eukaryotic cell division

Eukaryotic Cell DivisionOccurs by Mitosis

Q: What type of cell does mitosis occur in?

A: Somatic cells or body cells (2n)

The Cell CycleCell cycle = period from the beginning of one

cell division to the beginning of the next.

Why is cell division important?

The Cell CycleThree important functions of cell division for

organisms:

1.Growth – grow from single cell to multi-cellular organism

2.Maintenance – replacement of worn out cells (e.g. Blood cells)

3.Repair – cell division regenerates damaged tissues

Cells divide for an organism to surviveResult of cell division

= two new cells (daughter cells) that are identical to the original cell (parent cell)

Why are the daughter cells identical?• They contain an exact copy of the parent cell’s

hereditary material – DNA (deoxyribonucleic acid)– DNA store the instructions that determine the details

of the organism’s life (characteristics, functions, life span)

Cells divide for an organism to surviveDNA – is store in the nucleus of eukaryotic cells

- it forms thread-like coils called chromatin, which we usually can’t see

- when a cell divides, the chromatin condenses and forms chromosomes, which we can see

Why is cell Replication in Eukaryotes more complicated?

• complicated because:

– DNA is divide among several linear chromosomes

– DNA is contained within a nucleus

– cell has several membrane bound organelles

Source:http://commons.wikimedia.org/wiki/File:Kasvisolu.png

Three Stages of the Cell Cycle• Stage 1 – Interphase

– Growth and preparation of cell for division – DNA replication occurs in this stage– Consists of G1, S, G2 phases

• Stage 2 – Mitosis– Division of the nucleus– Consists of 4 phases

• Stage 3 – Cytokinesis– Division of the cytoplasm and organelles

Growth Stage

Division Stage

The Eukaryotic Cell Cycle

*Separation of centrosomes

Spindle fibres from opposite poles attach to the centromere of each chromosome

* Spindle fibres shorten

• Division of cytoplasm (cell pinches in two)

• creates a cleavage furrow

• Cleavage furrow

Chromosome Structure