Key concepts in Biology

    Cards (27)

    • eukaryotic cell = cell with a nucleus and membrane bound organelles
    • prokaryotic cell = single celled microorganisms
    • Animal cellsnucleus, cell membrane, mitochondria and ribosomes
      Plant cellsnucleus, cell membrane, cell wall, chloroplasts, mitochondria, vacuole and ribosomes
      Bacteriachromosomal DNA, plasmid DNA, cell membrane, ribosomes and flagella
    • Plant cells:
      • Cell wall- rigid made of cellulose which supports and strengthens cell
      • Chloroplasts- where photosynthesis occurs for food and contains chlorophyll
      • Large vacuole- contains cell sap for internal pressure for support
    • Animal cells:

      • Nucleus- contain genetic material that controls activites of cell(chromosomes)
      • Ribosomes- translation of genetic material in synthesis of proteins.
      • Mitochondria- reactions of respiration take place here which transfers energy for cell to work
      • Cell membrane- holds cell together controls what goes in and out.
      • Cytoplasm- gel-like substance where chemical reactions occur (contains enzymes)
    • Bacteria cell:
      • Chromosomal DNA- (long circular chromosome) controls activities and replication floats free
      • Cell membrane Plasmid DNA- small loops of extra DNA which contain genes like drug resistance
      • Flagellum- long hair like structure rotates to move away from toxins towards nutrients & oxygen
      • Ribosomes - protein synthesis
    • Sperm Cell Adaptations:
      • mitochondria (provides energy to swim)
      • tail (to swim to egg)
      • acrosome (stores enzymes to digest through egg membrane)
      • haploid nucleus
    • Egg Cell Adaptations
      • changes in the cell membrane after fertilisation (to stop anymore sperm getting in)
      • nutrients in the cytoplasm (feed embryo)
      • haploid nucleus
    • Ciliated Epithelial Cell Adaptations
      • line surface of organs
      • beat to move substances along the surface of tissue
      • lining airways to move mucus up throat to be swallowed and not get to lungs.
    • Light microscopes : low resolution and low magnifications
    • Electron microscopes : high resolution and high magnification
    • UNITS: (going up /1000) (going down x1000)
      • millimetre (10^3)
      • micrometre(10^6)
      • nanometre (10^9)
      • picometre (10^12)
    • ENZYME + SUBSTRATE -> ENZYME-SUBSTRATE COMPLEX -> ENZYME + PRODUCTS
    • Enzymes = biological catalyst that can break down molecules (digestion) or join substrate molecules (synthesis) if the substrate does not fit the active site the reaction will not be catalysed
    • Denature = when a enzyme becomes denatured there is a change to the enzymes active site therefore it cannot catalyse the reaction of its specific substrate.
    • TEMPERATURE - EFFECT ON ENZYMES
      • higher the temp=quicker the rate
      • if it gets to hot the enzyme will denature as bonds break= decrease in rate
    • pH - EFFECT ON ENZYMES
      • optimum pH (7) pepsin is pH (2) breaks down proteins in stomach.
      • if its too high or too low it will interfere with the enzymes bonds causing it to denature
    • SUBSTRATE CONCENTRATION - EFFECT ON ENZYMES
      • after a certain point there are too much molecules as all active sites are full the rate remains constant.
      • high the conc=faster the rate (more likely to meet substrate)
      1. Protein -> Amylase
      2. Starch -> Glucose
      3. Lipid -> Fatty Acids + Glycerol
    • ENERGY IN FOOD (J)= mass of water(g) X temp change of water(dc) X 4.2ENERGY PER GRAM OF FOOD (J/g) = energy in food (J) / mass of food (g)
    • DIFFUSION = the net movement of particles from a area of higher concentration to an area of lower concentration
    • OSMOSIS = the net movement of water molecules across a partially permeable membrane from a region of higher concentration to a region of lower water concentration.
    • ACTIVE TRANSPORT = the movement of particles across a membrane against a concentration gradient using energy transferred during respiration.
    • Biuret test - test for protein
      Purple (Positive)
      Pale blue (Negative)
    • Iodine Solution - Test for starch
      Blue-black (positive)
      Yellow-Brown (negative)
    • Benedict's solution - Test for reducing sugars
      Little - green
      More - yellow/orange
      Lots - brick red
      Blue (negative)
    • Ethanol emulsion test - test for fats and oils
      Cloudy emulsion (positive)
      Clear (negative)