Question 1

Which of the following best describes the structure of a typical bacterial chromosome?

Accepted Answer

Circular, double-stranded DNA compacted into a nucleoid

Question 2

A nucleosome consists of:

Accepted Answer

DNA wrapped around 8 histone subunits (2 each of H2A, H2B, H3, H4)

Question 3

Which of the following is NOT a function of telomeres in eukaryotic chromosomes?

Accepted Answer

Forming a recognition site for kinetochore proteins

Question 4

If a eukaryotic chromosome is 150 million base pairs (Mbp) long, approximately how many origins of replication would you expect it to have, assuming origins are spaced every 100,000 bp?

Accepted Answer

$$1500$$

Question 5

Which of the following statements about the compaction of eukaryotic DNA is correct?

Accepted Answer

Nucleosomes alone shorten DNA length about seven-fold

Question 6

Which of the following best explains why mitochondrial and chloroplast DNA is similar to bacterial DNA?

Accepted Answer

Both are circular and lack extensive histone association

Question 7

Which of the following modifications would most likely increase gene expression in a region of chromatin?

Accepted Answer

Histone acetylation

Question 8

A scientist observes a chromosome region that is highly condensed and transcriptionally inactive. This region is most likely:

Accepted Answer

Heterochromatin

Question 9

Which of the following is a key difference between viral and bacterial chromosomes?

Accepted Answer

Viral chromosomes can be either DNA or RNA, while bacterial chromosomes are always DNA

Question 10

Which of the following best describes the function of matrix-attachment regions (MARs) in eukaryotic chromosomes?

Accepted Answer

They anchor DNA to the nuclear matrix, forming radial loop domains

Question 11

A mutation that disrupts the function of the centromere would most likely affect which cellular process?

Accepted Answer

Chromosome segregation during mitosis and meiosis

Question 12

Which of the following best explains why the genome size of Plethodon larselli is more than twice that of Plethodon richmondi, even though both are salamanders?

Accepted Answer

Plethodon larselli has more repetitive DNA sequences

Question 13

Which of the following is the most tightly packed form of chromatin?

Accepted Answer

Metaphase chromosomes

Question 14

Which of the following best describes the composition of the nucleosome core particle?

Accepted Answer

An octamer of histone proteins and approximately 146 bp of DNA

Question 15

Which of the following is a major difference between eukaryotic and prokaryotic chromosomes?

Accepted Answer

Eukaryotic chromosomes have multiple origins of replication, while prokaryotic chromosomes typically have one

Question 16

Which of the following best explains why DNA must be tightly compacted in eukaryotic cells?

Accepted Answer

To fit the large genome into the small nuclear space

Question 17

Which of the following chemical modifications is most commonly associated with gene silencing?

Accepted Answer

DNA methylation (5-methyl cytosine)

Question 18

Which of the following best describes the role of the nuclear matrix in chromosome organization?

Accepted Answer

It organizes chromosomes into radial loop domains

Question 19

Which of the following is true regarding the percentage of protein-coding DNA in the human genome?

Accepted Answer

It is approximately 2%

Question 20

A mutation that prevents the formation of the 30-nm fiber would most likely result in which of the following?

Accepted Answer

Reduced compaction of chromatin, leading to increased DNA accessibility

Chromosome Structure and DNA Sequence Organization

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