Question 1

A.Define a "gene."
B.Consider two different species of yeast that have similar genome sizes.Is it likely that they contain the same number of genes? A similar number of chromosomes?

Accepted Answer

The answer of A.Define a "gene."
B.Consider two different species of...

Question 2

Match between columns Premises: Comparing the relative number of chromosome pairs is a good way to determine whether two species are closely related. Eukaryotic chromosomes contain many different sites where DNA replication can be initiated. Chromosomes exist at different levels of condensation, depending on the stage of the cell cycle.
The telomere is a specialized DNA sequence where microtubules from the mitotic spindle attach to the chromosome so that duplicate copies move to opposite ends of the dividing cell.

Accepted Answer

The Answer of False and True is...

Question 3

Avery, MacLeod, and McCarty carried out experiments to identify the class of biological molecule that carries heritable information.Explain how they identified the "transforming principle" that could convert a harmless strain of bacteria to a pathogenic one.

Accepted Answer

The answer of Avery, MacLeod, and McCarty carried out experiments...

Question 4

Explain the differences between chromosome painting and the older, more traditional method of staining chromosomes being prepared for karyotyping.Highlight the way in which each method identifies chromosomes by the unique sequences they contain.

Accepted Answer

The answer of Explain the differences between chromosome painting and...

Question 5

Which of the following best describes the mechanism by which chromatin-remodeling complexes "loosen" the DNA wrapped around the core histones?

Accepted Answer

A) They use energy derived from ATP hydrolysis to change the relative position of the DNA and the core histone octamer. 
B) They chemically modify the DNA, changing the affinity between the histone octamer and the DNA. 
C) They remove histone H1 from the linker DNA adjacent to the core histone octamer. 
D) They chemically modify core histones to alter the affinity between the histone octamer and the DNA.

Question 6

Specific regions of eukaryotic chromosomes contain sequence elements that are absolutely required for the proper transmission of genetic information from a mother cell to each daughter cell.Which of the following is NOT known to be one of these required elements in eukaryotes?

Accepted Answer

A) protein-coding regions 
B) origins of replication 
C) telomeres 
D) centromeres

Question 7

The process of sorting human chromosome pairs by size and morphology is called karyotyping.A modern method employed for karyotyping is called chromosome painting.How are individual chromosomes "painted"?

Accepted Answer

A) with a laser 
B) using fluorescent antibodies 
C) using fluorescent DNA molecules 
D) using green fluorescent protein

Question 8

Many of the breakthroughs in modern biology came after Watson and Crick published their model of DNA in 1953.However, chromosomes were identified earlier.In what decade did scientists first identify chromosomes?

Accepted Answer

A) 1880s 
B) 1920s 
C) 1940s 
D) 1780s

Question 9

Evidence suggests that the replication of DNA packaged into heterochromatin occurs later than the replication of other chromosomal DNA.What is the simplest possible explanation for this phenomenon?

Accepted Answer

The answer of Evidence suggests that the replication of DNA...

Question 10

You are a virologist interested in studying the evolution of viral genomes.You are studying two newly isolated viral strains and have sequenced their genomes.You find that the genome of strain 1 contains 25% A, 55% G, 20% C, and 10% T.You report that you have isolated a virus with a single-stranded DNA genome.Based on what evidence can you make this conclusion?

Accepted Answer

A) because single-stranded genomes always have a large percentage of purines 
B) by using the formula G − A = C + T 
C) because double-stranded genomes have equal amounts of A and T 
D) because single-stranded genomes have a higher rate of mutation

Question 11

The chromosomes we typically see in images are isolated from mitotic cells.These mitotic chromosomes are in the most highly condensed form.Interphase cells contain chromosomes that are less densely packed and

Accepted Answer

A) occupy discrete territories in the nucleus. 
B) share the same nuclear territory as their homolog. 
C) are restricted to the nucleolus. 
D) are completely tangled with other chromosomes.

Question 12

The human genome is a diploid genome.However, when germ-line cells produce gametes, these specialized cells are haploid.What is the total number of chromosomes found in each of the gametes (egg or sperm) in your body?

Accepted Answer

A) 22 
B) 23 
C) 44 
D) 46

Question 13

Interphase chromosomes are about __________ times less compact than mitotic chromosomes, but still are about __________ times more compact than a DNA molecule in its extended form.

Accepted Answer

A) 10; 1000 
B) 20; 500 
C) 5; 2000 
D) 50; 200

Question 14

Methylation and acetylation are common changes made to histone H3, and the specific combination of these changes is sometimes referred to as the "histone code." Which of the following patterns will probably lead to gene silencing?

Accepted Answer

A) lysine 9 methylation 
B) lysine 4 methylation and lysine 9 acetylation 
C) lysine 14 acetylation 
D) lysine 9 acetylation and lysine 14 acetylation

Question 15

Mitotic chromosomes are __________ times more compact than a DNA molecule in its extended form.

Accepted Answer

A) 10,000 
B) 100,000 
C) 1000 
D) 100

Question 16

Using the structures in Figure 5-70 as a guide, sketch the hydrogen bonds between the base pairs in DNA.Hint: The bases in the figure are all drawn with the −NH− that attaches to the sugar at the bottom of the structure.  
Figure 5-70

Accepted Answer

The answer of Using the structures in Figure 5-70 as...

Question 17

Which of the following is NOT a chemical group commonly found on core histone N-terminal tails for chromatin regulation?

Accepted Answer

A) methyl 
B) sulfhydryl 
C) phosphoryl 
D) acetyl

Question 18

Match between columns Premises: The polarity of a DNA strand results from the polarity of the nucleotide subunits. Hydrogen bonds between each nucleotide hold individual DNA strands together.
There are five different nucleotides that become incorporated into a DNA strand.
DNA molecules, like proteins, consist of a single, long polymeric chain that is assembled from small monomeric subunits.

Accepted Answer

The Answer of False and True is...

Question 19

The inactivation of one X chromosome is established by the directed spreading of heterochromatin.The silent state of this chromosome is __________ in the subsequent cell divisions.

Accepted Answer

A) completed 
B) switched 
C) erased 
D) maintained

Question 20

Consider the structure of the DNA double helix.
A.You and a friend want to split a double-stranded DNA molecule so you each have half.Is it better to cut the length of DNA in half so each person has a shorter length, or to separate the strands and each take one strand? Explain.
B.In the original 1953 publication describing the discovery of the structure of DNA, Watson and Crick wrote, "It has not escaped our notice that the specific pairings we have postulated immediately suggest a possible copying mechanism for the genetic material." What did they mean?

Accepted Answer

The answer of Consider the structure of the DNA double...

Exam 5: DNA and Chromosomes

A.Define a "gene." B.Consider two different species of yeast that have similar genome sizes.Is it likely that they contain the same number of genes? A similar number of chromosomes?

Indicate whether the following statements are TRUE or FALSE.If a statement is false, explain why it is false.