BIOL 2000 Lecture Notes - Meiosis, Mendelian Inheritance, Zygosity

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8 Feb 2013

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Recombinant product- a product of meiosis that differs from the haploid genotypes that give rise to the diploid meiocyte. Parental product- a product of meiosis that is the same as the haploid genotypes that gave rise to the diploid meiocyte. Dihybrid- an individual heterozygous at two genes. Coupling configuration- arrangement of linked alleles in dihybrid such that the two dominant alleles are on one chromosome, the two recessive alleles are on the other chromosome (ab/ab) Repulsion configuration- arrangement of linked alleles in a dihybrid such that the a dominant and a recessive allele are together on each chromosome (ab/ab) Cis dihybrid- a dihybrid in which the alleles are coupled. Trans dihybrid- a dihybrid in which the alleles are in repulsion. Map unit- the distane between two genes where one product of meiosis out of 100 is recombinant. Gene locus- the position of a gene within the genome. Linked- two genes that are on the same chromosome.

Related Questions

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

While working in a pathology lab, you are presented with a bovine blood sample (2n=60) that is suspected to have a genetic abnormality. You decide to karyotype the sample and diagnose trisomy 29. Assume two hypothetical genes A and B are located on chromosomes 28 and 29 respectively. How many alleles for each gene will be present in the Primary oocyte, secondary oocyte and ovum that produced the animal with the abnormal karyotype indicated above â Provide answers for all possible scenarios. (1.5 marks) Describe the number of chromosomes and chromatids in the Primary oocyte, Secondary oocyte and ovum that produced the animal with the abnormal karyotype indicated above â Provide answers for all possible scenarios. (1.5 marks) Another two hypothetical genes P and Q are located on chromosome 1; with the dominant alleles (P and Q) in repulsion phase, and recessive alleles (p and q) in repulsion phase on homologous chromosomes. Suppose a single crossing over occurs between the two genes during meiosis. What is the probability that the ovum that gave rise to karyotypically abnormal animal contains the dominant or recessive alleles in coupling phase? (1 mark) Suppose the animal had an XXY karyotype instead of trisomy 29. Did non-disjunction occur in the male or female parent (or both) and at which division(s), meiosis I or meiosis II? (1 mark)

While working in a pathology lab, you are presented with a bovine blood sample (2n=60) that is suspected to have a genetic abnormality. You decide to karyotype the sample and diagnose trisomy 29.

Assume two hypothetical genes A and B are located on chromosomes 28 and 29 respectively. How many alleles for each gene will be present in the Primary oocyte, secondary oocyte and ovum that produced the animal with the abnormal karyotype indicated above â Provide answers for all possible scenarios. (1.5 marks)

Describe the number of chromosomes and chromatids in the Primary oocyte, Secondary oocyte and ovum that produced the animal with the abnormal karyotype indicated above â Provide answers for all possible scenarios. (1.5 marks)

Another two hypothetical genes P and Q are located on chromosome 1; with the dominant alleles (P and Q) in repulsion phase, and recessive alleles (p and q) in repulsion phase on homologous chromosomes. Suppose a single crossing over occurs between the two genes during meiosis. What is the probability that the ovum that gave rise to karyotypically abnormal animal contains the dominant or recessive alleles in coupling phase? (1 mark)

Suppose the animal had an XXY karyotype instead of trisomy 29. Did non-disjunction occur in the male or female parent (or both) and at which division(s), meiosis I or meiosis II? (1 mark)

BIOL 2000 Lecture Notes - Meiosis, Mendelian Inheritance, Zygosity

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