Proteins

Question 1

name the various classes of naturally occurring amino acids

Answer 1

acidic amino acids - end with COO

basic amino acids - end with NH2

polar amino acids - end with OH

miscellaneous

aliphatic amino acids - R group consisting of hydrocarbon chain

Aromatic amino acids - r group consisting of hydrocarbon ring

Question 2

functions of proteins

Answer 2

structural - actin “scaffolds” within a cell or keratin in skin

functional - catalytic function of enzymes or antibodies in immune defence

Question 3

What is primary structure

Answer 3

sequence in which amino acid monomers are bonded together to form a polypeptide chain

20 possible occupants for each

2 amino acid monomers - dipeptide

3 amino acid monomers - tripeptide

more amino acid monomers added to form polypeptide chain

Question 4

What is secondary structure

Answer 4

3D arrangement of amino acids located near each other in the polypeptide chain

relies on hydrogen bonding between the amino hydrogen of one amino acid and the carboxyl oxygen of the other in same chain

alpha helix or beta sheet

Question 5

what is tertiary structure

Answer 5

when functional groups of “R” chains of amino acids in the polypeptide chain interact with one another

van der waals, ionic, hydrogen, disulphide bridges and hydrophobic interactions can all be involved

ie. functional proteins

some R groups are hydrophobic and some are hydrophilic

Question 6

What is quaternary structure

Answer 6

sometimes several polypeptides interact with one another to form a quaternary structure

Question 7

Particular properties that the possession of quaternary structure may confer on a protein

Answer 7

consisting of two or more identical or different polypeptide chains (subunits)

an individual subunit can change shape

various compounds can attach to these subunits ie. haem group to form haemoglobin

Question 8

Structure and function of fibrous proteins

Answer 8

structure - polypeptide chains organised approximately in parallel along a single axis, producing long fibers or large sheets

function - providing external protection, support, shape, and form

Question 9

Structure and function of globular proteins

Answer 9

structure - 3D molecular structure that has a shape that is anywhere from a sphere to a cigar

function -biological roles, including acting as enzymes, hormones, immunoglobulins, and transport molecules

Question 10

What is denaturation

Answer 10

when chemical bonds are disrupted - possibly destroyed - within secondary and tertiary structure

biological functionality is lost

rarely strong enough to break primary structure of individual peptide bonds - primary structure remains

Question 11

Describe the different types of conjugated proetins

Answer 11

Glycoproteins - proteins with >/= 1 carbohydrate molecules covalently attached, co-translational or post-translational modification where oligosaccharide chains are attached to a protein

Lipoprotein - protyeins can combine with lipids, found in cell membranes and transport hydrophobic molecules (eg. cholesterol transport in blood)

Metalloprotein - protein molecule with a metal ion within structure (co-factors), various functions (eg. enzymatic, signal transduction, transport and storage)