Genetics and Molecular Biology Final Exam

negatively supercoiled

A DNA molecule 300 bp long has 20 complete rotations. This DNA molecule is _____. A. positively supercoiled B. negatively supercoiled C. relaxed

relaxed

A DNA molecule 500 bp long has 50 complete rotations. This DNA molecule is ____. A. single-stranded B. positively supercoiled C. negatively supercoiled D. relaxed

Green = GG Variegated = Gg

A cross between two variegated plants yields progeny where 1/3 are green and 2/3 are variegated. What are the genotypes of the green progeny and the variegated progeny? A. Green = GG or Gg Variegated = gg B. Green = GG Variegated = Gg C. Green = Gg Variegated = gg D. Two genes are required to produce this inheritance pattern E. Two answers could be correct

37

A diploid organism has 2n = 36 chromosomes. How many chromosomes will be found in a trisomic member of this species?

laying down an RNA primer to start DNA replication

A eukaryotic cell containing defective DNA polymerase alpha would have difficultly performing which of the following? A. relieving tension in the DNA due to supercoiling B. creating an open replication fork in DNA by breaking hydrogen bonds C. connecting Okazaki fragments D. laying down an RNA primer to start DNA replication

5/16 ?

A family has 5 children. What is the probability of having 3 boys and 2 girls? A. 1/2 B. 3/8 C. 10/16 D. 5/16 E. None of the answers are correct

700 bp of DNA wrap around each histone

A novel organism has a genome complexed with three histone-like proteins. Nuclease digestion gives bands of 700 bp, 1400 bp, and 2100 bp. What is the likely explanation? A. 700 bp of DNA wrap around each histone B. the histones are different sizes and bind different lengths of DNA C. the histone-like proteins don't bind to DNA D. none of the above

1/128

AA Bb Cc Dd x Aa Bb Cc Dd What fraction of offspring will have the genotype Aa bb CC dd? A. 3/16 B. 1/32 C. 1/64 D. 1/128

3/16

Aa Bb x Aa Bb What fraction of offspring will have the phenotype A- bb? A. 1/32 B. 3/16 C. 3/32 D. 1/64

1/16

AaBb x AaBb What fraction of offspring will have the genotype AABB? A. 1/2 B. 1/4 C. 1/8 D. 1/16 E/ 1/32

conservative

After the first round of replication, Meselson and Stahl saw only one DNA band of density intermediate to DNA containing only 15N or 14N. After this observation, which hypothesis for DNA replication could be eliminated? A. conservative B. semiconservative C. dispersive D. both a and c

a short stretch of RNA nucleotides

All DNA polymerases require a primer with a 3' OH group to begin DNA synthesis. The primer is ______. A. a free DNA nucleotide B. a short stretch of RNA nucleotides C. a 3' OH group that is part of the primase enzyme D. all of the above

? no correct answer

An F1 mouse was crossed to a mouse homozygous for the B6 alleles. What percentage of offspring will have the genotype ArpC3B6/B6 M5ahl8129/B6? A. 0.5% B. 1.5% C. 3% D. 0.015%

44%

An organism that has the haplotypes AB and ab with 12% recombination frequency, what is the % of gametes with ab haplotype? A. 6% B. 12% C. 24% D. 44%

20%

Assume that long fingers are inherited as a recessive trait with 80% penetrance. Two people heterozygous for long fingers mate. What is the probability that their first child will have long fingers? A. 15% B. 50% C. 60% D. 20% E. none of the provided answers are correct

appear only when both parents carry a copy of the gene for the trait, which is more likely when the parents are related

Autosomal recessive traits often appear in pedigrees in which there have been consanguineous matings because these traits A. appear equally in males and females B. usually arises in children born to parents who are affected C. tend to skip generations D. appear only when both parents carry a copy of the gene for the trait, which is more likely when the parents are related

heterochromatin

Barr bodies are ____. A. heterochromatin B. euchromatin

pair of homologous chromosomes seen in early prophase I

Bivalent

Xo Y

Coat color in cats is determined by genes at several different loci. At one locus on the X chromosome, one allele (X+) codes for black fur; another allele (Xo) encodes orange fur. Females can be black (X+ X+), orange (Xo Xo) or a mixture of orange and black called tortoiseshell (X+ Xo). Males are either black (X+ Y) or orange (Xo Y). Bill has a female tortoiseshell cat named Patches. One night, Patches escapes from Bill's house, spends the night out, and mates with a stray male. Patches later gives birth to the following kittens: one orange male, one black male, two tortoiseshell females, and one orange female. What is the genotype of the stray male? A. X+ Y B. Xo Y C. X+ Xo Y D. can't be determined

eukaryotic chromosomes have many separate origins of replication, whereas prokaryotic chromosomes have a single origin of replication

DNA replication in eukaryotes differs from replication in prokaryotes in that ________. A. DNA replication in eukaryotes is conservative, whereas in prokaryotes it is semiconservative B. eukaryotes have bidirectional replication from an origin, whereas in prokaryotes replication proceeds in one direction from an origin C. eukaryotic chromosomes have many separate origins of replication, whereas prokaryotic chromosomes have a single origin of replication D. linear eukaryotic chromosomes are replicated by a mechanism called theta replication, whereas circular prokaryotic chromosomes are replicated by the rolling-circle mechanism

decrease the amount of genetic material in a particular chromosome

Deletions

increase the amount of genetic material in a particular chromosome

Duplication

?

Explain the pedigree.

?

Explain why sex-chromosome aneuploids are more common than autosomal aneuploids in humans and mammals.

each crossover takes place between only two of the four chromatids of a homologous pair

For single crossovers, the frequency of recombinant gametes is half because A. a test cross between a homozygote and heterozygote produces 1/2 heterozygous and 1/2 homozygous progeny B. the frequency of recombination is always 50% C. each crossover takes place between only two of the four chromatids of a homologous pair D. crossovers occur in about 50% of meiosis

0.213

From the cross, AB/ab x ab/ab, what is the recombination frequency if the progeny numbers are 72 AB/ab, 68 ab/ab, and 21 aB/ab? A. 0.213 B.0.271 C. 0.500 D. 0.787

autosomal traits

Genes found in the pseudoautosomal regions of the X and Y chromosome behave as A. sex-linked traits B. autosomal traits C. hemizygous alleles

be located in regions of relaxed chromatin

Genes that are transcriptionally active will ______. A. be less sensitive to DNase I digestion B. be located in regions of relaxed chromatin C. have more heavily methylated DNA D. all of the above will occur

9/16, 3/8, 1/16

Hearing loss is a recessive trait. Two heterozygous parents have 2 children. What are the probabilities of having 1) both children with normal hearing, 2) one child with normal hearing and one deaf child and 3) both children deaf? A. 1/4, 1/2, 1/4 B. 1/16, 1/2, 1/32 C. 9/16, 3/8, 1/16 D. 9/16, 3/8, 9/16

contains genes that are transcribed at high levels

Heterochromatin is characterized by all of the following EXCEPT that it _______. A. is present all over the inactive X chromosomes in female mammals B. contains genes that are transcribed at high levels C. is present on most of the Y chromosomes of male mammals D. remains highly condensed throughout the cell cycle E. is present at centromeres and telomeres

almost identical chromosomes one inherited from each parent

Homologous chromosomes

1

How many Barr bodies are present in an individual with Klinefelter syndrome (XXY)? A. 0 B. 1 C. 2 D. 3

340

How many nanometers long is a 1000 base pair strand of DNA?

all sons will be color blind

If a color-blind female has children, what do we know about all of her sons? A. half of the sons will be color blind B. all sons will be color blind C. all sons will have normal color vision D. she would not be able to have a son E. it is impossible to know without knowing the father's genotype

16

If a diploid cell has 4 pairs of homologous chromosomes, how many different gametes can be formed based on how they align in metaphase I of meiosis?

50

If a normal diploid somatic cell has 50 chromosomes. How many DNA molecules are in a cell after the first meiotic division?

100

If a piece of chromatin contained 200 copies of the histone H4, then how many nucleosomes would be present? A. 100 B. 200 C. 40 D. we cannot say. histones are randomly placed throughout chromatin

32

If a typical somatic cell has 64 chromosomes, how many chromosomes are expected in each gamete of that organism? A. 32 B. 16 C. 64 D. 128 E. 8

a 3:1 phenotypic ratio in males and the same in females

If the eye color trait Morgan studied in fruit flies had been caused by a single gene on an autosome, he would have expected which of the following in his F2? A. 1:1 phenotypic ratio in males and the same in females B. all red-eyed males and females C. all white-eyed males and females D. a 3:1 phenotypic ratio in males and the same in females

1/8

If the genotype of individual 1 in generation I is Aa, what is the probability that all offspring in generation II are Aa? A. 1/8 B. 1/2 C. 1/32 D. 10/32

5/8

If the probability of being blood-type A is 1/8 and the probability of blood O is 1/2, what is the probability of being either blood-type A or O? A. 5/8 B. 1/2 C. 1/8 D. 1/16

24

In a diploid organism with 48 total chromosomes, how many tetrads would be expected to form during meiosis? A. 12 B. 24 C. 48 D. 96

There is a 50% to 90% chance that the difference between expected and observed progeny is due to chance

In an experiment, you do a chi-square test comparing observed and expected progeny. Your calculated chi-square is 0.375. With 1 degree of freedom, this corresponds to a probability between 0.9 and 0.5. What does this mean? A. There is a 50% to 90% chance that you did the experiment correctly B. There is a greater than 50% chance that the difference between expected and observed progeny is due to something other than chance C. You probably made an error in calculating your expected progeny to obtain this probability D. There is a 50% to 90% chance that the difference between expected and observed progeny is due to chance

30%

In humans, 20% of bases in DNA are cytosine (C). What percentage of the bases are expected to be thymine (T)? A. 20% B. 25% C. 30% D. 40% E. 80%

2 full color : 1 chinchilla : 1 dilution

In mice, there is a set of multiple alleles of a gene for coat color. Four of these form an allelic series as follows: C = full color (wild type), cch = chinchilla, cd = dilution, c = albino Given that the gene locus is not sex-linked and that each allele is completely dominant to those lower in the list, what are the phenotypic ratios expected in the following cross? wild type (heterozygous for dilution) × chinchilla (heterozygous for albino) A. 3 full color : 1 dilution B. 1 full color : 2 dilution : 1 albino C. 2 full color : 2 dilution D. 2 full color : 1 chinchilla : 1 dilution

change the position of DNA sequences in a single chromosome without changing the amount of genetic material

Inversion

autosomal dominant

Many studies have suggested a strong genetic predisposition to migraine headaches, but the mode of inheritance is not clear. L. Russo and colleagues examined migraine headaches in several families, two of which are shown below. Qhat is the most likely mode of inheritance for migraine headaches in these families? A. autosomal recessive B. autosomal dominant C. x-linked recessive D. x-linked dominant

autosomal dominant

Mode of inheritance? A. autosomal recessive B. autosomal dominant C. x-linked recessive D. x-linked dominant

autosomal recessive

Mode? A. autosomal recessive B. autosomal dominant C. x-linked recessive D. x-linked dominant

autosomal dominant

Mode? A. autosomal recessive B. autosomal dominant C. y-linked D. x-linked dominant

y-linked

Mode? A. autosomal recessive B. autosomal dominant C. y-linked D. x-linked dominant

x-linked dominant

Mode? A. autosomal recessive B. autosomal dominant C. x-linked recessive D. x-linked dominant

autosomal dominant with incomplete penetrance, autosomal dominant but sex-limited and autosomal recessive

Mode? Select all that apply. A. y-linked B. autosomal dominant with incomplete penetrance C. autosomal dominant but sex limited D. autosomal recessive

x-linked recessive

On the basis of this pedigree, what is the most likely mode of inheritance for the disease? A. autosomal recessive B. autosomal dominant C. x-linked recessive D. x-linked dominant

44 or 40

One species has 32 chromosomes and another species has 24 chromosomes. In an allotriploid of these two species, how many chromosomes would there be? A. 44 or 40 B. 56 C. 84 D. 28 E. 48 or 36

incomplete dominance

Plants with large leaves are PP are crossed to plants with small leaves are P'P'. The offspring have medium leaves. This is an example of________. A. blending B. epistasis C. complementation D. incomplete dominance

increase the amount of genetic material in all chromosomes

Polyploidy

eukaryotic DNA polymerases are, in general, much more error-prone

Replication of eukaryotic chromosomes presents several challenges that are not found in prokaryotic cells. These challenges include all of the following EXCEPT A. removal and reassembly of nucleosomes B. eukaryotic DNA polymerases are, in general, much more error-prone C. replication of chromosome ends D. coordination of replication with the cell cycle

determined by genes on the sex chromosomes

Sex-linked characteristics are characteristics that are A. determined by genes on the sex chromosomes B. different between males and females C. involved in reproduction D. found in only one sex

either of two identical chromosomes following DNA replication that are joined at the centromere

Sister chromatids

2

Some sweet-pea plants have purple flowers and other plants have white flowers. A homozygous, true-breeding, variety of pea that has purple flowers is crossed with a homozygous, true-breeding, variety that has white flowers. All the F1 have purple flowers. When these F1 are self-fertilized, the F2 appear in a ratio of 9/16 purple to 7/16 white. How many genes are involved? A. 1 B. 2 C. 3

PP ww is purple

Some sweet-pea plants have purple flowers and other plants have white flowers. A homozygous, true-breeding, variety of pea that has purple flowers is crossed with a homozygous, true-breeding, variety that has white flowers. All the F1 have purple flowers. When these F1 are self-fertilized, the F2 appear in a ration of 9/16 purple to 7/16 white. We want to know the genotypes and corresponding phenotypes of the F2 progeny. Which of the following is WRONG? A. P- W- is purple B. PP ww is purple C. pp ww is white D. pp W- is white

PpWw

Some sweet-pea plants have purple flowers and other plants have white flowers. A homozygous, true-breeding, variety of pea that has purple flowers is crossed with a homozygous, true-breeding, variety that has white flowers. All the F1 have purple flowers. When these F1 are self-fertilized, the F2 appear in a ration of 9/16 purple to 7/16 white. What are the genotypes of the F1 parents? A. PpWw B. PPww C. ppWW

1 red : 1 purple : 0 white

Suppose a particular species of a tulip plant has three alleles for the gene that is responsible for flower color. The CR allele produces red tulips, the CP allele produces purple tulips, the CW allele produces white tulips. CR is dominant over CP and CW, and CP is dominant over CW. From the following cross CRCP x CWCW what is the expected phenotypic ratio? A. 1 red : 1 purple : 0 white B. 1 red : 0 purple : 0 white C. 1 red : 1 purple : 1 white D. 3 red : 1 purple : 0 white

that protein was the genetic material in phage

Suppose that Hershey and Chase found that phage ghosts contained 32P labels but the label was absent from infected E. coli. Furthermore, suppose they found 35S lacking in the ghosts and present in the infected E. coli. They would have concluded ______. A. that protein was the genetic material in phage B. that DNA was the genetic material in phage C. that somehow the radioactivity prevented DNA from getting into E. coli D. that protein and DNA together made up the genetic material E. none of the above

True

T/F? Autosomal mutations are heritable.

True

T/F? Children of a cross between a man who is blood-type A and a women of blood-type B could have blood type O.

False

T/F? During meiosis, chromosome ploidy reduction takes place in anaphase II.

False

T/F? From a cross of white-eyed females and red-eyed males, 1/2 of females will have white eyes.

False

T/F? Mutations in the mitochondrial genome can be passed from father to son.

True

T/F? Prokaryotes separate replicated circular chromosomes to opposite sides of the cell.

False

T/F? Sister chromatids separate during anaphase I of meiosis.

True

T/F? The null hypothesis should be rejected?

more condensed pair of chromosomes seen in later stages of prophase I

Tetrad

Y, transcription factor

The SRY gene is on the _____ chromosome and it encodes a ____ required for the male phenotype A. Y, transcription factor B. Y, serum response factor C. X, transcription factor D. X, serum response factor

heritability of the disease is high indicating that genes play a large role

The concordance rate for a disease was 68% in monozygotic twins and 39% in dizygotic twins. Which of the following is true? A. Too many variables are present making interpretation impossible B. Heritability of the disease is high indicating that genes play a large role C. The disease phenotype is largely determined by environmental factors D. This disease has variable penetrance

inversion

The expression of some genes is dependent upon their chromosomal position. Which kind of chromosome rearrangement would most likely cause a position-effect phenotype? A. deletion B. tandem duplication C. segmental duplication D. inversion E. all of the above

Contributes to genetic diversity of a species

The following statements describe either mitosis, meiosis, or both (mitosis and meiosis). Which of the following statements is unique to meiosis only? A. Contributes to genetic diversity of a species B. DNA is duplicated before cell division C. Results in genetically identical cells D. Used during asexual reproduction

size of the gametes; males produce small gametes and females produce larger gametes

The fundamental difference between males and females across all organisms is the A. presence or absence of a Y chromosome B. ability to nurture its offspring C. size of the gametes; males produce small gametes and females produce larger gametes D. presence or absence of two XX chromosomes

0

The pedigree above shows the segregation of a rare autosomal dominant trait that displays full penetrance. Assuming that V-2 marries a normal female and no new mutations are involved, what is the probability that their first child will be affected with the trait? A. 0 B. 1/4 C. 1/2 D. 3/4

move DNA from one chromosome to a nonhomologous chromosome

Translocations

all of the above

Trisomy and monosomy can be a product of nondisjunction in _____. A. meiosis I B. meiosis II C. mitosis D. both a and b E. all of the above

FG and fg

What are the F1 haplotypes? A. FG B. fg C. FG and fg D. Fg and fG

?

What could produce this pedigree?

CAGGTAAGTGTTTTT

What do you think the consensus sequence is?

AA or Aa

What is the genotype of individual 1 in generation I? A. AA B. Aa C. aa D. AA or Aa

autosomal recessive

What is the inheritance pattern? A. X-linked recessive B. X-linked dominant C. Autosomal recessive D. Autosomal dominant

autosomal recessive

What is the likely mode of inheritance in the following pedigree? A. X-linked recessive B. Autosomal dominant C. Autosomal Recessive D. X-linked dominant

STR

What is the most likely order of the linked genes R, S, and T if the distance between R and S is 22 m.u., the distance between S and T is 8 m.u., and the distance between R and T is 14 m.u.? A. RST B. STR C. TRS

one metacentric chromosome and one chromosome with two very short arms

What is the outcome of a Robertsonian translocation? A. two acrocentric chromosomes B. one metacentric chromosome and one chromosome with two very short arms C. one metacentric chromosome and one acrocentric chromosome D. two metacentric chromosomes

9:3:3:4

What is the phenotypic ratio for recessive epistasis when two heterozygous parents are crossed? A. 9:3:3:1 B. 9:7 C. 9:3:3:4 D. 12:3:1 E. depends on the trait

0.3

What is the recombination frequency?

1/4 red-eyed females, 1/4 white-eyed females, 1/4 red-eyed males, 1/4 white-eyed males

What phenotypes ratios would be expected in the F2 generation if white eyes was an X-linked dominant trait? (Parental cross of homozygous red-eyed females and white-eyed males) A. 1/4 red-eyed females, 1/4 white-eyed females, 1/4 red-eyed males, 1/4 white-eyed males B. 1/2 red-eyed females, 1/2 white-eyed males C. 1/2 white-eyed females, 1/2 red-eyed males D. 1/2 white-eyed females, 1/4 red-eyed males, 1/4 white-eyed males

haploinsufficient genes can result because too much gene product is produced

Which is NOT a way that deletions can cause abnormal phenotypes? A. if the centromere is deleted, then the whole chromosome could be lost during cell division B. recessive mutations may be expressed if the wild-type allele is deleted, a phenomenon called pseudo-dominance C. haploinsufficient genes can result because too much gene product is produced D. there may be an imbalance of gene products due to the lack of genetic information caused by deletion E. all of the above

translocations can cause regions of the chromosome to be duplicated

Which is NOT an effect of chromosomal translocations? A. translocated genes may become under the control of different regulatory sequences B. translocations can cause regions of the chromosome to be duplicated C. translocation breaks can disrupt existing gene function D. translocations can affect the number of chromosomes found in species through evolution

does not skip generations, affected offspring must have an affected parent unless they possess a new mutation, unaffected parents do not transmit the trait

Which of the following statements are true of autosomal dominant inheritance? Select all true answers. A. Does not skip generations B. Affected offspring mist have an affected parent unless they possess a new mutation C. Unaffected parents do not transmit the trait D. Affected fathers pass the trait to all their daughters E. When both parents are heterozygous, approximately one fourth of the offspring will be affected

negative supercoiled DNA is under-rotated and allows for easier strand separation during replication and transcription

Which statement is true regarding negative supercoiled DNA? A. negative supercoiled DNA is under-rotated and allows for easier strand separation during replication and transcription B. negative supercoiled DNA is not usually seen in cells C. negative supercoiled DNA has 10 base pairs per turn of its helix D. negative supercoiled DNA carries more negative charges than does positive supercoiled DNA

eye color

Which trait is most affected by genetics? A. measles B. tuberculosis C. high blood pressure D. eye color

the Tm of your sample would be greater than that od a sample that is very A-T rich

You are conducting an experiment where you must denature a strand of DNA that is very G-C rich. How would the melting temperature (Tm) of your DNA sample differ from that of a sample that is very A-T rich? A. the Tm is irrelevant to denaturation B. the Tm is only important for RNA C. the Tm of your sample would be the same as that of a sample that is very A-T rich D. the Tm of your sample would be less than that of a sample that is very A-T rich E. the Tm of your sample would be greater than that of a sample that is very A-T rich