Cell Cycle, Stages & Checkpoints

What happens during G1 phase?

Cell grows

What happens during S phase?

DNA and centrosomes replicate

What happens during G2 phase?

Cell grows and prepares for mitosis

What are the three parts of interphase?

G1

What happens during M phase?

Mitosis and cytokinesis occur

What is karyokinesis?

Division of the nucleus and replicated DNA into two nuclei

What is cytokinesis?

Division of the cytoplasm into two daughter cells

What does the G1 checkpoint check?

Whether the cell has enough resources and energy

What activates proteins to move the cell cycle forward?

Cyclins

What happens if a cell fails the G1 checkpoint?

It may enter G0

What does the G2 checkpoint check?

Whether DNA replicated correctly and is ready for division

How is DNA checked during replication?

DNA polymerases proofread and p53 helps respond to damage

What happens if a cell fails the G2 checkpoint?

DNA is repaired or the cell undergoes apoptosis

What does the M-phase checkpoint check?

Whether spindle fibers attach to all chromosomes

What is needed for proper spindle attachment?

Correct kinetochore formation and attachment

What happens if a cell fails the M-phase checkpoint?

Division pauses until attachment is corrected or apoptosis occurs

What is apoptosis?

Programmed cell death

What is p53?

A protein that can stop the cell cycle when DNA is damaged

What happens if cell cycle checkpoints fail?

Cells may divide uncontrollably and form tumors

What is G0?

A state in which a cell is not actively dividing

What is the correct order of the cell cycle?

G1 → S → G2 → M phase

What is a haploid cell?

A cell with one set of chromosomes (n)

What is a diploid cell?

A cell with two sets of chromosomes (2n)

If n = 3

how many chromosomes are in a diploid cell?

How many chromosomes and chromatids are present in G1 if 2n = 6?

6 chromosomes and 6 chromatids

How many chromosomes and chromatids are present after S phase if 2n = 6?

6 chromosomes and 12 chromatids

How many chromosomes and chromatids are present in G2 if 2n = 6?

6 chromosomes and 12 chromatids

What happens to chromosomes during prophase?

Chromosomes condense and become visible

What happens to chromosomes during metaphase?

Chromosomes line up in the middle of the cell

How many chromosomes and chromatids are present in metaphase if 2n = 6?

6 chromosomes and 12 chromatids

What happens during anaphase?

Sister chromatids separate and become individual chromosomes

How many chromosomes are present in the cell during anaphase if 2n = 6?

12 chromosomes total

What happens during telophase?

New nuclei form and chromosomes begin to uncoil

How many chromosomes are in each daughter cell after cytokinesis if 2n = 6?

6 chromosomes per daughter cell

What are homologous chromosomes?

Chromosomes with the same genes

What does 2n = 6 mean?

The diploid cell has 6 chromosomes