Question 1

Discuss how a nucleosome is constructed from DNA and histone proteins.

Accepted Answer

The answer of Discuss how a nucleosome is constructed from...

Question 2

Histones are small proteins composed of a preponderance of basic negatively charged amino acids.

Accepted Answer

Histones are small proteins composed of a preponderance of basic positively charged amino acids, which allow them to bind to the negatively charged DNA.

Question 3

You examine cells with a microscope and detect that there are two Barr bodies present in each cell.What is the most likely genotype of the cells?

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Question 4

Ignoring the detailed description of how DNA polymerase functions,discuss the roles that proteins play in reproducing chromatin structure.

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Question 5

Describe the ways in which telomeres are critical to chromosome function.

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Question 6

It appears that all origins of replication are active during all mitotic divisions that create an organism.

Accepted Answer

During mitotic divisions, only some origins of replication are active while others remain inactive. This is known as the "licensing" of replication origins and is important for ensuring that the DNA is replicated only once per cell cycle.

Question 7

Chromosomes are composed of chromatin.

Accepted Answer

Chromosomes are composed of condensed chromatin, which is a complex of DNA and proteins, including histones.

Question 8

Telomerase is an enzyme that consists of a protein portion in association with RNA.

Accepted Answer

Telomerase is composed of a protein component and an RNA component, which serves as a template for the synthesis of telomeric DNA.

Question 9

While duplicating an entire chromosome,DNA polymerase cannot begin the 5' end of a new strand without a primer.

Accepted Answer

DNA polymerase requires a primer to initiate the synthesis of a new strand. The primer provides a free 3' hydroxyl group onto which the polymerase can add nucleotides in a 5' to 3' direction.

Question 10

The Holliday model of recombination has been modified.The current model,termed the consensus model,is now consistent with current research.What are the five properties of recombination,as they are now understood?

Accepted Answer

The answer of The Holliday model of recombination has been...

Question 11

Which of the following enzymes is not required for recombination in the double-strand break repair model?

Accepted Answer

Double strand recombinase is not required for recombination in the double-strand break repair model. The process primarily involves endonuclease for cutting DNA, single-stranded DNA binding proteins to stabilize the open DNA, DNA polymerase for synthesizing new DNA strands, and ligase for sealing nicks in the DNA backbone.

Question 12

Describe the process of nucleosome decompaction that allows the transcription of RNA.

Accepted Answer

The answer of Describe the process of nucleosome decompaction that...

Question 13

Nucleosomes are evenly spaced along a chromosome,but they do not have a well-defined arrangement within the chromatin.

Accepted Answer

Nucleosomes do have a defined arrangement within chromatin. They are regularly spaced and positioned in a particular orientation along the DNA strand. This arrangement is important for gene regulation and chromatin structure.

Question 14

If removal of a DNA sequence disrupts chromosome segregation and reinsertion of the same sequence restores stable transmission,the sequence must lie within the centromere.

Accepted Answer

The centromere is responsible for proper chromosome segregation during cell division. Therefore, if disrupting a DNA sequence within it causes problems with segregation, then the sequence must be located within the centromere. The fact that reinsertion of the same sequence restores stable transmission also supports the idea that it is centromeric in nature.

Question 15

The linear chromosomes of eukaryotic cells terminate at both ends in protective caps called telomeres.

Accepted Answer

Telomeres are protective caps found at the ends of linear chromosomes in eukaryotic cells. Without telomeres, the ends of chromosomes would be susceptible to degradation, fusion with other chromosomes, and loss of genetic information.

Question 16

Design an experiment to demonstrate that recombination involved breakage and rejoining of DNA molecules.E.coli with phage grown in either heavy or light isotopes,and then after allowing for recombination (but not replication),separated the DNA by centrifugation in a CsCl density gradient.The recombinant molecules,consisting of various combinations of heavy or light molecules,would migrate to positions in between the non-recombinant molecules,which consisted entirely of either heavy or light DNA.

Accepted Answer

The answer of Design an experiment to demonstrate that recombination...

Question 17

Scaffold-associated regions (SARs)likely serve to attach chromatin loops to the condensation scaffold.

Accepted Answer

SARs, or scaffold-associated regions, are DNA sequences that are thought to bind to the condensation scaffold, helping to organize and tether chromatin loops for efficient packing during cell division. SARs have been identified in a variety of species and are believed to be important for maintaining chromosome structure and stability.

Question 18

Cohesins are a multisubunit protein complex that glue sister chromatids together after chromosome replication in the S phase of the cell cycle.

Accepted Answer

Cohesins are indeed a multisubunit protein complex that hold sister chromatids together after DNA replication.

Question 19

During metaphase of mitosis the chromosomes look like a tangled mass of grainy string scattered throughout the nucleus.

Accepted Answer

During metaphase of mitosis, the chromosomes line up at the equator of the cell in a distinct and organized pattern. They are not scattered throughout the nucleus like a tangled mass of grainy string.

Question 20

That histones have changed so little throughout evolution underscores the importance of their contribution to chromatin structure.

Accepted Answer

The statement is true. Histones are highly conserved proteins, meaning their amino acid sequences have changed very little throughout evolution. This suggests that they play a crucial role in maintaining chromatin structure and function.

Quiz 5: Dna Structure, Replication, and Recombination