What is Splanchnocranium?
1. Area of skull including sensory capsules
2. Are of skull including jaws derived from mandibular arch
3. Area of skull derived from hyoid arch
4. Area of skull including brain box and jaws
a) enriching of local flora and fauna with species from other geographical territories;
b) domestic (domesticised) animal;
c) organisms transferred by man from original territories;
d) animals and plants living in close relationship with man.
Mainak Majumder Jun 6th, 2018
d. animals and plants living in close relationship with man
"Synanthrope" is generally an undomesticated organism and especially an animal (such as a mouse, pigeon, or raccoon) that lives in close association with people and benefits from their surroundings and activities
Which of the following contributes nitrogen atoms to both Purine and Pyrimidine?
b. Carbamoyl Phosphate
Nucleotide biosynthesis in the cell can be grouped into two broad classes:
(1) de-novo synthesis and
(2) synthesis by salvage pathways.
I. De-novo synthesis (synthesis from scratch): it is a biochemical pathway in which nucleotides are synthesized new from simple precursor molecules.
II. Salvage pathway (recycle pathway): used to recover bases and nucleosides formed during the degradation of RNA and DNA
De-novo synthesis of purines:
The purine nucleotides of nucleic acids are adenosine 5-monophosphate (AMP; adenylate) and guanosine 5-monophosphate (GMP; guanylate), containing the purine bases adenine and guanine respectively. The first idea about purine nucleotide biosynthesis in the cell was come from the study of John Buchanan (1948) by radioactive tracer studies in birds by analyzing the biochemistry of uric acid (a purine present in the excreta of birds). The detailed biosynthetic pathways of the purine biosynthesis came latter in 1950 primarily by the works of Buchanan and G. Robert Greenberg.
Lipotropic factors are components that describe the action of Choline in the prevention and treatment of fatty livers. Lipotropic factors are produced naturally in the body. They are substances that have the ability to remove and prevent fatty deposits, such as Homocysteine, in the body.
The precursor to melatonin is serotonin, a neurotransmitter that itself is derived from the amino acid tryptophan. Within the pineal gland, serotonin is acetylated and then methylated to yield melatonin.
Serotonin and melatonin are both hormones that regulate various human functions such as sleep, appetite and mood. Serotonin, which is produced in the body, is known as a neurotransmitter; this means it is responsible for sending messages between nerve cells. Melatonin is a neurotransmitterlike substance that plays a vital role in regulating circadian rhythms, which in turn control sleeping patterns, hormone release and body temperature, among many other human functions.
Key Diferences between Melatonin and serotonin:
While serotonin has many important functions in the body, it may be most known for its role as a “feel good” hormone. Increased levels of serotonin are associated with feelings of happiness and relaxation. Low serotonin levels, on the other hand, are linked to weakened immune function and depression. Melatonin is most noted for its role as a sleep hormone. It is produced in the pineal gland in the brain when it's dark outside -- thus its nickname, “the hormone of darkness.” Deficiencies in this hormone can cause sleeplessness, among many other side-effects.
Melatonin is used as a treatment for insomnia, delayed sleep phase syndrome (DSPS), jet lag and insomnia associated with attention deficit-hyperactivity disorder (ADHD). It is also used for other conditions, including chronic fatigue, depression, irritable bowel syndrome and anti-aging, though there is no scientific evidence supporting these uses. Serotonin-affecting compounds are primarily used as treatments for depression. Prescription drugs known as selective serotonin re-uptake inhibitors (SSRIs) stop serotonin from being reabsorbed, which elevates serum serotonin levels and can improve depression symptoms. Too much serotonin can also cause problems. Serotonin syndrome is a life-threatening condition that can occur when more than one drug that affects serotonin levels is ingested.
The term neoteny is derived from Latin neotenia; neo + Greek teinein = to extend, meaning when larval life is extended. Neoteny also called juvenilization, is the retention, by adults in a species, of traits previously seen only in juveniles. Neoteny has two forms depending upon capability of individuals to breed.
Pedomorphosis was first proposed by WalterGarstang in 1922. The underlying mechanisms for this include heterochrony (change in features during development). Pedomorphosis is common in many animal species domesticated by humans, including dogs, chickens, pigs and cattle. It is believed to be a side-effect of the selective pressure of human-directed breeding for juvenile behavioral characteristics such as docility and cuteness. Pedomorphosis also occurs in termites and several species of cockroach. Humans are considered by some scientists to be pedomorphic, due to their flattened face, short jaw, and bulbous forehead compared to other adult primates.
Paedogenesis is the act of reproduction by an organism that has not achieved physical maturity. In other words paedogenesis is the production of offspring by an organism in its larval or juvenile form and elimination of the adult phase of the life cycle. It is associated with progenesis, where sexual maturity is achieved in the juvenile form and further physical maturity is not achieved. Paedogenesis is found in insects in which the larval stage reproduces without achieving maturity. It occurs in the females of certain beetles, Strepsiptera, bagworms, scale insects and gall midges.
EXAMPLES OF NEOTENY
Flightless birds such as ostriches, emus, cassowaries and kiwis are believed to have evolved by retaining characteers of chicks and losing ability to fly. Physical proportions of these birds resemble those of the chicks of flighted birds.
With human traits such as sparse body hairs and enlarged heads are thought to be reminiscent of baby primates. Lactose tolerance in adults is a form of neoteny now considered normal in certain populations that traditionally consume milk while most other humans are lactose intolerant as adults. Although females mature at an earlier age, women do not go on to acquire the toughened skin, coarse body hair, thyroid cartilage, bony eye ridges, or deepened voices which are the common inheritance of most adult hominoids and other primates. Paedomorphic characteristics in women are widely acknowledged as desirable by men. For instance, vellus hair is a juvenile characteristic. However, while men develop longer, coarser, thicker, and darker terminal hair through sexual differentiation, women do not, leaving their vellus hair visible.
Stephen Jay Gould was an advocate of the view that humans are a neotenous species of chimpanzee. The argument is that juvenile chimpanzees have an almost-identical bone structure to humans, and that the chimpanzee’s ability to learn seems to be cut off upon reaching maturity.
Another theory suggests that humans’ neotenous characteristics were an evolutionary strategy that enabled Cro-Magnons to gain predominance over neanderthals (and possibly H. erectus and H. heidelbergensis) by appealing to these species’ nurturing instincts through paedomorphic cuteness and to avoid territorial aggression.
Bolk (1926) provided an abbreviated list of human neotenic characters:
Our “flat faced” orthognathy.
Reduction or lack of body hair.
Loss of pigmentation in skin, eyes, and hair.
The form of the external ear.
The central position of the foramen magnum (it migrates backward during the ontogeny of primates).
High relative brain weight.
Persistence of the cranial sutures to an advanced age.
The labia majora of women.
The structure of the hand and foot.
The form of the pelvis.
The ventrally directed position of the sexual canal in women.
Small teeth and variations of the tooth row and cranial sutures. Late eruption of teeth.
Absence of eye brow ridges.
Absence of cranial crests.
Thinness of skull bones.
Position of orbits under cranial cavity.
No rotation of the big toe.
Prolonged period of infantile dependency and prolonged period of growth.
Long life span.
Crying is among the child-like behaviors. Certainly human facial anatomy and physiology are intricately engineered for both the discharge of tears and the facial and vocal expressions that accompany them to draw attention and sympathy.