Biology Chapter 11: DNA Replication and Cell Division

What is cell division?

The process by which cells make more cells.

What is DNA replication?

Making two DNA helices from one helix using the original DNA to create more DNA.

What does semi-conservative replication mean?

Replicated DNA consists of one original strand and one new strand.

What are origins of replication?

Locations where DNA replication begins, separating the two DNA strands and opening a replication bubble.

How do eukaryotic chromosomes replicate DNA quickly?

They have hundreds of origins of replication, allowing replication to proceed in both directions from each origin.

What is a replication fork?

The area where new strands of DNA are made during replication.

What role does topoisomerase play in DNA replication?

It relieves the strain of twisting in the double helix by breaking, swiveling, and rejoining DNA strands.

What is the function of helicase in DNA replication?

Helicase enzymes unzip the double helix at the replication forks.

What do single-strand binding proteins do?

They bind to and stabilize single-stranded DNA during replication.

What is the role of DNA polymerases?

They catalyze the synthesis of new DNA at a replication fork.

What is required for DNA polymerases to function?

A primer, a DNA template strand, and a free 3' OH.

What is primase?

An enzyme that adds the RNA primer, which is a short stretch of nucleotides.

What is the significance of the RNA primer in DNA replication?

It provides DNA polymerase with a double strand and a free 3' OH to begin synthesis.

What is the average rate of elongation for DNA polymerase in bacteria?

About 500 nucleotides per second.

What is the average rate of elongation for DNA polymerase in human cells?

About 50 nucleotides per second.

What happens during the separation of parental strands in DNA replication?

Parental strands are separated into templates for new strand formation.

What is a daughter DNA?

DNA formed after replication.

What is the basic principle of DNA replication?

Base pairing to a template strand.

What is the structure of DNA?

A double helix composed of two strands running in opposite directions.

What are the base pairing rules in DNA?

Adenine pairs with Thymine, and Cytosine pairs with Guanine.

What is the role of the sliding clamp in DNA replication?

It helps to hold the DNA polymerase in place on the DNA strand during replication.

What is the significance of the 5' and 3' ends in DNA?

They indicate the directionality of the DNA strand, which is crucial for replication.

What is a nucleoside triphosphate?

A nucleotide that is added to a growing DNA strand.

What happens to the phosphate groups when a nucleotide joins the DNA strand?

It loses two phosphate groups as a molecule of pyrophosphate.

In which direction can DNA polymerase synthesize DNA?

Only in the 5' to 3' direction.

What is the leading strand in DNA replication?

The newly synthesized daughter DNA strand that goes from 5' to 3' from a parental template that goes 3' to 5'.

What is the lagging strand in DNA replication?

The newly synthesized daughter DNA strand that goes from 3' to 5' from a parental template that goes 5' to 3'.

What are Okazaki fragments?

Segments of DNA synthesized on the lagging strand, joined together by DNA ligase.

What enzyme synthesizes Okazaki fragments?

DNA polymerase III.

What is the role of primase in DNA replication?

To make RNA primers for the leading and lagging strands.

What is the function of DNA ligase?

To seal the gaps between Okazaki fragments on the lagging strand.

What is the 'end replication problem' in linear DNA?

The lagging strand cannot replicate all the way to the end of the template DNA strand, leaving unreplicated sections.

What are telomeres?

The ends of linear chromosomes, consisting of repeated sequences.

What is the function of telomerase?

An enzyme that adds telomeres to the ends of chromosomes.

How does a lack of telomerase activity affect cells?

It limits the number of times a cell can divide.

What is the significance of the antiparallel orientation of DNA strands during replication?

It necessitates the existence of both leading and lagging strands.

What occurs when two replication bubbles meet?

DNA ligase seals the gap in the sugar-phosphate backbone.

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

To stabilize single-stranded DNA and prevent it from re-annealing.

What is the overall direction of DNA replication?

From the origin of replication, moving outward in both directions.

What is the role of helicase in DNA replication?

To unwind the DNA double helix at the replication fork.

What is the purpose of the sliding clamp in DNA replication?

To hold DNA polymerase in place on the DNA strand.

What is a primer in DNA replication?

A short segment of RNA that provides a starting point for DNA synthesis.