Dark fur color appears to be an adaptation for mice living in dark environments, as both the frequency of the characteristic and the allele that generates it have altered. These findings further back with the theory that selection is context-dependent, as dark mice were preferred in some contexts but not in others.
<h3>
What is mutation?</h3>
A mutation is defined as a change in the sequence of genetic letters, called bases, within a molecule of DNA.
In a population, more offspring are born than can survive, resulting in competition among people. Individuals that possess a certain trait are more likely to live and/or produce more offspring than those who do not possess that trait. The context in which a species exists influences its selection. Characteristics that are advantageous in one setting may be detrimental in another.
New mutations cause black color.
- Fur color is controlled by many genes (4:29).
- Most genes are identical, but dark and light rock
- pocket mice differ in one gene (Mc1r; 4:55).
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I have provided the options below:
a. 150
b. 225
c. 300
d. 450
e. 75
Answer:
150
Explanation:
Hardy-Weinberg law states, the allelic frequencies of a gene that is, q and p follow the relationship p^2+q^2+2pq = 1, if the population is in equilibrium.
Therefore p^2+q^2+2pq = 1, can be used to calculate the percentage of the allelic frequencies i.e. p^2 and q^2
Allelic frequency = 0.75.
Therefore, the percentage of the allele in the population would be given by
0.75^2 = 0.5625 = 56%.
And the total number of individuals with this allele in the population:
number of individuals = 56×300÷100
= 168 or
150 nearest figure.
Answer: zap70, ITAM.
Explanation:
An antigen is any substance that is capable of stimulating an immune response by activating lymphocytes, which are the body’s infection-fighting white blood cells. Examples of antigens could be proteins that are part of bacteria or viruses or components of serum and red blood cells from other individuals, all of them are foreign antigens originated outside the body. However, there can also be autoantigens (which are self-antigens), originated within the body. In normal conditions, the body is able to distinguish self from nonself. <u>And the antigens that represent a danger induces an immune response by stimulating the lymphocytes to produce antibody or to attack the antigen directly</u>. This is called an antigenic stimulation of the immune system.
ZAP-70 (Zeta-chain-associated protein kinase 70) is a protein that is part of the T cell receptor, thereby it plays a critical role in T-cell signaling. When the TCR (receptor of T cells) is activated by the presentation of the specific antigen through the MHC, a protein called Lck acts to phosphorylate the intracellular CD3 chains and the ζ chains of the TCR complex, allowing the binding of the cytoplasmic tyrosine kinase, ZAP-70. Lck then phosphorylates and activates ZAP-70, which in turn phosphorylates another molecule in the signaling cascade called LAT (short for Linker of Activated T cells), a transmembrane protein that serves as an anchor site for several other proteins. The tyrosine phosphorylation cascade initiated by the Lck culminates in the intracellular mobilization of calcium ion (Ca2+) <u>and the activation of important signaling cascades within the lymphocytes.</u> These include the Ras-MEK-ERK pathway, which is based on activating certain transcription factors such as NFAT, NFκB and AP-1. These transcription factors regulate the production of of certain gene products, most notably cytokines such as interleukin-2 that promote the long-term proliferation and differentiation of activated lymphocytes.
The ITAM motifs (immunoreceptor tyrosine-based activation motif) are sequences of four amino acids present in the intracellular tails of certain proteins that serve as receptors within the immune system. Thus, <u>some receptors such as the TCR have ITAM sequences that, when activated, trigger an intracellular reaction based on consecutive phosphorylations</u>. Kinases are recruited for this purpose.
So, ZAP-70 is a protein tyrosine kinase with a role in T-cell receptor signal transduction. During T-cell activation, ZAP-70 binds to ITAM and becomes tyrosine phosphorylated. The binding of ZAP-70 to the phosphorylated ITAM is able to activate its kinase activity, <u>and relieves the inhibition of the transcription factor which regulates genes that are involved in the immune reaction</u>.
Answer The species is known from three individuals, all of which were found in the Habib Rahi Rock Formation of Pakistan
Maiacetus is significant because of how well the skeletons were preserved. Over 90% of the bones from the male were found intact, which is almost unheard of for a specimen this old!
Their skeletons have all been found among fossils of sea-creatures which suggests they lived in the sea.
The fore-snout is starting to elongate. An elongated fore-snout is found in all modern whales and all transitional whales after Maiacetus.
<span>In the right atrium, the auricle and anterior wall exhibit obvious muscular ridges called MUSCULI PECTINATI.
Musculi pectinati or pectinate muscles are identified as specialized intracardiac muscle. The muscular ridges are like combs. These ridges help the right atrium dilate without much walls stress during adverse loading conditions.</span>