Question 1

1.Which of the following RNAs is the least abundant in a typical cell?

 

mRNA

 

rRNA

 

snRNA

 

tRNA

1 points 

Question 2

1.Protein synthesis can occur while the mRNA molecule is being synthesized in:

 

Prokaryotes only.

 

Eukaryotes only.

 

Unicellular organisms only.

 

Multicellular organisms only.

1 points 

Question 3

1.Which of the following bases is not found in RNA?

 

A

 

C

 

G

 

T

 

All of these are found in RNA.

1 points 

Question 4

1.Histones are proteins that

 

are frequently associated with eukaryotic DNA

 

are frequently associated with prokaryotic DNA

 

are never found in association with DNA

 

contain a high percentage of residues with carboxylic acid side chains

1 points 

Question 5

1.The hydrogen bonding interactions in a Watson-Crick AT base-pair involve what units in the adenine base?

 

N-1 and the amino group on C-6

 

N-1 and N-3

 

N-7 and the amino group on C-6

 

N-7 and C-8

1 points 

Question 6

1.Which of the following statements is true for double-stranded DNA?

 

The amount of A is the same as the amount of T, and the amount of G is the same as the amount of C.

 

The amount of A is the same as the amount of C, and the amount of G is the same as the amount of T.

 

More than one of the above is true.

1 points 

Question 7

1.Where can drugs or polypeptides bind to DNA?

 

The minor groove only.

 

The major groove only.

 

Either the minor or major groove.

 

Neither the minor or major groove.

1 points 

Question 8

1.Which is the dominant form of DNA found in the cell?

 

A

 

B

 

Z

 

H

1 points 

Question 9

1.Deoxyadenylate (dA) is a:

 

purine base

 

pyrimidine base

 

purine based nucleoside

 

purine based nucleotide

1 points 

Question 10

1.Which conclusion can be drawn from the experimental observation that a single strand of DNA contains 2100 dA residues and 1800 dT residues?

 

There must have been some loss of material in the extraction because the number of dA and dT residues must be the same.

 

This is a palindromic sequence.

 

There must be 2100 dT and 1800 dA residues on the complementary strand.

 

none of these

1 points 

Question 11

1.Which of the following characteristics is associated with the B form of DNA?

 

the sugars are located in the interior of the double helix

 

the distance between base pairs along the axis of the helix is 8 Ã…

 

the major and minor grooves are readily apparent

 

the planes of the bases make about a 20 degree angle with the helix axis

1 points 

Question 12

1.Which of the following is the most common modification of nucleic acid bases?

 

addition of a methyl group

 

addition of a carboxylic acid

 

addition of a fluorine

 

reduction of a carbonyl to an alcohol

1 points 

Question 13

1.The three-dimensional structure of transfer RNA has been determined by

 

analytical ultracentrifugation

 

gel electrophoresis

 

ultraviolet spectroscopy

 

x-ray crystallography

1 points 

Question 14

1.In analytical ultracentrifugation the sedimentation coefficient, which is expressed in Svedberg units (S), characterizes a sedimenting particle on the basis of

 

size only

 

shape only

 

both size and shape

 

neither size nor shape

1 points 

Question 15

1.The following types of RNA are common to all organisms, except:

 

mRNA

 

rRNA

 

snRNA

 

tRNA

 

All types are found in all organisms.

1 points 

Question 16

1.The fundamental differences between RNA and DNA are

 

the organic bases only

 

bases, ribose units, and the phosphodiester linkage

 

bases, ribose units, and the glycosidic bond type

 

bases and the ribose units only

1 points 

Question 17

1.Which of the following statements concerning ribosomes is true?

 

They consist of two RNA subunits, one of which is larger than the other.

 

They contain both RNA and protein.

 

They can be dissociated and reassembled by controlling the Mg2+ concentration of the medium.

 

All of these are true.

1 points 

Question 18

1.Base pairs with a propeller-twist

 

are found only in Z-DNA

 

have optimum base stacking

 

bind water in the minor groove

 

have stronger hydrogen bonds than base pairs without a propeller twist

1 points 

Question 19

1.The backbone of nucleic acids consists of

 

a phosphodiester bond between the 2' and 5' hydroxyl groups of neighboring sugars

 

a phosphodiester bond between the 3' and 5' hydroxyl groups of neighboring sugars

 

a glycosidic bond between a pyrimidine and a sugar

 

a glycosidic bond between a purine and a sugar

1 points 

Question 20

1.Transfer RNA molecules are characterized by all the following, except:

 

They are one of the largest of the RNAs.

 

Cloverleaf shape.

 

Many modified bases.

 

Extensive secondary and tertiary structure.

 

All of these characterize transfer RNA molecules.

1 points 

Question 21

1.Which of the following statements concerning the B-form of DNA is false?

 

It twists in a left-handed direction.

 

The distance between base pairs is 3.4Ã….

 

The width of a base pair is about 1.1 nm.

 

The diameter, including the phosphate, is about 20 Ã….

1 points 

Question 22

1.Which piece of DNA will have the higher Tm, one with a cytosine plus guanine content of 30% or one with a cytosine plus guanine content of 50% if both are heated under the same experimental conditions?

 

30% cytosine plus guanine will have the higher Tm.

 

50% cytosine plus guanine will have the higher Tm.

 

Their Tm's will be the same.

 

There's no way to predict for this information.

1 points 

Question 23

1.Eukaryotic and prokaryotic ribosomes can be compared in all these ways, except:

 

Both have large and small subunits.

 

Eukaryotic ribosomes are larger.

 

Both contain the same number of RNA molecules.

 

Eukaryotic ribosomes contain more proteins.

 

All of these statements are accurate comparisons.

1 points 

Question 24

1.The nucleotide sequence of DNA is which level of structure?

 

primary

 

secondary

 

tertiary

 

quaternary

1 points 

Question 25

1.The helix can be untwisted by the action of which type of topoisomerase?

 

Type I only

 

Type II only

 

Both types I and II

 

Topoisomerases cannot untwist the helix.

1 points 

Question 26

1.The Z-form of DNA

 

does not exist in nature.

 

is right-handed.

 

tends to occur in purine-only sequences.

 

tends to occur in pyrimidine-only sequences.

 

tends to occur in alternating purine-pyrimidine sequences.

1 points 

Question 27

1.Which of the following nucleobases is a purine?

 

adenine

 

cytosine

 

thymine

 

uracil

1 points 

Question 28

1.The study of DNA changes that are not reflected in the base sequence is called:

 

Molecular biology

 

Histology

 

Epigenetics

 

Physical genetics

1 points 

Question 29

1.The outside diameter of a piece of DNA is closest to

 

2 Ã….

 

20 Ã….

 

200 Ã….

 

2000 Ã….

1 points 

Question 30

1.The oligonucleotide AGGUCCAUUGAAp, is best described as

 

an RNA oligonucleotide with a 3'phosphate

 

an RNA oligonucleotide with a 5'phosphate

 

a DNA oligonucleotide with a 3'phosphate

 

a DNA oligonucleotide with a 5'phosphate

1 points 

Question 31

1.Which of the following groups is not found in nucleosides?

 

Phosphates

 

Purines

 

Pyrimidines

 

Sugars

 

All of these are found in nucleosides

1 points 

Question 32

1.Eukaryotic mRNA requires

 

less processing after synthesis than prokaryotic mRNA.

 

more processing after synthesis than prokaryotic mRNA.

 

about the same amount of processing after synthesis as prokaryotic mRNA.

1 points 

Question 33

1.The melting profile for a DNA is found to differ in two different salt solutions. In 0.001 M NaCl, Tm = 55 °C, and in 0.01 M NaCl, Tm = 65 °C. The fundamental reason for this change is

 

higher salt concentration increases the electrostatic repulsions between phosphates

 

the base stacking is more effective in high salt

 

hydrogen bonding between complementary bases in enhanced at high salt

 

higher salt concentration decreases the electrostatic repulsions between phosphates

1 points 

Question 34

1.The strands in the double helix

 

both run in the same 3' to 5' direction, i.e., they are parallel.

 

have their 3' to 5' directions opposed, i.e., they are anti-parallel.

 

can be either parallel or anti-parallel.

 

are perpendicular to one another.

1 points 

Question 35

1.The human genome has 3 x 109 base pairs (bp) of DNA. If this were one continuous molecule and extended such that each nucleotide was separated from the adjacent nucleotide by 4 Ã…, as proposed in the Watson and Crick model, what would the end-to-end distance be?

 

1 meter

 

1 centimeter

 

1000 centimeters

 

1014 Ã…

1 points 

Question 36

1.Which best describes the relationship between the nucleobases in a piece of DNA?

 

They are parallel to the helical axis.

 

They are perpendicular to the helical axis.

 

They are randomly oriented with respect to the helical axis.

1 points 

Question 37

1.Base pairs with a propeller-twist

 

are found only in Z-DNA

 

have optimum base stacking

 

bind water in the minor groove

 

have stronger hydrogen bonds than base pairs without a propeller twist

1 points 

Question 38

1.Quaternary structure refers to the non-covalent interaction(s) between polymeric units, such as two or more monomer protein units that noncovalently interact. Which of the following scenarios for nucleic acids most closely resembles quaternary structure?

 

self-assembly of subunits in the tobacco mosaic virus

 

interaction of DNA with proteins

 

RNA and protein association in ribosomes

 

All of these

1 points 

Question 39

1.The Tm for melting the double helix is:

 

The temperature at which the helix starts to open.

 

The midpoint of the range over which the helix denatures.

 

The temperature at which the helix is completely open.

 

The energy needed to melt the DNA.

 

None of these is correct.

1 points 

Question 40

1.In a melting profile for DNA, the absorbance at 260 nm increases as result of the disruption of the DNA structure. What is the fundamental physical basis for the absorbance increase?

 

the effective concentration of DNA changes

 

denatured DNA absorbs light more strongly than native DNA because the bases have become unstacked

 

native DNA absorbs light more strongly than denatured DNA because the bases are stacked

 

the absorbance of DNA is highly sensitive to temperature

1 points 

Question 41

1.Calculate the length/diameter ratio for the extended E. coli DNA (4 Ã… between adjacent nucleotides). E. coli DNA has 2 x 106 bp.

 

4 x 105

 

1 x 105

 

3 x 108

 

3 x 106

1 points 

Question 42

1.The three dimensional structure of nucleic acids can include all except:

 

Supercoiling

 

Base stacking

 

Hairpin loops

 

Circular molecules

 

All of these can be included in the three dimensional structure

1 points 

Question 43

1.Supercoiling of DNA

 

is not observed in prokaryotes

 

requires the action of topoisomerase enzymes

 

does not require ATP

 

is not observed in eukaryotes

1 points 

Question 44

1.Which of the following is not true?

 

The amount of UV absorbance increases, but the wavelength does not change as DNA nears its melting point

 

Once DNA is denatured, it cannot renature

 

The melting temperature partially depends on the GC content

 

The nature of the solvent the DNA is in can affect the melting temperature

1 points 

Question 45

1.RNA is hydrolyzed in basic solution, but DNA is not. This occurs because

 

thymine is found in DNA, and uracil is not

 

DNA is double stranded, and RNA is single stranded

 

DNA contains 2'-deoxyribose, but RNA does not

 

RNA has modified bases, but DNA does not

1 points 

Question 46

1.The double helix of DNA is which level of structure?

 

primary

 

secondary

 

tertiary

 

quaternary

1 points 

Question 47

1.What distinguishes nucleotides from nucleosides?

 

Nucleosides lack the phosphate group.

 

Nucleosides lack the sugar group.

 

Nucleosides lack a nitrogenous base.

1 points 

Question 48

1.Which of the following best describes the structure of a nucleosome?

 

DNA wrapped around an octomer containing two each of H2A, H2B, H3, and H4 with H1 on the outside.

 

DNA wrapped around an octomer of H1 with H2A,B, H3 & H4 on the outside.

 

DNA wrapped around a octomer of either H2A/H2B or H3/H4 with H1 on the outside.

 

DNA wrapped around a tetramer of either H2A/H2B or H3/H4 with H1 on the outside.

1 points 

Question 49

1.Hydrophobic bonding via pi-clouds is referred to as

 

base stacking.

 

propeller twist.

 

hyperchromicity.

 

supercoiling.

1 points 

Question 50

1.Which of the following modifications is likely to happen to the mRNA in a eukaryotic cell?

 

capping of the 5' end

 

addition of a poly-A tail to the 3' end

 

removal of intervening sequences (introns)

 

All of the above occur in eukaryotic cells.

 

2012

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Status NEW Posted 26 Apr 2017 06:04 AM My Price 20.00

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