TOPIC 1A- LIPIDS

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TRIGLYCERIDES
One molecule of glycerol and 3 fatty acids attached to it
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STRUCTURE OF A TRIGLYCERIDE
Fatty acids have hydrocarbon tails which are hydrophobic,
tails make lipids insoluble,
fatty acids have same structure but hydrocarbon tail varies
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BASIC STRUCTURE OF FATTY ACIDS
Carbon atom,
oxygen,
hydroxyl group,
variable 'R' group hydrocarbon tail
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CONDENSATION REACTION: TRIGLYCERIDES
Fatty acid joining onto glycerol molecule,
ester bond forms- water is released,
happens twice more to form triglyceride
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FATTY ACIDS
Saturated: don't have any double bonds between carbon atoms
Unsaturated: have at least one double bond between carbon atoms- cause chain to kink
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PHOSPHOLIPIDS
Lipids in cell membranes are phospholipids,
phospholipids: phosphate group, glycerol molecule, 2 fatty acids
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PHOSPHOLIPID STRUCTURE
Phosphate group is hydrophilic,
fatty acid tails are hydrophobic
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STRUCTURE OF TRIGLYCERIDE RELATING TO ITS FUNCTION
Long hydrocarbon tail-lots of chemical energy-lots of energy released when broken down,
lipids contain twice energy per gram as carbohydrates
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STRUCTURE OF TRIGLYCERIDES RELATING TO ITS FUNCTION 2
It's insoluble, don't affect water potential of cell-water cannot enter cells by osmosis,
fatty acid tails are hydrophobic- face inwards,
glycerol hydrophilic heads face outwards shielding tail from water
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STRUCTURE OF PHOSPHOLIPIDS RELATING TO ITS FUNCTION
Make a bilayer of cell membranes ,
heads are hydrophilic and tails are hydrophobic so they form a double layer,
heads facing out towards water,
centre of bilayer is hydrophobic- water soluble substances can't pass
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EMULSION TEST: LIPIDS
Shake substance with ethanol until it dissolves,
then pour solution into water
Positive test- milky emulsion
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PROTEINS MONOMERS AND POLYMERS
Monomer- amino acids,
polymer- polypeptide
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GENERAL STRUCTURE OF AMINO ACIDS
Carboxyl group,
Amine group,
R group,
central carbon,
hydrogen
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CONDENSATION REACTION: POLYPEPTIDES
Amino acids join together in condensation reaction to form polypeptides,
water is released during reaction
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PEPTIDE BOND
Bond formed between amino acids
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PRIMARY STRUCTURE
Sequence of amino acids in polypeptide chain
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SECONDARY STRUCTURE
Folding or coiling of polypeptide chain into an alpha helix or beta pleated sheet,
held by hydrogen bonds
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TERTIARY STRUCTURE
Further folding of polypeptide chain into complex 3D structure,
held by bonds between R groups
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BONDS BETWEEN R GROUPS
Ionic: chemical bond between 2 ions of opposite charge
Hydrogen: between polar molecules
Disulphide bridges: between 2 cysteines
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QUATERNARY STRUCTURE
More than one polypeptide chain held together by bonds
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GLOBULAR PROTEINS
Involved in biochemical functions,
they are soluble,
e.g. enzymes
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FIBROUS PROTEINS
Structural proteins,
they are insoluble,
e.g. keratin in hair and collagen
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CALCULATING Rf VALUES
Rf= distance from origin to solute/
distance from origin to solvent front
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ENZYMES STRUCTURE
Spherical in shape- tight folding of polypeptide chain
They're soluble
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ANTIBODIES FUNCTION
Involved in immune response,
made of 2 light polypeptide chains and 2 heavy polypeptide chains bonded
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TRANSPORT PROTEINS
Channel proteins are in cell membranes,
they contain hydrophobic and hydrophilic amino acids- cause protein to fold up- form a channel,
these transport molecules and ions across membranes
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STRUCTURAL PROTEINS
Strong,
have long polypeptide chains parallel to each other with cross-links between them,
they contain keratin and collagen
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BIURET TEST: PROTEINS
1. Add few drops of sodium hydroxide solution
2. Then add copper (II) sulfate solution
Positive test- turns purple
Negative test- stays blue
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Other cards in this set

Card 2

Front

STRUCTURE OF A TRIGLYCERIDE

Back

Fatty acids have hydrocarbon tails which are hydrophobic,
tails make lipids insoluble,
fatty acids have same structure but hydrocarbon tail varies

Card 3

Front

BASIC STRUCTURE OF FATTY ACIDS

Back

Preview of the front of card 3

Card 4

Front

CONDENSATION REACTION: TRIGLYCERIDES

Back

Preview of the front of card 4

Card 5

Front

FATTY ACIDS

Back

Preview of the front of card 5
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