The Cell Cycle - Chapter 11 AQA AS Biology
Chapter 11 - AQA AS Biology
- Created by: H.N
- Created on: 28-12-12 14:36
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- The Cell Cycle
- Replication of DNA
- ensures all daughter cells have correct info to produce enzymes + proteins they need
- cell division - whole cell divides (follows nuclear division)
- semi- conservative replication
- requirements
- 4 types of nucleotides each with their bases of A, G, C + T must be present
- both strands of DNA must act as a template for attachment of nucleotides
- DNA polymerase - castalyse reaction
- source of chemical energy - to drive process
- the process
- 1. enzyme DNA Helicase breaks H bonds linking the base pairs of DNA
- 2. double helix separates into 2 strands + unwinds
- 3. energy activates these nucleotides
- 2. double helix separates into 2 strands + unwinds
- 1. enzyme DNA Helicase breaks H bonds linking the base pairs of DNA
- requirements
- Mitosis
- takes place when cell is NOT dividing = INTERPHASE
- continuous process
- 4 stages:
- 4. TELOPHASE = chromatids reach poles, become indistinct, nuclear envelope + nucleolus reform, spindle disintegrates
- importance
- produces 2 daughter nuclei that have the same no. of chromosomes as the parent cell + each other
- Growth
- Repair
- differentiation
- the cell cycle
- 1) INTERPHASE
- occupies most of the cell cycle, no division takes place.
- split into 3 parts
- 1. 1st Growth (G1) phase - cell grows, more organelles produced + proteins made
- 2. Synthesis (S) phase - DNA replicated
- 3. 2nd Growth (G2) phase - organelles grow + divide, energy stores increased
- 2. Synthesis (S) phase - DNA replicated
- 1. 1st Growth (G1) phase - cell grows, more organelles produced + proteins made
- 2) NUCLEAR DIVISION
- nucleus divides either into 2 (mitosis) or 4 (meiosis)
- 3) CELL DIVISION
- whole cell divides into 2 (mitosis) or 4 (meiosis)
- length of complete cell cycle varies amongst organisms
- cancer
- group of diseases caused as a result of damage to genes that regulate mitosis + the cell cycle
- leads to uncontrolled growth of cells
- abnormal group of cells = tumor - can develop in any organ of the body
- 1) INTERPHASE
- Replication of DNA
- 4. TELOPHASE = chromatids reach poles, become indistinct, nuclear envelope + nucleolus reform, spindle disintegrates
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