B2 part 1

B2 part 1

Cells
1. Animal cells
  1. Cell membrane
  2. Nucleus
  3. Cytoplasm
  4. Mitochondria
2. Plant cells
  1. Cell membrane
  2. Nucleus
  3. Cytoplasm
  4. Mitochondria
  5. Cell wall
  6. Central vacuole
  7. Chloroplasts
3. Bacteria
  1. Chromosomal DNA
  2. Cell membrane
  3. Some have a flagellum
  4. Cell wall
  5. Plasmid DNA
DNA
1. Breakdown of DNA
  1. Cell nucleus
    1. Chromosome
      1. String of genes
        A gene is a short piece of DNA
2. Double helix
3. Base Pairs
  1. A = adenine
  2. T = thymine
  3. C = cytosine
  4. G = guanine
4. Extracting DNA
  1. Fruit mashed up and mixed with salty water and detergent
    1. This breaks open the cells and helps release the DNA
      1. Protease enzyme is added to filtered mixture, helps to break up proteins
        Breaking up proteins releases more DNA
        Ice-cold ethanol is poured into the mixture, makes DNA separate from liquid
5. Discovery
  1. Maurice Wilkins and Rosalind Franklin use X-rays to study DNA structure
  2. Franklin studied X-ray photographs of DNA to work out how atoms were grouped
  3. Watson and Crick interpreted data from other scientists, Franklin's X-ray photos were the final clue
6. Human Genome Project
  1. 18 different countries
  2. Collaborated to decode the human genome
  3. This is the order of bases on all the human chromosomes
Genetic engineering
1. Advantages
  1. Human insulin using GM is quicker and cheaper
  2. Golden rice contains vitamins helping prevent disease
2. Disadvantages
  1. A few diabetic people react badly to this insulin
  2. Golden rice seeds = expenisive
3. How is it done?
  1. A gene is cut out of a human chromosome using enzymes
    1. A DNA plasmid is taken out of a bacterium and cut open using enzymes
      1. The human insulin gene and the plasmid are mixed together
        The human insulin gene and the plasmid are stuck together to make a new plasmid
        The new plasmid with the human insulin gene is put back into a bacterium
        The bacterium will still make human insulin
Mitosis and Meiosis
1. Mitosis
  1. Mi-two-sis
    1. Makes two cells
  2. MiTosis
    1. IdenTical cells
  3. Diploid means double (two sets of) chromosomes
  4. Cell division that happens in body cells
  5. The cell that divides is called a parent cell
  6. Used in asexual reproduction
  7. Used in growth and repairing damaged parts of the body
2. Meiosis and reprduction
  1. Fertilisation takes place during sexual reproduction
  2. Fertilisation is when a male gamete combines with a female gamete
    1. Produces a zygote
  3. Sexual reproduction produces variation in offspring
  4. Fertilisation
    1. Gametes are haploid cells
    2. Sperm cell carries chromosomes from mother, egg cell carries mother chromosomes
    3. Gametes fuse at fertilisation
    4. Zygote is formed - it has one set of chromosomes from each gamete
  5. Meiosis
    1. Cell division
    2. Happens when a diploid cell divides to produce haploid gametes
    3. Parent cell is diploid - has two sets of chromosomes
    4. Parent cell splits in two twice, four different daughter cells are produced
    5. Daughter cells are haploid cells (each has one set of chromosomes)
Clones
1. Diploid nucleus is removed from adult body cell
2. Nucleus removed from egg cell, nucleus put in empty body cell
3. Cell simulated with an electric pulse to start mitosis
4. Cell divides and grows as an embryo
5. Embryo placed in uterus of surrogate mother
6. Advantages and disadvantages
  1. Animal cloned has good features
  2. It is more difficult to clone a mammal than a plant, many attempts needed. Lots of attempts = expensive
  3. Cloned mammals may suffer more health problems than usual
  4. Any genetic defect in the in parent will be passed on to the offspring
Stem cells
1. Embryonic
  1. Embryo destroyed when cells removed - some people think embryos have a right to life
  2. Body rejects them without use of drugs
  3. Produce any type of cell
  4. Easy to extract from embryo
2. Adult
  1. No embryo destroyed
  2. If taken from the person to be treated, the body will not reject it
  3. Produce a few types of cells
  4. Difficult to find and extract from tissue
3. Replace faulty cell with healthy, so person is well again
4. May produce cancer cells instead of healthy cells

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	Criado por Lucy Sherburn mais de 7 anos atrás