What Happens During the G1 Phase and How Does Genotype Affect It?

  • Thread starter Thread starter jenc305
  • Start date Start date
  • Tags Tags
    Phase
Click For Summary
SUMMARY

The G1 phase of the cell cycle involves eukaryotic chromosomes that consist of one long linear DNA molecule and many genes organized linearly, confirming option d as correct. In the context of genetic inheritance, when crossing individuals with genotypes XXYY and xxyy, the F1 generation produces XxYy offspring. Given that no recombination occurs between genes X and Y, the expected phenotype ratio in the F2 generation is 9/16 for the XY phenotype, confirming option e as the correct answer for the second question.

PREREQUISITES
  • Understanding of the cell cycle phases, particularly G1 phase
  • Knowledge of eukaryotic chromosome structure
  • Familiarity with basic Mendelian genetics and phenotype ratios
  • Concept of genetic linkage and recombination
NEXT STEPS
  • Study the details of the G1 phase in the eukaryotic cell cycle
  • Explore the structure and function of eukaryotic chromosomes
  • Learn about Mendelian genetics, focusing on dihybrid crosses
  • Investigate genetic linkage and the implications of recombination frequency
USEFUL FOR

Students of biology, genetics researchers, educators teaching cell biology and genetics, and anyone interested in understanding the implications of genotype on phenotype during the cell cycle.

jenc305
Messages
16
Reaction score
0
G1 Phase and Genotype

I need help with two questions. I am unable to find the first answer from my book. I have an idea of what the answer is but I'm not positive.
Thank you.

At the G1 phase of the cell cycle, a eukaryotic chromosome consists of

a)one long linear DNA molecule stretching the length of the chromosomes
b)two linear DNA molecules joined together end to end at the centromere
c)many genes adjacent to each other in a linear organization
d)both a and c are correct
e)both b and c are correct

I think it's d.

I've got another questions I'm stuck on.

Two genes, X and Y, are located on the same chromosome. X is dominant over x and Y is dominant over y. These two genes are located so close together that, within the limits of this experiment, no recombination is seen between them. An individual whose genotype is XXYY is crossed to an individual whose genotype is xxyy. The F1 generation progeny is crossed to produce an F2 generation. Among the F2 generation what fraction of individuals would be expected to have the phenotype XY?
a)0
b)3/16
c)1/4
d)1/2
e)9/16

My guess would be e. F1 generation would create a progeny of XxYy. So if crossed with another individual with genotype XxYy then they would create a F2 progeny of 9:3:3:1 ratio.
 
Last edited:
Biology news on Phys.org
I think I figured out question 2. Since the question states that there is no recombination than the F1 progeny would have to come out 1/2 XXYY and the other 1/2 xxyy. Same goes for the F2 generation. So the answer must be d, right?
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 6 ·
Replies
6
Views
5K
  • · Replies 25 ·
Replies
25
Views
8K
  • · Replies 1 ·
Replies
1
Views
4K
  • · Replies 6 ·
Replies
6
Views
15K
Replies
2
Views
4K
  • · Replies 4 ·
Replies
4
Views
8K
  • · Replies 3 ·
Replies
3
Views
4K