Chapter 9 - Chapter 9: Chromosomes, the...

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View Full Document Right Arrow Icon Chapter 9: Chromosomes, the Cell Cycle, and Cell Division I. Why cells divide? a. Need large surface area to carry out chemical processes (absorption) b. More smaller cells have a greater surface area than one large cell c. Cells divide to: i. Reproduce ii. Grow (an organism; root) iii. Regenerate (snake skin) II. Cell Division a. Reproductive signal released – start division i. Comes from within cell or outside cell b. DNA replication c. DNA (and organelles in eukaryotes) distribution to both cells d. Cytokinesis - New material added to cell membrane/wall to separate III. Prokaryotes i. Binary Fission ii. Division Rate depends on environment 1. Reproductive signals = nutrient availability/environmental conditions iii. 1 chromosome 1. long strand of DNA w/ proteins on it 2. mostly circular a. + (basic) histone proteins bind to – (acidic) DNA b. some viruses, mitochondria/chloroplasts iv. parts of circular chromosome 1. ori – origin of replication 2. ter – terminus of replcation; prevents it from over-replicating v. replication 1. DNA threaded through group of proteins 2. Two ori’s of DNA go to opposite ends of cell (cell swells) 3. DNA near ori bind proteins (hydrolyze ATP) a. This binding of proteins releases energy to pull ori’s to other ends 4. Pinch plasma membrane w/ protein filaments 5. New cell wall made IV.Eukaryotes a. Reproduction signal depends on entire organism not just single cell i. b. Many chromosomes c. Organisms form from fusion of gametes from both parents to make single cell d. Mitosis – produces 2 identical cells e. Meiosis – produces gametes f. Cell Cycle (2 phases)
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View Full DocumentRight Arrow Icon i. Interphase (most of its time spent here) 1. G1 (most varied in time; most time spent) a. Initial growth b. Metabolizing; carry out its natural process c. Receives reproductive signal at end of G1 d. G0 – cells that don’t need to divide sit in this phase e. Restriction point at end of G1 i. Need signal 1. Growth factor 2. Nutrients 3. Cell size (too big = divide) 4. DNA damage 2. S a. DNA replication (still held together) 3. G2 a. Prepare for mitosis b. Make spindle fibers to pull apart the chromosomes i. Made and organized by centrosomes (2 perpendicular
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This note was uploaded on 01/27/2011 for the course BIOSC 0160 taught by Professor Bledsoe during the Spring '08 term at Pittsburgh.

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Chapter 9 - Chapter 9: Chromosomes, the...

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