protein structure

Question 1

draw the structure of an amino acid

Answer 1

from flashcard

Question 2

what are the 4 different groups on an amino acid ?

Answer 2

• amine group
• carboxyl group
• hydrogen group
• variable group

Question 3

how many options are there for the R group ?

Answer 3

20

Question 4

what kind of bond is formed between 2 amino acids during a condensation reaction ?

Answer 4

a peptide bond

Question 5

Draw how 2 amino acids are joined together

Answer 5

from notes

Question 6

what is a protein ?

Answer 6

proteins are polymers, made up of the monomer : amino acids

Question 7

how many different amino acids are there ?

Answer 7

20

Question 8

how is a polypeptide chain created ?

Answer 8

when more amino acids are added to a dipeptide

Question 9

what is the molecule called when a peptide forms between 2 amino acids ?

Answer 9

the molecule is called a dipeptide

Question 10

what are the different levels of structure in a protein ?

Answer 10

• primary structure
• secondary
• tertiary
• quaternary

Question 11

what is meant by the primary structure of a protein ?

Answer 11

it is the order / sequence of amino acids in the polypeptide chain

Question 12

what is meant by the secondary structure of a protein ?

Answer 12

when the sequence of amino acids causes parts of a protein molecule to bend into an alpha helix shape or a beta pleated sheet.

Question 13

draw the structure of an alpha helix shape

Answer 13

notes

Question 14

draw the structure of a beta pleated sheet

Answer 14

notes

Question 15

how are the structures of the secondary protein held together ?

Answer 15

hydrogen bonds hold the secondary structures shape

Question 16

where do the hydrogen bonds form in the secondary structures ?

Answer 16

hydrogen bonds form between the C=O groups of the carboxyl group of one amino acid and the H in the amine group of another amino acid

Question 17

what is the tertiary structure of a protein ?

Answer 17

• the further folding of the secondary structure
• to form a unique 3D shape
• held in place by ionic, hydrogen and disulfide bonds

Question 18

where do the ionic and disulfide bonds form ?

Answer 18

they form between the R groups of different amino acids

Question 19

when do disulfide bonds occur ? and why ?

Answer 19

they only occur sometimes
because there must be a sulfur in the R group for the bond to occur

Question 20

where do hydrogen bonds form in a protein ?

Answer 20

hydrogen bonds form between all levels of the structure

Question 21

where do hydrophobic interactions occur in a protein ?

Answer 21

they occur between non-polar sections of the protein

Question 22

where do disulfide bonds occur in a protein ?

Answer 22

they occur between 2 cysteine amino acids

Question 23

name the bonds in the tertiary structure in order of weakest to strongest ?

Answer 23

hydrogen bonds
ionic bonds
disulfide bonds

Question 24

state the molecular formula of cysteine

Answer 24

CH2SH

Question 25

what is meant by the quaternary structure of a protein ?

Answer 25

a protein made up of more than 1 polypeptide chain

Question 26

what is an example of a quaternary structure of a protein ?

Answer 26

haemoglobin
- it has 4 polypeptides

Question 27

what happens to the bonds if the protein is denatured ?

Answer 27

it means that the bonds which hold the tertiary and secondary structure (ionic and hydrogen bonds break ) in shape break and therefore the unique 3D shape is lost

Question 28

what are conditions that may denature a protein ?

Answer 28

• too high temperature
• too high/too low pH (too many H+ or OH-)

Question 29

state the importance of the primary structure.
and what impact will that have on an enzyme ?

Answer 29

if even one amino acid in the sequence is different it will cause the ionic/hydrogen/disulfide bonds to form in a different location
which will result in a different 3D shape
so in enzymes, they will have a different shaped active site and so will be non-functioning

Question 30

specific function is due to what ?

Answer 30

specific function is due to the specific shape

Question 31

what can a functional protein contain ?

Answer 31

it may contain one or more polypeptides