Genetics Test 4

An individual with Huntington disease has two normal parents. What are plausible explanations for this pattern of inheritance?

-A spontaneous mutation occurred in the mother's germline to produce a mutant HD allele. -A spontaneous mutation occurred in the father's germline to produce a mutant HD allele. -Huntington disease shows incomplete penetrance.

How do quantitative traits arise?

-The trait is polygenic. -The trait is controlled by a single gene and the environment.The trait is controlled by a single gene and the environment. Correct

When all phenotypic variation is due to genetic variation, the heritability is

1

four overlapping phases of animal development

1. First phase of development Formation of body axes 2. Second phase of development Segmentation of the body 3. Third phase of development Determination of structures within segments 4. Fourth phase of development Cell differentiation

In a normal distribution, what percentage is the population is covered by plus or minus one standard deviation above and below the mean?

68%

You are carrying out an RNA-Seq experiment. You encounter a problem with attaching the oligonucleotide linkers to the RNA fragments. At what step will RNA-Seq be halted?

At the cDNA synthesis step In RNA-Seq, oligonucleotide linkers are necessary for making cDNA via RT-PCR. The PCR primers are complementary to the oligonucleotide linkers. Therefore, if the linkers couldn't be added, the experiment would be halted at the cDNA synthesis step.

What is the correct order of gene expression that results in animal development? A= cell differentiation genes B= maternal-effect genes C= homeotic genes D= segmentation genes

BDCA

Which of the following DNA sequence repeats within the Huntington gene would be associated with the development of HD?

CAG repeats

You wish to introduce a specific missense mutation into a specific cell type in live adult mice. What is the best way to achieve this goal?

CRISPR-Cas technology with donor DNA

What cellular events must occur to establish the body pattern in an animal?

Cell division Cell migration Cell differentiation Apoptosis

Which of the following statistics is used to compare two variables?

Correlation

What is the role of a dideoxynucleotide in DNA sequencing?

Dideoxynucleotides are missing both the 2' OH and 3' OH groups and terminate strand synthesis.

A quantitative trait locus (QTL) can only contain one gene. T/F

F

Both members of identical and fraternal twin pairs have the same likelihood of expressing the same genetic disease. T/F

F

Genetic diseases are spread by shared environmental conditions T/F

F

Genetic diseases occur at the same rate in all human populations. T/F

F

RNA-seq involves directly sequencing the RNA. T/F

F

A molecular marker is a gene that shows a phenotype in the organism. T/F

False

You are working in a mouse lab. You use CRISPR-Cas technology to inactivate a gene that you suspect is involved in retinal development in eye cells. What type of strategy are you using?

Gene Knockout Reverse Genetics

Pyrosequencing is an example of a high-throughput, next-generation sequencing technology. What is a crucial detail of the procedure?

Including the enzyme luciferase

When scientists examined horse and human globin genes, they found that human and horse β globin genes had 25 differences, whereas human β globin and human α globin genes show 84 differences. If you were to compare the horse β globin and human α globin genes how many differences do you think you would find?

More than 84 Because there are 84 differences between paralogs and 25 between orthologs, we can deduce that the duplications that led to the paralogs within the same species (α-globin and β-globin) occurred before the evolutionary divergence of mammals.

A restriction fragment length polymorphism is an example of a molecular marker. T/F

T

Genetic disorders are more common in families with one affected member as compared to the general population. T/F

T

Many human and animal genetic disorders share similar characteristics.T/F

T

Molecular markers can vary between individuals. T/F

T

Molecular techniques make it easier to identify many molecular markers rather than allelic differences that affect traits in a species T/F

T

Most genetic diseases have a specific age of onset. T/F

T

You discover a mutation in p21 that makes it unable to respond to p53. What effect do you expect this to have on cells?

This mutation will promote cancer.

Only females exhibit the trait when it is lethal to males, and affected mothers have a 50% chance of passing the trait to daughters.

X-linked dominant

Males are much more likely to exhibit the trait, and mothers of affected males often have brothers or fathers who are affected.

X-linked recessive

Narrow sense heritability has to do with

additive genes

An affected offspring usually has one or two affected parents, and the trait occurs equally in both sexes

autosomal dominant

Frequently an affected offspring has two unaffected parents, and the trait occurs equally in both sexes.

autosomal recessive

The difference between broad and narrow sense heritability is that __________.

broad sense heritability takes into account different types of genetic variation including additive alleles, dominant and recessive alleles, and epistatic genes Narrow sense heritability assumes additive alleles have the largest effect. Broad and narrow sense heritability numbers can be the same if there is little effect on phenotype by dominant and recessive genes and epistatic genes.

Chromatin immunoprecipitation involves __________.

chemical cross linking of DNA to protein The DNA sequence is being isolated by CHIP for analysis, not the protein.

The proteins ________ work together to cause the release of the transcription factor that is bound by the retinoblastoma protein.

cyclin and cyclin-dependent kinase

Mutated forms of the Rb protein __________.

do not bind to E2F thereby promoting uncontrolled cell division

If a mutation occurs that causes one of these genes to be expressed in an area where expression does not normally occur, the outcome is referred to as a __________.

gain-of-function mutation

A ________ consists of two or more __________within the genome of a particular species.

gene family paralogs

If the environmental effect on a trait is relatively low then the distribution of phenotypes is more closely correlated with their ______

genotypes.

In general the more genes that are involved in the development of a trait the _____ the number of phenotypic classes that can occur.

greater

Broad sense heritability formula

h^2=Vg/Vp or h^2=Vg/(Vg+Ve)

The amount of phenotypic variation due to genetic variation is also referred to as

heritability

Two genes that are derived from the same ancestral gene are

homologs.

In the laboratory an ______ strain may be used to study environmental effects because the variation due to genetics will be 0.

inbred

A normal distribution is common if the trait is determined by the cumulative effect of many small __________factors.

independent

A geneticist cannot make sense of a pedigree he has put together for a newly discovered disease that he suspects is transmitted genetically. One possible explanation is __________.

locus heterogeneity

Quantitative trait loci are frequently mapped using

molecular markers.

Two homologous genes found in different species are called

orthologs.

The protein ________ checks for damaged DNA, thereby acting as a "quality control" for the cell.

p53

Two or more homologous genes within a single species are termed

paralogs.

Mapping of QTLs relies on the correlation of the inheritance of a specific ______ with a unique piece of DNA.

phenotype

Mapping of QTLs relies on the correlation of the inheritance of a specific _______ with a unique piece of DNA.

phenotype

promote cancer or prevent cancer? A mutation in ras that makes it unable to become "always active."

prevent

promote cancer or prevent cancer? Duplication of the BRCA-1 gene.

prevent

promote cancer or prevent cancer? A mutant of Rb that was always phosphorylated.

promote

promote cancer or prevent cancer? A p53 mutant that cannot detect DNA damage.

promote

promote cancer or prevent cancer? Cyclin proteins that didn't degrade at the appropriate time in the cell cycle.

promote

A __________ is a normal cellular gene that through a __________ mutation becomes an oncogene.

proto-oncogene; gain-of-function

A region of a chromosome that contains one or more genes that affect a trait is called a

quantitative trait locus.

In colon cancer, activation of ______, an oncogene, contributes to the development of a carcinoma.

ras

To be most useful for mapping there should be _________ crossing over between the marker and the gene controlling the trait

relatively little

To be most useful for mapping there should be __________ crossing over between the marker and the gene controlling the trait

relatively little

The International HapMap Project is an effort to identify differences in individual bases known as __________.

single nucleotide polymorphisms

Genome wide association studies are performed to __________

try to correlate genomic differences with diseases

Polygenic inheritance means that the transmission of a trait is governed by ___ or more genes.

two