B3 Summary

B3 Summary

Cell division and Growth
1. Meiosis = Gametes
  1. Haploid
  2. Each cell is genetically different
2. Mitosis = New cells for growth
  1. Genetically identical
  2. Diploid
3. Multicelluar
  1. Grow larger
  2. More complex
  3. Use cell differentiation
4. Undifferentiated cells (Stem Cells) can develop into different cells, tissues and organs
5. Growth can be measured in; Height, Dry Mass and Wet Mass
  1. Dry mass is best
6. Plants and animals grow differently
Respiration and the Circulation
1. Aerobic respiration uses oxygen
  1. Glucose + Oxygen > Carbon Dioxide + Water (+ ATP)
    1. C6 + H12 + 6O2 > 6CO2 + 6H2O +ATP
2. Anaerobic respiration takes place during hard exercise when there is insufficient oxygen available
  1. Glucose > Latic Acid + ATP
    1. Latic acid builds up in muscles causing pain and fatigue
      1. acts as oxygen debt and has to be broken down in the liver after exercise
3. Red blood cells carry oxygen around the body
4. Mammals have a double circulatory system
5. Arteries carry blood away from the heart
6. Veins carry blood back to the heart
7. Capilaries link arteries to veins
Changing Genes and Cloning
1. Nuclear transfer (Dolly the Sheep ) involves placing the nucleus of a body cell into an egg cell
2. New Cloning Technology
  1. Produce a certain number of benefits
  2. Involve certain risks
  3. Raise ethical issues
3. Plants can be cloned by tissue culture or cuttings
4. Cloning plants is easier than animals because plant cells retain the ability to differentiate
5. Selective breeding may reduce the gene pool leading to inbreeding
6. Genetic engineering is useful but raises ethical issues
7. Gene therapy involved changing a persons genes to cure disorders
DNA, Proteins and Mutations
1. Chromosome > Gene > Base
2. Proteins are coded for by DNA
  1. The base sequence codes for the order of amino acids
  2. Each amino acid is coded for by 3 bases
3. Enzymes are specific and work by a "lock and key" mechanism
4. Protein synthesis occurs on ribosomes in the cytoplasm
5. The code needed to produce a protein is carried from DNA to ribosomes by a molecule call mRNA
6. Enzyme activity is affect by pH and Temperature
  1. Lower collision rates at lower temperatures
  2. Denaturing at extremes of pH and high temps
7. Proteins are long chains of amino acids
  1. Can be structural (Collagen), hormones (insulin), enzymes or carrier molecules (mRNA)
8. Mutations lead to production of different proteins
  1. Change in bases in DNA can change the amino acid sequence

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