Genetics Final Exam

Questão 1 de 112

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The full chemical name of DNA is .

Explicação

Questão 2 de 112

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The protein, , is needed to lay down a segment of RNA complementary to the DNA before replication can begin.

Explicação

Questão 3 de 112

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An origin of replication generally has (how many?) replication forks.

Explicação

Questão 4 de 112

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The discontinuous lagging strand on a replication fork consists of that are later ligated together to form one strand of DNA.

Explicação

Questão 5 de 112

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The E. coli chromosome contains (how many?) origin(s) of replication?

Explicação

Questão 6 de 112

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A prokaryote lacks a membrane.

Explicação

Questão 7 de 112

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Recombination is probably always initiated by of DNA.

Explicação

Questão 8 de 112

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The strand is synthesized continuously during DNA replication.

Explicação

Questão 9 de 112

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A enzyme recognizes a specific DNA sequence and is able to cleave the DNA generating either “blunt” or “sticky” ends of the DNA.

Explicação

Questão 10 de 112

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A virus that infects bacterial cells is called a .

Explicação

Questão 11 de 112

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The genetic material of some viruses such as pi X 174 and M13 is .

Explicação

Questão 12 de 112

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The genetic material of the viruses that cause polio and AIDS is .

Explicação

Questão 13 de 112

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Topoisomerase supercoils by nicking the DNA.

Explicação

Questão 14 de 112

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In E. coli, recombination begins at sites where recBCD nicks and displaces a strand.

Explicação

Questão 15 de 112

1

Which of the following is not true of DNA?

Selecione uma das seguintes:

It is acidic.
It contains deoxyribose.
It is found in cell nuclei.
It contains phosphate.
It contains proteins.

Explicação

Questão 16 de 112

1

The molecule of heredity is:

Selecione uma das seguintes:

RNA
DNA
protein
carbohydrate
none of the above

Explicação

Questão 17 de 112

1

The four subunits which compose DNA are called:

Selecione uma das seguintes:

phosphodiesters
proteins
nucleotides
nucleosides
polymers

Explicação

Questão 18 de 112

1

DNA is localized mainly in the

Selecione uma das seguintes:

cell membrane
endoplasmic reticulum
vacuoles
chromosomes
None of the above

Explicação

Questão 19 de 112

1

Each nucleotide of DNA is made up of:

Selecione uma das seguintes:

a deoxyribose sugar
a nitrogenous base
a phosphate
A and B only
All of the above

Explicação

Questão 20 de 112

1

The polarity of DNA synthesis is:

Selecione uma das seguintes:

5' → 3'
3' → 5'
5' → 2'
2' → 5'
none of the above

Explicação

Questão 21 de 112

1

In the Hershey and Chase experiment designed to determine the molecule of heredity, what was radiolabeled with 35-S?

Selecione uma das seguintes:

protein
DNA
RNA
rRNA
none of the above

Explicação

Questão 22 de 112

1

The ratio of _____ is 1:1.

Selecione uma das seguintes:

guanine to adenine
adenine to thymine
cytosine to adenine
uracil to cytosine
none of the above

Explicação

Questão 23 de 112

1

X-ray data showed that the spacing between repeating units along the axis of the DNA helix is:

Selecione uma das seguintes:

2.0 angstroms.
3.4 angstroms.
20 angstroms.
34 angstroms.
none of the above

Explicação

Questão 24 de 112

1

X-ray data showed that the DNA helix undergoes one complete turn every:

Selecione uma das seguintes:

2.0 angstroms.
3.4 angstroms.
20 angstroms.
34 angstroms.
none of the above

Explicação

Questão 25 de 112

1

________ bonds are responsible for the chemical affinity between A and T (or G and C) nucleotides.

Selecione uma das seguintes:

Ionic
Covalent
Hydrogen
Electro-ionic
none of the above

Explicação

Questão 26 de 112

1

_______ -form DNA spirals to the right and is the major form of naturally occurring DNA molecules.

Selecione uma das seguintes:

A
B
D
Y
Z

Explicação

Questão 27 de 112

1

The nucleotide that is present in RNA but not DNA is:

Selecione uma das seguintes:

thymine
uracil
adenine
cytosine
guanosine

Explicação

Questão 28 de 112

1

DNA replication occurs through a _________process.

Selecione uma das seguintes:

conservative
semiconervative
dispersive
transferal
none of the above

Explicação

Questão 29 de 112

1

During complementary base pairing, enzymes join the base's nucleotide to the preceding nucleotide by a __________bond.

Selecione uma das seguintes:

Hydrogen
Ionic
Phosphodiester
Electrostatic
None of the above

Explicação

Questão 30 de 112

1

During early interphase the state of the DNA can be described as:

Selecione uma das seguintes:

a single continuous linear double helix.
a double helix replicated semiconservatively.
a double helix replicated conservatively.
single-stranded DNA.
None of the above

Explicação

Questão 31 de 112

1

During the S phase of interphase, the state of the DNA can be described as:

Selecione uma das seguintes:

a single continuous linear double helix.
a double helix replicated semiconservatively.
a double helix replicated conservatively.
a triple helix replicated semiconservatively.
None of the above

Explicação

Questão 32 de 112

1

The step in DNA replication in which the replication proteins open up the double helix and prepare for complementary base pairing is called:

Selecione uma das seguintes:

Initiation
Elongation
Termination
Translation
Translocation

Explicação

Questão 33 de 112

1

The step in DNA replication in which the proteins connect the correct sequence of nucleotides into a continuous new strand is called:

Selecione uma das seguintes:

Initiation
Elongation
Termination
Translation
Translocation

Explicação

Questão 34 de 112

1

The step in DNA replication in which two replication forks moving in opposite directions may meet is called:

Selecione uma das seguintes:

Intiation
Elongation
Termination
Translation
Translocation

Explicação

Questão 35 de 112

1

The group of enzymes able to relax supercoils in DNA is called:

Selecione uma das seguintes:

Primases
Helicases
Topoisomerases
Telomeres
Ligases

Explicação

Questão 36 de 112

1

How many replication forks depart from an origin of replication?

Selecione uma das seguintes:

one
two
three
four
none of the above

Explicação

Questão 37 de 112

1

The protein that progressively unwinds DNA ahead of each replication fork is called:

Selecione uma das seguintes:

Primase
Helicase
Topoisomerase
Telomerase
Ligase

Explicação

Questão 38 de 112

1

In eukaryotic cells, replication proceeds from ____ origin(s) of replication.

Selecione uma das seguintes:

no
one
two
several
many

Explicação

Questão 39 de 112

1

Eukaryotic chromosomes have evolved special structures at the ends of chromosomes to ensure the replication of the two ends of linear chromosomes. These structures are

Selecione uma das seguintes:

methylases
capping proteins
ligases
telomerases
single-stranded binding proteins

Explicação

Questão 40 de 112

1

Which of the following is NOT involved in ensuring the accuracy of a cell's genetic information?

Selecione uma das seguintes:

redundancy
repair enzymes
precision of replication machinery
DNA polymerase proofreading mechanism
Restriction endonucleases

Explicação

Questão 41 de 112

1

The process of _________ is extremely important in generating genetic diversity.

Selecione uma das seguintes:

Translation
Transcription
Recombination
Transformation
None of the above

Explicação

Questão 42 de 112

1

Any deviation from the expected 2:2 segregation of parental alleles that results from recombination is known as:

Selecione uma das seguintes:

Allelic exchange
Gene conversion
Crossing over
Recombination
DNA replication

Explicação

Questão 43 de 112

1

Recombination involves the breakage and reunion of DNA molecules from:

Selecione uma das seguintes:

homologous nonsister chromatids
homologous sister chromatids
heterologous nonsister chromatids
heterologous sister chromatids
None of the above

Explicação

Questão 44 de 112

1

The nicking of DNA that initiates recombination during mitosis may be due to all but:

Selecione uma das seguintes:

instruction from normal cell-cycle program
X-rays
Chemical change
Physical change
Radiation

Explicação

Questão 45 de 112

1

What radiolabeled substance did Hershey and Chase use to label the protein component of the bacteriophage in their study to determine whether protein or DNA was necessary for phage production?

Selecione uma das seguintes:

nitrogen
carbon
sulfur
phosphorous
iodide

Explicação

Questão 46 de 112

1

If 35% of the bases in a region of the mouse genome are cytosine, what percentage in that region are adenine?

Selecione uma das seguintes:

15%
20%
30%
35%
none of the above

Explicação

Questão 47 de 112

1

The complementary sequence of 5' AATTCGCTTA 3' is:

Selecione uma das seguintes:

5' AATTCGCTTA 3'
3' AATTCGCTTA 5'
5' TAACGCTTAA 3'
5' TAAGCGAATT 3'
3' TAAGCGAATT 5'

Explicação

Questão 48 de 112

1

Two strains of S. cerevisae (yeast) are crossed. One has the genotype ABC and the other abc. Five sets of the resultant tetrads are noted below. In which set did a gene conversion event occur?

Selecione uma das seguintes:

abc, aBc, AbC, aBC
abc, abc, ABC, ABC
aBc, aBc, AbC, AbC
abC, abc, ABc, ABC
Abc, Abc, aBC, aBC

Explicação

Questão 49 de 112

1

Recombination occurs during meiotic ________.

Selecione uma das seguintes:

anaphase
interphase
prophase
metaphase
none of the above

Explicação

Questão 50 de 112

1

Without __________ regions on the DNA during recombination, gene conversion could not occur.

Selecione uma das seguintes:

homoduplex
heteroduplex
homotriplex
heterotriplex
none of the above

Explicação

Questão 51 de 112

1

Occasionally, a loss of function mutation may occur in the telomerase enzyme in a cell. What is likely to be the result of this mutation on the DNA in the cell over the the course of several rounds of mitosis?

Selecione uma das seguintes:

chromosome length will gradually increase
chromosome length will gradually decrease
chromosome length will stay constant
chromosomes will fail to dissociate after replication
none of the above

Explicação

Questão 52 de 112

1

Bacterial DNA is resistant to degradation by its own restriction enzymes through the protection of:

Selecione uma das seguintes:

Methylases
Recombinases
Topoisomerases
Ligases
Primases

Explicação

Questão 53 de 112

1

Hershey and Chase relied on ________ to physically separate the infected bacterial cells from the phage ghosts.

Selecione uma das seguintes:

radioactivity
gel filtration
ion exchange
centrifugation
none of the above

Explicação

Questão 54 de 112

1

Meselson and Stahl relied on equilibrium density gradient centrifugation in a _______ solution to resolve the DNA containing 14N from the DNA containing 15-N.

Selecione uma das seguintes:

radiolabeled phosphate
calcium chloride
radiolabeled nitrogen
sodium acetate
cesium chloride

Explicação

Questão 55 de 112

1

Preencha os espaços em branco para completar o texto.

Match the scientist with their contribution to understanding more about DNA
a. early recombination models
b. transformation
c. semiconservative replication
d. x-ray structure of DNA
e. revised recombination models
f. basic structure of DNA
g. DNA = molecule of heredity
h. discovery of “nuclein”
i. nucleotide ratios in DNA
j. famous phage blender experiment

55. Watson and Crick

56. Chargaff

57. Franklin and Wilkins

58. Griffith

59. Hershey and Chase

60. Miescher

61. Meselson and Stahl

62. Holliday

63. Meselson and Radding

64. Avery, MacLeod and McCarty

Explicação

Questão 56 de 112

1

Clique em cada ponto laranja e digite a resposta correta.

Diagram Matching (Match the region or item on the diagram with the correct term from the list below)

-lagging strand

-leading strand

-origin

-RNA primer

-Okazaki fragment

-helicase

-polymerase

Explicação

Questão 57 de 112

1

A phosphodiester bond joins one nucleotide together in the DNA polymer.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 58 de 112

1

Prokaryotes have a circular chromosome surrounded by a nuclear membrane.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 59 de 112

1

Transformation in bacteria results from the uptake of foreign DNA.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 60 de 112

1

DNA is highly negatively charged throughout the molecule and therefore has no

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 61 de 112

1

A region of DNA 100 bp in length has the potential to be represented by 4100 unique sequences.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 62 de 112

1

Viruses use only DNA as their genetic material.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 63 de 112

1

Restriction enzymes are molecular weapons which cut DNA that bacteria use in their fight to protect themselves from DNA viruses.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 64 de 112

1

Human DNA is replicated in a conservative manner.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 65 de 112

1

In DNA replication, new DNA is produced in a continuous bi-directional fashion.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 66 de 112

1

DNA topoisomerase supercoils DNA to get it out of the way of DNA polymerase.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 67 de 112

1

Accuracy of replication is enhanced by the redundancy of DNA, enzymatic repair of damaged DNA and the remarkable precision of the cellular replication machinery.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 68 de 112

1

A 2:2 segregation of parental alleles is known as gene conversion.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 69 de 112

1

Recombination events are limited to only “hot spots” along a chromosome.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 70 de 112

1

Gene conversion in which a small segment of information from one homologous chromosome transfers to the other can give rise to an unequal yield of two different alleles.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 71 de 112

1

Alternative resolutions of the Holliday intermediate are responsible for whether or not crossing over or gene conversion occurs.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 72 de 112

1

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Genes that “travel” together from one generation to the next more often than not exhibit .

Explicação

Questão 73 de 112

1

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A probability test that measures “goodness of fit” between observed and predicted results is a test.

Explicação

Questão 74 de 112

1

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A hypothesis that predicts no linkage between genes is called the hypothesis.

Explicação

Questão 75 de 112

1

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Genes that can serve points of reference on a chromosome are useful as genetic markers while cytologically visible abnormalities that also make it possible to keep track of chromosomes are called markers.

Explicação

Questão 76 de 112

1

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The movement of chiasmata toward the end of a chromosome is called .

Explicação

Questão 77 de 112

1

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One percentage point of recombination, or recombination frequency, is a unit of measure called either centimorgan or .

Explicação

Questão 78 de 112

1

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Crossovers do not occur independently and the occurrence of one crossover reduces the likelihood of another occurring elsewhere on the chromosome this is called .

Explicação

Questão 79 de 112

1

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A tetrad that contains four recombinant class haploid cells is known as a ditype.

Explicação

Questão 80 de 112

1

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A tetrad that carries four kinds of haploid cells: two different parental and two different recombinant class spores is referred to as .

Explicação

Questão 81 de 112

1

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Mistakes in mitosis during development often result in organisms containing tissues of different genotypes.

Explicação

Questão 82 de 112

1

The R/r and S/s genes are linked and 10 map units apart. In the cross Rs/rS  rs/rs what fraction of the progeny will be RS/rs?

Selecione uma das seguintes:

5%
10%
25%
40%
45%

Explicação

Questão 83 de 112

1

If the map distance between genes A and B is 10 map units and the map distance between genes B and C is 25 map units, what is the map distance between genes A and C?

Selecione uma das seguintes:

15 map units
35 map units
Either 15 map units or 35 map units, depending on the order of the genes
The map distance between A and C can not be predicted from this data

Explicação

Questão 84 de 112

1

In Drosophila, singed bristles (sn) and cut wings (ct) are both caused by recessive, X-linked alleles. The wild type alleles (sn+ and ct+) are responsible for straight bristles and intact wings, respectively. A female homozygous for sn and ct+ is crossed to a sn+ct male. The F1 flies are interbred. The F2 males are distributed as follows:
sn ct 13
sn ct+ 36
sn+ ct 39
sn+ ct+ 12
What is the map distance between sn and ct?

Selecione uma das seguintes:

12 m.u.
13 m.u.
25 m.u.
50 m.u.
75 m.u.

Explicação

Questão 85 de 112

1

What is the value of X2 for a test of the hypothesis that the sn and car genes are unlinked?

Selecione uma das seguintes:

0.5
1.0
2.0
0.4
20

Explicação

Questão 86 de 112

1

What is the p value from this test? (Pick the most accurate choice.)

Selecione uma das seguintes:

p > 0.5
0.5 > p > 0.1
p < 0.1
p < 0.05
p < 0.01

Explicação

Questão 87 de 112

1

Suppose the L and M genes are on the same chromosome but separated by 100 map units. What fraction of the progeny from the cross LM/lm x lm/lm would be Lm/lm?

Selecione uma das seguintes:

10%
25%
50%
75%
100%

Explicação

Questão 88 de 112

1

The pairwise map distances for four linked genes are as follows: A-B = 22 m.u., B-C = 7 m.u., C-D = 9 m.u., B-D = 2 m.u., A-D = 20 m.u., A-C = 29 m.u. What is the order of these four genes?

Selecione uma das seguintes:

ABCD
ADBC
ABDC
BADC
CADB

Explicação

Questão 89 de 112

1

The zipper-like connection between paired homologs in early prophase is known as a:

Selecione uma das seguintes:

spindle fiber
synaptic junction
synaptomnemal complex
chiasma
none of the above

Explicação

Questão 90 de 112

1

The measured distance between genes D and E in a two point test cross is 50 map units. What does this mean in physical terms?

Selecione uma das seguintes:

D and E are on different pairs of chromosomes.
D and E are linked and exactly 50 map units apart.
D and E are linked and at least 50 map units apart.
either A or B
either A or C

Explicação

Questão 91 de 112

1

Suppose an individual is heterozygous for a pair of alleles (e.g. A/a). Under what conditions would a crossover in a somatic cell of this individual lead to a clone of cells homozygous for a? (Pick the most precise answer.)

Selecione uma das seguintes:

The crossover would have to occur between the A locus and the centromere and involve two homologous (non-sister) chromatids.
The crossover would have to occur between the A locus and the end of the chromosome and involve two homologous (non-sister) chromatids.
The crossover would have to occur on the same chromosome arm as the A locus and involve two homologous (non-sister) chromatids.
The crossover would have to occur on the same chromosome as the A locus and involve two homologous (non-sister) chromatids.
The crossover would have to occur between the A locus and the centromere and involve two sister chromatids (not homologous) chromatids.

Explicação

Questão 92 de 112

1

Suppose an individual is heterozygous for two linked pairs of alleles on the same chromosome arm, Ab/aB such that the A locus is closer to the centromere than the B locus. Under what conditions would a crossover in a somatic cell generate a twin spot, i.e. two adjacent clones of cells, one clone homozygous for a and the other clone homozygous for b?

Selecione uma das seguintes:

The crossover would have to occur between the A locus and the centromere locus and involve two homologous (non-sister) chromatids.
The crossover would have to occur between the A locus and the B locus locus and involve two homologous (non-sister) chromatids.
The crossover would have to occur between the B locus and the end of the chromosome locus and involve two homologous (non-sister) chromatids.
A double crossover would have to occur, with one crossover between the A locus and the centromere and a second crossover between the A and B loci locus and both crossovers would have to involve two homologous (non-sister) chromatids.
No crossover in a somatic cell could generate a twin spot.

Explicação

Questão 93 de 112

1

What happens physically during the process of crossing over?

Selecione uma das seguintes:

Two homologous chromatids break and rejoin at random sites along the chromosome.
The genetic information on one chromatid is replaced by copying genetic information from a homologous chromatid without there being any physical exchange between the chromosomes.
Two homologous chromatids break and rejoin at precisely the same site along the chromosome so that there is no loss or gain of material on either product.
It is not known what occurs during crossing over.

Explicação

Questão 94 de 112

1

Here is a list of events during meiosis I. It is not in the correct order.
A) Homologous chromosomes are roughly aligned but not physically linked.
B) Homologous chromosomes segregate to opposite poles.
C) Homologous chromosomes are linked by synaptonemal complexes.
D) Homologous chromosomes are linked by chiasmata.
E) Chromosomes replicate.
What is the correct order of these events?

Selecione uma das seguintes:

ACDBE
AECDB
EACDB
EADCB
CDABE

Explicação

Questão 95 de 112

1

Some of the larger human chromosomes typically contain multiple chiasmata during meiotic prophase. If you were to carefully study the distribution of these chiasmata, what would you find?

Selecione uma das seguintes:

Chiasmata are randomly distributed along chromosomes.
All chromosome pairs have the same number of chiasmata.
A single chromosome pair always has the same number of chiasmata in every meiotic cell.
Chiasmata are spaced along a chromosome arm more regularly than would be expected by chance.
Chiasmata are spaced more irregularly along a chromosome arm than would be expected by chance.

Explicação

Questão 96 de 112

1

Recombination due to crossing over occurs only rarely in mitosis.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 97 de 112

1

When considering the chi-square test, a p-value of 0.05 is often considered significant but is actually an arbitrary assignment of significance.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 98 de 112

1

Chiasmata are structures of cross over between sister chromatids of homologous chromosomes.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 99 de 112

1

Chiasmata can be seen through a light microscope and are sites of recombination.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 100 de 112

1

Three-point crosses are more tedious and less accurate than two-point crosses.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 101 de 112

1

Chromosomal interference is not uniform and may significantly vary within a region of a single chromosome.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 102 de 112

1

Genetic mapping distance calculated for a chromosome is directly related to physical distance along that chromosome.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 103 de 112

1

Genes chained together by linkage relationships are known collectively as a linkage group.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 104 de 112

1

Ascospores are haploid cells that can germinate, replicate by mitosis, and survive as haploid individuals.

Selecione uma das opções:

VERDADEIRO
FALSO

Explicação

Questão 105 de 112

1

The Hardy-Weinberg equilibrium principle yields which of the following conclusions?

Selecione uma das seguintes:

If the allele frequencies in a population are given by p and q, the genotype frequencies are given by p2, 2 pq and q2.
The allele frequencies in a population will not change over time.
If the allele frequencies in a population are given by p and q, the genotype frequencies are given by p2 and q2. d. The first and third answers are correct.
The first and second choices are correct.

Explicação

Questão 106 de 112

1

The HIV epidemic is unlikely to lead to an increase in the CCR5 delta-32 allele over the short term because ___________________.

Selecione uma das seguintes:

In populations with high selection pressure, the allele frequency is low.
the allele is recessive and deleterious.
The first and second choices are correct.
in populations with a high frequency of the allele, selection pressure is relatively low.

Explicação

Questão 107 de 112

1

Over the long term, selection favoring the rare phenotype in a polymorphic population (i.e., negative frequency dependent selection), will __________ genetic diversity in the population.

Selecione uma das seguintes:

decrease
increase
maintain

Explicação

Questão 108 de 112

1

Which of these statements is true for underdominance?

Selecione uma das seguintes:

Allele frequencies will tend to move towards fixation or loss.
Allele frequencies will tend to move toward a stable equilibrium.
Allele frequencies may initially hover at an unstable equilibrium, but will eventually change.

Explicação

Questão 109 de 112

1

When selection acts against a recessive allele that is initially at high frequency in a population, ____________________.

Selecione uma das seguintes:

the frequency of the allele will stay high for a long time, then decline slowly.
the allele declines in frequency until it is eliminated.
the frequency of the allele will be unchanged;
the population will remain in Hardy-Weinberg equilibrium. the frequency of the allele will decline rapidly, and then stabilize at very low frequency.

Explicação

Questão 110 de 112

1

When selection favors heterozygotes over homozygotes, ____________________.

Selecione uma das seguintes:

both alleles are maintained at a frequency different from that predicted by Hardy-Weinberg principles based on the strength of selection against the recessive allele.
the selective advantage enjoyed by the deleterious allele in the heterozygote exactly
genetic diversity in the population can be maintained indefinitely, in spite of selection acting against the allele. balances the selective disadvantage suffered by homozygous recessive individuals.
The first two choices are both correct.
The first three choices are correct.

Explicação

Questão 111 de 112

1

When selection favors homozygotes over heterozygotes ____________________.

Selecione uma das seguintes:

genetic variation among populations will decline.
the most common outcome will be that the most common allele will become fixed (will increase to a frequency of 1) in the population.
both alleles are maintained in the population at frequencies different from those predicted by Hardy-Weinberg principles.
the genetic variation within a population is maintained over time

Explicação

Questão 112 de 112

1

Pier and his colleagues have suggested that cystic fibrosis is maintained at relatively high levels in people of European ancestry because of heterozygote superiority; specifically, he proposposes that heterozygotes are more resistant to typhoid fever than are the dominant homozygotes. Evidence in favor of this hypothesis includes which of the following findings?

Selecione uma das seguintes:

The mutation rate for new loss-of-function mutations in the CFTR gene is too low for the prevalence of the disease to be explained by mutation/selection balance.
Pier and his colleagues have found, in 11 European countries, an association between the severity of typhoid fever outbreaks and the frequency of the delta-F508 allele (the most common loss-of-function mutation) a generation later.
Pier et al. engineered cells homozygous for functional CFTR alleles, homozygous for a common loss-of-function allele, and heterozygous for the two. The loss-of-function homozygotes were virtually impervious to invasion by typhoid fever-causing bacteria; heterozygotes were more vulnerable, but accumulated 86% fewer bacteria than did the dominant homozygotes.
All of the choices above are correct.
Salmonella typhi bacteria manipulate their host cells, causing them to express more CFTR protein on their membranes.

	Criado por Engela Zalmy mais de 7 anos atrás

Kocher, Thomas. University of MD, College Park. Genetics Final Exam Review Fall 2016

Genetics Final Exam

Questão 1 de 112

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The full chemical name of DNA is .

Explicação

Questão 2 de 112

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The protein, , is needed to lay down a segment of RNA complementary to the DNA before replication can begin.

Explicação

Questão 3 de 112

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An origin of replication generally has (how many?) replication forks.

Explicação

Questão 4 de 112

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The discontinuous lagging strand on a replication fork consists of that are later ligated together to form one strand of DNA.

Explicação

Questão 5 de 112

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The E. coli chromosome contains (how many?) origin(s) of replication?

Explicação

Questão 6 de 112

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A prokaryote lacks a membrane.

Explicação

Questão 7 de 112

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Recombination is probably always initiated by of DNA.

Explicação

Questão 8 de 112

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The strand is synthesized continuously during DNA replication.

Explicação

Questão 9 de 112

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A enzyme recognizes a specific DNA sequence and is able to cleave the DNA generating either “blunt” or “sticky” ends of the DNA.

Explicação

Questão 10 de 112

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A virus that infects bacterial cells is called a .

Explicação

Questão 11 de 112

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The genetic material of some viruses such as pi X 174 and M13 is .

Explicação

Questão 12 de 112

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The genetic material of the viruses that cause polio and AIDS is .

Explicação

Questão 13 de 112

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Topoisomerase supercoils by nicking the DNA.

Explicação

Questão 14 de 112

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In E. coli, recombination begins at sites where recBCD nicks and displaces a strand.

Explicação

Questão 15 de 112

Which of the following is not true of DNA?

Selecione uma das seguintes:

Explicação

Questão 16 de 112

The molecule of heredity is:

Selecione uma das seguintes:

Explicação

Questão 17 de 112

The four subunits which compose DNA are called:

Selecione uma das seguintes:

Explicação

Questão 18 de 112

DNA is localized mainly in the

Selecione uma das seguintes:

Explicação

Questão 19 de 112

Each nucleotide of DNA is made up of:

Selecione uma das seguintes:

Explicação

Questão 20 de 112

The polarity of DNA synthesis is: