Proteins Flashcards
1
Q
What is the structure of an amino acid?
A
- A central carbon atom
- A amine group to the left
- A carboxyl group to the right
- A variable group at the top
- A hydrogen group at the bottom
2
Q
How many amino acids do all living organisms contain?
A
20
3
Q
How does a peptide bond form?
A
- A condensation reaction between the OH from the carboxyl group of one amino acid and the H from the amine group of another amino acid
-This forms a dipeptide
4
Q
What is polymerisation?
A
The process in which many amino acids are joined together through a series of condensation reactions
5
Q
What is the primary structure of a protein?
A
- The sequence of amino acids in a polypeptide chain
6
Q
What is the secondary structure of a protein?
A
- Due to the overall of positive charge in the amine group and
the negative charge of the carboxyl group, hydrogen bonding occurs - This results in the automatic coil into either an alpha helix or beta pleated sheet
7
Q
What is the tertiary structure of a protein?
A
- When amino acids coil and fold further, this causes a specific 3D shape maintained by bonds such as ionic bonds, disulfide bridges and hydrogen bonds
8
Q
How do disulfide bridges form?
A
- between two molecules of cysteine as their R groups contain sulphur
- These are fairly strong and not easily broken
9
Q
How do ionic and hydrogen bonds form?
A
between oppositely charged parts of molecules
10
Q
What is the quaternary of proteins?
A
- Proteins that contain many polypeptide chains held together by bonds
11
Q
What is the difference between fibrous and globular proteins?
A
Globular = circular and compact
FIbrous = long and therefore used to make fibres
12
Q
What is the test for proteins?
A
- Add drops of sodium hydroxide to your food sample to make it alkaline
- Add drops of copper sulfate solution
- A positive test is a colour change from blue to purple
(biuret)
