Biology - Biological Molecules 2

biology molecules section 2

Phospholipid structure

________ allows to form glycolipids by combining with carbohydrates within the membrane.

Proportion of oxygen

________ to carbon and hydrogen is smaller than in carbohydrates.

Peptide bond

________ can be broken by hydrolysis forming its two constituent amino acids.

purple coloration

A(n) ________ indicates the presence of peptide bonds and hence a protein.

hydrogen bonds

The chains run parallel to each other and are crossed linked by ________ which adds strength.

Hydrophilic phosphate heads

________ help to hold the surface of csm.

Insulation

________: fats are slow conductors of heat and when stored beneath the body surface helps to retain body heat.

Protection

________: fat is stored around delicate organs such as kidney.

form

Branched ________ has many ends each of which can be acted on by enzymes so glucose monomers can be released very rapidly.

amino acids

Linked ________ have both- NH and- C= O groups on either side of every peptide bond.

fatty acid

Has hydrophobic tails (________ molecules) that repels water but is fat soluble.

Specific 3D shape

________ gives its function and allow interaction with other molecules.

presence of lipids

5- a milky white emulsion indicates ________.

major component of plant

Cellulose a(n) ________ cell walls and provide rigidity to the plant cell.

Polar molecules

________; in aqueous environment, phospholipid molecules form a bilayer within cell surface membranes, forming hydrophobic barrier.

carbon hydrogen bonds

High ratio of energy- storing ________ to carbon atoms, so excellent source of energy.

Hydrogen bonds

________- numerous but easily broken.

Amino acids

________ join together to form peptide bonds by condensation reaction and gives water.

polar molecules

Insoluble in water since they are large non- ________.

amino acid

Water made by combining an- OH from the carboxyl group of a(n) ________ and a- H from the amino group from another ________.

source of energy

when oxidised, they produce more than twice the energy the same mass of carbohydrate and release valuable water

waterproofing

lipids are insoluble in water so it is useful for waterproofing

insulation

fats are slow conductors of heat and when stored beneath the body surface helps to retain body heat

protection

fat is stored around delicate organs such as kidney

Test for lipids

emulsion test

1

take a completely dry and grease free test tube

2

to 2cm^3 of the sample being tested, add 5cm^3 of ethanol

3

shake the tube thoroughly to dissolve everything

4

add 5cm^3 of water and shake gently

5

a milky white emulsion indicates presence of lipids

amino acids

basic monomer units

Primary structure of proteins

polypeptides

disulfide bridges

very strong

ionic bonds

formed between any carboxyl group and amino groups that are not involved in forming peptide bonds

hydrogen bonds

numerous but easily broken