Biological molecules

  • Created by: amm242
  • Created on: 17-05-18 11:23
What is a monosaccharide?
Soluble substances which are monomers of carbohydrates eg. glucose, fructose and galactose
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How do you test for reducing sugars?
Benedict's reagent is heated with a reducing sugar to produce a brick red precipitate
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What is a disaccharide?
Monosaccharides are joined in condensation reactions to form glycosidic bond
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Give example of disaccharides
Maltose (glucose+glucose), Lactose (glucose+galactose), Sucrose (glucose+fructose)
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How do you test non reducing sugars?
If Benedict's test does not turn red, add dilute HCl to new sample and heat, then add NaHCO3 to neutralise. Should now turn Benedict's red
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What is a polysaccharide?
Insoluble polymers made up of many monosaccharides
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How do you test for starch?
Drop starch solution onto spotting tile and add potassium iodide which turns blue-black
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Describe the structure of starch
Alpha glucose, branched or unbranched chains (compact coil)
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How is starch adapted to store energy?
Insoluble so doesnt affect water potential, too large to diffuse, compact, branched form hydrolysed quickly
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Describe the structure of glycogen
Alpha glucose, short, highly branched chains
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How is glycogen adapted to store energy?
Insoluble so doesnt draw in water, doesnt diffuse, compact, highly branched allowing quick hydrolysis
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Describe the structure of cellulose
Beta glucose, straight unbranched chains running parallel with H bonds inbetween
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How is cellulose adapted to provide support and rigidity?
Straight unbranched chains, H bonds between chains, form microfibrils
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What is the role of lipids?
Cell membranes, source of energy, waterproofing, insulation, protection
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Describe a lipid
Contain C, H & O, insoluble in water, soluble in organic solvents
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Describe the structure of triglycerides
Three fatty acids attached to one glycerol with ester bond formed by condensation reaction
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What is the structural difference between saturated & unsaturated fats?
Saturated = no double C-C bonds, Unsaturated = double C=C bond
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What does mono-unsaturated mean?
More than one double bond is present
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How are triglycerides adapted to their functions?
Lots of energy storing C-H bonds, low mass:energy, non-polar so dont affect osmosis
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What is a phospholipid?
No glycerol and one fatty acid is replaced by a phosphate molecule. They have hydrophilic heads and hydrophobic tails
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How are phospholipids adapted to their functions?
Form hydrophobic barrier between inside and outside of cell, form glycolipids for cell recognition, hold water at cell membrane
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Describe the structure of an amino acid?
Amino group (NH2), Carboxyl group (COOH), H atom, variable R group
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What is the primary structure of proteins?
Amino acids joined by peptide bonds to form polypeptide chains. Sequence is determined by DNA
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What is the secondary structure of proteins?
Hydrogen bonds form between H and O forming alpha helix or beta pleated sheet
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What is the tertiary structure of proteins?
Further twisting of helix by disulfide bridges, ionic & H bonds to form specific 3D structure
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What is the quaternary structure of proteins?
Lots of polypeptide chains linked, possibly with non-protein groups
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How do you test for proteins?
Biuret test: equal amounts of copper sulfate and sodium hydroxide mixed with sample turns purple
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What do globular proteins do?
Carry out metabloic functions eg. enzymes & haemoglobin
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What do fibrous proteins do?
Have structural functions eg. collagen
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Describe the strcuture of fibrous proteins?
Long chains running parallel to each other linked by cross bridges and wound tightly around each other
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Other cards in this set

Card 2

Front

How do you test for reducing sugars?

Back

Benedict's reagent is heated with a reducing sugar to produce a brick red precipitate

Card 3

Front

What is a disaccharide?

Back

Preview of the front of card 3

Card 4

Front

Give example of disaccharides

Back

Preview of the front of card 4

Card 5

Front

How do you test non reducing sugars?

Back

Preview of the front of card 5
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