BIOL10005 Lecture 8: BIOL10005 Lecture 8 Notes

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ceriseeagle929

20 Sep 2018

School

University of Melbourne

Department

Biology

Course

BIOL10005

Professor

Dawn Gleeson

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Document Summary

Homologues segregate at meiosis, accounting for mendel"s principle of segregation. No independent assortment, gametes not produced in equal frequency which is called linkage. Humans have 22 di erent autosomes and one pair of sex chromosomes. Many genes reside on each chromosomes and homologous chromosomes carry the same set of genes. Linkage between genes is never complete because of the crossing over between homologous chromosomes chromosomes. Alleles of di erent genes located on the same chromosome should be transmitted together. They should be linked and not follow mendel"s principle of independent assortment. If two genes are close together on a chromosome, alleles may recombine only rarely assort independently. A direct test of independent assortment is the test cross of double heterozygote with a double recessive homozygote. If two genes are far enough, the high frequency of crossing over means that the alleles. Crossing over leads to recombination between teens on a pair of homologous.

Related Questions

The syntenic genes A and Z are linked. A cross between two parents, AAzz and aaZZ, produces F₁ progeny with the AaZz genotype. What are the possible arrangements of alleles on the F₁ progeny's chromosomes?

A/Z or a/z

The answer is not AZ/az

Genes that are on the same chromosome can assort independently when

they are very close together on a chromosome and crossing over occurs rarely between the genes.

they are far apart on a chromosome and crossing over occurs rarely between the genes.

they are far apart on a chromosome and crossing over occurs frequently between the genes.

they are syntenic.

Genes on the same chromosome cannot assort independently.

Please help me with these two!

1. What is the chromosome theory of inheritance?

2. Understand how independent assortment can cause gametes to have four combinations of alleles when an individual is heterozygous for two genes on two different chromosomes.

3. What are linked characters and linked genes? Understand why linked genes will not independently assort.

4. How can crossing over affect linked genes?

5. What are recombinant gametes?

6. Define recombinant frequency. Be able to use the recombinant frequency to determine how close two genes are on a chromosome.

7. What is a linkage map?

8. What is the function of the SRY gene on the Y chromosome? What happens if you don't have this gene?

9. Know how sex is determined in mammals, birds, bees and ants, and reptiles.

10. How many autosomes and sex chromosomes do normal human haploid and diploid cells have?

11. What does it mean for a gene to be X-linked or Y-linked?

12. Be able to answer word problems and fill out a Punnet square involving an X-linked recessive trait.

13. Which sex is more likely to have an X-linked recessive disorder? Understand why.

P.s The most simple answer would be preferable. I would be copping the notes over that you will provide to my noteb book and add my details to it.

greylocust179

Which of these statements is incorrect?

Syntenic genes are located on the same chromosome.

Independent assortment results in recombinant chromosomes.

You can reliably predict the relative genetic distance fromgenesâ physical distance on a chromosome.

Linked genes are always syntenic.

What is the relative genetic distance between two linked genesif the recombination frequency is 0.49?

0.49 cM

4.9 cM

49 cM

490 cM

What statement best explains the distortion in Mendelian ratiosobserved by Bateson & Punnett in 1905? (Reminder: they found anoverrepresentation of F2 offspring showing both dominant orrecessive phenotypes, and an underrepresentation of offspringdisplaying one dominant and one recessive phenotype)

Human error: they should have been more careful about theirexperimental setup.

Gene linkage: Genes for flower color and pollen shape arephysically close on the same chromosome, leading to a breakdown inthe independent assortment of the alleles for these traits.

Chromosome crossover: Homologous recombination of twochromatids during meiosis caused the alleles to shuffle, resultingin a breakdown of the independent assortment of the alleles forthose genes.

Random variation: No two situations are alike. In finitepopulations, you are going to get some variation across a mean.

When determining the relative genetic distance between twogenes, why is dihybrid back-cross preferable over traditionaldihybrid cross?

9:3:3:1 phenotypic ratio is easier to work with than 1:1:1:1ratio.

Genotypes of the offspring can be determined based on theirphenotype.

If the genes are independently assorted, the dihybrid back-crosswould result in only 2 genotypes in the F1 generation.

B and C

Why do we map genes?

To understand how genes interact with each other

Comparative genomics analysis

To determine the genotype of an organism

All of the above

coralox210

BIOL10005 Lecture 8: BIOL10005 Lecture 8 Notes

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