The two strands are antiparallel, with one running $$5' \to 3'$$ and the other $$3' \to 5'.$$

Question 1

Which of the following best describes the role of histone proteins in eukaryotic cells?

Accepted Answer

They package and organize DNA into nucleosomes, facilitating chromatin structure.

Question 2

Which chemical modification of histone tails is most commonly associated with gene activation?

Accepted Answer

Acetylation

Question 3

A DNA molecule contains 30% adenine. According to Chargaff's rules, what percentage of guanine would you expect?

Accepted Answer

$$20\%$$

Question 4

Which experiment provided the first direct evidence that DNA is the genetic material?

Accepted Answer

Avery, MacLeod, and McCarty's experiment with DNase, RNase, and protease

Question 5

Which of the following statements about the structure of DNA is correct?

Accepted Answer

The two strands are antiparallel, with one running $$5' 	o 3'$$ and the other $$3' 	o 5'.$$

Question 6

During transcription, which strand of DNA serves as the template for RNA synthesis?

Accepted Answer

The template (non-coding) strand

Question 7

Which of the following best explains why prokaryotic DNA must be circular?

Accepted Answer

It prevents the loss of genetic material during replication.

Question 8

Which of the following is a correct match between a theory of inheritance and its definition?

Accepted Answer

Epigenesis: Children develop from an undifferentiated mass through a series of steps.

Question 9

Which of the following best describes the difference between euchromatin and heterochromatin?

Accepted Answer

Euchromatin is loosely packed and transcriptionally active; heterochromatin is densely packed and inactive.

Question 10

A mutation changes a codon from UAU to UAA in an mRNA sequence. What is the most likely consequence?

Accepted Answer

Premature termination of translation

Question 11

Which of the following statements about nucleosomes is correct?

Accepted Answer

A nucleosome consists of DNA wrapped around a core of eight histone proteins.

Question 12

Which of the following best describes the difference between ribose and deoxyribose?

Accepted Answer

Deoxyribose has a hydrogen at the 2' carbon, while ribose has a hydroxyl group.

Question 13

Which of the following is a pyrimidine base found in DNA?

Accepted Answer

Cytosine

Question 14

Which of the following best explains the outcome of Griffith's critical experiment with heat-killed IIIS and living IIR bacteria?

Accepted Answer

The mouse died because the IIR bacteria were transformed by genetic material from the heat-killed IIIS.

Question 15

Which of the following is the correct order of events in gene expression?

Accepted Answer

Transcription → Translation → Protein folding

Question 16

Which of the following best describes the function of the p-arm on a chromosome?

Accepted Answer

It is the shorter arm of the chromosome.

Question 17

Which of the following is true regarding the hydrogen bonding between DNA bases?

Accepted Answer

$$A$$ pairs with $$T$$ via two hydrogen bonds.

Question 18

Which of the following is a function of the H1 histone protein?

Accepted Answer

It binds to linker DNA between nucleosomes, helping to compact chromatin.

Question 19

Which of the following best describes the difference between exons and introns?

Accepted Answer

Exons are coding sequences that remain in mature mRNA, while introns are non-coding and are removed.

Midterm 1

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