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BIO 235 Exam 2 With 100% Correct Answers 2023
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BIO 235 Exam 2 With 100% Correct Answers 2023
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BIO 235 Exam 2 With 100% Correct Answers 2023Independent assortment - Correct Answer-Genes assort independently of each other when they are on opposite chromosomes
Linkage - Correct Answer-Two genes on a single pair of homologs; exchange occurs between two non-sister chromatids
Chiasmata - Correct Answer-Location of exchange of information between chromatids
when does crossing over occur? - Correct Answer-prophase I of meiosis
How often does recombination occur? - Correct Answer-Very frequently
What determines how often genes will cross over? - Correct Answer-Their distance from
one another. The closer they are, the less likely they are to cross over.
What does it mean when genes are linked? - Correct Answer-they are on the same chromosome; assort independently
Describe how geneticists detect linkage of a gene - Correct Answer-1. Select true-
breeding lines that are homozygous dominant for one trait & homozygous recessive for the other trait (ygr ANL / ygr ANL & YGR anl / YGR anl). Parents produce dihybrid F1 population (ygr ANL / YGR anl)
2. Cross the F1 dihybrid with a homozygous recessive (ygr anl / ygr anl). This will result in an F2 pop. where the dihybrid traits segregate.
3. Cross each F2 individual with a homozygous recessive
How do you determine if the genes are linked or not after performing a test cross? - Correct Answer-If the ratio is 1:1:1:1, they assort independently and are unlinked
If the ratio for the recombinant class is less than the parental class, you know they do not assort independently and are linked
Parental class - Correct Answer-original arrangement of alleles on the two chromosomes (no recombination); came from meiosis unchanged
Recombinant class - Correct Answer-does not have chromosomes passed from parents
How is distance between genes found? - Correct Answer-The farther apart two genes are located on a chromosome, the higher the probability that a recombinant event takes place between them Recombinant frequency (RF) - Correct Answer-percentage of the total progeny that are recombinant type
6% RF = ___________ - Correct Answer-6 map units OR 6 centimorgans
From a test cross, you observe that there are 350 offspring for each parental genotype and 150 for each recombinant genotype. What is the distance of the recombinant genes? - Correct Answer-30 map units
What is one problem with relying on RF in linkage mapping? - Correct Answer-Genetic distance is massively underestimated when genes are father apart
Genetic distances are not additive - RF will never be >50%
The farther apart they are, the less reliable the numbers are
Double-crossover is more likely the further they are from each other
Double-crossover - Correct Answer-One crossover will switch the alleles of homologous
chromosomes, but another crossover will reverse the effects of the first, restoring the original parental combination of alleles. This leaves you with non-recombinant genotypes even though a portion of the chromosome crossed over
Linkage group - Correct Answer-Alleles of different genes that are located on the same chromosome and tend to be inherited together
Haplotype - Correct Answer-a group of genes within an organism that was inherited together from a single parent; A group of alleles of different genes on a single chromosome that are closely enough linked to be inherited usually as a unit
Phenotypic marker - Correct Answer-mark of position on chromosome that allows you to
create a map of the chromosome
How are phenotypic markers similar to highway markers? - Correct Answer-They don't change or do anything, they just help you know where you are at
How can you calculate the frequency of double crossover (DCO) events? - Correct Answer-product rule
If the frequency of a single crossover between A and B is 12%, the frequency for B and C is 18%, what is the frequency of a double crossover between A and C? - Correct Answer-0.18*0.12 = 0.0216
21.6%
Chromosomal Interference - Correct Answer-Crossovers do not occur independently
Crossover between A and B decreases the chance of a crossover between B and C
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