Question 1

DNA isolated from Aspergillis has an adenine content of 25%.Based upon this information,what is the %G + %C within the Aspergillis DNA?
A)0%
B)25%
C)50%
D)75%
E)The answer cannot be determined from this information.

Accepted Answer

In DNA, the amount of adenine (A) equals the amount of thymine (T), and the amount of guanine (G) equals the amount of cytosine (C). If adenine is 25%, then thymine is also 25%, making A+T = 50%. Therefore, G+C must also be 50% to make the total 100%.

Question 2

A recently isolated bacterial strain has been given to you for general characterization of the genome.You begin by isolating the DNA and subjecting it to thermal denaturation.You use Escherichia coli (E.coli)DNA as a reference.  Based on the information in the graph,you can determine that the DNA of the new strain has a high
A)G-C content with respect to E.coli.
B)pyrimidine content with respect to E.coli.
C)A-T content with respect to E.coli.
D)purine content,with respect to E.coli.
E)histone content with respect to E.coli.

Accepted Answer

A

Question 3

Which of the following are components of Chargaff's rules of bases?
A)% purines = % pyrimidines
B)%C + %T = %A + %G
C)%A = %T
D)%G = %C
E)All of these are true.

Accepted Answer

Chargaff's rules of bases state that in DNA:- % purines = % pyrimidines- %C + %T = %A + %G- %A = %T- %G = %C

Question 4

In 1928,Frederick Griffith's experiments with Streptococcus pneumoniae suggested that
A)bacteria do not incorporate the DNA of other bacteria.
B)attenuated R (rough)bacteria easily revert to the wild type (virulent).
C)RNA was the genetic material.
D)heat-killed bacteria could somehow "transform" live bacteria.
E)protein was the genetic material.

Accepted Answer

Griffith's experiments showed that when he mixed heat-killed virulent (smooth) bacteria with live non-virulent (rough) bacteria, the live bacteria became virulent. This suggested that the live bacteria had been "transformed" by something from the dead bacteria, which was later identified as DNA, not protein or RNA.

Question 5

Which of the following shows Chargaff's equivalence?
A)RNA
B)single-stranded DNA
C)histones
D)double-stranded DNA
E)deoxyribose

Accepted Answer

Chargaff's equivalence, which states that in double-stranded DNA the amount of adenine (A) equals thymine (T) and the amount of cytosine (C) equals guanine (G), applies specifically to the structure of double-stranded DNA.

Question 6

The information encoded in DNA is used within a cell in a two-stage process.The two stages of this process are called
A)denaturation and renaturation.
B)base-pairing and denaturation.
C)replication and division.
D)transcription and translation.
E)replication and transcription.

Accepted Answer

The two stages of the process by which information encoded in DNA is used within a cell are transcription and translation. In transcription, the DNA sequence of a gene is transcribed to produce an RNA molecule. This RNA, typically messenger RNA (mRNA), is then used in translation to produce a protein.

Question 7

Following reports that the amount of DNA varied over time within cells,scientists in the early 1900s concluded that the genetic material had to be
A)DNA.
B)RNA.
C)protein.
D)lipids.
E)carbohydrates.

Accepted Answer

In the early 1900s, scientists believed that proteins, with their complex structures and variability, were the genetic material rather than DNA. This was because proteins were thought to have the necessary complexity to carry genetic information, a view that was not challenged until the Avery-MacLeod-McCarty experiment in 1944 and ultimately overturned by the Hershey-Chase experiment in 1952, which provided strong evidence that DNA is the genetic material.

Question 8

Which of the following statements regarding the Watson-Crick model of DNA is false?
A)It is the most common biological form of DNA.
B)The two DNA strands form a left-handed helix.
C)The two DNA strands are antiparallel.
D)The bases are "stacked" in the center of the molecule.
E)The backbone consists of alternating sugars and phosphates.

Accepted Answer

The Watson-Crick model of DNA describes a right-handed double helix, not a left-handed one.

Question 9

In an experiment like that of the 1952 Hershey and Chase experiments,³⁵S was added to a phage replicating within its bacterial host.The new phage particles were carefully isolated and used to infect fresh bacterial cells in the absence of any radioisotopes.Where would you expect to find the ³⁵S radioisotope immediately after infection? A)in the phage ghosts outside the bacterial cells B)incorporated into the bacterial matrix proteins C)incorporated into the bacterial DNA D)inside the bacterial cells,but separate from the bacterial DNA E)inside the bacterial cells,but separate from the bacterial proteins

Accepted Answer

The ³⁵S radioisotope labels the sulfur in the protein coat of the phage. After infection, the protein coat remains outside the bacterial cell as a phage ghost, so the ³⁵S would be found there.

Question 10

Which of the following model organisms were used in experiments demonstrating that DNA was the genetic material?
A)mice
B)amoeba
C)humans
D)tobacco plants
E)bacteria and bacteriophages

Accepted Answer

Experiments by Avery, MacLeod, and McCarty, as well as the Hershey-Chase experiment, used bacteria and bacteriophages to demonstrate that DNA is the genetic material.

Question 11

Avery,MacLeod,and McCarty (1944)demonstrated that DNA was the genetic material by treating heat-killed Streptococcus pneumoniae S (smooth)strain with DNase,thereby preventing transfer of the "transforming substance" from the killed S strain to the live R (rough)strain when the two were mixed together and injected into mice.Another way that one could demonstrate transformation in bacteria would be to extract DNA from
A)an R strain and mix it with cells of an S strain.
B)both S and R strains and mix it to allow recombination to take place.
C)an ampicillin-sensitive strain and mix it with cells of an ampicillin-resistant strain.
D)an S strain and mix it with cells of an R strain.
E)None of the above are correct.

Accepted Answer

The correct answer is to extract DNA from an S strain and mix it with cells of an R strain. This would potentially allow the R strain to take up the DNA from the S strain and undergo transformation, possibly converting to an S phenotype if the DNA includes genes responsible for the S strain's smooth capsule. This is analogous to the original experiment by Avery, MacLeod, and McCarty, which demonstrated that DNA is the material responsible for genetic transformation.

Question 12

DNA is different from RNA in that
A)RNA contains an additional oxygen atom on the ribose sugar.
B)RNA is made up five bases,whereas DNA is made up of four.
C)RNA cannot exist as a double helix.
D)in general,RNA molecules are longer than DNA molecules.
E)All of these statements are true.

Accepted Answer

RNA contains an additional oxygen atom on the ribose sugar, which is a key difference between RNA and DNA. RNA has ribose sugar, while DNA has deoxyribose sugar, lacking one oxygen atom.

Question 13

When examining a five-carbon sugar to determine if it is ribose or deoxyribose,one looks to see if there are two H on the ________ carbon in the structure.
A)1'
B)2'
C)3'
D)4'
E)5'

Accepted Answer

The key difference between ribose and deoxyribose sugars is the presence of an -OH group (hydroxyl group) on the 2' carbon in ribose, whereas deoxyribose has an -H (hydrogen) instead of the -OH on the 2' carbon. Thus, to distinguish between the two, one looks for the presence of two hydrogen atoms on the 2' carbon, which indicates deoxyribose.

Question 14

Circular DNA molecules found in nature are
A)positively supercoiled.
B)negatively supercoiled.
C)not supercoiled,due to their small size.
D)always oriented in a triple helix to conserve space.
E)always in the Z-DNA formation.

Accepted Answer

Negatively supercoiled DNA is common in nature because it allows for easier unwinding and separation of the two strands, which is necessary for processes such as replication and transcription. Positive supercoiling does occur under certain conditions, but negative supercoiling is more prevalent in living cells. Circular DNA molecules, such as plasmids in bacteria, are often negatively supercoiled to facilitate these essential biological processes.

Question 15

The base composition in DNA isolated from cow liver cells is 28% adenine; what percent of the bases are cytosine?
A)14%
B)22%
C)28%
D)36%
E)56%

Accepted Answer

In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). Since the amount of adenine is 28%, thymine will also be 28% because of base pairing rules. This accounts for 56% of the DNA bases, leaving 44% to be divided equally between cytosine and guanine. Therefore, cytosine makes up 22% of the bases.

Question 16

The 5' end of a DNA molecule can be chemically distinguished from the 3' end because there is a(n)________ group at the 5' end and a(n)________ group at the 3' end.
A)amine; carboxyl
B)phosphate; sulfate
C)hydroxyl; hydrogen
D)phosphate; hydroxyl
E)amine; hydroxyl

Accepted Answer

The 5' end of a DNA molecule has a phosphate group attached to it, while the 3' end has a hydroxyl group. This distinction is fundamental to the structure and function of DNA.

Question 17

What characteristic is shared between most prokaryotic and mitochondrial genomes?
A)<5 % protein-coding genes
B)>20% interspersed repeats
C)circular chromosomes
D)linear chromosomes
E)circular chromosomes with <5 % protein-coding genes

Accepted Answer

Most prokaryotic and mitochondrial genomes share the characteristic of having circular chromosomes.

Question 18

The scientist credited with the discovery of DNA (nuclein)from white blood cells in pus on surgical bandages is
A)Johann Friedrich Meischer.
B)Eduard Zacharias.
C)Fredrick Griffiths.
D)Martha Chase.
E)Oswald Avery.

Accepted Answer

Johann Friedrich Miescher is credited with the discovery of DNA, which he initially called "nuclein" after isolating it from the nuclei of white blood cells found in pus on surgical bandages in 1869.

Question 19

An example of a purine is
A)thymine.
B)guanine.
C)deoxyribose.
D)cytosine.
E)ribose 5-phosphate.

Accepted Answer

Guanine is a purine, one of the two types of nitrogenous bases found in DNA and RNA. The other type is pyrimidine. Thymine and cytosine are pyrimidines, while deoxyribose and ribose 5-phosphate are sugars, not nitrogenous bases.

Question 20

Mitochondrial and chloroplast genomes typically
A)are composed of primarily noncoding DNA.
B)encode all of the proteins needed for aerobic respiration and photosynthesis,respectively.
C)encode for ribosomal and transfer RNAs.
D)encode some of the proteins needed for aerobic respiration and photosynthesis,respectively.
E)encode some of the proteins needed for aerobic respiration and photosynthesis,respectively,as well as ribosomal and transfer RNA.

Accepted Answer

Mitochondrial and chloroplast genomes encode some of the proteins required for their respective functions (aerobic respiration in mitochondria and photosynthesis in chloroplasts), but not all proteins involved in these processes. They also encode ribosomal RNAs (rRNAs) and transfer RNAs (tRNAs) necessary for protein synthesis within these organelles.

Quiz 16: The Structural Basis of Cellular Information: Dna, chromosomes, and the Nucleus

DNA isolated from Aspergillis has an adenine content of 25%.Based upon this information,what is the %G + %C within the Aspergillis DNA?

Which of the following are components of Chargaff's rules of bases?

In 1928,Frederick Griffith's experiments with Streptococcus pneumoniae suggested that

Which of the following shows Chargaff's equivalence?

The information encoded in DNA is used within a cell in a two-stage process.The two stages of this process are called

Following reports that the amount of DNA varied over time within cells,scientists in the early 1900s concluded that the genetic material had to be

Which of the following statements regarding the Watson-Crick model of DNA is false?

Which of the following model organisms were used in experiments demonstrating that DNA was the genetic material?

DNA is different from RNA in that

When examining a five-carbon sugar to determine if it is ribose or deoxyribose,one looks to see if there are two H on the ________ carbon in the structure.

Circular DNA molecules found in nature are

The base composition in DNA isolated from cow liver cells is 28% adenine; what percent of the bases are cytosine?

The 5' end of a DNA molecule can be chemically distinguished from the 3' end because there is a(n) group at the 5' end and a(n) group at the 3' end.

What characteristic is shared between most prokaryotic and mitochondrial genomes?

The scientist credited with the discovery of DNA (nuclein) from white blood cells in pus on surgical bandages is

An example of a purine is

Mitochondrial and chloroplast genomes typically