Unit 1

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Created by
Cheryl Foudji

Cards (25)

  • Glycogen polymer of alpha glucose in animal cells
    * branched = many terminal ends for hydrolysis, glucose released quickly
    ● insoluble = doesn't affect the water potential of cells & does not diffuse out of cells
    ● compact= store more glucose in a small space
  • Triglycerides
    *Insoluble hydrocarbon chain = no effect on water potential of cells, hydrophobic insoluble in water
    -large molecules, large chemical energy store, protection as molecules in large and lower density (cushioned)
    -high ratio of C-H bonds in the fatty acid tails= lots of energy released when respire, water released when hydrolysed (camels)
    -low mass to energy ratio- low density, lots of energy stored with a low mass, buoyancy of aquatic
  • Structure of DNA
    ● sugar-phosphate backbone & many H-bonds provide stability
    ● Polynucleotide=long molecule stores lots of
    genetic information
    ● weak H-bonds break so strands separate for replication
    - lots of H bonds stabilise helix
    ● helix is compact for storage in nucleus
    ● double-stranded for semi-conservative replication
    ● complementary base pairing for accurate replication= 2 strands parallel
  • Semiconservative replication of DNA:
    1. Unwinding of double helix
    2. DNA helicase breaks H-bonds between base pairs in polynucleotide strands
    3. Each strand acts as a template.
    4. Free nucleotides attach to exposed bases on template strands
    by complementary base pairing
    5. H bonds reform
    6. DNA polymerase joins nucleotides to new DNA strand.
    -formation of phosphodiester bonds between nucleotides

    7. semiconservative as each contains 1 old and 1 new strand
  • proteins
    *polymer of amino acids
    *joined by peptide bonds
    *formed by condensation reaction
    primary structure sequence and order of amino acids
    *secondary is folding of polypeptide chain due to hydrogen bonding
    tertiary is 3d folding due to hydrogen/ionic and disulfide bonding
    *quaternary is two or more polypeptide chains
  • ATP is useful in many biological processes as:
    -ATP releases in small manageable amounts so energy isn’t wasted
    -Quickly broken down so energy is released quickly
    -ATP can’t pass out of cell so the cell always has an immediate supply of energy
    -ATP : energy released in small and manageable amounts so can be quickly transported around the cell
    -Phosphorylates other compounds making them more reactive
    -Involves a single reaction
  • Water is biologically important as :
    *high specific heat capacity= many H-bonds= acts as a buffer so the water in living organisms can stay at a sable temperature
    *High latent heat of vaporisation= provides a cooling effect= little loss of water through evaporation
    *good solvent= good transport medium= metabolite reactions
    -strong cohesion forces creates surface tension so surface of water acts as habitat
    strong cohesion forces between water molecule so supports columns of water in plants
    -metabolite- used in hydrolysis, condensation
  • The structure of mRNA:
    ● Long ribose polynucleotide (but shorter than
    DNA).
    ● Contains uracil instead of thymine.
    ● Single-stranded & linear (no complementary
    base pairing).
    ● Codon sequence is complementary to exons of 1 gene from 1 DNA strand
  • Structure of tRNA:
    ● Single stranded
    ● Folded into clover shape (some paired bases).
    ● Anticodon on one end, amino acid binding site on the other:
    a) anticodon binds to complementary mRNA codon
  • Starch is a polymer of alpha glucose in plant cells
    -(amylose & amylopectin 1-6)
    *insoluble in water so it doesn't affect the water potential of cells
    *Coiled helix so can fit many molecules in a small area
    *polymer of a glucose so provides glucose for respiration
    *large molecule so can't cross the cell membrane
    *branched so more ends or fast breakdown/enzyme action
  • cellulose is a polymer of beta glucose
    (prevents bursting under turgor pressure, holds stem up)
    s=● 1,4 glycosidic bonds
    ● straight-chain, unbranched molecule
    *many H-bonds that give strength
    *many hydrogen bonds form micro fibrils that provide rigidity/strength
  • Describe how the structures of starch molecules are related to their functions.
    1. Helical so compact
    2. Large molecule sO does not affect water potential of cell
    3. Highly branched so glucose is (easily) released for respiration
    4. Large (molecule) so cannot leave cell
  • Describe how the structures of cellulose molecules are related to their functions.
    1. Long, straight/unbranched chains of beta glucose
    2. Joined by hydrogen bonding
    3. To form microfibrils
    4. That provides rigidity/ high tensile strength
  • Describe the chemical reactions involved in the conversion of polymers to monomers and monomers to polymers.
    • a condensation reaction joins monomers together and forms a chemical bond and releases water
    • a hydrolysis reaction breaks a chemical bonds between monomers and uses water
    3. and 4. Paymers must contain many monomers.
    3. and 4: suitablo examples includeamino acid and polypeptide, protein, enzyme, anobody ornucleodido and polynuckotide, DNA or RNABeta glucose and coñulose.
  • Describe the biochemical tests you would use to confirm the presence of lipid
    • add / dissolve in ethanol and shake sample in mixture until clear
    • add water and mix
    • white / milky emulsion should form
  • Describe the biochemical tests you would use to confirm the presence of non-reducing sugar
    • Do Benedict's test and stays blue (negative result)
    • Boil with acid (HCl) then neutralise with alkali (NaOH)
    • Heat with Benedict's reagent and solutions turns from blue to (brick) red precipitate
  • Describe the biochemical tests you would use to confirm the presence of amylase in a sample
    • add biurets reagent and sample turns lilac / purple
  • Give two ways in which the hydrolysis of ATP is used in cells
    • to provide energy for other reactions
    • to phosphorylate other compounds to make them more reactive
  • Describe the roles of iron in cells.
    Iron ions
    • Haemoglobin binds with oxygen
  • Describe role of sodium ions in cells
    • Co-transport of glucose and amino acids into cells
    • sodium moves out by active transport (3Na - 2K pump)
    • Creates a sodium concentration/diffusion gradient
    • Affects osmosis / water potential
  • Describe role of phosphate ions in cells
    • Affects osmosis/water potential:
    • Joins nucleotides/in phosphodiester bond in DNA
    • Used to produce ATP
    • Phosphorylates other compounds usually making them more reactive
    • Hydrophilic part of phospholipid bilayer
  • Give two properties of water that are important in the cytoplasm of cells.
    • Polar molecule:Acts as a universal solvent
    • solvent
    Metabolic reactions occur faster in solution
    • Reactive
    • Takes place in hydrolysis and condensation reaction:
  •  DNA is a polymer of nucleotides. Each nucleotide contains an organic base.Explain how the organic bases help to stabilise the structure of DNA.
    • Hydrogen bonds between the base pairs holds two strands together
    • Many hydrogen bonds provides strength
  • Describe two differences between the structure of a tRNA molecule and the structure of an mRNA molecule.
    • tRNA is 'clover leaf shape', mRNA is linear
    • tRNA has an amino acid binding site, mRNA does not
    • tRNA has anticodon, mRINA has codon
    • tRNA has hydrogen bonds, mRNA does not
  • Describe how the structure of glycogen is related to its function.
    • Helix/coiled/branched so compact
    • Polymer of glucose so easily hydrolysed
    • Branched so more ends for faster hydrolysis to glucose
    • Glucose (polymer) so provides respiratory substrate for energy
    • Insoluble so does not affect water potential / osmosis of cells