Eukaryotic Cell Division Occurs by Mitosis Q: What type of cell does mitosis occur in? A: Somatic cells or body cells (2n)
The Cell Cycle Cell cycle = period from the beginning of one cell division to the beginning of the next. Why is cell division important?
The Cell Cycle Three important functions of cell division for organisms: Growth – grow from single cell to multi-cellular organism Maintenance – replacement of worn out cells (e.g. Blood cells) Repair – cell division regenerates damaged tissues
Cells divide for an organism to survive Result 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 survive DNA – 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 Guess how much DNA fits into the nucleus? 2m
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
Cleavage furrow Division of cytoplasm (cell pinches in two) creates a cleavage furrow
Chromosome Structure