Test 8-10

Use the following words to fill in the blanks below. Frequency, gene pool, alleles, population, polymorphic loci, and allele frequency. The __________ describes how often a particular DNA sequence is found in a population. The collection of all _____ present in a population is termed the _____. _______ are variants that occur in a population at a ___frequency__ greater than 0.01.

1. allele frequency 2.alleles 3. gene pool 4. polymorphic loci 5. frequency

This question is about Mendel's pea experiments. What genotype and phenotype proportions are expected from a cross between two plants that are heterozygous for pea color and shape? The parent plants have round, yellow peas. Please select all that apply. 1/4 wrinkled peas 1/16 YY RR 1/2 Yy Rr 4/16 yy rr 3/4 yellow peas

1/4 wrinkled peas 1/16 YY RR 3/4 yellow peas

What does 10 centiMorgans (cM) represent? 10% recombination between two genes on different chromosomes 10% recombination between two genes on the same chromosome 1% recombination between two genes on the same chromosome 1% recombination between two genes on different chromosomes

10% recombination between two genes on the same chromosome

An experiment was conducted with Drosophila flies carrying recessive white-eye and yellow-body alleles. The white and yellow genes are on the X-chromosome. The parental (P0) individuals were homozygous white-eye, normal body female and red-eye, yellow-body male. F1 females had a wild-type phenotype and F1 males had normal bodies and white eyes. F1 individuals were then mated. What phenotypes are expected in the F2 generation? Please select all that apply. ~25% of females have white eyes 100% of females have a normal body There are very few wild-type males ~25% of males have white eyes

100% of females have a normal body There are very few wild-type males

Fill in the blank. Redundancy is where more than one gene can perform a particular function. If genes A and B are redundant for a particular phenotype, ___/16 offspring from a cross between AABb and aabb would be expected to exhibit the phenotype.

16

In an experiment, two homologous chromosomes with alleles as shown below (original homologous chromosomes) underwent meiosis and to product four chromosomes (resultant chromosomes). How many crossovers appear to have occurred during meiosis?

2

In a cross between parents with the genotypes A/a;B/b and a/a;b/b, where the A and B loci are unlinked, __% of the offspring will have a phenotype that differs from the phenotype of both parents.

50

The maximum map distance that can be observed in a cross concerning two loci is ___ map units.

50

When considering the inheritance of multiple independent traits, it is often simpler to multiply the probability of each individual trait to determine the probability of the overall phenotype. Assuming inheritance is independent, in a cross between two tall pea plants with yellow round peas and purple flowers, genotype YyRrTtPp, what is the probability that offspring will be tall and have white flowers and produce yellow wrinkled peas? Your answer should be the value of A in the fraction A/256

9

What is a polymorphic gene? A gene that has more than one common variant A polymorphic gene is one with more than one common variant. The different common alleles can be considered to be part of the normal allele population. An example is the ABO blood type alleles. Page reference: p320 A gene that has accumulated more than the usual number of mutations. A gene that has multiple functions A gene that is always heterozygous

A gene that has more than one common variant

Which of the following statements about genetic and physical maps are true? Please select all that apply. A genetic map unit always corresponds to the same amount of DNA for a particular species A physical map shows the location of genes on the DNA molecule The order of genes is the same in physical and genetic maps Physical maps give the probability that alleles of two genes will be inherited together

A physical map shows the location of genes on the DNA molecule The order of genes is the same in physical and genetic maps

A cross between two true-breeding strains (P0 generation) with genotypes A/A;b/b and a/a;B/B results in an F1 genotype of A/a;B/b. If this is test-crossed to a/a;b/b, which of the following offspring have parental phenotypes? Please select all that apply. A/a;B/b A/a;b/b a/a;B/b a/a;b/b

A/a;b/b a/a;B/b

What does linkage disequilibrium refer to? Genes on the same chromosome Association of phenotypes Sex-linked phenotypes Genes on different chromosomes

Association of phenotypes

What does a Manhattan plot show? The inheritance pattern of a particular trait. The genes associated with a particular trait The distribution of phenotypes in a population Associations of phenotypes with locations on the chromosomes

Associations of phenotypes with locations on the chromosomes

Match the phenotypes to their dominance descriptions for the following example. Growth of a heterozygote, Yy, is the same as that of homozygote YY. Homozygote yy does not grow. Yy produces about half as much pigment as YY, and yy does not produce any pigment. ______ Growth ______ DNA sequence _____ Pigment Production A. Incomplete Dominance B. Dominant C. Co-dominance

B. Dominant C. Co-dominance A. Incomplete Dominance

Microarrays can be used to examine gene expression and also to conduct genome-wide association studies (GWAS). Which of the following are true about these microarrays? Please select all that apply. Both expression microarrays and GWAS arrays are made of printed DNA features Both expression microarrays and GWAS arrays are hybridized with genomic DNA Both expression microarrays and GWAS arrays are made of printed RNA features Expression microarrays contain features from genes, GWAS arrays contain features from the whole genome

Both expression microarrays and GWAS arrays are made of printed DNA features Expression microarrays contain features from genes, GWAS arrays contain features from the whole genome

Cystic fibrosis (CF) is a common disease in European populations. Most individuals with the disease have the same mutation in the CF gene. What does this suggest about the evolution of CF? Carriers of the European CF mutation are descended from the same person The CF mutation first arose in Africa The CF mutation is more common in homozygotes than in heterozygotes There is a common variant for CF

Carriers of the European CF mutation are descended from the same person

What is the term for a mutation whose phenotypic effects are only seen under certain environmental conditions? Recessive Conditional Dominant Co-dominant

Conditional

How does gene duplication contribute to evolution? Gene duplication results in less gene product being made Organisms containing duplicated genes are less fit Gene duplication results in an increased number of chromosomes Duplicated genes can be more tolerant of mutations than non-duplicated genes

Duplicated genes can be more tolerant of mutations than non-duplicated genes

Exome sequencing is powerful technique that has been used to identify genes linked to a number of rare genetic conditions. Which of the following is a disadvantage of exome sequencing? Exome sequencing does not directly identify the gene, but identifies only the region of the genome containing the gene. Exome sequencing does not identify conditions linked to regulatory regions. Exome sequencing only identifies conditions associated with recessive alleles. Exome sequences are more difficult to analyze than whole genome sequences

Exome sequencing does not identify conditions linked to regulatory regions.

Inferring a genotype from a phenotype can be challenging due to a range of complicating factors that may also affect the phenotype. Which of the following factors can influence phenotype? Please select all that apply. Exposure to toxins Gene regulation Nutritional conditions Temperature

Exposure to toxins Gene regulation Nutritional conditions Temperature

Complex traits are affected by multiple genes. Individuals with the same phenotype for a complex trait will also share the same genotype. false true

False

For a locus to be classed as polymorphic, the second most common polymorphism must be found at least 10% of the time. false true

False

If recombination rate is high, then a particular combination of alleles is likely to be transferred to the next generation intact. true false

False

True or false? Coat color in Labrador retrievers is usually yellow, black, or chocolate brown. This is determined by alleles of the E gene and the B gene. Dogs with recessive e alleles (ee) are yellow, even when the B locus is functional. This means that the B gene is epistatic to the E gene. True False

False

True or false? Mutations with more extensive deleterious pleiotropic effects are more likely to be subject to positive selection than mutations with less extensive effects. True False

False

True or false? Phenotypic ratios in offspring are sometimes unexpected, indicating that not all genetic inheritance follows Mendel's principles. True False

False

When genes are on the same chromosome, the alleles on one of the two homologous chromosomes are considered to be in trans. false true

False

Nine features of a GWAS array are shown, as well as the hybridization results from an experiment (hybridized = red, not hybridized = white). What is the genotype of the person being investigated? G/A, T/C, T/T A/C, A/A, G/A G/G, T/T, G/G G/G, A/T, C/T

G/G, A/T, C/T

Which if the following statements about human evolution and diversity is true? Most of the genetic diversity in humans is found outside of Africa Genetic diversity is greater in Africa than in other regions of the world Humans first evolved in the Middle East Human populations are a subset of the genetic diversity found in the Middle East

Genetic diversity is greater in Africa than in other regions of the world

Ascomycete fungi are valuable models for studying recombination. Which of the following are advantages of these systems? Please select all that apply. Haploids can undergo meiosis Haploid progeny can be analyzed directly Test crossing is not always needed The four products of meiosis remain together

Haploid progeny can be analyzed directly Test crossing is not always needed The four products of meiosis remain together

What term is used for a block of alleles that is inherited together? Genome Polymorphism Haplotype Marker

Haplotype

In the ABO blood system, what genotypes do two parents need to have in order to be able to produce children with all the possible ABO blood types. Please select all that apply. IBIB IAIB ii IAIA IBi IAi

IBi IAi

Which of the following can a genome-wide association study not do? Identify haplotypes associated with a trait Identify causative genes underlying a trait Identify multiple regions of the genome that influence a trait Identify different haplotypes in different populations

Identify causative genes underlying a trait

What is the difference between co-dominance and incomplete dominance? a) In co-dominance, both alleles produce sufficient protein. In incomplete dominance, neither allele makes sufficient protein. b) In co-dominance, the phenotype reflects both alleles. For incomplete dominance, the phenotype lies between the phenotypes of the parent alleles. c) In co-dominance, the phenotype lies between the phenotypes of the parent alleles. For incomplete dominance, the phenotype of both alleles is seen. d) In co-dominance, neither allele produces sufficient protein. In incomplete dominance, both alleles make sufficient protein.

In co-dominance, the phenotype reflects both alleles. For incomplete dominance, the phenotype lies between the phenotypes of the parent alleles.

Which of the following pieces of evidence suggest that genetic factors have an influence on height? Please select all that apply. Japanese Americans tend to be shorter than Swedish Americans Sibling heights are often more similar to each other than to heights of others in the same environment. Adopted children are closer in height to their birth parents than their adopted parents Identical twins are not always the same height

Japanese Americans tend to be shorter than Swedish Americans Sibling heights are often more similar to each other than to heights of others in the same environment. Adopted children are closer in height to their birth parents than their adopted parents

Genetic analysis in model organisms such as Drosophila cannot easily be replicated in humans. Which of the following factors are true of Drosophila but not humans? Please select all that apply. Haploid gametes Large numbers of offspring Short generation times Crossovers between homologous chromosomes

Large numbers of offspring Short generation times

Consider two genes, A and B, with alleles A & a, and B & b. In a population, 60% of gametes have A and 40% have a; 90% of gametes have B and 10% have b. In an experiment, 625 gametes are AB, 408 are aB, 72 are Ab, and 45 ab. Which of the following statements are true about genes A and B in this population? Please select all that apply. Linkage disequilibrium is not present Alleles A and B are linked Linkage disequilibrium is present Alleles A and B are not linked

Linkage disequilibrium is not present Alleles A and B are not linked

What term is used for a gene that contributes to more than one phenotype? Dominant Pleiotropic Epistatic Complex

Pleiotropic

Why are regions between genes (intergenic regions) often chosen as mapping markers in genome-wide association studies? Please select all that apply. Intergenic regions are less likely to contain crossovers during meiosis Variation in intergenic regions is more strongly linked to ethnicity than is variation in genic regions Polymorphism frequency in intergenic regions is usually unaffected by the health of the individuals Intergenic regions are usually not under positive or negative selection

Polymorphism frequency in intergenic regions is usually unaffected by the health of the individuals Intergenic regions are usually not under positive or negative selection

What molecular genetics term is used for making a connection between the gene as it relates to a phenotype and the gene in terms of its DNA sequence? Positional cloning Linkage Mapping Genome-wide association

Positional cloning

What term is used for genes that affect the phenotype of a complex trait? Polygenic traits Quantitative trait loci Polymorphic genes Multifactorial traits

Quantitative trait loci

Why are lethal alleles usually recessive? Lethal alleles prevent an organism reproducing Recessive lethal alleles can be passed from generation to generation but dominant lethal alleles are not inherited. Dominant lethal alleles are very uncommon but recessive lethal alleles are very common Lethal alleles are usually dominant rather than recessive

Recessive lethal alleles can be passed from generation to generation but dominant lethal alleles are not inherited.

Which of the following statements about double-crossovers are true? Please select all that apply. Double-crossovers result in the rate of recombination between two loci being overestimated The chance of double crossovers occurring between two loci increases with the distance between the loci Double crossovers result in the estimated map distance between two loci being underestimated The probability of a double crossover occurring between two loci is higher than the probability that a single crossover will occur between the same loci.

The chance of double crossovers occurring between two loci increases with the distance between the loci Double crossovers result in the estimated map distance between two loci being underestimated

What is the purpose of a complementation test? To determine whether lethal alleles are present To determine whether an organism is homozygous or recessive at a particular locus. To determine whether an allele is dominant or recessive To determine whether two mutants with the same phenotype have defects in the same gene

To determine whether two mutants with the same phenotype have defects in the same gene

What are cytological maps used for? To determine the gene responsible for a trait To determine the recombination rate between loci To examine changes in chromosomal structure To examine whether cells are undergoing meiosis

To examine changes in chromosomal structure

Phenotypes are not always inherited in a predictable Mendelian manner. Which of the following are possible reasons for this? Please select all that apply. Meiosis is required for Mendelian inheritance Traits may be influenced by multiple genes A trait may be affected by the environment Alleles may not be completely dominant

Traits may be influenced by multiple genes A trait may be affected by the environment Alleles may not be completely dominant

Genes that are located close together on a homologous chromosome are more likely to be inherited together than genes that are further apart. true false

True

People with a genetic disease that is common in one population but uncommon in other populations usually have the same haplotype. true false

True

True or false? Mendel's law of independent assortment suggests that the inheritance of one gene or trait does not influence the inheritance of a separate unlinked trait.

True

Two genes can be syntenic and unlinked. true false

True

An experiment is performed with a mutant yeast strain that cannot survive without being given tryptophan. The yeast strain is transformed with a plasmid containing gene A or a plasmid containing gene B. Yeast cells transformed with gene B require supplementary tryptophan to survive, but yeast transformed with gene A can survive in the absence of tryptophan. Which of the following conclusions can be drawn from this experiment? Please select all that apply. Tryptophan is essential for growth in this yeast species Gene B is not needed for tryptophan synthesis Gene A is not needed for tryptophan synthesis Gene B is needed for tryptophan synthesis Gene A is needed for tryptophan synthesis

Tryptophan is essential for growth in this yeast species Gene A is needed for tryptophan synthesis

What is a tetrad? The structure that joins chromosomes to microtubules Four paired homologous chromosomes Two pairs of sister chromatids The cellular structure that contains the four products of meiosis

Two pairs of sister chromatids

The On-line Mendelian Inheritance in Man (OMIM) database is an important resource for human genetics. Most of the content in OMIM relates to monogenic diseases. Which of the following conditions are not generally thought to be monogenic? Please select all that apply. Huntington disease Type 2 diabetes Cystic fibrosis Hypertension

Type 2 diabetes Hypertension

What is meant by variable expressivity? a) When penetrance is 100% b) When an allele is sometimes dominant and sometimes recessive c) When a group of affected individuals do not all have exactly the same mutant phenotype d) When members of a group of true-breeding wild-type individuals sometimes exhibit the phenotype of a recessive gene

When a group of affected individuals do not all have exactly the same mutant phenotype

Which of the following statements about the offspring of a cross between two carriers of a lethal recessive gene are true? Please select all that apply. Offspring genotypes follow a 2:1 ratio Where the wild-type gene is dominant, all surviving offspring have the same phenotype The genotypes of the offspring follow the same Mendelian patterns as for crosses not involving lethal genes 50% of live offspring display the heterozygous phenotype

Where the wild-type gene is dominant, all surviving offspring have the same phenotype The genotypes of the offspring follow the same Mendelian patterns as for crosses not involving lethal genes

Syntenic blocks are sections of chromosomes that have remained largely intact during evolution. For example, human chromosome 4 corresponds to syntenic blocks on mouse chromosomes 3, 5, and 8. Which of the following statements about synteny are true? Please select all that apply. a) X chromosomes are largely syntenic between placental mammals b) The ancestor of humans and mouse had syntenic blocks as in human and these were rearranged to make different chromosomes in mouse c) The ancestor of humans and mouse probably had similar syntenic blocks to those currently seen in mouse and human d) No crossovers occur in syntenic blocks

X chromosomes are largely syntenic between placental mammals The ancestor of humans and mouse probably had similar syntenic blocks to those currently seen in mouse and human

Alleles for hairy body, curled wings, and glass eyes are on the same Drosophila chromosome. There are 23.5 map units between hairy and curled and 13 map units between curled and glass. One percent of offspring from a test cross had double crossovers. Was crossover interference observed? No. Interference is 0% Yes. Interference is 33% No. Interference is 100% Yes. Interference is 67%

Yes. Interference is 67%

There are four alleles: Cr, Cy,Cb, and Cw. Individuals homozygous for these allels have red, yellow, black , and brown hair, respectively. Cr_individuals have red hair. Heterozygotes carrying Cy do not have yellow hair. In a cross between homozygous Cb and Cw individuals, ¾ of the offspiring have brown hair. a. Cr,Cy,Cb,Cw b. Cr,Cb,Cw,Cy c. Cb,Cr,Cw,Cy d. Cr,Cw,Cb,Cy Cr 2 Cw 1 (most dominant) Cb 3 Cy 4 (least dominant) All Cr individuals have red hair, regardless of the other alleles, so this must be most dominant. Similarly, Cy heterozygotes do not have yellow hair, so all the other alleles must be dominant to Cy. In a cross between Cb and Cw, the heterozygotes have brown hair (CbCb = black, CbCw = brown, CwCw = brown), so Cw is dominant to Cb. Page reference: p318

a. Cr,Cw,Cb,Cy

Which of the following statements about lactase persistence in humans are true? Select all that apply. a. Lactase persistent is a derived condition b. Lactase persistence is an example of a positive selection c. The mutation rate in the lactase gene is higher in herding populations than in non-herding populations d. Lactase persistence is due to mutations in the lactase gene e. Most people do not exhibit lactase persistence

a. Lactase persistent is a derived condition b. Lactase persistence is an example of a positive selection e. Most people do not exhibit lactase persistence

A Drosophila parent fly heterozygous for alleles for black body, dumpy wings, and purple eyes was test-crossed to a fly that was homozygous recessive for all three genes. The genes are all on the same chromosome. The offspring had the following phenotypes in the following numbers: What were the genotypes of the chromosomes in the parent? Please select all that apply. b+ p d+ b+ p+ d b p+ d+ b p d b+ p+ d+ b p+ d

b p d b+ p+ d+

Which of the following statements about heterozygote advantage are true. Select all that apply. a. The AA genotype is more advantageous than the Aa genotype b. The locus under selection is polymorphic c. Alleles do not become fixed with heterozygote advantage d. Heterozygote advantage is a type of purifying selection

b. The locus under selection is polymorphic c. Alleles do not become fixed with heterozygote advantage

Which structure that forms during meiosis leads directly to the formation of recombinant chromosomes? sister chromatid crossover centromere microtubule

crossover

A group of organisms in a specific place and time that is capable of genetic exchanges is termed an ______ population.

effective

If all individuals in a population carry the same allele for a particular gene, then the allele is said to be ____ in that population

fixed

Migrating humans often lived in small groups, and by chance the genetic diversity in these groups may have been different to the diversity in the wider population. This phenomenon is known as the ____ ___

founder effect

What term is used for the fraction of phenotypic variation that can be attributed to genetic differences among individuals? mean variance heritability quantitative traits

heritability

If fewer than 100% of individuals that are homozygous for a mutant allele exhibit the mutant phenotype, the mutant allele is described as having reduced______

penetrance

Match the missing words in the following phrase. Dominance is defined by the [A], not the [B], of the [C]. If this is the same as in the [D] for one of the alleles, then that allele is dominant. phenotype genotype heterozygote homozygote

phenotype :A genotype :B heterozygote :C homozygote :D

A Drosophila fly heterozygous for alleles for black body, dumpy wings, and purple eyes was test-crossed to a fly that was homozygous recessive for all three genes. The genes are all on the same chromosome. The offspring had the following phenotypes in the following numbers: What is the order of the genes on the chromosome? dumpy - purple - black purple - black - dumpy black - purple - dumpy black - dumpy - purple

purple - black - dumpy