module 2 - 3.6-3.7 proteins

Question 1

what are polymers called?

Answer 1

polypeptides

Question 2

what are polymers/ polypeptides made up of?

Answer 2

amino acids

Question 3

what is the structure of an amino acid? (diagram)

Answer 3

H R O
\ | //
N - C - C
/ | \
H H OH

Question 4

which group is the 2 H and N atom in?

Answer 4

amino group

Question 5

what is the R group called?

Answer 5

variable group

Question 6

which group is the second C, double bonded O and OH in?

Answer 6

carboxylic group

Question 7

how are dipeptides formed?

Answer 7

condensation (loss of H2O)

Question 8

which parts of the amino is replaced to form a dipeptide?

Answer 8

OH and H (replaced with peptide bond between C and N)

Question 9

what shape does a single amino acid form?

Answer 9

tetrahedral shape

Question 10

which is the simplest of the amino acids that possesses a hydrogen atom for its R group?

Answer 10

glycine

Question 11

what do proteins function as?

Answer 11

hormones, oxygen transporters, and enzymes

Question 12

what to proteins look like under a microscope?

Answer 12

they are huge three-dimensional molecules (at a microscopic complex)

Question 13

what happens when an amino acid has a carboxylic acid group in the R group?

Answer 13

it has 2 acid groups and one basic group, overall the amino acid is an acidic molecule

Question 14

what happens when an amino acid have an amino (basic) acid group in the R group?

Answer 14

it has 2 basic groups and one acid group, overall the amino acid is a basic molecule

Question 15

what are the two sulfur containing amino acids?

Answer 15

cysteine and methionine

Question 16

what is the structure of proteins?

Answer 16

• consist of 1 or more polypeptide chain folded into complex 3-dimensional shapes
• different proteins have different shapes

Question 17

what is the primary structure of proteins? (1Y)

Answer 17

the order of amino acids in a polypeptide chain is determined by DNA

Question 18

what is the secondary structure for proteins? (2Y)

Answer 18

the chain may coil into a spiral (alpha helix)

Question 19

what is the tertiary structure for proteins? (3Y)

Answer 19

the whole chain may then be further folded (after 2Y) to form a complex Globular shape (3D)

Question 20

what is the quaternary structure for proteins? (4Y)

Answer 20

some proteins are made up of more than one polypeptide chain, chains combine together by bonds

Question 21

within the secondary structure, what may the proteins form other than an alpha helix?

Answer 21

beta pleated sheet, where 2 parts of the chain lie close together and hydrogen bonds link one part of the chain to another

Question 22

when do polypeptide chains form?

Answer 22

when amino acids bond together in a particular sequence

Question 23

what does the primary structure of a protein depend on?

Answer 23

the number, type and sequence of amino acids that make up a linear chain (together with the peptide bonds that hold them together)

Question 24

which 2 bonds hold long chains together?

Answer 24

hydrogen bonds
disulphide bonds

Question 25

where are disulphide bonds formed?

Answer 25

between sulphur containing amino acids

Question 26

what are proteins that are rolled into a ball?

Answer 26

globular
soluble in water
important for metabolism
(alpha helix)

Question 27

what are long and thin proteins?

Answer 27

fibrous
insoluble in water
structural
(beta pleated sheet)

Question 28

what are the secondary structures of protein molecules?

Answer 28

alpha helix
beta pleated sheet

Question 29

why does a beta pleated sheet fold at each end?

Answer 29

to help with strength

Question 30

what bond is a beta pleated sheet held together by?

Answer 30

hydrogen bonds

Question 31

what type of helix is the alpha helix coiled into?

Answer 31

right handed helix

Question 32

in the alpha helix, where do the hydrogen bonds form between?

Answer 32

between oxygen and hydrogen atoms that have been brought into close proximity

Question 33

what do the hydrogen bonds do to the secondary structure?

Answer 33

stabilise it

Question 34

what type of chain is formed when within the beta pleated sheet?

Answer 34

anti-parallel chains

Question 35

what is formed when the oxygen and hydrogen atoms are brought into close proximity within the beta pleated sheet?

Answer 35

forms hydrogen bonds

Question 36

which structure do globular proteins display?

Answer 36

tertiary structure

Question 37

what is myoglobin?

Answer 37

a globular protein found in muscle cells

Question 38

what is the structure of haemoglobin?

Answer 38

quaternary structure

Question 39

what does haemoglobin consist of?

Answer 39

4 polypeptide chains that are held together by weak forces

Question 40

what do oppositely charged groups of carboxylic acid and amino acid groups form?

Answer 40

ionic bonds

Question 41

why do many hydrophobic R groups tend to cluster towards the interior of the protein molecule?

Answer 41

to form hydrophobic reactions

Question 42

what are hydrophobic reactions also known as?

Answer 42

covalent bonds (hold the structures together)