Cell Cycle and DNA replication

What are the two main stages of the cell cycle?

M phase and interphase.

What occurs during the G1 phase of interphase?

Kinases are made, it's a preparatory phase for S, and it checks for DNA damage.

What happens during the S phase of interphase?

DNA is replicated, with a checkpoint for errors in replication.

What is the function of helicase in DNA replication?

Helicase separates strands of the parent DNA by breaking hydrogen bonds between base pairs.

Define the G2 phase of interphase.

The size and protein content of the cell increases, with a checkpoint ensuring all chromosomes are replicated.

What is the G0 phase in the cell cycle?

Cells pause in the cell cycle, exit, but can still perform specialized functions.

Describe the M phase in the cell cycle.

It includes mitosis and cytokinesis, with a checkpoint for the proper attachment of spindle fibers to sister chromatids.

What is the role of DNA polymerase in DNA replication?

DNA polymerase synthesizes the new DNA strand and requires a primer.

How does DNA replication differ in prokaryotes and eukaryotes regarding the origin of replication?

Prokaryotes have a single origin of replication while eukaryotes have multiple origins.

What is the end replication problem?

It arises because the last RNA primer on the lagging strand creates a gap that cannot be filled with nucleotides.

How do telomeres resolve the end replication problem?

Telomeres are repeating sequences added to the ends of linear chromosomes, and telomerase contains RNA complementary to these sequences.

What distinguishes the leading strand from the lagging strand in DNA replication?

The leading strand is synthesized continuously while the lagging strand is synthesized in fragments.

What would happen if replication machinery components were dysfunctional?

Replication would not occur properly, affecting critical processes like strand separation and synthesis.

What effect would decreased telomerase activity have on cell division?

It would lead to shorter chromosomes over time due to incomplete capping.

How are heavy and light nitrogen isotopes used in DNA replication studies?

They distinguish between different models of DNA replication by observing the density of resulting DNA strands.

What is the significance of analyzing data from centrifugation experiments in DNA replication?

It determines whether the data support models like conservative, semi-conservative, or dispersive replication.