Question

a. a cell (whose diploid number is 24), is in the g1 phase.
a. how many chromosomes does it have?
b. how many chromatids does it have?
c. what phase of the cell cycle is the cell in?
b. the cell enters the s phase.
a. how many chromosomes does it have?
b. how many chromatids does it have?
c. what phase of the cell cycle is the cell in?
c. the cell enters the first phase of meiosis i.
a. how many chromosomes does it have?
b. how many chromatids does it have?
c. what phase of the cell cycle is the cell in?
d. the cell enters the second phase of meiosis i.
a. how many chromosomes does it have?
b. how many chromatids does it have?
c. what phase of the cell cycle is the cell in?
e. the cell enters the third phase of meiosis i.
a. how many chromosomes does it have?
b. how many chromatids does it have?
c. what phase of the cell cycle is the cell in?
f. the cell enters the final phase of meiosis i.
a. how many chromosomes does it have?
b. how many chromatids does it have?
c. what phase of the cell cycle is the cell in?
g. the cells enter the first phase of meiosis ii.
a. how many chromosomes does it have?
b. how many chromatids does it have?
c. what phase of the cell cycle is the cell in?
h. the cells enter the second phase of meiosis ii.
a. how many chromosomes does it have?
b. how many chromatids does it have?
c. what phase of the cell cycle is the cell in?
i. the cells enter the third phase of meiosis ii.
a. how many chromosomes does it have?
b. how many chromatids does it have?
c. what phase of the cell cycle is the cell in?
j. the cells enter the final phase of meiosis ii.
a. how many chromosomes does it have?
b. how many chromatids does it have?
c. what phase of the cell cycle is the cell in?
k. write the number of chromosomes and chromatids in each cell below.
answer the following questions using the diagram here.
what term is given the structures located at letter a?
what process is occurring at the structures at letter b?
what is significant about the outcome of the structures at letter c?

Explanation:

Step1: Recall cell - cycle and meiosis basics

In G1 phase, a diploid cell has its normal chromosome number. Given diploid number \(2n = 24\), so chromosome number \(= 24\) and chromatid number \(= 24\) (since DNA has not replicated yet).

Step2: S - phase characteristics

In S - phase, DNA replication occurs. Chromosome number remains the same (\(24\)) but each chromosome now has 2 chromatids, so chromatid number \(= 48\).

Step3: Meiosis I characteristics

In meiosis I, the cell starts as diploid. In the first few phases of meiosis I (prophase I - metaphase I), chromosome number \(= 24\) and chromatid number \(= 48\). In anaphase I, homologous chromosomes separate, reducing the chromosome number per cell to 12 in the final phase of meiosis I, but chromatid number remains 24 (as sister chromatids are still attached).

Step4: Meiosis II characteristics

In meiosis II, starting from prophase II, the chromosome number per cell is 12. In prophase II - metaphase II, chromatid number is 24. In anaphase II, sister chromatids separate, reducing chromatid number to 12 in the final phase of meiosis II.

Answer:

A.
a. 24
b. 24
c. G1
B.
a. 24
b. 48
c. S
C.
a. 24
b. 48
c. Prophase I of meiosis I
D.
a. 24
b. 48
c. Metaphase I of meiosis I
E.
a. 12
b. 24
c. Anaphase I of meiosis I
F.
a. 12
b. 24
c. Telophase I of meiosis I
G.
a. 12
b. 24
c. Prophase II of meiosis II
H.
a. 12
b. 24
c. Metaphase II of meiosis II
I.
a. 12
b. 12
c. Anaphase II of meiosis II
J.
a. 12
b. 12
c. Telophase II of meiosis II
For the bottom - part:
What term is given the structures located at letter A? Homologous chromosomes
What process is occurring at the structures at letter B? Crossing - over
What is significant about the outcome of the structures at letter C? Genetic variation