Category: Biology
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Leopard Gecko: Description, Habitat, & Facts
Continue ReadingLeopard Gecko
Leopard Gecko is ground-dwelling reptiles belong to the genus Eublepharis and come under the order Squamata. These geckos live a solitary life and have an average lifespan of 15 years.
They reside in dry rocky grasslands and weigh around 54 to 65 grams. This genus comprises 3-5 species that are commonly found in Asia and the Middle East. The leopard gecko has been adapted as a pet by many and maybe the first lizard species to be domesticated.
The species include E. macularius commonly known as leopard gecko, E. fuscus known as West Indian leopard gecko, and E. turcmenicus, known as East Indian leopard geckos.
Leopard Gecko Physical Description
The genus is named for the fully functional eyelids present in the species they comprise. These sturdy small lizards are referred to as leopard geckos due to the presence of spotted patterns in shades of brown and yellow.
They possess long tails that are the same length as their torso. They use their tails to evade predators and later regenerate them. The regenerated tail would be less symmetrical and may be shorter than the original tail.
The adult length measures up to 20.5-27.5 cm and they have tough bumpy skin around their neck, back, and head. They also shed their skin as they grow. The sexes have subtle differences and can be segregated only on close inspection of their undersides.
Leopard Gecko Range, Habitat, and Behavior
They are native to the Middle East and southwestern and eastern Asia where they dwell in rocky grasslands. During the day they often live in burrows on the ground to escape the heat and are commonly nocturnal.
They have strong eyesight that helps them to hunt insects at night. They ambush small insects like mealworms, crickets, and caterpillars. Their predators are reptiles like snakes and foxes and other mammals.
These predators also eat their eggs. They employ their sense of sight and hearing to avoid predation. They camouflage well with their surroundings and may utilize this to hide from their predators.
Burrowing helps them not only to stay cool but also to avoid their predators. There is not enough information on their interactions with other members but they do come together for mating.
In the wild, they abide in loose colonies but live a solitary life. Whereas in the case of captivity also they usually are kept alone.
Leopard Gecko Reproduction
Breeding occurs in the summer months in the wild. The females store sperms and produce 2 eggs at a time, and they may lay about 20 eggs in a period of one month. After 3 to 4 weeks of copulation, the first eggs are laid.
The incubation period of eggs may vary due to factors like humidity and temperature; they typically require about 30 to 90 days for the young to hatch. The young ones on hatching weight only 3 gram and has a length of 6.5 to 8.5 cm.
They are independent from the moment they hatch. The sex of the young is determined by temperature as in other reptiles. The temperature of their environment during incubation determines their sex.
At around 26-29°C that is in colder temperatures, more females will be produced. While in case of warmer temperatures more males are produced. This process of temperature determinant sex determination happens in the first 2 weeks after an egg is laid.
Fun Facts about Leopard Gecko!
These beautiful lizards are docile geckos. In recent times there is an increasing trend of adopting them as pets as they are not large or venomous. They exhibit various interesting characteristics.
They cannot climb well like other geckos this can be attributed to their size and shape. They also do not have adhesive lamellae that help other geckos to cling to smooth vertical walls or surfaces. The fact that leopard geckos enjoy hot, dry conditions is a misconception that may arise due to the ranges they occur in.
They are usually found in dry hot regions like Afghanistan. They are adapted to such conditions for their survival in these regions. They often inhabit the coolest regions of the range like rocky grasslands and may prefer them over desert plains.
But this becomes disadvantageous for the geckos during winter months when they come close to near freezing conditions. During such times they enter brumation after moving in their burrows.
Brumation is the state of semi-hibernation that utilizes a similar hibernation as seen in cold animals but differs in terms of their metabolism processes. Before going into brumation, the gecko will try to increase their fat reserve stores. During the winter months, they burrow deep and live there without food for months.
They the temperature increases then they may wake up sometimes, to drink some water. They unlike hibernating mammals are influenced by ambient temperature changes.
This species is a common pet species with approximately 3 million individuals bred in the United States itself. They also have more color morphs due to selective breeding than their wild species.
Leopard Gecko Citations
- Constitutive cardiomyocyte proliferation in the leopard gecko (Eublepharis macularius). J Morphol . 2018 Sep;279(9):1355-1367.
- The nocturnal leopard gecko (Eublepharis macularius) uses UVb radiation for vitamin D 3 synthesis. Comp Biochem Physiol B Biochem Mol Biol . 2020 Dec;250:110506.
- The tongue of Leopard Gecko (Eublepharis macularius): LM, SEM and confocal laser study. Anat Histol Embryol . 2020 Jan;49(1):51-59.
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Sea Otter: Description, Habitat, & Facts
Continue ReadingSea Otter Definition
Sea Otter is a endangered otters belong to the genus Enhydra and come under the order Carnivora. These marine predators may weigh up to 14-45 kg. They are found in offshore and coastal marine habitats along the west coast of North America.
They are also the smallest marine mammals that due to hunting have become endangered and exist in only a small fraction of their original historic range.
What is Sea Otter?
Sea Otter are medium-sized mammals that are members of the family Mustelidae. Sea otters are the largest of this weasel family and are the only members who do not partake in burrowing.
They have brown fur with shades of lighter tan and yellow on the adult heads. They possess small black eyes, small ear flaps, and long whiskers. One of its adaptations includes its nostrils that they can close during long dives and broad long webbed hind feet that make them efficient swimmers.
Their clawed short front paws equipped with pads help in gripping the slippery prey targets. They also have sharp pointed front teeth as other mammals that aid in tearing and slicing their food apart and their round flat molars help them grind and crush the food. These adaptations help these mammals to survive in marine habitats.
Sea Otter Distribution
They are ubiquitous along with the range from Alaska to Mexico. Their historic range extended even across North Pacific to Japan and Russia. They were endangered due to the increased demand for their fur in the 1740s, which nearly drove them to extinction.
They prefer the coastal waters, though some may be found offshore as well in this range. They dwell in sheltered regions that provide them protection from extreme ocean winds. They spend their whole life in water that makes them distinct from other weasel family members.
Sea Otter Diet and Predators
These carnivorous predators prey on sea urchins and are usually diurnal according to their foraging pattern. They normally forage in the early morning, late afternoon, and even around midnight. They rest during the middle of the day and night.
They forage on the seafloor by diving up to 100 ft depth. They also feed on crustaceans like crabs, mollusks, and sometimes even fish. They feed primarily on sea urchins in abundance till they stain their teeth purple.
Their predators include sea lions and orcas. Eagles may also prey on young otters. Pups are also vulnerable to predators like coyotes and bears. Though white sharks overlap some parts of their ranges there is no evidence that they prey on them.
Sea Otter Reproduction
They exhibit polygyny where the males have multiple partners. They breed throughout the year and the phenomenon of delayed implantation is also seen in them. This delay permits them to give birth in favorable conditions and can also be influenced by the presence of alternate males.
The females give birth to one pup at a time following a gestation period of 6 months. These pups till the age of 2 months, stick around their mothers and will often ride on their backs. The pups start to dive and catch their own food around 2 months.
Females will nurse them for another 3 more months. They attain sexual maturity at 3 to years and males often mature 1-2 years later or slower than females.
Sea Otter Conservation
They had a large range in historical times and were up to 300,000 in number. They were poached extensively in the colonial era generally for their pelt during 1741 to 1911 due to which their numbers dropped to over 1000 and their range was also significantly reduced. As a result of the protective conservation measures, their numbers inclined again to approximately two-thirds of their original range.
Fun Facts about Sea Otter!
They have charismatic personalities and appearance due to which they are gaining popularity. Their importance that was once limited to a pelt has since then emerged as an important keystone species.
i. Thick Fur
They have dense fur where up to 150,000 hair follicles are present per square centimeter that makes them the densest in all animal kingdoms. This may be one of the reasons why their fur was so valued in the colonial period.
The fur comprises waterproof long guard hairs that are spotted over their shorter underfur that keep the waterway from their skin. They only need their fur for keeping warm and no fat layer like other marine mammals are required.
ii. Regulators
They as a keystone and predator species check the population of organisms they feed on. In their absence, the sea urchins may overtake the kelp. This leads to wasting away from sea kelp forests that are significant as they provide habitat for various species and are also the nursery for commercially fished species. The presence of sea otters helps in avoidance of such situations and thus maintain the kelp forest.
iii. Tool Time
They are intelligent organisms that make powerful foragers. They can employ tools like rocks to dislodge their feed like mollusks from the substrate.
Sea Otter Citations
- Aquatic Adaptation and Depleted Diversity: A Deep Dive into the Genomes of the Sea Otter and Giant Otter. Mol Biol Evol . 2019 Dec 1;36(12):2631-2655.
- Wild sea otter mussel pounding leaves archaeological traces. Sci Rep . 2019 Mar 14;9(1):4417.
- Prolonged recovery of sea otters from the Exxon Valdez oil spill? A re-examination of the evidence. Mar Pollut Bull . 2013 Jun 15;71(1-2):7-19.
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Levator Scapulae: Definition, Anatomy, & Examples
Continue ReadingLevator Scapulae Definition
Levator Scapulae comprises a strap-like muscle also called lev scap that is found on the back of the neck on either side. A posterior view makes them difficult to observe as they are hidden by the trapezius muscles which are also present in the back.
These 2 muscles originate from the back of the neck and from either side they descend towards the upper back and shoulders. They primarily function to rotate shoulders and to elevate them. Any dysfunction or shoulder, neck, or back pain may be lead to tightness in these muscles.
What is Levator Scapulae?
Levator Scapulae muscles have their origin from posterior bony projections or tubercles of the cerebral vertebrates: C1, C2, C3, C4. This muscle is inserted towards the superior broad part of the medial border of the scapula or shoulder blade from the superior angle to the inner triangular cavity.
These are supplied by dorsal scapular nerves and the nerves of the cervical plexus (C3-C5). The former emerges from the root of C5 of the branchial plexus and innervates 3 muscles: rhomboid major, the levator scapulae, and the rhomboid minor.
Anatomic Variation in Levator Scapulae
The attachments in this muscle are variable in different individuals. Research has revealed the presence of other potential accessory attachment sites where it can also be inserted like the muscles of serratus posterior superior, muscles in the upper back, and the upper ribs and their associated muscles.
These variations in attachments may be the cause of inflammation and pain as they also impact the function of these muscles.
Levator Scapulae Function
The name of this muscle is derived from its function that is the movement of the scapula and the shoulders. The contraction of these muscles helps in elevating or raising the shoulders that can be usually seen when we shrug our shoulders. It also regulates the downward rotation of the shoulder wherein the scapula move downwards.
This movement can follow the elevation of the arms and brings the arms to arrest position as in simple exercises. So, to summarize the basic movement of arms is brought about by 2 rotations, the downward and the upward rotation.
Elevating arms require upward rotation while bringing them down requires downward rotation. If the shoulders are pushed towards each other from the posterior side, then they come together and results in a posture where the chest sticks outside.
This movement is referred to as adduction and is also a function of the levator scapulae. For these functions or movements, these muscles also require the aid of accessory muscles like the trapezius, pectoralis minor, and the major and minor rhomboids.
Levator Scapulae Associated Pain
Overworking of these muscles can result in inflammation and pain that is also a common issue that the majority of people face when they complain of skeletal muscle pain. Slumping over or frequent elevation of shoulders can result in tightness and inflammation.
This might be common in people who work in desk jobs often involving computer work. To avoid this the chairs and desk should be ergonomically designed. This is also vulnerable for people who have a head forward posture or in individuals who usually carry a heavy weight on one side of their shoulders and in people who engage in repetitive arm movement requiring sports or activities like shot putters, tennis players, and swimmers.
The resultant pain may be felt in the areas surrounding this muscle like the shoulders, neck, shoulder blades, and upper back or directly in the muscle itself.
This tightness or inflammation can cause dysfunctions in the movement of the shoulders and even in cervical structures and can even cause cervicogenic headaches. The cause of these pain issues can be tracked to the manipulated insertion points of this muscle.
The pain and chronic inflammation experienced in this muscle are known as levator scapulae syndrome, a historic term of this medical condition.
Levator Scapulae and Myofascial Pain Syndrome
This kind of pain is associated with the trigger or pressure points of the muscles. The overuse of any muscle or other associated muscles can result in the development of hypersensitive regions that are tight.
For example, strenuous exercises or training practices in sports activities may cause repetitive contractions of muscles. One of the common sites of these pressure points is the levator scapulae muscle.
The worsening of these pressure points leads to the development of myofascial pain syndrome. The pathology of this disorder is unclear and is suggested as a subtype of fibromyalgia.
Levator Scapulae Treatment
The symptoms can be treated and reduced by physiotherapy and massage that decreases the tightness, pain, and inflammation to an extent. Further, the overuse of muscles should be avoided by doing stretching exercises that help in the relaxation of muscles and prevent them from becoming taunt.
If the pain is not relieved by these steps then the patient may be advised to take local steroid injections into the pressure points.
Levator Scapulae Citations
- Anatomic variations of levator scapulae in a normal cohort: an MRI study. Surg Radiol Anat . 2017 Mar;39(3):337-343.
- Morphometric properties of the levator scapulae, rhomboid major, and rhomboid minor in human fetuses. Surg Radiol Anat . 2018 Apr;40(4):449-455.
- Low-grade myofibroblastic sarcoma of the levator scapulae muscle: a case report and literature review. BMC Musculoskelet Disord . 2020 Dec 10;21(1):836.
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Zygomatic Arch: Definition, Process, & Examples
Continue ReadingZygomatic Arch Definition
Zygomatic Arch also known as cheekbone, it refers to the parts from both temporal bone and zygomatic process that forms an arch. The zygomatic process is the extension of the temporal bone that attaches through a process to the zygomatic bone. This results in the formation of a tunnel by the 2 extensions through which tendon and muscles can pass.
What is Zygomatic Arch?
This feature is observed in all synapsids that have a hole in the temporal bone known as temporal fenestra. This hole was apparent and clearly distinct in ancestral mammal-like reptiles, while in modern mammals it molds with the eye orbit.
In humans and other primates, the eye sockets do not connect directly with the zygomatic arch. This arch helps in providing attachment points to several types of tissue of the skull. The hole permits the passage of the temporalis muscle and other associated tendons to pass under this arch and attach to the mandible bone of the skull.
The tendons of the temporalis muscle are linked to a small extension of the mandible known as the coronoid process that is tucked under the zygomatic bone. The masseter muscle which comprises a large muscle responsible for the movement of the jaw is attached directly to the large part of the mandible and the zygomatic arch.
This muscle is primarily involved in all jaw movements and the temporalis muscle aids in providing the extra tension required to mash, chew or grind food. The zygomatic arch and the linked structures help in providing attachment points for these muscles due to their large surface area.
"Zygomatic Arch also known as cheekbone"
Whenever we are chewing our food, we can feel the action of both these muscles. If fingers are laced between the eye and the ear and then during chewing the hard bone can be noticed.
The masseter muscle flexes on the bottom area while the temporal muscle flexes and produces a bulge above the zygomatic arch, during chewing of food. Chewing is a complex process that requires both these muscles.
This occurs only in mammals, whereas in other animals like lizards or birds, their size of the mouth is limited that also restricts the type and size of the food they can ingest. Sharks and other certain organisms have sharp teeth that they employ to cut the prey into huge chunks but even these are not chewed but rather swallowed.
In mammals, the presence of a zygomatic arch helps them to grind and chew their food. This not only enhances the rate of digestion but also expands their diet.
Zygomatic Arch Citations
- Using the zygomatic arch as a reference line for clinical applications and anthropological studies. Surg Radiol Anat . 2019 May;41(5):501-505.
- Zygomatic Arch Parosteal Osteosarcoma in Dogs and a Cat. Vet Pathol . 2019 Mar;56(2):274-276.
- Osteochondroma of the Zygomatic Arch: A Case Report and Review of the Literature. J Oral Maxillofac Surg . 2018 Sep;76(9):1912-1916.
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Miosis: Definition, Causes, & Examples
Continue ReadingMiosis Definition
Miosis implies constriction of the pupil and is also called myosis. This medical term pertains to the action of small eye muscles that helps in closing or constriction of pupils. This can be a response to the altering light intensity of the environment that requires reducing the amount of light entering the eyes.
Various recreational and medicinal drugs can also cause miosis. It can serve as a diagnostic symptom for impaired driving and can be a reason for the arrest. The term can be confused with terms for cell division like meiosis and mitosis.
Miosis Causes
Miosis results due to the local actions of contraction and relaxation of 2 muscles present in the iris of the eyes. Iris seen under the protective cornea represents the colored part of the eyes. The size of the pupil is regulated by the iris sphincter and iris dilator muscles that cause miosis are the relaxation and contraction of two muscles in the iris of the eye.
Pupils regulate the amount of light entering the eyes that will pass through the lens and will be focused on the retina. The retina contains specialized cells that help to detect light signals that are then sent as signals to optic nerve and then finally to the brain.
The photosensitive ganglions are the specialized cells in the eyes that sense the intensity of light received by the eyes. They signal the brain and the ANS through the optic nerve.
The ANS then based on the input received will continually automatically adjust the pupil size. If the light intensity entering the eyes and hitting the retina is high then miosis will happen, resulting in constriction of pupils.
During this process, the iris sphincter muscle will contract, and simultaneously the iris dilator muscles relax. This will cause constriction of pupils and to reduce the amount of light entering the eyes.
If pupils are constricting too much then again the ganglion will deduce then signal the brain leading to dilation of muscles and is called mydriasis.
Miosis Features
There can be various factors affecting and causing miosis. There is a complex pathway involved in this pathway that engages different regions of the brain and many neurons and chemicals. This pathway can be influenced or impaired by drugs like antipsychotic medications, nicotine, eye drops, and opioids.
Some of these chemicals may result in anisocoria, a condition where mydriasis occurs in one eye and miosis in the other. The alterations in light intensity caused by various recreational drugs can contribute to altered perception.
Diseases or nerve tissue degeneration may also cause miosis. Miosis can be observed in other animals besides humans, though the mechanism to regulate the quantity of light entering the eyes may differ.
Only 2 groups of animals have developed complex eyes, the cephalopods, and the vertebrates. The structure of eyes may differ as they rose from convergent evolution due to similar selection pressures.
Miosis Citations
- Posttraumatic headache with ptosis, miosis and chronic forehead hyperhidrosis. Headache . 1990 Jan;30(2):64-8.
- Ptosis and Miosis Associated with Fibrosing Mediastinitis. Am J Case Rep . 2021 Jan 12;22:e927556.
- Opioid-induced Miosis Is Unaltered by Obstructive Sleep Apnea: Comment. Anesthesiology . 2020 Feb;132(2):399-400.
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Lysogenic Cycle: Definition, Steps, & Examples
Continue ReadingLysogenic Cycle Definition
Lysogenic Cycle demonstrates a method utilized by viruses to replicate its genome using the host cell molecular machinery.
What is Lysogenic Cycle?
A virus can generally undergo 2 types of replication, the lytic cycle or the lysogenic cycle. In the case of the lysogenic cycle, replication is the main aim as the DNA is replicated but gene products are not expressed.
Whereas in the lytic cycle, the DNA replicates several times and proteins are translated utilizing the host’s machinery. The lysogenic can be usually observed in bacteria or prokaryotes and is also seen in eukaryotes.
A bacteriophage injects its genetic material into its host that is bacteria. The DNA may incorporate into the genetic material of the bacteria and whenever the bacterial cell would divide then the viral DNA would also be replicated using the same molecular machinery of the cell.
It does not alter the molecular processes rather it utilizes them. The quantity of viral DNA produced is less and the machinery is not hijacked as in the lytic cycle. Even though the viral DNA lays latent for some, it can employ the host cell to replicate its DNA through the lysogenic cycle without requiring any effort.
In favorable conditions, the viral DNA may be induced and then it moves to the lytic cycle. Then the viral DNA is transcribed and translated to produce protein coats that are needed to carry the genetic material of the virus.
When the bacteria becomes full of these virions, then they may lyse releasing these intracellular viruses that are ready to infect another host. The lysogenic cycle may continue if conditions are not suitable for the lytic cycle.
This dormant bacterial cell replicates the viral DNA and continues doing so till the lytic cycle is activated. This bacteria that is undergoing a lysogenic cycle may look healthy to an observer.
Lysogenic Cycle Steps
Step 1: The bacteriophage virus injects its DNA into the bacteria that would serve as its host into the cytoplasm, or intermembrane space between the cell wall. This viral DNA integrates into the host genome and is now known as prophage.
Step 2: The viral DNA replicates when the bacterial cell divides and does not have any additional proteins.
Step 3: The viral DNA may continue in the lysogenic cycle, or if conditions are favorable it may switch to the lytic cycle. In the lysogenic cycle, many copies of viral DNA occur in the bacterial cell as the viral DNA is replicated along with the bacterial DNA.
Step 4: When the viral DNA switches to lytic cycle, they employ the host’s machinery to produce the viral proteins required in their assembly and then the virus are packaged.
Step 5: These newly formed temperate viruses are released by the lysis of the cell and they are ready to infect other hosts. After infecting they can start the lysogenic cycle again. If the host condition is not great then they opt for the lytic cycle.
Lysogenic Cycle Citations
- Differential expression of cro, the lysogenic cycle repressor determinant of bacteriophage A2, in Lactobacillus casei and Escherichia coli. Virus Res . 2014 Apr;183:63-6.
- The lysogenic cycle of the filamentous phage Cflt from Xanthomonas campestris pv. citri. Virology . 1987 Feb;156(2):305-12.
- Lysogenic versus lytic cycle of phage multiplication. Cold Spring Harb Symp Quant Biol . 1953;18:65-70.
- Modulation of Lactobacillus casei bacteriophage A2 lytic/lysogenic cycles by binding of Gp25 to the early lytic mRNA. Mol Microbiol . 2016 Jan;99(2):328-37.
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Amino Acid Chart: Structure, Types, & Examples
Continue ReadingAmino Acid Chart
Amino acid, any of a group of organic molecules that consist of a basic amino group (―NH2), an acidic carboxyl group (―COOH), and an organic R group (or side chain) that is unique to each amino acid.
Amino acids play central roles both as building blocks of proteins and as intermediates in metabolism. The 20 amino acids that are found within proteins convey a vast array of chemical versatility. The precise amino acid content, and the sequence of those amino acids, of a specific protein, is determined by the sequence of the bases in the gene that encodes that protein.
Amino Acid Chart
Amino Acid Types
i. Essential Amino Acid
Amino acids are of 3 types: non-essential, essential, and conditional. Essential Amino Acid comprise 9 amino acids that form a group, these amino acids cannot be synthesized de novo inside the body so they are important to ingest in the diet.
Amino acids form the monomers that makeup protein polymers with the help of peptide bonds. Depending on the type and number of amino acids that make a protein they can vary in structure and function.
Histidine: This amino acid is essential during the development and growth of children, but it is not required in adults unless kidneys are impaired. It functions in growth, maintaining the nervous system, and forms the metabolite of histamine neurotransmitters.
One of its most significant functions is to regulate the concentration of heavy metals like molybdenum, copper, iron, manganese, and zinc and to metabolize them. If there are high level of trace metals in the system, but histidine amount is low then the depletion of histidine stores occur resulting in mineral-enzyme deficiencies.
Isoleucine: They are often taken as supplements to increase endurance in athletes. It together with valine and leucine comprise 70% of all proteins found in the human body.
They function in hemoglobin synthesis, tissue repair, and regulating energy levels and glucose levels. As they are relatively safe to consume in large quantities they are a popular ingredient of supplements in sports.
Leucine: Leucine is one of the important members of the BCAA essential amino acid group. They have a role in fat catabolism without any decline in muscle mass as a result, they are incorporated in weight loss supplements.
Weight loss can be increased by combining intake of leucine with vigorous exercise. Vegans usually have low leucine levels as it is found in dairy and meat products.
Lysine: These amino acids aids in calcium absorption and are important for nervous system function and to maintain healthy muscle movement. It is also involved carnitine and collagen synthesis. Legumes are rich source of lysine for vegans.
Deficiency of this amino acid causes dizziness, retarded growth, nausea, fatigue, and infertility. It can be administered to neurological patients to lower seizure events, but lysine-0restricted diets are needed for pyridoxine-dependent epilepsy.
Methionine: It is found abundantly in meat, whole-grain foods, and dairy products and hence not required as a supplement. If methionine metabolism is impaired then it affects fatty acids and lipid biosynthesis that can lead to atherosclerosis.
It contains elemental sulfur in its structure. The other amino acid that contains sulfur is cysteine. Sulfur is crucial in the formation of anti-oxidants.
They are taken in form of supplements suffering from liver ailments and people that suffer from dominance of hormone Low methionine supplements also improve cancer outcome and cell longevity according to researchers.
Phenylalanine: It is involved in the biosynthesis of adrenaline, tyrosine, and noradrenaline the latter increases memory and mental alertness, decreases appetite, and boosts mood.
Phenylketonuria refers to the disorder where phenylalanine hydrolase is lacking due to which the metabolism of phenylalanine is impaired and it accumulates in the body. This causes mental retardation is no intervention is done to treat this condition.
Threonine: This amino acid along with methionine and aspartic acid promotes the metabolism of fat in the liver that helps prevent steatosis. They are also important for maintaining the integrity of the nervous system.
They are often taken as supplements by people suffering from Lou Gehrig’s disease and multiple sclerosis. It is involved in the synthesis of elastin, glycine, collagen, serine, and muscle production. Research is focusing on employing this amino acid in colitis therapy.
Tryptophan: It is one of the common health store supplements and ingredients that boost mood and energy levels. It is the precursor of melatonin, serotonin, structural proteins, and enzymes so it has become a popular ingredient in the health industry to treat conditions like migraine.
The emergence of various research studies focusing on blood-brain barrier and gut synthesized serotonin, highlights the significance of this amino acid. It has clinical significance and is administered to reduce ADHD symptoms, alleviate anxiety, treat menopausal depression and restless leg syndrome.
Valine: This amino acid is a part of BCAAs besides isoleucine and leucine that exhibit a different structural form than the rest of amino acids and are often utilized in dietary supplements. It is abundantly found in green leafy vegetables and kidney beans.
This amino acid is involved in many physiological functions like it can enhance sleep quality and calm the nervous system in times of stress and improve cognitive processes.
This is also involved in the recovery of tissues, growth, and repair and is endorsed as a supplement by athletes for building endurance. They also form a component of weight loss supplements as they decrease appetite.
ii. Non-Essential Amino Acids
They comprise 12 amino acids that can be synthesized in the body itself, but certain people may take further provide themselves with their supplements or high protein diets.
These non-essential amino acids include arginine, aspartate, alanine, cysteine, serine, tyrosine, taurine, glycine, glutamate, proline, glutamine, and asparagine. The deficiency of these can be inborn and can form dysfunctional proteins.
For instance, if there is a low synthesis of glycine amidinotransferase and arginine it can cause muscular impairments and mental retardation.
Another example is the lack of glutathione synthetase that can lead to progressive neurologic disorders, oxidative stress, hemolytic anemia, and metabolic acidosis.
iii. Conditional Amino Acids
6 amino acids are conditional that are tyrosine, proline, glutamine, glycine, cysteine, and arginine. These amino acids are synthesized by the human body but under some circumstances their production is limited. Such conditions denote natural temporary physiological conditions like stress conditions or in babies born preterm cannot synthesize arginine.
Amino Acid Chart Citations
- A common periodic table of codons and amino acids. Biochem Biophys Res Commun . 2003 Jun 27;306(2):408-15.
- Amino acid kinetics and the response to nutrition in patients with cancer. Int J Radiat Biol . 2019 Apr;95(4):480-492.
- Amino Acid Transport Across the Mammalian Intestine. Compr Physiol . 2018 Dec 13;9(1):343-373.
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Solvent: Definition, Types, & Examples
Continue ReadingSolvent Definition
Solvent is defined as any molecule that can dissolve other molecules (solutes). Solvent molecules pull apart the solute molecules such that they are uniformly distributed in the solvent.
The solvent can be gas, liquid, or solid. The homogenous solution formed as a result of the dissolution of solutes cannot be physically separated but a chemical process ned to be employed for their separation.
Types of Solvent
There are 2 types of molecules non-polar or polar. Polar molecules are charged and carry different electrical charges on different sides, while nonpolar molecules do not have a static charge. Both these kinds do function as solvents.
i. Polar Solvent
The negative and positive ends of the atom interact both with each other as well as the solute in a polar solvent. Solute dissolves as the electric charges of solvent pull on different atoms of the solute.
For example, Salt an ionic compound is dissolved in polar solvent as the oppositely charged molecules are pulled apart. The positive ions of solute are pulled by the negative side of the polar solvent, while the positive ions are pulled by the positive side of the solvent. This leads to uniform distribution of solute in the solvent.
ii. Nonpolar Solvent
Their mechanism of dissolution is also similar to polar solvents. They often form spontaneous dipoles that have opposite charges linking bonds. This causes the adjacent solvent molecules to form dipoles.
These momentary interactions are responsible for the dissolution of nonpolar solutes. But when we compare polar and nonpolar solvents, the interaction in polar compounds is much stronger. It is also the reason why the polar and nonpolar solvents do not mix.
Solvent Examples
i. Water
It is the universal biological solvent that is very important. Cells of all living entities are dependent on water. The unique structure of water aids in its properties as a solvent.
Oxygen atoms in water being more electronegative pull the electrons towards them that renders them electrically negative. The hydrogen atoms of water only get a small share of shared electrons that gives them a positive charge. This results in making water a strong dipole molecule that can help in the dissolution of a wide variety of solutes.
The molecules and ions in the cell can be easily dissolved in water as it is a polar solvent. Some non-polar substances are also present in a cell that cluster together and shield themselves away from water.
The bilipid membrane is also formed as a result of this property of water. In the membrane, the phospholipids are present such that the hydrophilic head that projects outside while the non-polar tail is shielded from the aqueous environment in the bi-lipid membrane that comprises 2 leaflets.
When the phospholipid layers are brought together, the differential properties of the head and tail of phospholipid lead to the formation of a water barrier. Special proteins like carriers and channels are required for the passage of molecules inside and out of cells.
These solute molecules are to be transported along the concentration gradient with the aid of solvent. If the solvent gets saturated then no more solutes can be dissolved. The ocean can be considered a big solution of various chemicals and salts. When raindrops fall on the soil, they dissolve some solutes.
These are then carried through water and flow downstream into the river and then ultimately into the ocean. Many aquatic organisms rely on these solutes as they act as important salts or nutrients.
ii. Solvents in Everyday Cooking
Deglazing is a common procedure of cooking where the sticky bottom part of the pan is dissolved into a solvent. Both kinds of solvents can be employed to remove the caramelized part utilizing heat.
Oil, a non-polar substance is often used to fry a variety of food items as they create a hot solution. This can infusion of solutes in oil to the fried food. Water can also be employed for deglazing for creating soup, gravy, or other sauces.
Solvent Citations
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Glutamic Acid: Definition, Types, & Examples
Continue ReadingGlutamic Acid Definition
This non-essential amino acid has a molecular formula C5H9NO4. When the carboxyl group of this amino acid loses a proton under physiological conditions it gets a negative charge and now it forms glutamate amino acid.
Glutamate is found abundantly in the brain and it also acts as a neurotransmitter. Glutamic acid comprises the building block of many proteins.
What is Glutamic Acid?
Glutamic acid is represented by symbols Glu or E. Like with all amino acids it also has an amino-terminal end, side-chain, and carboxyl-terminal end. The side chain in the case of this amino acid has a carboxylic acid group. The GAA and GAG codons code for the polypeptide chain.
Glutamic acid like other amino acids except glycine has both L and D-form stereoisomers. L-form is normally seen in the case of the living organism. The D-stereoisomer form of glutamic acid in cells of the liver and in the cell wall of bacteria.
The blood-brain barrier cannot be crossed by glutamate amino acid as a result it needs to be synthesized in the brain itself from α-ketoglutarate or glutamine and it cannot be obtained by the diet.
Glutamic Acid vs Glutamate
Glutamate can be formed from glutamic acid when it loses a proton. Glutamic acid has the formula CH2CH2COOH, while glutamate has the formula CH2CH2COOH. Glutamate is basically the anion of glutamic acid.
This aliphatic amino acid has a pKa value of 4.1so in an environment of pH more than 4.1, it will exist in the polar negatively charged form. Hence, glutamic acid is mostly observed as glutamate in physiological conditions in the human body.
Glutamic Acid vs Glutamine
Both these amino acids are often confused as they have similar names. Glutamic acid has an amine group instead of a carboxy group as in Glutamine that is represented as Gln or Q.
Food that is high in glutamic acid like yeast, shellfish, and soy sauce give an umami flavoring that has a pleasant savory taste. Glutamate is often employed as a flavor enhancer in form of MSG.
Glutamic Acid Function
Glutamic acid comprises various proteins and it or specifically glutamate also functions as a primary excitatory neurotransmitter in the CNS. As a result, it is highly abundant in nervous tissue and in the brain.
Neurotransmitters are signaling molecules or chemicals in the nervous tissue. Acetylcholine, dopamine, and adrenaline are all examples of neurotransmitters. Glutamate receptors are located on the plasma membrane of astrocytes and neurons.
These include kainite, AMPA, metabotropic receptors, and NMDA. Glutamate bind to the receptors to excite them as it is an excitatory neurotransmitter that will increase the likelihood of an action potential or nerve impulses that function in signaling.
Glutamate like other neurotransmitters is stored as vesicles at chemical synapses. Glutamate is released via exocytosis when a nerve impulse travels to the synapse. This released neurotransmitter will bind glutamate receptors in the adjacent cell.
Out of the 4 glutamate receptors AMPA, kainite, and NMDA are ionotropic that on activation lead to the opening of ion channels. In the case of metabotropic receptors, a second messenger is involved that functions in signaling.
Glutamate as a neurotransmitter is involved in synaptic plasticity that is important for the memory and learning process.
This enzyme aids in the conversion of glutamate to gamma-aminobutyric acid (GABA). GABA is an inhibitory neurotransmitter that forms from glutamate and binds to GABA receptors.
This binding is inhibitory and decreases the likelihood of the formation of the action potential. This binding can have a sedative effect, for instance, alcohol and drugs like benzodiazepines activate GABA receptors.
Clinical Relevance of Glutamic Acid
Impaired glutamate signaling can result in dysfunctions and resulting disorders in the brain.
Neurodegenerative Disease: Several neurodegenerative disorders can be traced to the chronic excitation by glutamate in neurons. For example, Alzheimer’s and Huntington’s disease, and other motor neuron disorders. The mechanism behind this is glutamate excitotoxicity that can impair nerve cells and even kill them.
Psychiatric Disorders: In the case of psychiatric disorders like bipolar disorder and schizophrenia excessive glutamate activity has been observed. Pharmacological drugs like ketamine that specifically target the glutamate system are being considered for treatment in these cases.
Substance Abuse: It also takes part in reward pathways and is thus involved in addiction development and maintenance. Cognitive processes like sensitization, habit learning, reinforcement, craving and conditioning, relapse, and craving.
Glutamic Acid Citations
- Gamma-fluorinated analogues of glutamic acid and glutamine. Amino Acids . 2003 Apr;24(3):245-61.
- Glutamic acid, twenty years later. J Nutr . 2000 Apr;130(4S Suppl):901S-9S.
- Microbial production of poly-γ-glutamic acid. World J Microbiol Biotechnol . 2017 Sep 5;33(9):173.
- Images are created with BioRender.com
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Protostome: Definition, Types, & Examples
Continue ReadingProtostome Definition
These organisms form a clade that exhibits protostomy during early development. They along with Xenacoelomorpha and Deuterostomes comprise the group Bilateria. The organisms constituting this group are bilaterally symmetrical and triploblastic.
What is Protostome?
In embryo development, two gametes—sperm and an egg—fuse to form a zygote. After a zygote forms by syngamy of the 2 gametes, it is divided into 2 poles by an axis. The bottom pole forms the vegetal pole, while the to pole forms the animal pole.
The zygote divides repeatedly by cleavage to form a mass of blastomere cells called a morula. The pattern of cleavage is what distinguishes protostome and deuterostome.
Protostomes exhibit spiral cleavage wherein the cleavage occurs long angle resulting in spirally arranged blastomeres. The arrangement of cells changes such that blastoderm, a layer of cells envelope blastocoel that is a yolk or fluid-filled cavity and this forms a blastula.
Gastrulation starts at this stage leading to the formation of 3 germ layers. These 3 germ embryonic cells in a triploblastic organism give rise to all the organs and tissues. The development of blastopore starts the process of gastrulation.
The blastopore cells start migrating inwards to create an inner tube that will later develop into an endoderm that gives rise to the GI tract and digestive system. The outer layer ectoderm forms the nervous system and the epidermis.
The layer between these 2 layers is known as mesoderm and it gives rise to muscles and connective tissue. Another significant distinguishing feature that sets apart protosomes from deuterostomes is the purpose of the blastopore. In the case of protosomes, the blastopore will develop into the mouth while in deuterostome it develops into the anus.
In protostome the cavity opposite to the blastopore develops into the anus. The name Protostome is derived from the Greek words proto and stoma that means that the mouth develops first.
Types of Protostomes
Two taxonomic groups come under Protostomes:
Lophotrocozoa: This group includes organisms that grow by extending the skeleton size as in mollusks that add calcium carbonate to the edge of their shells to grow larger.
Brachiopods, mollusks, annelid worms, rotifers, bryozoa, and Platyhelminthes comprise this group. Examples of this group include squid, leeches, earthworms, and bivalve mollusks.
Ecdysozoa: This group comprises the nematodes, arthropods, and tardigrades. They possess a 3-layered cuticle, that has a soft interior and an exoskeleton which is the hard exterior.
They periodically shed and re-grow their exoskeleton to grow via the process of ecdysis. They unlike other protostomes do not undergo spiral cleavage during embryonic development. Examples of ecdysozoans include crustaceans, insects, roundworms, spiders, etc.
Protostome Body Plans
These triploblastic and bilaterally symmetric organisms can have 3 different body plans:
i. Worm-like: These types of protostomes are characterized by a cavity inside their body that is well developed and is known as coelom that helps in the circulation of body fluids and functions like a hydrostatic skeleton that employs fluid pressure for movements.
Based on their feeding system they can be further classified:
a. Spoon worms or Echiura utilize a structure known as proboscis to acquire and move food. They are present in front of the mouth region and trap food and then using cilia move it to the mouth region.
b. Penis worms or Pripulida are characterized by the presence of a toothed throat that can be extended inside out to capture the prey and once the prey is captured they retract its back for consumption.
c. Ribbon worms or Nemertea employ proboscis that is present inside the body above the gut. The proboscis has a barbed tip and it is extended to capture prey by entangling it or by using venom.
ii. Arthropod Body Plans: Arthropods have segmented bodies that have 3 parts that include head, thorax, and abdomen. They comprise crustaceans, all insects, myriapods, and arachnids. They also have jointed appendages and are the most abundant taxonomic group.
They are named after the presence of jointed limbs and have a chitinous exoskeleton that also contains sclerotin proteins that harden them. The muscles are attached directly to the exoskeleton for movement. The coelom is reduced and is involved in providing space for organs and the circulation of fluids.
iii. Mollusk Body Plan: These marine groups comprises Chitons, Bivalves, Gastropods, and Cephalopods. Their body plan has 3 major parts:
a. The foot: this is responsible for movement and is constitutes a large muscle at the base of the animal.
b. The visceral mass: it contains external gills and internal organs. Thye help foot in movement.
c. The mantle: forms the layer that envelops visceral mass and secretes calcium carbonate to form shells.Â
Protostome Citations
- Evolutionary convergence of higher brain centers spanning the protostome-deuterostome boundary. Brain Behav Evol . 2008;72(2):106-22.
- Body-plan evolution in the Bilateria: early antero-posterior patterning and the deuterostome-protostome dichotomy. Curr Opin Genet Dev . 2000 Aug;10(4):434-42.
- Calcium signaling and endoplasmic reticulum dynamics during fertilization in marine protostome worms belonging to the phylum Nemertea. Biochem Biophys Res Commun . 2014 Aug 1;450(3):1182-7.
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