Cell Reproduction and Cell Reproduction and GrowthGrowth

Cell Division

MC

Limits on Cell SizeLimits on Cell Size• Diffusion is more efficient over short distances• DNA limitations (has to be able to make

proteins for whole cell)• Surface area – to – volume ratio

Cell ReproductionCell Reproduction

• 1 somatic cell (parent cell) reproduces to make 2 identical somatic cells (daughter cells)…

Interphase (G1, S, G2)Cell Division- Prophase Metaphase Anaphase Telophase Cytokinesis

The Cell Cycle The Cell Cycle (phases in the life cycle of a cell)(phases in the life cycle of a cell)

What happens in What happens in each of these phases each of these phases

of the cell cycle?of the cell cycle?

InterphaseInterphase

• Cell grows in size and metabolizes• Chromosomes duplicated

•G1-growth phase 1

•G2-growth phase 2

•S-synthesis

1. Prophase1. Prophase

• Chromatin coils up into chromosomes(Chromosomes are made up of 2 sister chromatids

attached by a centromere)

• Nucleus disappears• Centrioles move to poles • Spindle forms

2. Metaphase2. Metaphase• Chromosomes attach to the

spindle and line up on the equator of the cell.

• Spindle fibers attach to each sister chromatid at the centromere.

3. Anaphase3. Anaphase

• Sister chromatids separate and move to opposite poles as spindle fibers shorten

4. Telophase4. Telophase

• Chromatids reach poles• Chromosomes unwind• Nuclei reform• Spindle fibers break down

5. Cytokinesis5. Cytokinesis

• Division of the cytoplasm…separation of the 2 new cells

Cytokinesis:Cytokinesis: Animal Animal vs. vs. PlantPlant

• Plasma membrane pinches in (cleavage furrow)

• Cell is pinched in two

• Cell plate laid down along equator

• Plasma membrane forms around each cell

• New cell walls form on each side of cell plate

Mitosis

Summary

Check your BRAIN!Check your BRAIN!

1. Describe how a cell’s surface area-to-volume ratio limits its size.

2. Why is it necessary for a cell’s chromosomes to be distributed to its daughter cells in such a precise manner?

3. How is the division of cytoplasm different in plants and in animals?

4. List the 4 phases of mitosis.

Key TermsKey Terms• Chromosomes• Chromatin• Sister chromatids• Centromere• Spindle (spindle fibers)• Centrioles• Cleavage furrow• Cell plate• Interphase• Prophase• Metaphase• Anaphase• Telophase• Cytokinesis