Class notes Biology Cell Division/Reproduction Biology 11, ISBN: 9780070915800

Cell Division/Reproduction
Chapter 4

Cell Theory
- All living things have 1 or 1+ cells
- Cells are the smallest units of living organisms
- New cells only come from pre-existing cells

Somatic cells - Body cells of animals/plants excluding reproductive cells

Functions of cell division:
- Growth
- Repair damaged tissues/organs
- Replace dead cells

Cell Cycle
Interphase
- Growth1
- Major period of growth
- Synthesizes many new
molecules for S phase
- Synthesis phase
- DNA (chromatin = uncondensed
fibres) replication
- Growth2
- Synthesizes more molecules

Meiosis & Mitosis must go through interphase to
go through G1 + G2 to grow and Synthesis to replicate DNA.

Mitosis
Division of nucleus material
- Prophase
- Chromatin condenses into chromosomes
- 2 copies of one chromosome (sister chromatids joined by centromere)

, - 46 double-stranded chromosomes (92 chromatids)
- Nuclear membrane + nucleolus disappears
- Spindle fibres are formed from centrosomes and move to opposite
poles
- Fibres and centrosomes called the spindle apparatus
- Centrosomes are an area while centrioles are the organelle




- Metaphase
- Spindle fibres guide chromosomes to the equator & attach to
centromere




<-- 4 chromosomes
- Anaphase
- Centromere splits apart and sister chromatids are separate
- 46 single-stranded chromosomes on each side
- Single-stranded Diploid
- Spindle fibres shorten and pull chromosomes to opposite poles




8 chromosomes
- Telophase
- Begins when chromosomes reach opposite poles