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HNRS 1007 Lecture Notes - Lecture 12: Genetic Variation, Zygosity, Look It Up

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coffeeshark80
5 Nov 2014
School
LSU
Department
Honors
Course
HNRS 1007
Professor
Li Cata

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Document Summary

Alternate versions of genes account for variations in inherited characteristics: called alleles, each gene resides at specific locus on a specific chromosome. For each character, an organism inherits two alleles (one from each parent) Identical alleles--- homozygote (aa or aa: different alleles--- heterozygote (aa) If two alleles are different, the dominant allele determines the organism"s appearance and the other has no noticeable effect (merely carries on gene) A and b antigens are found on the surface of red blood cells. Humans are not good subjects for genetic research. However, basic mendelian genetics endure as the foundation of human genetics: albinism. Albinism is a recessive condition characterized by a lack of pigmentation in skin and hair (aa- homozygous dominant , aa- heterozygous. If you have a child with albinism, both you and your partner must be carriers. Refer to pedigrees for the autosomal recessive trait of albinism.

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Related Questions

A strong understanding of the difference between gene and allele is needed now. We covered allele interactions in the lesson before this one. Allele interactions deal with a single gene and its alleles. Alleles, versions of a gene, can interact when placed together in a heterozygote.

We are now looking at two genes and how they interact. To more easily understand how two genes interact, we will only be considering the normal alleles and null alleles of both genes. Normal alleles will be dominant, null alleles will be recessive. In addition, the two genes are UNLINKED. The various interactions are made evident in standard F2 generations: Two purebred parents are crossed, a dihybrid F1 is formed, the dihybrid F1 is selfed, and F2 generation is examined. One must remember, the progeny of dihybrid selfs are always in a fixed genotype distribution: 9 A _ B_ : 3 A _ bb : 3: aa B _ : 1 aa bb. BUT, with genes interacting the phenotypic ratios are changed.

Please focus on how genes interact. You do not need to know specific pathways or organisms.

Answer the following questions.

2. There is a hypothetical plant called rat-ear. Red and pink varieties flourish in Hawaii and Long Island, NY. All the red and pink varieties can be bred true. Surprisingly, when the Hawaiian pink is bred with the Long Island pink, all the resulting progeny are red. When these red progeny are selfed the next generation has 333 red flowered and 259 pink flowered plants. The breeders breathe a sigh of relief. What do the breeders understand about the petal pigmentation of rat-ear plants?

QUESTION 1

Jim is blood type A, his brother John is type O and his sister Jane is type AB. What are the genotypes of their parents?
A.
IAi and IBi
B.
IAIA and IBIB
C.
IAi and IBIB
D.
IAIB and ii
E.
IAIA and IBi

QUESTION 2

Which of the following is true for alleles that show incomplete dominance?
A.
Heterozygotes have a genotype like the dominant allele.
B.
Homozygotes have a genotype like the recessive allele.
C.
Heterozygotes have a phenotype intermediate between the dominant and recessive alleles.
D.
Homozygotes have the same phenotype as the heterozygotes.
QUESTION 3

Which principle of inheritance concluded that when games are formed in meiosis, the two alleles of each gene separate from one another, and each gamete receives only one allele?
A.
independent assortment
B.
heterozygosity
C.
segregation
D.
dominance
QUESTION 4

Which term best describes a condition in which alleles at one locus can alter the expression of alleles at another locus?
A.
polygenic inheritance
B.
codominance
C.
multiple alleles
D.
pleiotropy
E.
epistasis
QUESTION 5

A single unit of genetic information located on a chromosome defines:
A.
a trait
B.
an allele
C.
a chromosome
D.
a locus
E.
a gene
QUESTION 6

The physical expression (appearance or function) of an organism's genes defines:
A.
genotype
B.
a single characteristic
C.
physiology
D.
mutation
E.
phenotype
QUESTION 7

Palomino horses (golden color with a blond mane) are an incompletely dominant trait produced by the combination of the chestnut color allele and the cream color allele. If you wanted to produce as many palominos as possible, which mating strategy below would be the best choice?
A.
Chestnut x Cream
B.
Palomino x Cream
C.
Palomino x Chestnut
D.
Palomino x Palomino
QUESTION 8

Which term best describes the effect of a single gene on multiple aspects of the phenotype?
A.
epistasis
B.
pleiotropy
C.
multiple alleles
D.
codominance
E.
polygenic inheritance
QUESTION 9

Which term best describes the separate expression of both alleles for a single trait in the same cell?
A.
multiple alleles
B.
codominance
C.
pleiotropy
D.
epistasis
E.
polygenic inheritance
QUESTION 10

One form of a gene found on a single chromosome defines:
A.
an allele
B.
a locus
C.
a chromosome
D.
a trait
E.
a gene
QUESTION 11

A chocolate lab (whose mother was a yellow lab) is mated with a black lab whose genotype is BbEe. What fraction of the offspring would be expected to be yellow labs?
A.
1/4
B.
none
C.
1/2
D.
3/16
E.
1/8
QUESTION 12

What type of allele is always expressed regardless of whether the individual is homozygous or heterozygous for it?
A.
Both the dominant and recessive alleles
B.
Recessive allele
C.
Allosteric allele
D.
Lethal allele
E.
Dominant allele
QUESTION 13

Given the parents AABBGgHhrr × AabbGgHhRr, assume simple dominance and independent assortment. What proportion of the progeny will be expected to have the genotype AaBbggHHrr?
A.
1/256
B.
1/64
C.
1/16
D.
1/32
E.
1/128
QUESTION 14

___________________ is defined as having two of the same type of allele for a particular trait.
A.
Homozygous
B.
Dominance
C.
Incomplete dominance
D.
Heterozygous
E.
Genotype

QUESTION 15

The physical position of an allele on a single chromosome defines:
A.
an allele
B.
a chromosome
C.
a gene
D.
a locus
E.
a trait
QUESTION 16

Which term best describes two or more genes affecting the phenotype in an additive fashion?
A.
codominance
B.
polygenic inheritance
C.
multiple alleles
D.
pleiotropy
E.
epistasis

Expression vectors inprokaryotes do not make functional eukaryotic gene products inbacteria very well because

Answer Not sure which one ?!

· the codon sequence for prokaryotes is differentthan the codon sequence in eukaryotes

· there are no disulfide bridges formed in proteinsnormally made in prokaryotes

· prokaryotic expression vectors cannot translateeukarytic sequences

· eukaryotic genes have introns, and prokaryotesdon't

· eukaryotic genes have exons and prokaryotesdon't


I create a knockout mouseusing the agouti/black fur system \. When I cross the agoutioffspring of the originally engineered mouse, I find a ratio of 2agouti mice to 1 black furred mouse. What is the bestexplanation?

Answer not sure which one?!

· The gene knocked out was recessive.

· The gene knocked out was dominant.

· The gene knocked out was a lethalgene.

· The knockput was integrated into a random spot,and did not knockput the original gene.

A restriction enzyme cuts DNAand leaves the following end

xxCTGCA
xxG

Which of the following could be the sequence of the correspondingend of the other end of the cut DNA?

Answer

· xxG
xxCTGCA

· xxC
xxGTGCA

· xxCCGAT
xxG

· xxGGCTA
xxC


An SNP always occurs dueto

Answer

· a one base-pair change.

· a three base-pair change.

· a single restriction site change.

· a single amino acid change.

· None of these.


I PCR out a mutated gene in apatient with Lisenbee chorea (the inability to dance in acoordinated fashion) and I compare it to another patient with thatsame disease phenotype. One subject had a mutation on chromosome 4,and the other subject couldn't rock it because of a mutation onchromosome 5. This is an exampe of

Answer

· pleitropy

· locus heterogeneity

· allelic heterogeneity

· dominant negative mutation

· penetrance

In his experiments, Mendelnoted that when two traits are involved in a genetic cross, theyare inherited independently of each other. Though Mendel didn'tknow about chromosomes, this still holds true (mostly)because

Answer

· genes on the same chromosome are often mixedthrough meiotic crossover during the formation ofgametes.

· variant alleles of the same gene do not interferewith the phenotypic expression of the gentoype in different geneticloci.

· most higher organisms are diploid, making only twoalleles available for every genetic locus, and there is a 50/50chance of geting either allele from a single parent.

· expression of phenotypes can vary from thegenotypes because of encironmantal influences.

· chromosomes often recombine

Anticipation is caused by amutation that increases in expressivity over subsequentgenerations.

Answer

· True

· False

Question 44

I have a genotype that shouldproduce a specific phenotype, but some of the individuals with thegenotype do not demonstrate any evidence of the phenotype. I wouldconsider this an example of

Answer

· allelic heterogeneity.

· locus heterogeneity.

· penetrance.

· expressitivity.

· sheer luck.

Question

Which of the following doesnot occur during the PCR reactions?

Answer

· Changes in the reaction temperature by athermocycler

· Denaturation at high temperatures

· Synthesis of oligonucleotide primers

· Extension of primers by DNA polymerase

· Annealing of oligonucleotide primers

Question

DNA markers, or variantnon-coding regions of DNA, are DNA polymorphisms that are usefulfor genetic mapping.

Answer

· True

· False

A mosaic is an organismwith

Answer

· multiple genotypes within one organism

· multiple alleles within one genotype

· more than one color of fur

· transgenes added to the zygote beforedevelopement

· a wt phenotype but a mutated genotype

Question

Genotype causesphenotype.

Answer

· No, gentoype just influences phenotype.

· Yes, genotype is the DNA sequence that createsphenotype.

Question

A true genetic chimera can becreated by

Answer

· mutating a gene early on in the development of anorganism resulting in different alleles being present in theadult

· multiple fertilized eggs or zygotes fusing to formone embryo

· adding a transgene to the genome of an organismduring fetal development only

· adding cells of a different species to an adultorganism

· adding a transgene to the genome of an animal atany stage in development

Question

The ABO blood group can bestbe explained by the concept of _______.

Answer

· dominant traits

· recessive traits

· allelic heterogeneity

· locus heterogeneity

· vampirism

If a loss of functionmutation creates a dominant phenotype, it may be becauseof

Answer

· haploinsufficiency

· penetrance

· expressivity

· allelic heterogeneity

· locus heterogeneity

Please select the best matchfor each.

Answer

· PCR: Technique used to generatecopies of a DNA fragment

· Southern blot : Screeningprocedure used to assay DNA fragments

· RFLPs : DNA fragments generatedby restriction enzymes that vary in length betweenindividuals

· Northern blot : Screeningprocedure used to assay mRNA fragments

· Electrophoresis Movement ofmacromolecules in an electrical field

Answer

A.

Screening procedure used toassay DNA fragments

B.

Movement ofmacromolecules in an electrical field

C.

Screening procedure used toassay mRNA fragments

D.

DNA fragments generated byrestriction enzymes that vary in length betweenindividuals

E.

Technique used to generatecopies of a DNA fragment

A gene mutates, and theprotein produced has a novel way of interacting with the cell, andcreates a new phenotype because of this new functionality. This iscalled

Answer

· pleitropy

· locus heterogeneity

· allelic heterogeneity

· dominant negative mutation

· gain of function dominant mutation

Question 62

Mutations in the somaticchromosomes may be inherited by the next generation.

Answer

· True

· False


A degenerate PCR primer withmany variant sequences must be used to make multiple copies of agene

Answer

· if only the protein sequence of the gene productis known to construct the primers

· if the DNA you are using is cDNA to constructthe primers

· if the DNA you are using is genomic DNA to becopied

· if the DNA you are trying to copy iscDNA

· if the vector is prokaryotic and the transformedcell is eukarytotic

Question

Please select the best matchfor each term.

Answer

· Restriction enzyme


· PCR C

· Plasmid

· YAC A

· Dideoxynucleotide

Answer

A.

Endonuclease isolated frombacteria

B.

Eukaryotic cloningvector

C.

Method for amplification ofDNA sequences

D.

Small circular fragment ofDNA

E.

Molecule used in DNAsequencing

Question

A couple goes on MauryPovitch, and the results are in: you are not the father. But noother man impregnated the female (granted, unlikely for a MauryPovitch guest, but work with me here) and he must be the father.DNA analysis claims otherwise, though the child definitely wasmom's (poor thing). What may be going on here?

Answer

· the child is parthenogenic because the motheractually impregnated herself like a shark, and the child's DNA isall mom's

· the child had a mutation that changed the genethat is used to trace paternity

· the child is a mosaic because he is actually a setof twins fused early during fetal development, and therefore camefrom 2 eggs and 2 sperm

· the dad may have germ-line mosaicism, meaning thatthe genotype of his sperm is different from his somaticgenotype

· mitochondrial DNA only comes from mom, so there isno way to tell whobthe baby's father is