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  • Created by: zasina
  • Created on: 17-04-15 19:52
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  • Topic 3
    • Cells
      • Eukaryotic complex - plants and animals. linear DNA, dont always have a cell wall, many organelles
        • Organelles - specific parts of cells (usually membrane bound)
      • Prokaryotic - simpler, bacteria/algae. Smaller, circular DNA, no nucleus, polysaccharide cell wall,  no mitochondria, smaller ribosomes
      • Protein transport. Ribosomes, rough endoplasmic rectilium, folded, Golgi apparatus, processed - vesicles - fuse to cell membrane
      • Cells - tissue - organs - systems
      • Cell cycle/mitosis. Growth and division. Interphase: G1,S,G2 - and prepares to divide. DNA replicated ATP increased Mitosis, then cytoplasmic division
    • Sexual reproduction
      • Gametes - sex cells, join by fertilization to form a zygote (divides and develops) passing DNA. Animals - sperm/egg cell (ovum) Plants - pollen grains,ovules. Body cells full number 46, 23 from each
        • Meiosis - produces gametes, half number of chromosomes. DNA replicates identical chromosomes, homologous pairs - separated in first division, sister chromatids separated in second division. 4 gametes genetically different
          • Genetic variation- crossing over of chromatids, swapping sections - same genes, different combo of alleles Independent assortment of chromosomes - different combonations from maternal/paternal
      • Sperm cell - lots of mitochondria energy for tail, nucleus, acrosome digestive enzymes - zona pellucida, flagellum swimming
        • Fertilisation - Mammals - oviduct through cervix/uterus. Acrosome reaction - contact with zona pellucida, digestive enzymes through cell membrane, fuses - cortical granules thicken zona pellucida prevent other sperm.
          • Egg cell - much larger, cell membrane, follicle cells for protection, zona pellucida, nucleus
          • Plants - embryo sac. Pollen grain on stigma, absorbs water splits open, digests through style by tube nucleus. Ovary - through micropyle, embryo sac in ovule. One fuses with egg nucleus, other with polar nuclei - food store endosperm
      • Egg cell - much larger, cell membrane, follicle cells for protection, zona pellucida, nucleus
    • Stem Cells
      • Differentiation into specialised cells -  Totipotent: ability to give rise to all cell types Pluripotent: some cells (specialised)
      • Unspecialised cells can develop into any type of cell. Divide by mitosis become new cells. Human embryo/adult tissue to replace(bone marrow)
      • Different gene expression - some genes are activated, active mRNA transcribed and translated. Proteins modify cell - specialised.
      • Medicine



Most things on here apart from mitosis phases 

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