Q: According to the central dogma of molecular biology, what is the correct sequence of information flow?

$$\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$$

Question 1

Which enzyme is responsible for unwinding the DNA double helix during DNA replication, and what is its primary function?

Accepted Answer

Helicase; catalyzes the separation of DNA strands

Question 2

During DNA replication, which strand is synthesized discontinuously, and what is the name of the short fragments produced?

Accepted Answer

Lagging strand; Okazaki fragments

Question 3

A patient is exposed to UV radiation, which causes thymine dimers in their DNA. Which DNA repair mechanism is most likely to fix this damage?

Accepted Answer

Nucleotide excision repair

Question 4

According to the central dogma of molecular biology, what is the correct sequence of information flow?

Accepted Answer

$$	ext{DNA} ightarrow 	ext{RNA} ightarrow 	ext{Protein}$$

Question 5

Which of the following mutations is most likely to result in a frameshift and potentially severe consequences for the protein product?

Accepted Answer

Insertion or deletion of a nucleotide

Question 6

A chromosome segment is reversed end to end. What type of chromosomal mutation does this describe?

Accepted Answer

Inversion

Question 7

During transcription in eukaryotes, what modification is added to the 5' end of the mRNA to enhance stability and facilitate export from the nucleus?

Accepted Answer

5' methylguanosine cap

Question 8

Which process involves the removal of introns from pre-mRNA, resulting in a mature mRNA molecule ready for translation?

Accepted Answer

Splicing

Question 9

What is the function of the sigma factor in prokaryotic transcription?

Accepted Answer

Binds to promoter regions to initiate transcription

Question 10

Which codon serves as the universal start codon for translation, and what amino acid does it code for?

Accepted Answer

AUG; methionine

Question 11

A mutation changes a codon from GAA to GAG, both of which code for glutamic acid. What type of mutation is this?

Accepted Answer

Silent mutation

Question 12

Which site on the ribosome is responsible for holding the tRNA carrying the growing polypeptide chain during translation?

Accepted Answer

P site

Question 13

What is the role of DNA ligase during DNA replication?

Accepted Answer

Joins Okazaki fragments on the lagging strand

Question 14

Which of the following best explains the wobble pairing hypothesis?

Accepted Answer

It allows a single tRNA to recognize multiple codons due to flexible base pairing at the third position

Question 15

Which of the following is NOT a function of the core RNA polymerase in prokaryotes?

Accepted Answer

Binding to the promoter region without the sigma factor

Question 16

A patient’s karyotype reveals a segment of chromosome 9 attached to chromosome 22, resulting in a fusion gene. What type of chromosomal mutation is this?

Accepted Answer

Translocation

Question 17

Which of the following statements about exons and introns is correct?

Accepted Answer

Introns are removed during RNA splicing, while exons are retained in the mature mRNA

Question 18

Which of the following codon-anticodon pairings is possible due to wobble base pairing?

Accepted Answer

Codon GCU with anticodon GCI (where I = inosine)

Question 19

Which process is responsible for converting genetic information from DNA into RNA?

Accepted Answer

Transcription

Question 20

During translation, what event occurs when a stop codon is encountered in the mRNA?

Accepted Answer

Release factors bind to the ribosome, terminating polypeptide synthesis

DNA Replication, Central Dogma, and Gene Expression: Study Notes

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