MBG 2040 Chapter Notes - Chapter 7: Centimorgan, Interphase, Sex Linkage

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whiteelk758

27 Feb 2018

School

University of Guelph

Department

Molecular Biology and Genetics

Course

MBG 2040

Professor

Krassimir Joseph Yankulov

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Document Summary

In this way, then, the possibility for nondisjunction is minimized, and aneuploidy in the gametes is largely prevented. Linkage between genes is detected as a deviation from expectations based on mendel"s. Principle of independent assortment: the frequency of recombination measures the intensity of linkage. Late in prophase i, crossovers become visible as chiasmata. Linkage between human genes can be detected by analyzing pedigrees: pedigree analysis also provides estimates of recombination frequencies to map genes on human chromosomes. Suppression of recombination by inversions seems to have played an important role in the evolution of the sex chromosomes in mammals: through natural selection, functional genes have been retained on the x chromosome, but on the. Y chromosome most of the genes have degenerated through the accumulation of random mutations: thus, today the y chromosome has fewer functional genes than the x chromosome, and the ones that remain are arranged in a different order.

Related Questions

For genetics:

how do we parental classes in meiosis come about ? Is there no recombination or crossing over occurring? But in my textbook it says that if recombination did not occur, nondisjunction during meiosis I would be a common, rather than a rare occurrence, and species could not retain the same number of chromosomes in successive generations.

I am confused on how linked genes have more parental types than recombination types, i understand that the linked genes are inherited together because they are close together on the same chromosome.

I guess my question is, do all chromosomes undergo recombination and crossing over in meiosis? And the parental classes are parental because were just looking for those certain linked genes that are inherited together?

thank you!

aquamarineduck901

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

Fill in the blank, each word can be used more than once.

word bank- crossing over, avoid predation, reproduce,independent assortment, phenotypes, frequencies, nucleotides,meiosis, protein, prophase, segregation, gene, allele, amino acids,fertilization, arrangement, chromosome.

A(n) _________ is one of multiple forms of the same gene.

These different forms of genes are in the same locus of a(n)_________, but they have slightly different sequences of________.

During ________ I of meiosis, genes of homologous chromosomesalign side-by-side.

Then in a process called _________, homologous chromosomesrandomly line up double-file at the center of the cell and thenseperate. Since alleles are randomly distributed, this processcreates variation among the gametes. After ________ with a gametefrom the other sex, variation among gametes will create variationamong the offspring.

Some offspring will have a more favorable combination of allelesthan others, and will therefore survive and ________ moresuccessfully, leading to more favorable alleles in the nextgeneration. However, sometimes conditions change, andonce-favorable phenotypes may becomes less favorable.

Scientists hope that they will soon be able to use biotechnologyto track the ________ of alleles over multiple generations, therebywatching evolution as it occurs.

taupewolf882

MBG 2040 Chapter Notes - Chapter 7: Centimorgan, Interphase, Sex Linkage

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