Ask Question, Ask an Expert

+1-415-315-9853

info@mywordsolution.com

Ask Biology Expert

"Consider a pair of homologous chromosomes heterozygous for three genes (e.g., ABC/abc) during prophase I of meiosis. Let the sister chromatids of one homolog be numbered 1 and 2 (ABC); and the sister chromatids of the other homolog be numbered 3 and 4 (abc).

"Assume a double crossover occurs in this pair of chromosomes that results in chromatids of the genotype Abc, ABC, aBc and abC. If the first crossover (the one between A and B) involves chromatids 1 & 4, which chromatids could be involved in the second crossover?"

A. 1 & 2
B. 1 & 3
C. 1 & 4
D. 1 & 3 or 1 & 4 or 2 & 3 or 2 & 4
E. any two of the four chromatids

I'm a little confused about how to set up this problem. When the problem says "sister chromatids...1 and 2 (ABC)" and "sister chromatids...3 and 4 (abc)" does that mean that ABC are on both chromatids 1 and 2, and abc are on both chromatids 3 and 4? I.e.,

1 A----B----C
2 A----B----C
3 a----b----c
4 a----c----c

If not, I'm not sure which alleles are on which chromatids.

Also, I initially thought that answers A and E could not be correct because I thought that only nonsister chromatids could cross over. But if that's true, how does a double crossover between 1 and 3 or 1 and 4 produce the genotype ABC? Couldn't that only be obtained with a double crossover between 1 and 2? Or does a crossover + and reverse crossover count as a double crossover? I.e.,

1 A---B---C
3 a---b---c

crosses once between A and B to produce A---b---c, and once more between A and B to produce A---B---C?

As you can see, I'm a little confused. Can you please describe how to do this problem, and include the answer so that I can make sure I understand your explanation when I try to problem on my own?

Biology, Academics

  • Category:- Biology
  • Reference No.:- M928183

Have any Question? 


Related Questions in Biology

You have just cloned a gene from cucumber that when mutated

You have just cloned a gene from cucumber that, when mutated, causes pale green instead of green seedling in cucumber. You want to clone out the orthologous gene (this means the same gene) from Arabidopsis and find out i ...

The mutation for huntingtons disease appears to have

The mutation for Huntington's disease appears to have originated in Western Europe, with a prevalence of 7 in 100,000 people. However, an isolated population in Lake Maracaibo in Venezuela, of European descent, have an i ...

Assignment150 word minimum for question 1 only any

Assignment 150 word minimum for question #1 ONLY. Any materials used in answering the questions must be put in your own words and the reference(s) must be properly cited. 1. According to some scientists, in developing co ...

Lets discuss the role of the intestinal microbiota in the

Let's discuss the role of the intestinal microbiota in the maintenance of health and the many opportunistic pathogens that cause disease when the delicate balance of normal microbiota in this region of the body is distur ...

Which cultures would be more likely to focus on external

Which cultures would be more likely to focus on external controls? Which cultures would consider direct controls to be more important than indirect controls? Be specific and explain your answer.

Steroids hormonessuch as testosterone are derived from

Steroids hormones,such as testosterone, are derived from cholesterol. What type of macromolecule are they?

Formatnbsp at least one page in length 1-inch margins size

Format:   At least one page in length, 1-inch margins, size 11 font, double spaced.  Sources:   All sources must be properly cited within  and  at end of paper. Use MLA or APA style. Please do the following: Go to the in ...

1 the ductus arteriosus and the ductus venosus are two key

1) The ductus arteriosus and the ductus venosus are two key vessels in the fetal circulation that are absent in the adult circulation. What are their function in the fetus? Why are they necessary? 2) At birth, the fetal ...

What is inbreeding depression please give some examples of

What is inbreeding depression? Please give some examples of inbreeding depression in dogs and cats?

Bacterial srnas activate and repress translation by

Bacterial sRNA's activate and repress translation by exposing or covering RBS (ribosome binding site) on mRNA. Riboswitches also activate and repress translation by exposing or covering RBS on mRNA. How do these two regu ...

  • 4,153,160 Questions Asked
  • 13,132 Experts
  • 2,558,936 Questions Answered

Ask Experts for help!!

Looking for Assignment Help?

Start excelling in your Courses, Get help with Assignment

Write us your full requirement for evaluation and you will receive response within 20 minutes turnaround time.

Ask Now Help with Problems, Get a Best Answer

WalMart Identification of theory and critical discussion

Drawing on the prescribed text and/or relevant academic literature, produce a paper which discusses the nature of group

Section onea in an atwood machine suppose two objects of

SECTION ONE (a) In an Atwood Machine, suppose two objects of unequal mass are hung vertically over a frictionless

Part 1you work in hr for a company that operates a factory

Part 1: You work in HR for a company that operates a factory manufacturing fiberglass. There are several hundred empl

Details on advanced accounting paperthis paper is intended

DETAILS ON ADVANCED ACCOUNTING PAPER This paper is intended for students to apply the theoretical knowledge around ac

Create a provider database and related reports and queries

Create a provider database and related reports and queries to capture contact information for potential PC component pro