1.6 Proteins Flashcards
1
Q
What are the monomers of proteins?
A
Amino acids
2
Q
What is a dipeptide?
A
Two amino acids joined together
3
Q
What is a polypeptide?
A
More than two amino acids joined together
4
Q
What is a protein made of?
A
One or more polypeptides
5
Q
Describe the structure of an amino acid
A
- a carboxyl group ~ -COOH
- amine group ~ -NH2
- R group ~ variable side group
6
Q
How many amino acids do living things share?
A
20
7
Q
How are polypeptides formed?
A
- amino acids are linked together by condensation reactions
- molecule of water is released
- bond formed is a peptide bond
8
Q
Describe the primary structure of proteins
A
Sequence of amino acids in the polypeptide chain
9
Q
Describe the secondary structure of a protein
A
- hydrogen bonds form between amino acids in the chain
- either coil into an α helix
- or fold into a β pleated sheet
10
Q
Describe the tertiary structure of a protein
A
- coiled or folded structure in secondary is often coiled or folded further
- more bonds form between parts of the chain ~ hydrogen or ionic
- disulfide bridges form when two molecules of cysteine are close together
- single chain proteins = tertiary structures is the final 3D structure
11
Q
Describe the quaternary structure of a protein
A
- for proteins made of several different polypeptide chains
- proteins made of more than one chain (haemoglobin, insulin, collagen) the quaternary structure is the final 3D shape
12
Q
List 3 examples of proteins
A
- enzymes
- channel proteins
- transport proteins
13
Q
What is the function of enzymes?
A
- roughly spherical in shape due to tight folding of polypeptide chains
- soluble
- have roles in metabolism like digestives enzymes
- some help to synthesise (make) large molecules
14
Q
What is the function of a transport enzyme?
A
- channel proteins
- they’re in membranes - - hydrophobic and hydrophilic amino acids
- these amino acids cause the protein to fold up into a channel
- these proteins transport molecules and ions across the membrane
15
Q
What is the function of a structural protein
A
- physically strong
- consist of long polypeptide chains lying parallel to each other with cross links
- eg keratin and collagen
