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Biology~AS

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Biology~AS

AS level biology

Biological molecules
- Carbohydrates
  - Sugars, Starch, Glycogen, Cellulose
    - Starch
      - α glucose
      - Plants
      - Medium-term storage
      - Tight double helix
      - Branched areas allow hydrolysis
    - Cellulose
      - β glucose
      - Plants
        Cell wall
      - Straight chains
        Hydrogen bonds between chains
    - Glycogen
      - α glucose
      - Animals
      - energy storage
  - Monosaccharides
    - All carbohydrates made from
    - Monomers
      - Glucose, galactose and fructose
        Same no. of atoms diff. arrangement
        Glucose
        α glucose
        H then OH
        β glucose
        OH then H
      - 2 make a disaccharide
  - Disaccharides
    - Condensation reaction
      - Forms glyosidic bond
      - Loss of water molecule
  - Polysaccharides
- Lipids
  - contain C, H little O
  - Dissolve in solvents NOT water
  - phospholipids
    - Hydrophobic 'tails'
      - 2 fatty acid tails
    - Hydrophillic 'heads'
      - Glycerol + phosphate group
  - Saturated-solid no C=C
    - Max. no. of H atoms
  - Unsaturated kink C=C
  - Triglycerides
    - Condensation reaction
      - Ester Bond
    - Carboxyl group
  - NOT POLYMERS
- Proteins
  - Contains C, O, H, N, S
  - Amino acid is monomer
    - Acidic Carboxyl group
    - Joined by Condensation reaction
      - Peptide bond
    - Amino Group
  - Structure
    - Primary
      - Linear sequence of amino acids
      - Peptide bonds only
    - secondary
      - Polypeptide chain coiled or twisted
        α helix
        β sheet
      - Hydrogen & peptide bonds
    - Tertiary
      - Compact globular chain
      - Disulphide (covalent) Ionic Hydrogen & peptide bonds
    - Quaternety
      - More than one poplypeptide chain
  - Globular
    - Metabolic functions
      - Tertiary structure
        Compact shape
        Not stable
  - Fibrous
    - Structural functions
      - Long chains wound into helix
        Linked by cross bridges
        very stable
Biochemical tests
- Test for reducing sugar
  - Add Benedicts Heat in water bath
  - +ve result: brick red colour
- Test for non reducing sugar
  - Heat in water bath w/h HCL Neutralise w/h NaOH Add Benedicts Heat in water bath
  - +ve result: brick red colour
- Test for startch
  - Add Iodine
  - +ve result: turns blue/black
- Test for proteins
  - Add Biuret Solution
  - +ve result: turns lilac
- Tests for lipids
  - Add ethanol and shake
  - +ve result: cloudy white
DNA and RNA
- DNA
  - Structure
    - DNA is a polymer
      - made up of nucleotides
    - Nucleotide
      - Nitrogenous base
        Adenine===Thymine Guanine===Cytosine
      - Phosphate group
      - Deoxyribose sugar
        5 carbon
        One less oxygen than RNA
      - Phosphodiester bonds
        Between Bases phosphate and sugar
    - Polynucletide chains
      - Joined by hydrogen bonds
        Via condensation reactions
        reativley weak
        Double helix makes stronger
  - Replication
    - DNA Polymerase
    - DNA Helicase
    - Hydrolysis
    - Condensation reaction
    - Semi-Conservative Replication
      - Evidence
        Meselson and Stahl
- RNA
  - Differences to DNA
    - Ribose sugar
    - Single standed
    - Adenine===Uracil Guanine===Cytosine
    - Shorter
ATP
- Adenosine Triphosphate
  - Nucleotide derivative
    - Adenosine
- Use
  - Energy stored in high energy bonds between phosphate groups
    - Coupled w/h other reactions
      - Active transport
      - Minimises energy loss
  - Phosphorylation
- Differences
  - No. phospahte
    - ATP
      - Three
    - ADP
      - Two
    - AMP
      - One
Cells
- Eukaryotic cells
  - Animal and Plant
    - Nucleus
      - Nucleolus
        RNA and ribosomes made
      - Nuclear pore
        allows movement of mRNA
        Holes in the membrane
    - Cell membrane
      - Phospholipid bilayed
        Polar hydrophillic heads
        Polar means electrons are not equally shared
        Non-polar hydrophobic fatty acids
        Non-polar means electrons are equally shared
        cholesterol sits between phospholipids
        gives membrane more stability
      - Glycoprotein
        acts as antigen
        Recognise as self
      - Glycolipid
      - extrinsic protein
        Lying on the surface of bilayer
      - Intrinsic protein
        all the way through the bilayer
      - Fluid mosaic model
        constantly changes shape
    - Cytoplasm
      - Semi-liquid
      - most chemical reactions happen here
      - contains dissolved ions
    - Ribosomes
      - aid manufacture of proteins
    - Mitochondria
      - Double membrane
        Enclosing a semi-fluid
      - energy release
        Aerobic respiration
        ATP
    - Endoplasmic Reticulum
      - Smooth
        no ribosomes
      - Rough
        Ribosomes
    - Golgi body
      - Flattened sacks separated by a membrane
    - vesicle
      - Transport vessel
      - Made of phospholipds
    - Centrioles
      - microtubles
  - Plants only
    - Chloroplast
      - Contains chlorophyll
      - Enable photosynthesis
    - Vacuole
      - Important for structure
      - contains mineral ions in water
    - Cell wall
      - Structure
Microscopy
- Resolution
  - The smallest distance between two particles which allows them to be distinguished as separate artlicles
  - Half the wavelength of the medium used
- Microscopes
  - TEM
    - Best resolution
    - Beam of electrons pass through specimen
      - Detected on a fluorescent screen
    - Thin sections of specimen needed
  - SEM
    - 3D image
    - Specimen coated in heavy metals
    - Thicker structures can be seen
      - Electrons do not have to pass through sample
    - Resolution is lower than TEM
- Magnification
Enzymes
- Inhibitors
  - Competetive
  - Non-competetive
- Stucture
  - Proteins
    - Globular
  - Active site
    - A specific pattern of amino acids that is complementary to a particular substrate
    - Model
      - Lock and key
      - Induced fit
- Biological catalyst
- Effects on rate of reaction
  - Temperature
    - Increase in temp Increase in RoR Until optimum
      - Increase in kinetic energy
        More successful collisions
        More enzyme-substrate complexes formed
        Increase rate of reaction
    - Higher than optimum
      - High temp. causes the bonds in the tertiary structure to break
        Denatures active site
        Less enzyme-substrate complexes are formed
        Decrease rate of reaction
  - pH
    - Not optimum
      - Excess H+ and OH- ions
        Interfere with charges in bonds of tertiary structure
        Causes them to break
        Less enzyme substrate complexes formed
        Decrease rate of reaction
    - optimum
      - No excess H+ and OH- ions
  - Substrate conc
    - <----
  - Enzyme conc
    - Increase
      - More enzymes to collide w/h substrate
        More enzyme-substrate complexes formed
        Increase rate of reaction
        Up to a point
    - Decrease
      - Less enzymes to collide w/h substrate
        Less enzyme-substrate complexes formed
        Decrease rate of reaction
Diffusion
- Osmosis
  - Water potential
    - Higher the Ψ purer the water
      - 0Ψ= pure water
    - From an are of high Ψ to an area of low Ψ
  - Solute potential
  - Partially permeable membrane
  - Cells
    - Plant
      - Turgidity
      - plasmolysis
    - Animal
      - haemolysis
- Definition
  - The natural passive net movement of the particles within a gas or a liquid from a region of high concentration gradient to  an area of lower concentration until a dynamic equilibrium is reached
  - Passive
    - Not requiring energy
  - Net movement
    - overall movement
  - dynamic equilibrium
    - Equal overall but still particles moving
Active Transport
- Against the conc. gradient
  - From an area of low to high
- Requires energy
  - In the form of ATP
- Uses carrier proteins
  - At like pumps
- Uses
  - Small Intestine
    - Uptake of glucose and amino acids
  - Plant roots
    - Absorption of mineral ions
  - Kidneys
    - Excretion of hydrogen ions and urea
  - Muscle cells
    - Exchange of K and Na ions and minerals
Cell replication
- Meiosis
  - Genetic variation
    - Recombination of homologous chromosomes
      - Crossing over
    - Independent segregation of homologous chromosomes
      - Order in which chromosomes line up along side their homologous pair
  - Mutations
    - Biology 2
    - 1 in a billion bases replicated is a mistake
      - These mutations can be passed on but not every offspring will have them
  - Meiosis I
    - First division
  - Meiosis II
    - second division
- Mitosis
  - Interphase
    - S
      - DNA replicated
    - G1
      - period of cell growth
    - G2
      - 2nd period of cell growth
  - Prophase
    - Chromosomes condense
    - nuclear envelope disinigrates
  - Metaphase
    - chromosomes align at the equator
  - Anaphase
    - Chromosomes pulled apart by spindle fibres
  - Telophase
    - Nuclei separate
    - Daughter nuclei are genetically identical
Digestion
- Enzymes
  - Carnohydrases
    - Starch to maltose
      - Amalyse
        Salivary and pancreatic
      - Maltose to glucose
        Maltase
        Hydrolysis
      - Hydrolysis
      - Breaks glycosidic bond
  - Lipases
    - Triglycerides
      - Lipase
      - Monoglycerides
      - Fatty acids
      - Glycerol
  - Proteases
    - Endopeptidases
    - Exopeptidases
    - Dipeptidases
- Absorption
  - Carbohydrates
  - Lipids
  - Proteins
- Adaptations of small intestine
  - Villi and microvilli
    - Increase surface are
  - Muscle tissue
    - Remain in contact with food
  - Blood flow
    - Conc. gradient
  - single cell
    - Short diffusion pathway
Water
- Dipolar
  - Hydrogen bonds form between oxygen and water
    - Of different water molecules
- High specific heat capacity
  - Hydrogen bonds
    - more energy required to break these
      - Boiling point increases
- Large latent heat of evaporation
  - Lot energy require to evaporate 1 gram of water
    - Why sweat is an effective way of cooling in animals
- Strong cohesion
  - Tendency of water molecules to stick together
    - Surface tension
      - Allows water to be pulled up tubes
        xylem in plants
- The role of inorganic ions
  - H+
    - Determining pH
      - Function of enzymes
  - PO3+
    - ATP
      - storing energy
    - DNA
      - Structural role
  - Fe 2+/3+
    - Haemoglobin
      - Transport of oxygen
  - Na+
    - Transport of glucose and amino acids
      - Na/K pump

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Descrição: Biology AS mind map
Criado por: Usuário eliminado · mar 2017
Atualizado: 12 mar 2017
Visualizações: 19
Tags: aqa as biology science
Histórico: Criado por Holly Bamford · 21 set 2015

Copiado por yasmeen khalifa · 12 mar 2017
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Biology~AS

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