The researchers will use mice instead of opossums or humans to determine whether the cells of the ear bones originated from the same embryonic cells as the cells that form the jaw in other vertebrates because in this type of experiment, organisms that are ideal are the ones that have a short life span, easy to be researched on and easy to mantain.
It will be very tedious and demanding to use opossums and humans in this type of practical experiment because,it is against the culture and norms guilding human living and existence to use humans as model organisms,opossums as well are very bad model organisms because unlike the mice,opossums are long lived and it will be very difficult to raise and maintain an opossum in a laboratory.
Humans and mice are both mammals just that human is a higher mammal but they share similar features in terms of pattern of development,though there is a clear difference during their early development,so because of the common ancestry shared by the mice and humans,the result of the experiment on the mice with share a close similarity with the pattern that is expected in humans.
Answer:
Punnett square is a square diagram which is used to predict the genotype of the offspring produced by particular cross.
Let P and p be the alleles of the gene responsible for the flower colors in a plant.
The genotype of both the parents is given as heterozygous that is, Pp.
Two types of gametes would be formed P and p.
The cross is shown in the image below.
The cross would be result in offspring with three types of genotypes PP, Pp and pp in 1:2:1.
<h2>GPCRs and RTKs</h2>
Explanation:
1) Phosphorylation of receptor can terminate signal or desensitize receptor: GPCRs because when signal persists a protein kinase receptor is activated,this further catalyse the phosphorylation of several serine residue at cytosolic phase of 7 transmembrane
Phosphorylated transmembrane recognized by arrestin protein blocks interaction between trimeric G protein and receptor thus blocks signal transduction
2) Autophosphorylation of receptor can initiate signal: RTKs because receptor dimerization activates intrinsic tyrosine kinase activity by which they phosphorylate its own tyrosine residue on cytosolic phase
3) Structure contains seven transmembrane helices: GPCRs because it consists of single polypeptide and spans the membrane 7 times hence called 7 transmembrane;it recognizes external signal and activates trimeric G protein
4) Ligand binding induces conformational change in receptor: RTKs because normally RTK exist in monomeric form in absence of any ligand molecule but when any ligand molecule binds receptor starts to dimerize
5) Receptor activation causes phosphorylation of its cytosolic subunits: RTKs because when receptor gets activates the intrinsic tyrosine kinase activity by which they phosphorylate its cytosolic subunits
6) An example is the insulin receptor: Insulin receptor is present on plasma membrane and belongs to RTK family and always exist in dimeric form
7) Transports some ligands through the membrane: Neither GPCR nor RTK;ligand gets transported through the membrane through ligand gated channel
8) An example is the epinephrine receptor: Epinephrine is an endocrine hormone produced by adrenal glands in stress condition and prepare body for fight and flight;Epinephrine uses GPCR signalling pathway by four different types of membrane receptors in different tissues
9) Activate heterotrimeric G proteins directly: Transmembrane protein of GPCR recognizes the external signal and activates G protein,activated G protein binds with effector enzyme and activate it which further produce or destroy secondary messenger that carry message from cell surface to cell interior
