Biological Molecules Flashcards
What is a monosaccharide?
Single monomer sugar e.g. glucose, galactose, fructose
What is a dissacharide?
Sugar made from two monosaccharide polymers e.g. maltose, sucrose, lactose
What is a polysaccharide?
Polymers made from many monosaccharide (sugar) molecules e.g. starch, glycogen, cellulose.
What reaction forms polysaccharides?
Condensation reaction
What reactions breaks down polysaccharides?
Hydrolysis reaction
What bond joins two sugar molecules?
Glycosidic bond
What is the test for reducing sugars?
Add equal volume of benedicts solution to the food sample, gently heat in a water bath, if sugar present it will turn red/orange
What is the test for non-reducing sugars?
If test for non-reducing sugar is negative take a fresh sample and add hydrochloric acid then neutralise with sodium hydrogen carbonate solution. Then add equal volume of benedicts and repeat test for reducing sugar.
What is the difference between alpha and beta glucose?
Their H and OH groups are on different positions in the carbon ring
Give two adaptations of starch
Insoluble, large, compact, easily hydrolyzed/can be broken down easily
Give two adaptations of glycogen
Insoluble, compact, highly branched so can be broken down easily
Give two adaptations of cellulose
Long straight chains, chains run parallel, chains grouped in microfibrils, strong
Explain the difference between starch and cellulose
Starch is a coiled storage molecule.
Cellulose is a straight structural molecule
What is a trigylceride?
Molecule made from three fatty acids and a glycerol molecule
What is a phospholipid?
Molecule made from two fatty acids, a glycerol molecule and a phosphate molecule
What bond joins fatty acids to glycerol?
Ester bond
What reaction joins fatty acids to glycerol?
Condensation reaction
Name some roles of lipids within the body
Source of energy, waterproofing, insulation, protection
What do the terms hydrophilic and hydrophobic mean?
Hydrophilic - Interacts/attracted to water
Hydrophobic - Moves away from water
Give two adaptations of triglycerides
Good energy source, large amounts of energy in a small volume, insoluble, water source
Give two adaptations of phospholipids
Polar so form bilayer (for cell membranes), can form glycolipids
What is the test for lipids?
Put 2cm^3 sample of food into a clean test tube and add 5cm^3 of ethanol. Shake tube thoroughly to dissolve. Add 5cm^3 water and shake. Cloudy emulsion indicates fat is present.
Name the 4 key parts of an amino acid
Amino group, carboxyl groups, hydrogren atom, R group
What bond joins amino acids together?
Peptide bond
What is the primary structure of a protein?
The combination/sequence of different amino acids joined together in the polypeptide
What is the secondary structure of a protein?
3D shape of the polypeptide chain caused by hydrogren bonds between the NH and CO groups
What is the tertiary structure of a protein?
Secondary structure that is twisted and folded by further bonds such as disulfide bridges, ionic bonds and hydrogen bonds
What is the quaternary structure of a protein?
A complex molecule made from several different polypeptide chains that are linked together
Explain why heat and pH can change the structure of a protein
Extreme heat and pH can break the bonds in the tertiary and secondary structures causing the protein to lose it’s 3D shape.
What is the test for proteins?
Add biurets reagent to the sample and check for colour change. If it goes purple a protein is present.
Name the two types of protein
Fibrous and globular
Explain how fibrous proteins are suited to their function.
Structural function, closely packed, tightly wound, with several fibres twisted to form strong fibres.
Explain how globular proteins are suited to their function.
Metabolic function, soluble molecules, specific shape.
Give examples of different types of proteins within the body.
Enzymes, antibodies, haemoglobin, collagen, keratin, muscles ect.
