Chapter 9 - www.thelifewire.com Chapter 9: Chromosomes, the...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
www.thelifewire.com 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)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
www.thelifewire.com 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
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/27/2011 for the course BIOSC 0160 taught by Professor Bledsoe during the Spring '08 term at Pittsburgh.

Page1 / 6

Chapter 9 - www.thelifewire.com Chapter 9: Chromosomes, the...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online