proteins

Question 1

what is the monomer of a protein?

Answer 1

an amino acid

Question 2

how are proteins linked to DNA?

Answer 2

order of bases=amino acid order=protein which coded for a characteristic

Question 3

what is the general structure of an amino acid?

Answer 3

R
H—- | ===O
N–C–C
H—- | —–OH
H

Question 4

how many naturally occurring amino acids are there? give examples

Answer 4

20 eg. serine, glutamine, leucine
each with a different R group

Question 5

what do 2 amino acids join together?

Answer 5

condensation reaction forms peptide bond, molecule of water produced
-OH and H removed

Question 6

what is the primary structure of an amino acid?

Answer 6

-the specific order of amino acids in a polypeptide
-determined by DNA sequence of gene

Question 7

bonds in primary structure

Answer 7

covalent bonds

Question 8

what is the secondary structure?

Answer 8

-polypeptide sections twist and fold into shapes
-alpha helix and beta pleated sheet (flat)

Question 9

bonds in secondary structure

Answer 9

hydrogen bonds form along polypeptide chain, due to attracting O and H charges

Question 10

what is the tertiary structure?

Answer 10

-overall 3D shape of the polypeptide chain
-critical for how protein functions

Question 11

bonds in tertiary structure

Answer 11

hydrogen bonds, ionic bonds, disulfide bonds, non polar hydrophobic interactions

Question 12

what is the quaternary structure?

Answer 12

-shows how the individual sub units (polypeptide chains) are arranged to form a larger 3D structure
-shows position of any prosthetic groups

Question 13

bonds in quaternary structure

Answer 13

hydrogen, van der Waals, forces between non polar side chains

Question 14

what is a prosthetic group?

Answer 14

when proteins are accompanied by non protein molecules which make up the structure and help to carry out the role

Question 15

what is a conjugated protein?

Answer 15

a globular protein with a non protein element called the ‘prosthetic group’

Question 16

what is a globular protein+ examples

Answer 16

spherical soluble protein
eg. haemoglobin, insulin, enzyme

Question 17

structure of haemoglobin

Answer 17

-quartnenary protein with 4 polypeptides-2 alpha helix, 2 beta pleated sheet
-prosthetic ‘haem’ group

Question 18

function of haemoglobin

Answer 18

-transports oxygen
-‘haem’ group binds irreversibly to oxygen

Question 19

structure of insulin

Answer 19

-spherical, compact, soluble
-complex shape, folds into tertiary shape
-has precise shape for receptors

Question 20

function of insulin

Answer 20

-hormone that regulates blood glucose concentration

Question 21

enzyme structure

Answer 21

-quartnernary protein
-contains 4 ‘haem’ prosthetic groups

Question 22

enzyme function

Answer 22

-catalyses reaction
-interacts with hydrogen peroxide to speed up its breakdown

Question 23

fibrous proteins meaning and examples

Answer 23

insoluble and strong proteins with structural role for support/protection
-collagen, keratin, elastin

Question 24

collagen function

Answer 24

-connective tissue in skin, tendons, ligaments and nervous system

Question 25

collagen properties

Answer 25

-stable as R groups repel
-flexible, rope like for movement
-closely packed triple helix
-durable due to tropocollagen-proteins join end to end to form long fibrils which cross link to produce strong fibred

Question 26

keratin function

Answer 26

-protective skin barrier
-helps form hair and nails
-heals wounds

Question 27

keratin properties

Answer 27

-large proportion of cysteine
-form strong disulfide bonds
-strong, inflexible, insoluble

Question 28

elastin function

Answer 28

-gives structure and flexibility to expand and retract

Question 29

elastin properties

Answer 29

-quaternary structure made for stretching molecules
-tonoelastic-elastin joins together

Question 30

strength of hydrogen bonds in tertiary structure

Answer 30

individually weak but collectively stable

Question 31

strength of ionic bonds in tertiary structure

Answer 31

stronger than H bonds

Question 32

strength of disulfide bonds in tertiary structure

Answer 32

very strong

Question 33

strength of hydrophobic/hydrophillic interactions in tertiary structure

Answer 33

weak interactions