The Cell Cycle

A Review

What is the Cell Cycle?The time and activities that take place from one cell division to the nextOrFrom cell “birth” to cell “death”Alternation between Interphase and Mitosis

A look at the cell cycle

G1

S

G2

M

G1 S G2 M

Components

Interphase (G1, S, G2) and Mitosis (M)Gap 1: birth to DNA replicationSynthesis: DNA duplicationGap 2: gap before mitosisMitosis: nuclear division (followed by cytokinesis)

Mitosis: The steps

Prophase

Prometaphase*

Metaphase

Anaphase

Telophase

Cytokinesis*

*extensions from the “PMAT” skeleton of mitosis

Prophase

Chromatin condenses into ChromosomesSister chromatids attached at centromereNuclear envelope still present

PrometaphaseNuclear envelope disappears

Sister chromatids clearly visible and attach to spindle via kinetochore

Metaphase

Chromosomes align at metaphase plate

Homologous pairs align SEPARATELY

Anaphase

Sister chromatids sever at centromere

V-shaped chromatids

Movement toward opposite poles

Telophase

Two visible sets of chromosomes

Nuclear envelope reforms

Cytokinesis

Cell division: cytoplasm divides

Formation of new cell membrane

Cytokinesis vs. Interphase:Chromosomes still visible

Textbook Reference Materials

Chapter 4 second Edition

Title: The Chromosome Theory of Inheritance

Glossary

Chromatin: undifferentiated mass of thread-like DNA/protein in cell nucleus during interphase

Chromosomes: self-replicating structures in cells; contains DNA; visible during Prophase of mitosis

Glossary cont.

Sister chromatids: duplicated IDENTICAL chromosomes attached at centromere after SynthesisCentromere: condensed region of a chromosomeKinetochore: protein structure at centromere that acts as molecular “motor for chromatids

Glossary Cont.

Metaphase plate: imaginary equatorial line midway between cell poles

Selected Web Sites

http://www.cellsalive.com/

cell cycle

mitosis

http://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/problems.html

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