish such as the sturgeon and coelacanth are included in this group.
The length of the notochord can be around 3-4 feet in these organisms and will be really thick about half an inch. This huge notochord is used as a spine in notochord by these fish. However, how it protects the spinal cord and what it is made of are different in them. In invertebrates, the spinal cord is surrounded by the bony vertebrae and protects it on all sides.
This protection is not found in animals, which have only a notochord, and in these organisms, the spinal cord sits between the notochord and the skin. The spinal cord and notochord are protected by armored plates and thick skin in animals like sturgeon and coelacanth.
Invertebrates, the notochord is converted into cushioning intervertebral discs that provide protection to the vertebrae from smashing together. By the time a human is around 4 years old. However, the spine with other materials entirely replaces the original notochord.
Notochord Structure
There are several structural molecules such as glycoproteins, form the notochord, which resembles cartilage in many ways. Under a microscope, the cross-section of the notochord appears as a series of concentric rings.
The rings surrounded by each other are layers of the notochord and are made of various molecules, which provide strength and elasticity to the notochord. The glycoproteins and other structural molecules extend from cells and are spaced apart in the notochord.
A large vacuole is found in each cell that can pressurize. The cells push against each other and the surrounding structural materials by pressurization. The notochord becomes extra rigid due to this, which helps the organisms in swimming quickly.
Notochord Function
The notochord becomes a very important and useful structure to attach muscles to due to its strength. To flex properly, muscles need places for attachment. In small invertebrates, the muscles attach down the length of the notochord, due to this they can use muscles all over to swim.
It provides enough support for most of the muscles of the body of some large fishes, which rely on notochord. The cells of the notochord create turgor pressure that makes it extra rigid. While many organisms get enough support from this. In vertebrates, this body plan is taken one step further with the spine.
The spine is made of bone, which increases its rigidity and also protects the spinal cord by fully encompassing it. It is also recorded that during normal vertebrate embryogenesis, the notochord serves important signaling functions.
The proteins secreted by the notochord stimulate the formation of organ systems. This process is known as organogenesis, which starts when the embryo is a hollow ball of cells known as the gastrula. Gastrula has three layers, and the notochord arises from the middle layer, known as mesoderm.
The process of organogenesis is further started with the secretion of several chemical signals from the notochord. Eventually, the spine is created with the formation of bones, and the notochord gets sandwiched between these vertebrae. The vertebrae also protect the notochord from the bones rubbing and smashing together.
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Germ Cells: Definition, Types, & Function
Continue ReadingGerm Cell Definition
The unipotent stem cells that can divide and produce gametes are called germ cells. The gametes of haploid sex cells are produced by a germ cell, which undergoes meiotic cell division and produces genetically unique gametes. These gametes fuse during fertilization and form diploid zygotes. The germ cells produce eggs in females and sperms in male organisms.
What is Germ Cell?
Gametes are formed by the germ cells in all sexually reproducing organisms. Invertebrates are the precursors of male sperm cells and female egg cells. The germline is collectively called to all the germ cells in an organism.
In the early stages of embryonic development, the germline separated from the somatic cell line. Both the cell lines have very different functions. All the body structures are made up of somatic cells, whereas the gametes are made of germ cells and help in the transmission of genetic information to offspring.
The main difference between germ cells and sperm cell is, the germ cells divide by meiosis whereas somatic cells divide by mitotic division. The term unipotent means they can only become one other type of cells such as germ cells such as an egg or a sperm.
The gametes fuse and form a diploid zygote during fertilization, which is a totipotent cell. The totipotent cell can give rise to all other types of body cells.
Function of Germ Cell
Germ cells can give rise to gametes. Thus, a person can pass the genetic information to their offspring by germ cells and they are the original cells of all sexually reproducing organisms. Natural selection and evolution occur due to the inheritance of DNA and maximal genetic variation among gametes are ensured by the fact that germ cells divide by meiosis.
Development of Germ Cell
In humans, the stem cells known as primordial germ cells (PGCs) give rise to the germ cells. They originate in the epiblast region of the embryo. After migration of PGCs into the developing gonads, they divide by meiosis and give rise to either sperm or egg cells.
The gametes produced by meiosis are non-identical, haploid cells, which contain a single set of chromosomes. The zygote is formed by the fusion of haploid egg and sperm during fertilization, which contains DNA from both parents. The germline preserves the genetic information in the offspring which further passes on over generations of reproduction.
Germ Cell and Meiotic Division
Meiotic division only takes place in the germ cells of the body. Meiosis produces four, haploid, non-identical gametes, while mitosis produces two, diploid, genetically identical daughter cells.
Originally, germ cells are diploid cells and become haploid after meiotic division to form gametes. The gametes should be haploid to ensure that the offspring get the correct number of chromosomes are fertilization. Thus, the germ cell undergoes meiotic division to halve the number of chromosomes.
The gametes produced by meiosis are genetically unique, which ensures the genetic diversity within the species.
Stages of Meiosis in Germ Cell
There are two stages in meiosis: meiosis I, and meiosis II. During the interphase stage of the cell cycle, the DNA replicates to make its copy. During a complete round of meiosis, the germ cell divides twice and produces four haploid gametes.
i. Meiosis I
Prophase I: The DNA has already replicated, when the cell enters prophase I. At this stage, each chromosome consists of two sister chromatids that are identical and connected by a centromere.
The formation of the meiotic spindle takes place during prophase I and after the condensation of chromosomes, homologous pairs are formed. The process of crossing over occurs between the homologous chromosome pairs, in which a few genetic material exchanges. This ensures that the sister chromatids are not genetically identical.
Metaphase I: During metaphase, the homologous pairs line up in the middle of the cell and the chromosomes attach to spindle fibers.
Anaphase I: The chromosomes are pulled by the meiotic spindle fibers and drag one chromosome from each pair to opposite poles of the cells. The sister chromatids are still attached.
Telophase I and Cytokinesis: The chromosomes reach the end of the cell and the cytoplasm of the cell splits by the process of cytokinesis. It creates two non-identical daughter cells. In meiosis I, the haploid cells are produced with half of the number of chromosomes as the original germ cell.
i. Meiosis II
Prophase II: In meiosis II, the daughter cells produced by meiosis I undergo further division. During prophase II, the condensation of chromosomes takes place, and meiotic spindle forms.
Metaphase II: The chromosome is lined up along the middle of the cell and then each sister chromatid attaches to the spindle fibers.
Anaphase II: The sister chromatids are pulled by the spindle fibers towards the opposite poles of the cell and one from each chromosome move to opposite ends of the cell.
Telophase II and Cytokinesis: During telophase, the chromosomes reach the ends of the cell, and then the cytoplasm of the divided by cytokinesis. The two cells, which undergo meiosis II, produce four non-identical haploid cells.
In male organisms, four sperm cells are produced by meiosis or the process called spermatogenesis, while in females, the germ cell produces a single egg cell and four polar bodies, which cannot be fertilized. The process is known as oogenesis in females.
Location of Germ Cell
In an organism, the germ cells are found in the gonads. They are found in the testes of male vertebrates and female vertebrates, they are located in the ovaries.
Germ Cell Citations
Germ Cells Are Forever. MINIREVIEW| VOLUME 132, ISSUE 4, P559-562, FEBRUARY 22, 2008.
Germ line is the sex cells
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Blue Shark: Description, Habitat, & Fun Facts
Continue ReadingBlue Shark Classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Carcharhiniformes
Family: Carcharhinidae
Genus: Prionace
Species: P. glauca
Blue Shark Description
The blue shark is a medium-sized pelagic shark. The dorsal side of the shark is indigo-blue colored with its long and sleek structures. The shark migrates for long distances and can swim rapidly.
The body of the blue shark is up to 10 ft long and its weight is about 400 pounds in the largest specimens. They have a slender body with large pointed pectoral fins and two dorsal fins.
The lower lobe is smaller than the upper lobe and the tail is relatively large. While they roam the oceans, their tail sways side-to-side and provide excellent swimming power. They contain a pointed snout and large, black eyes that set over their smallmouth.
The blue sharks are very graceful swimmers due to their tapered bodies. The underside of the blue shark is off-white while the dorsal side is indigo-blue colored.
Blue Shark Distribution and Range
The blue sharks are distributed throughout the temperate and tropical waters of the world’s oceans. They are epipelagic species found along the coasts of every continent except Antarctica. They live in offshore waters and occasionally come to the coast, particularly in temperate waters where the divers can observe them.
Blue Shark Prey and Predators
Squid is the most common prey item of the blue shark. They also feed on other species including octopuses and cuttlefish and shellfish such as lobsters and crabs. In some cases, they also prey on sea birds, snatch them from the surface while they rest.
Some large shark species such as the tiger shark and great white shark are the predators of blue sharks. Orcas also feed on shark species. As compared to large adults, young sharks are more vulnerable to predators.
Besides all of them, humans are the greatest threat to the shark species, almost 20 million blue sharks are killed every year by fisheries.
Blue Shark Reproduction
Blue sharks nourish their young in their uterus thus they are called viviparous species. At a time, a female shark gives birth to 25 -50 live pups. In some cases, litters of around 135 pups have been observed.
The length of a newborn pup is around 16 to 20 inches and from the moment of birth, they are independent. The blue shark is listed as near threatened by the IUCN red list of threatened species.
Fun Facts About Blue Shark
i. A shark’s shark
The appearance of the blue shark can be described as the quintessential shark. Their shape is like a torpedo but generally, they are lethargic and move slowly to conserve energy. However, they move very quickly while facing any threat of predator or if they find any prey. Their morphology including their slender body and large tail helps them to swim very fast.
ii. The great traveler
The pelagic blue shark is a great traveler and covers long distances during migration, thus they are found in most temperate and tropical waters. For example, they travel from the water of New England, the USA to South America, which is a confirmed migration pattern of blue sharks.
According to some other studies, they also travel from the west coast of Europe to northwest Africa and across the Atlantic. The total distance is 3,187km from where it was tagged to where it was caught.
iii. An unlikely threat
The blue sharks face the threat of predation from other larger shark species such as orca, and other predators, but besides them, they also have some less expected predators. For example, blue sharks are also eaten by northern elephant seals in Norway. Thus, even for a blue shark, the ocean can be a threatening place.
iv. A smaller problem
Rather than large predators including sharks and whales, the blue sharks have the greatest problem of threat of parasites. A tetrahylidean tapeworm known as Pelichnibothrium speciosum is one such parasite that spends its life in the body of a blue shark.
The parasite enters the body of the shark when it eats an infected intermediate host such as fish. The parasite obtains food and nutrients from the shark and also creates health issues such as digestive problems and deficiency of nutrients.
v. Truly thick-skinned
There are some interesting details about the reproductive behavior of the blue shark and the non-reproductive morphology of the species that may be impacted by this. The males tend to bite the females during courtship rituals and often leave scars.
The behavior is very common and with the help of this, an adult blue shark can be sexed simply by observing the bite marks around its head.
The female sharks have developed a thick skin as an adaptation to withstand this behavior by males and to protect themselves. As compared to the male blue sharks, the skin of females is approximately three times thick.
Blue Shark Citations
Prionace glauca – Blue Shark – Florida Museum.
Blue shark – Prionace glauca
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Titmouse: Description, Habitat, & Fun Facts
Continue ReadingTitmouse Classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Paridae
Genus: Baeolophus
Species: B. bicolor, B. atricristatus
Titmouse Description
Two distinct species of birds of the genus Baeolophus are referred to as the titmouse. These small songbirds are native to North America.
The titmouse belongs to the family Paridae, which also comprises chickadees and tits. The B. atricristatus is once thought of as a subspecies of B. bicolor, while now they are considered as separate species.
The color of titmouse is mostly grey with a rust-colored outline and white front, black forehead. A tufted grey Mohawk-like crest is also present in their head which is a characteristic feature of these birds.
The length of a titmouse is approximately 6 inches and the weight is only 21 grams or less than half a pound.
The preferred habitat of titmouse includes woodlands and deciduous forests. They also live in gardens and parks, where humans have disrupted their natural habitat.
They move to the ground to feed but spend most of the time in trees to avoid predation. They are omnivorous and feed on various insects such as caterpillars and wasps and other food items such as berries, nuts, and seeds. They gather food items in the tree and they are also regular visitors to bird feeders.
Titmouse Nesting and Reproduction
The female titmice make their nests in the holes and cavities in trees and sometimes also use the nest boxes made by humans. However, they cannot excavate the tree cavities and use old woodpecker nests when they cannot find a suitable nesting site.
The nest is prepared by both males and females and made with soft materials such as hair or fur from animals including pets. The shade snakeskin is also used by titmice, which may act as a predator deterrent.
About 5-7 small eggs are laid by females, which are about 1 inch long. The eggs are white or cream-colored that contain purple or brown spots. Interestingly, the fledglings of titmice that recently left the nest often help the parents to raise the young reproduce next year.
Some predators like snakes, raccoons, and skunks eat the eggs of titmice and also invade their nests. But the domestic cat is the primary predator of these songbirds. Hawk and Falcon are the major predators of adult titmice.
The lifespan of these birds is about 2.1 years in the wild but they can live more than 10 years if possible. The growth rate of the tufted titmouse population is 1.5% per year since 1960.
During this time, they have proliferated in most of the USA in human-developed areas. Their population is enough strong and they are listed as “least concern” by the IUCN.
Fun Facts About Titmouse
The tufted crest is the characteristic feature of this songbird with its charismatic and energetic behavior. But many other facts make them memorable.
i. Song
Due to their melodies voice, they are called songbirds. They tend to whistle from their perches with their vibrant and diverse song that may vary in about 20 different ways. Typical titmouse sings a repetitive or chant-like song of peter-peter-peter or here-here-here at lower pitches.
They sing a quickly whistled song of frequencies of about one to up to 35 songs per minute. Their songs play a role in communication and courting thus they sing most commonly during the breeding season.
As the neighboring titmice hear the song, it replies with the same song it indicates that they may learn or share songs in this way. At a young age, the juvenile titmice learn a song from their family and also take up the songs of their neighbors in their territory.
ii. A Homebody
Titmice are not migratory unlike most other songbirds, which migrate from the north in the summer to the south. However, the species are widespread and from their native Mississippi and Ohio, they moved across the United States and parts of Canada but the individual birds are non-migratory.
They do not relocate to avoid foul weather, instead, they live in areas that do not experience extreme conditions. Thus, they do not require migration to avoid cold.
iii. Killer Cats
Domestic cats are one of the biggest threats to songbirds including titmouse in the natural world. Cats kill approximately 1-4 billion songbirds per year in only the United States alone. Thus, domestic cats are the leading cause of mortality for songbirds, another cause is habitat destruction by humans.
Titmouse Citations
Grubb, Jr., T. C. and V. V. Pravasudov. 1994. Tufted Titmouse (Baeolophus bicolor), The Birds of North America (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, PA, and The American Ornithologists’ Union, Washington, D.C.
Tufted Titmouse, Baeolophus bicolor
Tufted Titmouse Identification
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Top 10 Best Bird Watching Websites
Continue ReadingTop 10 Best Bird Watching Websites
If you’re interested in bird watching, one of the first things you’ll want to do is find a few good websites dedicated to the activity. Luckily, there are many great bird watching websites out there, and this article will tell you how to find them easily and how to make use of their resources once you do.
1) eBird
eBird is an online database where birders can log their sightings and learn about birds on any continent. It’s become so popular that it led to a standalone app of its own, which you can download for free from iTunes.
Our number one pick for bird watching sites is TheBirdPedia. This site is an online compendium of knowledge about every aspect of birdwatching, from lists of different species, baby birds including baby owl and their preferred habitats to a field guide for quick reference on your smartphone or tablet. TheBirdPedia.com site also gives you ideas for planning trips and outings. If you love birds and enjoy being outdoors, check out TheBirdPedia today!
3) Audubon
This is a great place to start for all your bird watching needs. On Audubon, you can find an interactive list of North American birds, along with in-depth information on their different habitats and identification tips. The website also has a section dedicated to kids so they can better understand what they are seeing. In addition, Audubon offers a selection of beautiful photographs you can use as wallpapers or desktop backgrounds to show off your appreciation for these feathered creatures.
If you’re a fan of spotting and identifying birds, then BirdsFact is worth checking out. This website publishes bird-watching guides for more than 30 cities and towns across all 50 states. The guides are well organized by time of year—for example, there’s an overview on when to spot birds in each month, as well as what areas to check out in order to find your favorite species.
5) All About Birds
All About Birds is a comprehensive resource on all things bird, including everything from endangered species to how-to guides on feeding and caring for birds. It’s an ideal starting point for those looking to learn more about these remarkable creatures.
6) Hotspotter
Hotspotter allows you to search for locations where specific species have been spotted in Britain. There are some great photographs of different species and it’s easy to find out how many birds of each kind there were, when they were spotted and where they were seen. A great resource if you want to get out there and see some rare birds.
7) Birds Count
Birds Count is a great place to start your bird watching website search because it’s packed with user-submitted data. Create an account and make sure to record your sightings. The more data you submit, including location, time of day, number of birds present and even vocalizations, means that you’ll get better feedback when you’re searching for info on specific species or similar sightings in other areas.
8) World Life List
The World Life List is a list of all species of birds, living and extinct, that have ever been scientifically described. This is a dynamic list because ornithologists regularly publish new scientific names, descriptions and identifications of extant and recently extinct bird species as well as relevant information on subspecies, taxonomy, distribution and behaviour. New updates are made available several times per year. For more information visit About WL-Online.
9) National Geographic’s Checklist Project
What better place to start than with one of our nation’s finest natural resource management tools? The Checklist Project is a massive effort to put data about every species and subspecies into a format that can be used by both people in the field and those looking for information from home. The project’s website isn’t as slick as some, but it’s an incredible tool—and it doesn’t even scratch the surface of what they do.
10) Bird Watching Forums
You’ll find them in every city, town and forest from Alaska to Tasmania. Bird watching forums are a great way to connect with others who share your passion for birds. Not only can you find tips on where to go birdwatching, but also chat about everything from bird species to travel logistics. Even if you have no plans of leaving your hometown, it’s still worth joining a forum.
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Secretion: Definition, Types, & Function
Continue ReadingSecretion Definition
The method of moving molecules manufactured within a cell to the space outside of the cell is referred to as secretion. Usually, these secreted substances are called functional proteins. However, the range can include non-protein products such as steroids. This process is opposite to excretion in which the waste products are removed from the system.
Purpose of Secretion
The main purpose of secretion is to produce signals. The secreted substances act as short and long-distance signals for another cell. For instance, neurotransmitters are secreted by neurons send messages to neighboring neurons.
Similarly, several types of hormones are secreted by the pituitary gland travel via the bloodstream and act throughout the body. There are diverse functions of these long-distance signals such as they have roles in the kidney, reproductive organs, and metabolism.
The secreted substances also have important functional roles within an organ or tissue. For example, in the stomach, three different cell types occur in gastric glands and the components of gastric acid are secreted from the gland.
The lubricating mucus is secreted by the mucus cells and hydrochloric acid is secreted by parietal cells and the chief cells secrete the precursor to the protein-digesting enzyme, pepsin. All these substances help in the digestion of food inside the stomach.
How Does Secretion Occur?
Depending upon the cell type and the substance, the secretion can occur by many pathways. In some cases, the secreted material or substance inserts into the cell membrane while in others it must cross the plasma membrane. The examples of some major pathways are as follows-
i. ER-Golgi Pathway and Porosomes
In this pathway, the endoplasmic reticulum produces secretory products, which are then inserted into transport vesicles. The spherical containers made of the lipid bilayer are called vesicles.
The vesicles then travel to the Golgi apparatus, where the modification, packaging of the secretory material takes place. The products are marked for export and packed in special vesicles in the Golgi apparatus. The process is much similar to shipping and labeling a package and loading it into a delivery truck.
The chemical environment in the cytosol can cause chemical reactions and change the structure of proteins thus the compartmentalization of the secretory pathway is essential. The secretory vesicles then leave the Golgi apparatus and interact with the porosomes in the cytoskeleton while traveling.
The structure of the porosome is conical-shaped which is embedded in small pits in the plasma membrane. The pits swell after docking of vesicles and the content expel into the space outside due to resulting pressure. The material in the vesicle exit due to the increased diameter of the porosome.
A fusion ring is formed around the narrow portion of the porosome by several proteins that facilitate the release of vesicle content. The process is called exocytosis, in which a material is moved outside from inside of the cell membrane.
Some cells use a specialized form of exocytosis. The specific fusion proteins found in neurons allow rapid and synchronous neurotransmitter release that send a signal from one neuron to another.
ii. Membrane Transporters
Instead of exocytosis, some proteins in the cytosol move across the cell membrane via transporter proteins. In this pathway, the proteins are not packed in vesicles and are transported individually by specialized proteins found in the plasma membrane.
iii. Lysosomes
The major function of lysosomes is degradation but they also serve some other important roles such as secretion. The lysosomal secretory pathway is frequently used in certain specialized cell types such as the blood stem cells and pigment cells. Like secretory vesicles, the lysosomes fuse with the cell membrane and release its content. However, in this process, different proteins are used.
iv. Secretion in Prokaryotes
The membrane-bound organelles are not found in prokaryotes. Thus they lack ER and Golgi apparatus and secretion occurs by another pathway. For example, six different methods are used by gram-negative bacteria, labeled types I-VI.
All the methods move products across the cell membrane by using unique molecular structures. However, the substances secreted by bacteria are harmful to others, but the research is ongoing to use these substances in developing antibiotic treatments.
Secretion Citations
- Muscle and Bone Impairment in Infantile Nephropathic Cystinosis: New Concepts. Cells . 2022 Jan 5;11(1):170.
- Metabolic Implications of Immune Checkpoint Proteins in Cancer. Cells . 2022 Jan 5;11(1):179.
- Modulation of Bile Acid Metabolism to Improve Plasma Lipid and Lipoprotein Profiles. J Clin Med . 2021 Dec 21;11(1):4.
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