Biological Molecules

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  • Created by: Mary_07
  • Created on: 12-11-17 13:15
Describe how the structure of cellulose is related to its function.
Long, straight, unbranched chains. B-glucose joined by glycosidic bonds. Many hydrogen bonds provides strength and rigidity.
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Describe the structure of starch and how it relates to its function.
A-glucose joined by glycosidic bonds. Helix makes it compact. Branched increases surface area. Insoluble doesn't affect water potential. Large so can't diffuse out.
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Tryglyceride structure.
Contains ester bonds. Joins glycerol and 3 fatty acids.
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Phospholipid structure.
Phosphate group. 2 fatty acids. Glycerol.
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Differences between tryglycerides and phospholipids.
Phospholipids = replaces one fatty acid with phosphate. 2 ester bonds = phospholipids. 3 ester bonds = tryglycerides.
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What is an unsaturated fatty acid?
Double bonds between the carbon atoms in the hydrocarbon chain.
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What is a saturated fatty acid?
Single bonds between the carbon atoms in the hydrocarbon chain.
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Biochemical food test for lipids?
Emulsion Test; add ethanol, shake, add water, if a white emulsion appears then a lipid is present.
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Structure of an amino acid.
Amine group. Repeating hydrocarbon chain. Carboxyl group.
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Structure of a dipeptide.
2 amino acids joined together through a condensation reaction, creating a peptide bond.
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Primary structure of a protein.
Sequence of amino acids in the polypeptide chain, determines the tertiary structure because of the group.
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Secondary structure.
Basic folding of the polypeptide chain, a-helix (coils/twists) B-pleated sheet (folding), can be different throughout the polypeptide, contains hydrogen bonds between carboxylic acid group and amine group of another amino acid.
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Tertiary structure.
Further folding of the polypeptide chain which creates a specific 3D shape that is held together by hydrogen, ionic and disulfide bonds between the R groups of different amino acids.
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Quaternary structure.
More than 1 polypeptide chain joined together (e.g. ATP synthase, antibodies and haemoglobin).
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Biochemical food test for proteins.
Biuret Test; add Biuret reagent and if there is a protein present then there will be a colour change from blue to purple.
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What are enzymes?
Biological catalysts as they lower the activation energy by creating an enzyme-substrate complex (ESC).
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What is the induced fit hypothesis?
Active site isn't fully complementary. When the substrate enters the active site changes shape. This puts pressure of the bonds making them more easily hydrolysed, which lowers the activation energy.
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Temperature effecting enzyme reactions.
More kinetic energy, more successful collisions, more ESC's. Enzymes become saturated, H bonds break on tertiary structure, active site changes shape, no longer complementary to substrate, no ESC's.
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pH effecting enzyme reactions.
Low pH; more H+ ions. High pH; less H+ ions. Changed pH; broken H and ionic bonds, active site changes shape, no longer complementary to substrate. no ESC's.
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Substrate concentration effecting enzyme reactions.
At first it is the limiting factor - increase substrate concentration, increases rate of reaction. Reaction levels off as the active site are occupied, so the enzyme is the limiting factor.
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What is a competitive inhibitor?
Similar shape to substrate, complementary to active site, blocks active site, less ESC's produced, increases substrate concentration.
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What is a non-competitive inhibitor?
Binds to enzyme away from active site, changes its shape, no longer complementary so no ESC's form.
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Structure of a DNA nucleotide.
Deoxyribose sugar. Phosphate. Organic base (A=T C=G)
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Structure of a RNA nucleotide.
Ribose sugar. Phosphate. Organic base (A=U C=G)
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Semi-conservative replication.
DNA helicase separates strands by breaking hydrogen bonds. Leaves 2 template strands. New nucleotides join to complementary bases. DNA polymerase joins nucleotides together by forming phosphodiester bonds. Contains one old and one new strand.
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How is ATP made?
ADP + Pi = ATP Joined through a condensation reaction using the enzyme ATP synthase during respiration.
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Structure of ATP.
Ribose sugar. Adenine base. 3 phosphates. Nucleotide derivative.
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Why is ATP useful?
Pi used in phosphorylation to make molecules more reactive. Release energy in small usable amounts. ATP can be reformed. Immediate source of energy as it can't be stored.
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Why is water a useful molecule?
Acts as a solvent. Used in hydrolysis reactions. Doesn't lose heat easily (high specific heat capacity). High latency of vaporisation.
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Other cards in this set

Card 2

Front

Describe the structure of starch and how it relates to its function.

Back

A-glucose joined by glycosidic bonds. Helix makes it compact. Branched increases surface area. Insoluble doesn't affect water potential. Large so can't diffuse out.

Card 3

Front

Tryglyceride structure.

Back

Preview of the front of card 3

Card 4

Front

Phospholipid structure.

Back

Preview of the front of card 4

Card 5

Front

Differences between tryglycerides and phospholipids.

Back

Preview of the front of card 5
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