PROTEINS

Question 1

What are amino acids

Answer 1

the basic monomer unit that combine to make the polymer polypeptide

Question 2

What are the monomers of polypeptides

Answer 2

amino acids

Question 3

What are proteins make up of

Answer 3

1 or more polypeptides

Question 4

How many amino acids need to join to become a polypeptide

Answer 4

more than 2

Question 5

What is formed if 2 amino acids join

Answer 5

dipeptide

Question 6

What is the basic structure of amino acid

Answer 6

carbon atom attached to 4 chemical groups:

1) amine/ amino group (NH2)
2) carboxyl group (COOH)
3) hydrogen atom (H)
4) R group - variable (each amino acid has a different R group)

Question 7

How many amino acids do living things share

Answer 7

20

Question 8

What is the only amino acid that doesn’t have carbon in its side group

Answer 8

glycine

Question 9

Draw the basic structure of an amino acid

Answer 9

C attatched to R, COOH, H, H2N

Question 10

How are polypeptides formed

Answer 10

in a condensation reaction

Question 11

How is water made in the condensation reaction of amino acids

Answer 11

the OH group from the carboxyl group of one amino acid joins to the H group from another amino acid

Question 12

What bond is formed during the condensation reaction of amino acids and where is it formed between

Answer 12

peptide bond between carbon group of one amino acid and nitrogen atom of another

Question 13

When are polypeptides hydrolysed

Answer 13

during digestion

Question 14

What is polymerisation

Answer 14

the series of condensation reactions that joins many amino acid monomers together

Question 15

What is the result of polymerisation

Answer 15

chain of hundreds of amino acids called a polypeptide

Question 16

What is the sequence of amino acids in a polypeptide determined by

Answer 16

DNA

Question 17

How many structural levels of proteins are there

Answer 17

4

Question 18

What are the structural levels of proteins

Answer 18

1) Primary
2) secondary
3) tertiary
4) quaternary

Question 19

What is the primary structure

Answer 19

the sequence of amino acids in a polypeptide chain

Question 20

What does the primary structure determine

Answer 20

the polypeptide 3D shape and therefore its function

Question 21

What can a change in the amino acid in the primary structure lead to

Answer 21

a change in shape of the protein and possibly stop it carrying out its function

Question 22

What is the secondary structure of a protein

Answer 22

when the polypeptide chain has formed hydrogen bonds between the amino acids that cause it to change shape, into either an alpha helix or bea pleated sheet

Question 23

Where are the hydrogen bonds formed between on the amino acids

Answer 23

The positive charge on the H of the NH group, and the negative charge on the O of the C=O group

Question 24

What is the tertiary structure of a protein

Answer 24

when the polypeptide chain is coiled further due to the creation of more bonds (hydrogen, ionic, disulfide bridges)

Question 25

When are disulfide bridges formed

Answer 25

when 2 molecules of the amino acid cysteine come close together and the sulfur atom in one cysteine bonds to the sulfur atom in the other

Question 26

Are disulfide bridges strong and what does this mean

Answer 26

yes, they cannot be easily broken

Question 27

What is the quaternary structure of proteins

Answer 27

the way that different polypeptide chains in a protein are held together

Question 28

What is the final structure of a single polypeptide chain protein

Answer 28

teritary

Question 29

Give an example of a quaternary structure protein

Answer 29

haemoglobin

Question 30

What 4 functions do proteins have

Answer 30

1) enzymes 2) antibodies 3) transport proteins 4) structural proteins

Question 31

What shape are enzymes usually and why

Answer 31

spherical due to the tight folding of the polypeptide chains

Question 32

What do enzymes often have roles in

Answer 32

metabolism or synthesis

Question 33

Are enzymes soluble

Answer 33

yes

Question 34

What are antibodies used in

Answer 34

immune response

Question 35

What are antibodies make up of

Answer 35

2 light (short) and 2 heavy (long) polypeptide chains bonded together

Question 36

What regions do antibodies have and what varies within them

Answer 36

variable regions, the amino acid sequences vary

Question 37

What is another name for transport proteins

Answer 37

channel proteins

Question 38

Where are transport proteins found

Answer 38

cell membrane

Question 39

What causes the channel proteins to fold up and form a channel

Answer 39

they contain hydrophobic and hydrophilic amino acids

Question 40

What do these transport proteins transport

Answer 40

molecules and ions across membranes

Question 41

What do structural proteins consist of

Answer 41

long polypeptide chains lying parallel to each other with cross-links between them

Question 42

Give 2 examples of structural proteins

Answer 42

keratin (hair), collagen (connective tissue)

Question 43

Are structural proteins strong

Answer 43

yes

Question 44

What test is used for proteins

Answer 44

Biuret test

Question 45

How many steps are there in the Biuret test

Answer 45

3

Question 46

What are the steps for the Biuret test

Answer 46

1) Place a sample of the solution into a test tube 2) add sodium hydroxide solution at room temperature to make the solution alkaline 3) Add very dilute sodium copper sulfate solution and mux

Question 47

What indicates the presence of lipids

Answer 47

a colour change from blue to purple

Question 48

What are the 2 types of protein

Answer 48

fibrous and globular

Question 49

What functions do fibrous proteins have

Answer 49

structural

Question 50

What functions do globular proteins have

Answer 50

metabolic

Question 51

Give an example of a fibrous protein

Answer 51

collagen

Question 52

What is the primary structure of collagen

Answer 52

unbranches polypeptide chain

Question 53

What is the secondary structure of collagen

Answer 53

very tightly wound

Question 54

What helps the secondary structure be very tightly wound

Answer 54

lots of the amino acid glycine

Question 55

What is the tertiary structure of collagen

Answer 55

chain is twisted into a second helix

Question 56

What is the quaternary structure of collagen

Answer 56

3 polypeptide chains wound together (like that of a rope)

Question 57

Where is collagen found

Answer 57

in tendons