CORE CONCEPTS

Created by: Former Member
Created on: 30-05-19 15:41

View mindmap

Core concepts
- Membranes
  - Phospholipid bilayer
    - Phosphate head - hydrophilic
    - Fatty acid tail -hydrophobic
  - Glycoprotein
    - Carb. chain attached to extrinsic protein, for cell recognition
  - Cholesterol: stability
  - Glycolipid
  - Proteins
    - Extrinsic: cell signalling + cell recognition
    - Intrinsic: passage of polar molecules
  - Permeability
    - Higher temp = increase
    - More cholesterol = less fluid = decrease
    - Short unsaturated chains pack looser = increase
- Transport
  - Active transport: requires ATP to transport against gradient
  - Diffusion: transport down concentration gradient
  - Facilitated diffusion: transport of polar molecules down a concentration gradient
    - Uses intrinsic/ channel proteins
  - Osmosis: transport of water down ? gradient
  - Cytosis
    - Endocytosis: transport of large quantities into cell
    - Exocytosis: transport of large quantities out of cell
- Cell structure
  - Golgi body: modifies some proteins/lipids forms vesicles + lysosomes
  - Nucleus: codes for protein synthesis, nucleolus = sit of rRNA synthesis
  - RER: transports proteins to Golgi in vesicles
  - SER: synthesises + transports lipids to Golgi
  - Lysosomes: hydrolytic enzymes for autolysis/ phagocytosis
  - Ribosome: protein synthesis, 70S in prokaryotes
  - Mitochondria: site of aerobic respiration, ATP production
  - Cell wall: mechanical strength + support, prevents cell lysis
- DNA replication
  - DNA helicase breaks H bonds + unzips strand, free DNA nucleotides enter
    - Leading strand: DNA polymeraseforms phosphodiester bond 5'?3'
    - Lagging strand: DNA polymerase forms phosphodiester bond 5' to 3' in segments DNA ligase joins sections
- Protein synthesis
  - Translation
    - 2nd stage occurs in ribosome
    - 2x codon in ribosome then 2x tRNA line up anticodon then peptide form between a.a repeats until stop codon reached
      - tRNA reused
    - Amino acid attaches to correct tRNA
  - Transcription
    - 1st stage occurs in nucleus
    - DNA helicase then free RNA nucleotides then RNA polymerase then splicing and joining by DNA ligase
      - RNA polymeraseforms pho-sphodiester bond
- Biological compounds
  - Water
    - Cohesive, allows for transpiration stream
    - Polar
    - High latent heat of vaporisation, acts as coolant (eg. sweat)
    - Low viscosity, important for lubrication of joints
    - High SHC, stable temp for aquatic life
  - Carbohydrate
    - Monosaccharide
      - a-glucose, B-glucose, fructose, galactose
    - Disaccharide
      - Sucrose, maltose, lactose
    - Glycogen
      - Branched, compact, main glucose storage in body
    - Starch
      - Consists of amylose and amylopectin
        Amylose = 1,4 glycosidic bond
        
        Amylopectin= 1,4 glycosidic bond + 1,6 between branches
      - Branched, compact
    - Cellulose
      - a-glucose, straight chain (180? rotation)
      - Hydrogen bonds between chains
      - Structure in plants (cell wall)
    - Chitin
      - B-glcuose, straight chain, contains N
      - Insect exoskeleton
  - Lipids
    - Uses
      - Insulation
      - Buoyancy
      - High energy store
      - Metabolic water
      - Waterproof
    - Glycerol + fatty acid
      - Complex = plus extra molecule
    - Triglycerides: 3x fatter acid + 1 x glycol (ester bond)
  - Proteins
    - 1, 2, 3 and 4 structures
    - Globular and fibrous proteins
    - Enzymes, hormones, immunology
  - Food tests
    - Protein: add Biuret solution. Turn purple
    - Reducing sugar: addition of Benedict's solution + heat. Blue to red
    - Non-reducing sugar: addition of HCl + NaOH then Benedict's solution + heat. Blue to red
    - Starch: addition of iodine. Brown to blue/black
    - Lipids: add ethanol. Emulsion forms
- Enzymes
  - Use
    - Lowers activation energy by providing an alternative pathway
    - Increases rate of reaction
  - Immobilised enzymes
    - Biosensors
      - Instantly measure metabolite concentration
      - Digital (quantitative) and simple (qualitative) types
    - Advantages
      - Increased surface area
      - Easily removable + reusable
      - Works at higher temperature and wider pH
    - Disadvantages
      - Can reduce rate as rely on movement of substrate
      - Successful development is expensive
  - Inhibition
    - Competitive
      - Increase inhibitor decreases chance of substrate binding
      - Similar shape to substrate
      - Inhibitor binds to active site
    - Non-competitive
      - Binds to allosteric site and changes active site shape
      - Substrate can no longer bind
    - End product
      - Increase end product inhibits reaction as product binds as a non-competitive inhibitor
      - Decrease end product reverses inhibition so reaction starts again
  - Factors + graphs
    - pH: Highest ROR at optimum pH, extreme change stops reaction
    - Increase temperature Increase ROR up to a point, then denatures
    - Increase substrate concentration Increase ROR until enzyme is the limiting factor
    - Increase enzyme concentration Increase ROR until substrate is limiting factor
  - Key points
    - Globular protein
    - Specific to substrate
    - Polar
  - Theories

Get Revising

CORE CONCEPTS

Comments

Similar Biology resources: