Q: A DNA sequence is 5'-ATGCGTACG-3'. What is the sequence of its reverse complement?

$$5'\text{-}CGTACGCAT\text{-}3'$$

Question 1

A single nucleotide change in the DNA sequence of the β-globin gene leads to sickle cell anemia. Which of the following best describes the molecular consequence of this mutation?

Accepted Answer

A missense mutation that substitutes valine for glutamic acid at position 6 of the β-globin chain.

Question 2

In the Avery, MacLeod, and McCarty experiment, which treatment prevented transformation of avirulent bacteria, demonstrating the identity of the genetic material?

Accepted Answer

Treatment with DNase

Question 3

A single base-pair substitution occurs in the coding region of a gene, but the organism shows no observable change in phenotype. Which explanation is most likely?

Accepted Answer

The mutation is a silent mutation that does not change the amino acid sequence due to the redundancy of the genetic code.

Question 4

Which of the following is NOT a requirement for evolution by natural selection to occur?

Accepted Answer

Random mating with no differential survival

Question 5

Which historical experiment first demonstrated that a 'transforming principle' could transfer virulence between bacterial strains?

Accepted Answer

Griffith's experiment with Streptococcus pneumoniae

Question 6

Which of the following best describes the structure of a nucleosome?

Accepted Answer

A segment of DNA wrapped around a core of histone proteins

Question 7

Which chemical modification of histones is associated with open chromatin and active transcription?

Accepted Answer

Histone acetylation

Question 8

A DNA sequence is 5'-ATGCGTACG-3'. What is the sequence of its reverse complement?

Accepted Answer

$$5'	ext{-}CGTACGCAT	ext{-}3'$$

Question 9

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

Accepted Answer

Cytosine pairs with guanine via three hydrogen bonds.

Question 10

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

Accepted Answer

The non-coding (antisense) strand

Question 11

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

Accepted Answer

Heterochromatin is more condensed and generally not transcribed; euchromatin is less condensed and available for transcription.

Question 12

A chromosome is described as 16p13.3. What does the 'p' refer to in this cytogenetic location?

Accepted Answer

The short arm of chromosome 16

Question 13

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

Accepted Answer

Adenine

Question 14

If a diploid human cell contains 46 chromosomes, how many chromosomes are present in a human gamete?

Accepted Answer

23

Question 15

Which of the following best explains why DNA is negatively charged at neutral pH?

Accepted Answer

The phosphate groups in the backbone carry negative charges.

Question 16

Which of the following is the correct chronological order of major discoveries in genetics?

Accepted Answer

Mendel’s laws, Griffith’s transformation, Avery-MacLeod-McCarty, DNA sequencing

Question 17

Which of the following best describes the outcome of the first division of meiosis according to the modern interpretation?

Accepted Answer

It is reductional, separating homologous chromosomes.

Question 18

Which of the following is a direct result of histone methylation?

Accepted Answer

Chromatin becomes more condensed and transcriptionally repressed.

Question 19

Which of the following best explains why RNA is more soluble in acidic solutions than DNA?

Accepted Answer

RNA has a 2-hydroxyl group, making it more polar.

Question 20

A gene is located on the Crick strand of a chromosome. Which direction does the 5' end of this strand point?

Accepted Answer

Toward the chromosome’s long arm (q arm)

Foundations of Genetics: Structure, Function, and Historical Discoveries

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