Exam 3 Vocab & Multiple Choice Flashcards
Genetic Mosaicism
Individuals whose cells hold different genetic constitutions.
Genetic Counseling
The communication of genetic information relevant to the transmission of heritable disorders to patients.
Chiasma
A point of contact between two homologous chromosomes during meiosis which results in a crossover event.
Coupling
The configuration of normal alleles on the same chromosome.
Haplotype
A series of linked alleles on the same chromosome
Concordance
The percentage of twin pairs that both display the trait.
Crossing Over
The physical process of reciprocal exchange of chromosome segments at corresponding positions along homologous chromosomes.
Pedigree
A pictorial diagram of the genetic relationships among family members.
Interference
The degree with which a single cross over can inhibit other cross over events.
Proband
The first person to report their families’ genetic history to a genetic counselor.
Logarithm of Odds
The probability of obtaining the observed results under a specified degree of recombination divided by the probability of the observed results under the assumption the genes are independently sorting
(observed recombination divided by observed independment assortment)
Repulsion
each chromosome has one normal type allele and one mutant allele
Genetic counseling is an educational process that provides the patients and their families information about the genetic condition and what other important information?
A) Details of independent assortment
B) Mode of inheritance
C) Reproductive options
D) B and C
D) B and C
What assumptions underlie the use of adoption studies in genetics?
a. The adoptive parents and biological parents are not related.
b. The environments of the biological and adoptive parents are independent.
c. Adoptees have no contact with their biological parents after birth.
d. All of the above
d. All of the above
The Genetic Information Nondiscrimination Act is a law passed in 2008 that does the following.
a. Allows you to share your genetic information without consequence
b. Protects the privacy of your genetic data
c. Prohibits health insurers from using your genetic information to make decisions about coverage
d. None of the above
c. Prohibits health insurers from using your genetic information to make decisions about coverage
A father is distressed about whether he will pass his disease on to his children. His wife is unaffected and not a carrier. They have three sons. What proportion of his sons will inherit this disease that is known to be a X linked recessive trait?
a. 1⁄2 sons
b. All
c. None
d. 1⁄4 sons
c. None
Alfred Sturtevant discovered the relationship between recombination frequencies and the distance between two alleles on the same chromosome. Which of the following are not true for this relationship?
a. A recombination rate of 10% = 10 centimorgans
b. A recombination rate of 12% = 12 mapping units
c. A recombination rate of 5% = 8 centimorgans
d. A recombination rate of 18% = 18 mapping units
c. A recombination rate of 5% = 8 centimorgans
When attempting to find linkage of an allele with a trait of interest in a family linkage study what data structure is crucial and in contrast to the study design approach used for genome wide association studies (GWAS)?
a. Concordance in dizygotic twins
b. Pedigree
c. Case versus control of unrelated individuals
d. Assumption of independent assortment
b. Pedigree
In a 3-point test cross to determine gene order for genes a, b, and c on the same chromosome we estimate the recombination frequency between two of the three genes at a time, lets say we start with the a and b genes. To calculate the a and b recombination frequency we add up what observed crossover measures and divide this sum by the total progeny then multiply by 100?
a. Single crossovers for c
b. Single crossovers observed for a and b
c. Single and double observed crossovers for a and b
d. None of the above
c. Single and double observed crossovers for a and b
In studies on the influence of genes and the environment in cases of adoption the adopted individuals usually don’t share this factor with their biological parents.
a. 50% of the mothers genes
b. 50% of the fathers genes
c. Environment
d. All of the above
c. Environment
What percentage of genes do dizygotic twins share?
a. 25%
b. 50%
c. 100%
d. None of the above
b. 50%
(T/F) The coefficient of coincidence is used to determine the outcome of a chi-square test of independence.
False. The coefficient of coincidence is used to determine the estimate of interference among double crossovers.
(T/F) For independent assortment 50% of progeny will be parentals and 50% non-parentals.
True
(T/F) In a 3-point test cross double crossovers are more frequent than single crossovers between genes.
False. Always less frequent
(T/F) If the number of observed progeny shows a <50% recombination frequency for a test of linkage
between two genes we can conclude the genes are linked.
True
(T/F) A single crossover will switch the alleles on a single chromosome but another crossover can reverse the effects of the first thus restoring the original parental alleles combination
True
(T/F) The coefficient of coincidence value is first estimated prior to determining the extent of cross over interference
True
(T/F) A 3-point test cross, in order to place the middle gene and establish order we start with analyzing the single crossovers.
False. Double-crossovers are considered first
(T/F) In complete linkage, assuming coupling, all progenies are nonrecombinants
True
(T/F) Barbara McClintock and Harriet Creighton provided the first definitive evidence that independent assortment was a physical process
False. Evidence that recombination was the physical exchange between chromosomes using corn was there contribution.
(T/F) For single crossovers, the frequency of recombinant gametes is half the frequency of crossing over because each crossover takes place between only two of the four chromatids of a homologous pair.
True
X-linked Recessive Inheritance
- usually more males than females affected
- affected sons usually born to unaffected mothers thus skipping a generation
- approximately half of a carrier mothers sons are affected
- NEVER passed from father to son
- all daughters of affected father are CARRIERS
X-linked Dominant Inheritance
- both males and females are usually affected
- affected male parent passes the trait to ALL daughters and NO sons
- does not skip generations
- affected mothers if heterozygous pass the trait to half the sons and half the daughters
Autosomal Dominance Traits
- usually appears in both sexes with equal frequency
- both sexes transmit the trait to offspring
- affected individuals usually have an affected parent
- if one affected parent is heterozygous and the other parent is unaffected half of the offspring will be affected
- unaffected parents don’t transmit the trait
Autosomal Recessive Traits
- Usually appears in both sexes with equal frequency.
- Tends to skip generations.
- Affected individuals are usually born to unaffected parents.
- If both parents are heterozygous, Aa, then ~1/4 of the offspring will be affected.
- More frequent occurrence with consanguineous marriages.
Y Linked Traits
- always transmitted from father to son
- only males are affected
- does not skip generations
What does the interference estimate tell you?
___% of the time one crossover will interfere with the other
