Topic 2

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  • Prokaryotes
    • TOPIC 2
      • Gametogenesis
        • OOGENESIS
        • Fertelisation,
          • ACROSOME - sperm touches zona pellucida of egg, acrosome bursts releasing enzymes to digesst ZP
            • MEMBRANE FUSION - surfaces fuse so sperm can enter egg's cytoplasm
              • CORTICAL REACTION - vesicles inside egg (cortical granuals) fuse with cell membrane so no more sperm can enter
                • FERTILIZATION -  chromosome from sperm and egg combine to restore the diploid number
      • Chromosomal Mutation
        • Monosomy - Turners Syndrome, females missing an x chromosome - infertile
        • Polysomy - Downs syndrome, 2 copies of the same chromosome
      • Meiosis
        • Independent assortment and crossing over = variation
        • 1- a diploid parent cell gives rise to 2 haploid daughter cells each with 1 set of chromosomes
          • 2- separates the chromatids, 4 cells creates the gametes
      • Cell Cycle
        • Interphase, Grpwth 1, Growth 2, Ctokenesis
        • Mitosis
          • PROPHASE - centrioles move to opposite poles, chromosomes coli and become visible, nucleus dissapears.
            • METAPHASE - spindles fibers, centrioles, chromosomes, attached to spindles at centromere.
              • ANAPHASE - spindles contract, centromeres contract so chromatids can be pulled towards opposite poles.
                • TELOPHASE - nuclear membrane, nucleous, centrioles, chromosomes unwind
      • Viruses
        • DNA Viruses - contain DNA which act as a template for the manufacture of a new DNA and mRNA to make viral proteins
        • RNA Viruses - contain RNA and make new RNA from it.
        • Retroviruses - a special type of RNA virus where it directs the synthesis of the enzyme reverse transcriptase, which makes DNA versions of the RNA
        • Lytic Cycle - vial genetic material is dependent on host and ten they are released by lysis
        • Retrovirus - special lysogenic case, RNA is translated into DNA by reverse transcriptase
        • Lysogenic Cycle - viral nucleic acid id incoporated into host and spread.  may remain latent for years before spread.
      • Staining
        • IODINE SOLUTION - starch blue black
        • ETHANOIC ACID - stains DNA reddish purple
        • METHYLENE BLUE - stains nuclei and chromosomes blue
        • PHOTORGLUCIONOL - stains lignin, found in plant cells, red
      • Magnification
        • image size = actual size x magnification
      • Eukaryotes
        • Rough Endoplasmic Recticulum (ER) - single, flattened sacks enclosed by a membrane with ribosomes on the surface  proteins made here
        • Smooth ER- single, tubular sacks made of membrane lipids made here
        • 80s Ribosomes - site of protein synthesis
        • Golgi Apparatus - single curved sacks enclosed by a membrane, each one is smaller than the previous modifies and packages proteins for transport
        • Lysosome - single membrane destroys old organelles and pathogens using enzymes
        • Centrioles - 2 hollow cylinders  at right angles to each other form spindles in cell division
        • Nucleus - Double envelope with pores - stores DNA
        • Nucleolus - region of DNA + proteins making ribosomes
    • Plasmids - One or more, a small circular single length of DNA
      • Nucleoid - not membrane bound, folded up DNA
        • Cell Wall - made of peptoglycan
          • Gram +  = Thick, retains purple stain
          • Gram - = Thin doesn't hold purple stain but safrainin counter stain


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