BIOL 2299 Lecture Notes - Lecture 8: Mendelian Inheritance, Gene Mapping, Genetic Distance

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blackmole114

25 Oct 2016

School

Northeastern University

Department

Biology

Course

BIOL 2299

Professor

Vollmer Steven

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Document Summary

Locus=location of a gene on a chromosome. Alleles= alternate forms of gene on homologous pairs of chromosomes. Alleles segregate at meiosis 1 with homologous chromosomes. Alleles of different genes assort independently in gametes. Independent assortment of genes on different chromosomes in meiosis 1. Random alignment of non-homologous chromosomes in metaphase 1 causes independent assortment of genes. Genes(and their alleles) can be linked(ie inherited together) if they are located in close proximity on the same chromosomes. Recombination: crossing over of homologous chromosomes in prophase 1 of meiosis causes gene combinations to recombine and produces different allele combinations than parental types. Linkage is estimated by the frequency of recombination. Frequency of recombination(%): serves as a measure of genetic distance between genes and allows us to construct genetic maps - ie. e the positions of genes along chromosomes. Genes have well-defined positions along a chromosomes(called a locus) With linkage and recombination, we need to keep track of the positions of alleles on.

Related Questions

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

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