Explanation:
For a strand of DNA to form, nucleotides must be linked into chains, with the sugar phosphate groups alternating. DNA is made of the building block chemical called nucleotides. Nucleotides are made up of three main parts, a sugar group, a phosphate group, and some type of nitrogen base. Hope this answers, and is helpful! Have a great day! :))
A is the answer according to my notes
Answer:
b. skin from mouse 2
Explanation:
According to this question, a mice skin transplant is being conducted. Four mice labelled Mouse 1, Mouse 2, Mouse 3 and Mouse 4 are used for this experiment. A small patch of skin from mouse 2 (the donor) was transplanted onto mouse 1 (the recipient), however, it was eventually rejected by the recipient (mouse 1).
This transplant rejection is due to the fact that the recipient's immune system identifies the tansplanted skin as foreign, hence, begins to attack it, leading to the skin's necrosis or death. Based on this, the same transplant rejection will occur if skin patches from mouse 3 and 4 are used.
However, the immune system of mouse 1, which is the recipient, will identify skin patches from MOUSE 2 as less foreign than any other skin from other mice. This is because skin from that mouse has been used before, hence, the recipient's immune recognizes it when a follow-up transplant is conducted. This makes a follow-up transplant from MOUSE 2 be the least likely to be rejected.
when changes in a protein appear to accumulate at a constant rate over time is called option (c) i.e, Molecular clock.
<h3>What does molecular clock mean?</h3>
The term "molecular clock" refers to a method that estimates the time in prehistory when two or more life forms diverged by analyzing the mutation rate of biomolecules. Typically, nucleotide sequences for DNA, RNA, or amino acid sequences for proteins serve as the biomolecular data for these calculations.
Hedges, a biology professor at Penn State, claims that the molecular clock counts the mutations that accumulate through time in the gene sequences of various species rather than counting seconds, minutes, and hours.
Mutation and recombination, the two fundamental biological processes that give rise to all heritable variations, are the foundation of molecular clocks. Mutations are modifications to the genetic code of DNA, for as when the nucleotide Guanine (G) turns to Thymine (T).
To know more about molecular clocks refer to: brainly.com/question/8597562
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Answer:
A cell that has duplicated chromosome cannot be in<u> G1 phase.</u>
Explanation:
- G1, G2 and S phase are the divisions of the interphase i.e. the resting phase of the cell cycle.
- A cell cycle has two phases; interphase and M-phase.
- During interphase the cell grows and in M-phase it divides.
- G1 is the Gap between the M-phase and the S-phase.
- G2 is the gap between the S phase and M phase.
- DNA replication is confined to the S part of interphase.
- Since G1 phase comes before the S phase , we can say that a cell that has duplicated chromosome cannot be in G1 phase.
