Cell Division

Cell Types

1. Body Cells (Somatic Cells): All the cells of your body – except the sex cells.

2. Sex Cells – sperm, eggs – (Gametes): The cells used for reproduction.

Body Cells (Somatic Cells)

1. Chromosomes are in matched pairs called homologous (same) chromosomes—same size, shape, and carry the same genes for the same traits).

2. Humans have 46 chromosomes in EACH CELL! 3. (They are found in 23 pairs)

4. Chromosomes are copied right before the process of MITOSIS.

5. Goal: Make more cells—just like the original.

Sex Cells – eggs and sperm (Gametes)

1. Chromosomes occur as singles, not in pairs.

2. Human have 23 chromosomes in each gamete –one of each pair.

3. Sex cells are made during the process of MEIOSIS.

4. Goal: make reproductive cells with half the number of chromosomes.

Essentially it is wound up DNA

Also called Sister Chromatids or Homologous Chromosomes when occurring in pairs

One Chromatid is from the “mom” and one is from the “dad”

Structure of a Chromosome

Cell Cycle

Events of the Cell Cycle

G1: first GROWTH phase (growth, synthesis of new proteins and organelles)

S: DNA is doubled (chromosomes replicate)

G2: second GROWTH phase (organelles and molecules required for division are produced)

M phase: Cell Division (Mitosis)

Mitosis – 4 phases

Prophase

Metaphase

AnaphaseTelophase

Cytokinesis

Interphase

Interphase is the period of growth that occurs between cell divisions.

dfgsg

ProphaseChromosomes

become Possible to see.

Metaphase

Chromosomes pair and line up in the Middle of the cell.

AnaphaseThe chromatids are

pulled Apart into individual chromosomes and move toward opposite sides of the cell.

Individualchromosomes

Telophase

Chromosomes gather at opposite ends of the cell

Two new nuclei! (not quite 2 cells yet)

CytokinesisImportant note: This is not a phase of Mitosis

During cytokinesis, the cytoplasm pinches in half.

Each new cell is called a daughter cell

Each has an identical set of copied chromosomes