The Cell Cycle A Review

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

A look at the cell cycle

Components Interphase (G1, S, G2) and Mitosis (M) Gap 1: birth to DNA replication Synthesis: DNA duplication Gap 2: gap before mitosis Mitosis: nuclear division (followed by cytokinesis)

Mitosis: The steps Prophase Prometaphase* Metaphase Anaphase Telophase Cytokinesis* *extensions from the “PMAT” skeleton of mitosis

Prophase Chromatin Chromatin condenses into Chromosomes Sister chromatids Sister chromatids attached at centromere centromere Nuclear envelope still present

Prometaphase Nuclear envelope disappears Sister chromatids clearly visible and attach to spindle via kinetochorekinetochore

Metaphase Chromosomes align at metaphase plate 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 Synthesis Centromere: condensed region of a chromosome Kinetochore: 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 cell cycle mitosis orials/cell_cycle/problems.html test yourself