Biology

Biology

1. DNA and cell divsion

   • DNA
     • Genes
       • A short section of DNA
       • Each gene codes for a specific protein
         • This specifies which order the amino acids join together
       • Alleles- forms of gene
         • Dominant
           • Represented by an uppercase letter
           • Characteristics from a dominant allele develop if there is one or two of this allele in a pair
         • Recessive
           • Represented by a lowercase letter
           • The characteristics from this are only present if there are two in a pair
         • heterozygous (2 different alleles) homozygous (2 of the same allele)
     • Chromosomes
       • A cell nucleus contains these
       • Made from long DNA molecules
       • Found in pairs
   • Mitosis
     • It's important to remember the spelling as you have to spell it right to get the marks in your exam
     • This is the process by which BODY cells divide
     • The genetic material is copied
     • The cell divides to form two genetically identical body cells
     • Occurs during:
       • Growth
       • Cell repair
   • Gametes and fertilisation
     • Gametes
       • Male Gametes are Sperm
       • Female Gametes are Eggs
     • Contain one set of genetic information
     • Divide by Meiosis
       • See meiosis section
     • Fertilisation is the fusion of a male and female gamete
   • Differentiation and stem cells
     • Most animal cells become specialised at an early stage
     • Stem Cells
       • Made to form different types of cell
         • Come from embryos or adult bone marrow
   • Meiosis
     • It's important to remember the spelling as you have to spell it right to get the marks in your exam
     • Cells divide by meiosis to form gametes, when this happens:
       • Copies of the genetic information are made
       • The cell divides twice to form 4 gametes
     • Each gamete has a single set of chromosomes
       • BBC bitesize has an awesome diagram- http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/inheritance/dna_cell_divisionrev5.shtml

2. Cells

   • Parts of a cell
     • Animal and plant cells
       • Nucleus
         • Contains genetic material
       • Cytoplasm
         • Most chemical processes happen here
       • Cell Membrane
         • Controls, which substances enter and leave the cell
       • Mitochondria
         • Energy released by respiration here
       • Ribosomes
         • Protein synthesis happens here
     • Only plant cells
       • Cell Wall
         • Strengthens the cell
       • Chloroplasts
         • Absorbs light energy for photosynthesis
       • Permanent Vacuole
         • Filled with cell sap to help keep the cell enlarged
   • Bacterial cells
     • Single cell organism
     • The genetic material is not in a distinct nucleus
   • Specialised cells
     • Leaf cells
       • Absorbs sunlight for Photosythesis
       • Packed with chloroplasts closley packed cells
     • Root hair cell
       • Absorbs water and mineral ions from the soil
       • Long-large surface area
     • Sperm Cell
       • Fertilises an egg cell
       • Head contains genetic information and enzyme middle-food end-movement
     • Red blood cell
       • Contains haemoglobin to carry oxygem
       • Large surface area- no nucleus so more haemoglobin
   • Diffusion
     • Particles move from an area of high concentration to an are of low concentration

3. Photosynthesis

   • Carbon Dioxide+water--------> Glucose + Oxygen Light energy
   • Light energy is absorbed by chlorophyll
     • Then it is used to convert CO2 & H20 to 02 & C6H12O6
   • Some glucose is used for respiration some is converted to starch for storage
     • Storage of and use of glucose
       • Stored as starch, fats and oils
       • Used to produce Cellulose and proteins
   • Limiting Factors
     • Temperature
       • Plants cant photosynthesis if it is too cold or hot as the enzymes become denatured.
     • Light intensity
       • Increasing the light intensity increases the rate of photosynthesis
     • Carbon dioxide concentration
       • As CO2 concentration increase so does the rate of potosyntthesis
     • Graphs
       • See her for graphs showing limiting factors: http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/photosynthesis/photosynthesisrev2.shtml
       • Plateau-something else is the limiting fator

4. Proteins & enzymes

   • Amino Acids
     • Proteins made from long chains of amino acids
   • Enzymes
     • Biological catalysts
       • Catalyst-a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change
     • They have optimum temp. and pH at which their activity is greatest
     • Active site
       • Area were if hit the enzyme

5. Distribution of organisms

   • Quadrats
   • Physical factors that may effect the distribution
     • Temp.
     • Niutrients
     • amount of light
     • water avaliability
     • CO2 &O2 avaliability

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