cell biology and dna

What are the two major phases of the cell cycle?

Interphase and mitotic phase.

What occurs during interphase?

A long growth period between cell division including G1, S, and G2 phases.

What happens in the G1 phase of the cell cycle?

It is the primary growth phase where very active growth occurs.

What is the purpose of the S phase?

Synthesis of DNA occurs in preparation for cell division.

What is characterized by the G2 phase?

It is the final growth phase before cell division.

What is the mitotic phase?

It is the phase of the cell cycle where cell division occurs.

What are the two main processes involved in the mitotic phase?

Mitosis and cytokinesis.

What does mitosis involve?

Nuclear division where duplicated DNA is distributed between two daughter nuclei.

What is cytokinesis?

The division of cytoplasm that forms two new daughter cells.

How long does the complete cell cycle take?

18-24 hours.

How long do mitosis and cytokinesis take within the cell cycle?

1 hour.

What is a characteristic of cells that enter the G0 phase?

They enter a non-dividing state temporarily or permanently.

Give an example of cells that may enter G0 after adolescence.

Neurons and osteocytes.

What is DNA replication?

The process of copying DNA during cell division.

What happens during the first step of DNA replication?

DNA zips and uncoils, pulling apart the two strands.

What does DNA polymerase do?

It is the major DNA replicating enzyme.

What is a mutation?

An alteration in the DNA that may result from errors during replication.

What is a somatic cell mutation?

A mutation that may affect tissue functions or cause cancer but is not heritable.

What regulates cell reproduction?

Internal surveillance and control mechanisms including key checkpoints in the cell cycle.

What are the key checkpoints in the cell cycle?

G1, G2, and M checkpoints.

What external factors can modify the cell cycle?

Hormones, growth factors, and the presence of other cells.