Q: Which equation correctly represents the semi-conservative model of DNA replication?

$$\text{Parent DNA} \rightarrow \text{1 old strand} + \text{1 new strand}$$

Q: What is the central dogma of molecular biology?

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

Question 1

Which experiment provided the first strong evidence that DNA is the genetic material, and what was the key finding?

Accepted Answer

Avery, MacLeod, and McCarty's experiment showed that DNA could transform non-virulent bacteria into virulent forms.

Question 2

What is the function of a histone in DNA packaging, and how does it contribute to chromatin structure?

Accepted Answer

Histones help compact DNA by forming nucleosomes, which allow DNA to wrap around them and create higher-order chromatin structures.

Question 3

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

Accepted Answer

Heterochromatin is tightly packed and transcriptionally inactive, while euchromatin is loosely packed and transcriptionally active.

Question 4

During DNA replication, what is the role of Okazaki fragments and how are they joined together?

Accepted Answer

Okazaki fragments are short DNA segments synthesized on the lagging strand and are joined by DNA ligase.

Question 5

Which equation correctly represents the semi-conservative model of DNA replication?

Accepted Answer

$$	ext{Parent DNA} ightarrow 	ext{1 old strand} + 	ext{1 new strand}$$

Question 6

A mutation changes a codon from UAU (tyrosine) to UAA (stop). What type of mutation is this and what is its likely effect?

Accepted Answer

This is a nonsense mutation, which introduces a premature stop codon and likely truncates the protein.

Question 7

Why is PCR (Polymerase Chain Reaction) useful for molecular biology, and what is the role of the thermocycler?

Accepted Answer

PCR amplifies specific DNA sequences rapidly, and the thermocycler automates the temperature changes required for denaturation, annealing, and extension.

Question 8

Which enzyme is responsible for removing RNA primers during DNA replication in eukaryotes?

Accepted Answer

DNA polymerase I

Question 9

What is the central dogma of molecular biology?

Accepted Answer

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

Question 10

Which of the following best explains why CRISPR is considered a revolutionary tool in genetics?

Accepted Answer

CRISPR allows for precise, targeted editing of DNA sequences in living organisms.

Question 11

A researcher wants to clone a gene using restriction enzymes. What property of restriction enzymes makes them useful for this purpose?

Accepted Answer

Restriction enzymes cut DNA at specific recognition sequences, allowing for precise insertion of genes.

Question 12

Which process is responsible for removing introns from pre-mRNA in eukaryotic cells?

Accepted Answer

Splicing

Question 13

What is the function of the Cas9 protein in the CRISPR system?

Accepted Answer

Cas9 acts as a nuclease that cuts DNA at specific sites guided by RNA.

Question 14

Which of the following is a real-world application of DNA sequencing technology?

Accepted Answer

Identifying genetic mutations associated with inherited diseases.

Question 15

A patient has a mutation in the gene encoding DNA mismatch repair proteins. What is the most likely consequence?

Accepted Answer

Increased risk of cancer due to accumulation of replication errors.

Question 16

Which of the following best describes the role of tRNA during translation?

Accepted Answer

tRNA brings specific amino acids to the ribosome according to the codon sequence of mRNA.

Question 17

What is the function of a promoter in transcription?

Accepted Answer

A promoter is a DNA sequence where RNA polymerase binds to initiate transcription.

Question 18

Which DNA repair mechanism is most likely to fix a thymine dimer caused by UV radiation?

Accepted Answer

Nucleotide excision repair

Question 19

Which of the following statements about genetically modified organisms (GMOs) is correct?

Accepted Answer

GMOs are organisms whose genetic material has been altered using recombinant DNA technology.

Question 20

A scientist is studying the effect of a point mutation in a gene. Which type of mutation would most likely result in a change in the amino acid sequence?

Accepted Answer

Missense mutation

DNA Structure, Replication, RNA, and Molecular Methods: Cell Biology Study Guide

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