CELL CYCLE

How many cells do we begin with?

2

How do we get more?

Cell Cycle

INTERPHASE

G1 PHASE “gap 1” Phase period when cell growth and development occur

S PHASE “synthesis” Phase DNA replication / synthesis occurs

G2 PHASE “gap 2” Phase when organelles needed in cell division are made (centrioles, spindle fibers)

structure that contains genetic information (usually visible only in mitosis) CHROMOSOME

The set of 46 human chromosomes

the two identical parts on a chromosome CHROMATIDS

The middle part of the chromosome that holds together the sister chromatids CENTROMERE

MITOSIS

GOAL OF THE CELL CYCLE to create a new somatic cell exactly like the parent

MITOSIS process by which the nucleus of a cell is divided into two nuclei, each with the same number of chromosomes as the parent cell

1. PROPHASE The longest phase Chromosomes appear Centrioles move to opposite ends of the cell Chromosomes attach to the spindle Nucleolus and nuclear membrane breaks down

PROPHASE (cont…) The longest phase Chromosomes appear Centrioles move to opposite ends of the cell Chromosomes attach to the spindle Nucleolus and nuclear membrane breaks down

2. METAPHASE Shortest phase of mitosis Chromosomes line up at center of the cell

3. ANAPHASE Centromeres split Sister chromotids separate to form individual chromosomes Anaphase ends when the movement of chromosomes stops

4. TELOPHASE Chromosomes uncoil into chromatin Nuclear membrane reforms Spindle breaks apart

CYTOKINESIS The cytoplasm of the cell divides Forms two daughter cells that are exactly like the parent cell (each have one complete set of chromosomes)

Meiosis The process of cell division so that each new cell has 1/2 the number of chromosomes as the original.