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1.1.2 Molecules

(a) Amino Acids

(b) Peptide Bond Formation

(c) Proteins
1. Primary structure ­ the sequence that particular amino acids are linked together is called
the primary structure of a protein. The positioning and chemical behaviour of these amino
acids ultimately determines how the polypeptide chain folds up and…

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proteins like haemoglobin and enzymes possess a high degree of this type of secondary
structure. Beta pleated sheet forms stiffer pleated` sections where again hydrogen
bonding stabilises the shape.
3. Tertiary structure ­ the overall 3D shape one polypeptide chain folds into. It is stabilised
by several types of chemical…

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Waste such as urea and carbon dioxide

Heat is transferred around the body

(g) Water as Transport
Solvent- Allows water to act as a transport medium for polar molecules
Lubricant- Water's cohesive and adhesive properties mean that it is viscous
Thermoregulation- High specific heat capacity means bodies of water are…

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Vesicle moves towards membrane
Vesicle fuses to the membrane
Molecules released to the outside of the cell
Molecules move to membrane surface
Membrane invaginates and forms a vesicle around the molecules
Vesicle moves into cytoplasm

(l) Water Potential
Water potential is the tendency of a solution to gain or lose…

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plasma concentration to a safe level. This is usually done using an electronic device which
contains a biosensor. A test strip impregnated with the enzyme glucose dehydrogenase is
inserted into the sensor after a drop of blood has been placed in contact with the strip.
The enzyme converts the blood…

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It is compact, so a lot of glucose can be stored in a small space

It is a branched molecule, so there are lots of `ends' where glucose can be released

(t) Glycerol & Fatty Acids

(u) Triglycerides

(v) Fatty Acids

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(w) Phospholipids


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