protein

Question 1

what is proteins made up of

Answer 1

carbon, hydrogen, oxygen, nitrogen

Question 2

what are the functions

Answer 2

• enzymes to catalyse reactions
• carrier proteins transport molecules across membranes
• antibodies defend against diseases
• structural proteins support cells and tissues
• hormones transmit information
• transport proteins (haemoglobin) carry oxygen
• contractile proteins enable muscles to contract

Question 3

why do diffrent proteins carry out different functions

Answer 3

have different shapes

Question 4

what are make up proteins

Answer 4

amino acid polymer

Question 5

what 4 molecules are in an amino acid

Answer 5

-carboxylic acid group
- amine group
- hydrogen
- R- one of 20 different groups

Question 6

how many essensial amino acids are there

Answer 6

8
- cant be synthesised by the body

Question 7

what reaction joins amino acids

Answer 7

condensation reaction
- removes wtare molecule and forms a peptide bond between the amino group and carboxylic group of the other amino acid

Question 8

how is a polypeptide chain formed

Answer 8

the amino end and the carboxylic end of a dipeptide react with another amino acid

Question 9

what are the levels of protein structure

Answer 9

• primary
• secondary
• teritary
• quaternary

Question 10

what is the primary structure

Answer 10

the sequence of amino acids is held togtehre by peptide bonds (polypeptide)

Question 11

what is the secondary structure

Answer 11

folding of the primary structure

Question 12

types of secondary structure

Answer 12

alpha helix- when polypeptide chain coils
beta pleated sheet- folds

both held togteher by weak carbon bonds

Question 13

examples of secondary structure

Answer 13

keratin- functional protein

Question 14

what is the tertiary structure

Answer 14

further folding of the polypeptide chain to give more compex 3D shape

Question 15

what is found in both teriary and quaternary structure

Answer 15

• hydrogen bonds between polar R groups
• disulphide bonds- covalent bonds formed between sulphurs in the R group of amino acid cystiene
• ionic bonds between positively and negatively cahrges R groups
• hydrophobic interactions- between non-polar R groups which cluster together towards centre of molecule

Question 16

what is the quaternary stucture

Answer 16

made of more than one polypeptide chain

Question 17

example of quaternary structure

Answer 17

haemoglobin

Question 19

how do proteins denature

Answer 19

heating increases the kinetic energy causing atoms to vibrate and weak bonds to break
this can lead to the whole tertiary structure unraveling and the protein will be permanently denatured

Question 20

types of proteins

Answer 20

globular, fibrous

Question 21

properties of fibrous
proteins

Answer 21

• from fibres
• insoluble in water
• have structural roles found in skin, tendons, bones, cartilage
• doesnt contain a prosthetic group

Question 22

properties of fibrous proteins

Answer 22

• rolls up to form balls
• soluble in water
• metabolic role- carries oxygen in red blood cells
• contains a prosthetic group- haem

Question 23

properties of haemoglobin

Answer 23

• 4 folded polypeptide chains
• 4 iron conatining haem group
• compact and spherical
• soluble in water

Question 24

why is collagen strong

Answer 24

the collagen molecules cross link through covalent bonds to form fibres which give collagen its strength

Question 25

properties of collagen

Answer 25

• made from 3 identical left handed helix polypeptide cahins wound to make a triple helix
• in each cahin, the third amino acid is glycine
• chains held together by hydrogen bonds
• very stable/insoluble in water