Molecular Biology DNA Replication Quiz

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What is the primary function of DNA polymerase III during DNA replication?

Removes RNA primers from the lagging strand

Synthesizes the leading strand only

Extends the new DNA strand in both leading and lagging strands (correct)

Joins Okazaki fragments together

Which characteristic differentiates the leading strand from the lagging strand during DNA replication?

The leading strand is synthesized in the 5' to 3' direction

The leading strand requires multiple primers

The lagging strand is continuously synthesized

The lagging strand creates Okazaki fragments (correct)

What is the role of DNA ligase in DNA replication?

To synthesize new DNA strands

To act as a primer for DNA synthesis

To fill gaps left after RNA primer removal

To join Okazaki fragments by fixing single-strand nicks (correct)

What distinguishes DNA polymerase I from DNA polymerase III?

DNA polymerase I removes RNA primers and fills in gaps with DNA Signup and view all the answers

What happens during the removal of RNA primers in DNA replication?

DNA polymerase I replaces RNA with DNA Signup and view all the answers

What technique did Maurice Wilkins and Rosalind Franklin use to study the molecular structure of DNA?

X-ray crystallography Signup and view all the answers

What significant discovery did Franklin make regarding the structure of DNA?

The presence of a sugar-phosphate backbone Signup and view all the answers

How did Watson and Crick first misinterpret the base pairing in DNA?

They thought that bases paired like with like. Signup and view all the answers

What is the significance of the spacing of the nitrogenous bases in the DNA structure?

It contributes to the uniform width of the helix. Signup and view all the answers

What does the semiconservative model of DNA replication predict?

One daughter strand is old and one is new. Signup and view all the answers

Chargaff's rule states that adenine pairs with which nitrogenous base?

Thymine Signup and view all the answers

What was one of the first things Watson and Crick deduced from Franklin's X-ray images?

That DNA had a helical structure Signup and view all the answers

What is the primary function of DNA polymerase during DNA replication?

To proofread and correct incorrect nucleotides Signup and view all the answers

What are telomeres primarily responsible for in linear DNA molecules?

Postponing the shortening of DNA molecules Signup and view all the answers

What is true about the strands of DNA in relation to each other?

The strands are antiparallel. Signup and view all the answers

What mechanism is primarily utilized to correct mismatched nucleotides after DNA synthesis?

Mismatch repair mechanisms Signup and view all the answers

How often do errors occur in completed DNA molecules despite proofreading?

Approximately one in 10 billion Signup and view all the answers

What is the significance of mutations in DNA?

They are the primary source of genetic variation Signup and view all the answers

What is the primary function of histones in chromatin?

To provide the first level of DNA packing Signup and view all the answers

What distinguishes heterochromatin from euchromatin?

Heterochromatin is highly condensed and largely inaccessible for transcription. Signup and view all the answers

How does the modification of histones influence gene activity?

Acetylation enhances gene expression, while methylation often represses it. Signup and view all the answers

What role does the scaffold play in chromatin structure?

It condenses the 30 nm fiber into loops or supercoiled domains. Signup and view all the answers

During which phase of the cell cycle do chromosomes fully condense into mitotic chromosomes?

Mitosis Signup and view all the answers

What role does primase play in DNA replication?

It synthesizes a short RNA segment that serves as a primer. Signup and view all the answers

Which statement is true regarding DNA polymerase activity?

DNA polymerases require a primer and a DNA template strand to function. Signup and view all the answers

In which direction do DNA polymerases synthesize new DNA strands?

In the 5' to 3' direction. Signup and view all the answers

What characterizes the lagging strand during DNA replication?

It requires multiple primers and is formed in segments called Okazaki fragments. Signup and view all the answers

What distinguishes dATP from ATP in nucleotide synthesis?

dATP serves as a nucleotide for DNA, while ATP serves for RNA synthesis. Signup and view all the answers

How long are Okazaki fragments typically in eukaryotic cells?

100-200 nucleotides long. Signup and view all the answers

Why is the primer crucial for DNA synthesis?

It provides a free 3' OH group for DNA polymerase to add nucleotides. Signup and view all the answers

What is the rate of DNA elongation in human cells compared to bacteria?

Human cells elongate DNA at about half the rate of bacteria. Signup and view all the answers

What is the role of helicases in DNA replication?

Untwist the double helix at the replication forks Signup and view all the answers

Which statement is true regarding the speed of DNA replication in prokaryotes versus eukaryotes?

Prokaryotic replication is generally faster than eukaryotic replication Signup and view all the answers

What is the function of topoisomerase in the DNA replication process?

To relieve strain caused by tight twisting ahead of the replication fork Signup and view all the answers

Why is a primer necessary for DNA polymerase to begin synthesis?

It provides a free 3' hydroxyl (OH) group for bonding with dNTP Signup and view all the answers

What is one characteristic of DNA topoisomerase I?

It does not require ATP and reseals the nicked DNA Signup and view all the answers

What is the primary role of Taq polymerase in the PCR process?

To extend primers in the 5' to 3' direction Signup and view all the answers

Which step of the PCR process occurs at a temperature of 94-95°C?

Denaturation Signup and view all the answers

Which statement about DNA sequencing is true?

Nanopore methods identify nucleotides by measuring electrical current disruption. Signup and view all the answers

How does PCR facilitate gene cloning?

By providing a specific DNA fragment for use with a cloning vector Signup and view all the answers

What distinctive feature does third-generation sequencing offer compared to earlier techniques?

Longer read lengths allowing for comprehensive sequencing Signup and view all the answers

What is the purpose of nucleic acid hybridization in genetic engineering?

To pair one strand of nucleic acid with another complementary sequence. Signup and view all the answers

What is formed when a plasmid incorporates foreign DNA?

Recombinant DNA Signup and view all the answers

How do restriction enzymes contribute to the process of recombinant DNA technology?

They cut DNA at specific sequences to create fragments. Signup and view all the answers

What is the result of using gel electrophoresis in DNA analysis?

It separates nucleic acid fragments based on length. Signup and view all the answers

What is the main purpose of gene cloning?

To create multiple copies of a specific DNA segment. Signup and view all the answers

What is the primary function of the Cas9 enzyme in the CRISPR-Cas9 system?

To cut double-stranded DNA Signup and view all the answers

What is the purpose of using the CRISPR-Cas9 system to 'knock out' a gene?

To determine its function Signup and view all the answers

In the context of gene drive technology, what is the significance of engineering a new allele to favor its inheritance?

To rapidly propagate the engineered allele Signup and view all the answers

What concern does Jennifer Doudna highlight regarding the CRISPR technology?

The potential for misapplication and ethical issues Signup and view all the answers

In what way has CRISPR technology been applied to address sickle-cell disease?

By repairing a gene with a mutation Signup and view all the answers

What is the primary role of single-stranded binding proteins during DNA replication?

To stabilize unwound template strands. Signup and view all the answers

Which sequence correctly identifies the steps involved in synthesizing the lagging strand?

Synthesis occurs in fragments with the addition of RNA primers and joining of fragments by DNA ligase. Signup and view all the answers

What characterizes a bacterial chromosome compared to a eukaryotic chromosome?

Bacterial chromosomes are associated with very few proteins. Signup and view all the answers

Which of these enzymes is involved in replacing RNA primers with DNA nucleotides?

DNA polymerase I. Signup and view all the answers

What occurs after DNA polymerase III synthesizes fragment 4 during DNA replication?

It detaches and begins adding nucleotides to the leading strand primer. Signup and view all the answers