Proteins

Question 1

What are amino acid R group?

Answer 1

basic (positively charged) group NH
acidic (negatively charged) group  COO
Polar group (C=O) or (OH)
Hydrophobic (non-polar) group (CH3)

Question 2

what are 2 key protein structures?

Answer 2

Secondary structure
&
Tertiary structure

Question 3

What is a Secondary Structure?

Give examples

Answer 3

Stabilised by hydrogen bonds along the backbone of the Structures that can be formed from this are;
Alpha helices
Beta pleated sheets (anti/parallel)
Turns

Question 4

What is a Tertiary structure?

Give example of structures formed

Answer 4

Stabilised by many different interactions between the R groups of the amino acids:

Hydrophobic interactions
Ionic bonds
London dispersion forces
Hydrogen bonds
Disulfide bridges - these are strong covalent bonds between R groups that contain sulfur.

Question 5

What are 2 key Proteins to cause conformational changes

Answer 5

Ligands & Allosteric Enzyme

Question 6

What is a Ligand?

Answer 6

Substance that binds to a protein, changing its conformation
Binding sites of protein complementary in shape to ligand
The change in conformation causes the function of the protein the change.

Question 7

What is an Allosteric Enzyme

Answer 7

Have an allosteric site
Are regulated by a modulator
- Allosteric interactions show co-operativity where binding of one substrate causes the conformational change of other subunits and increases affinity.

Question 8

How is an Allosteric Enzyme regulated?

Answer 8

Modulator binds to allosteric site, causing a conformational change. This alters the affinity of the active site for the substrat

Question 9

Types of Allosteric Enzyme and how they work

Answer 9

Positive Modulator = increase enzyme affinity

Negative Modulator = decrease enzyme activity

Question 10

What is COOPERATIVITY

Answer 10

Oxygen binding to one subunit of haemoglobin alters the affinity of the others

Question 11

What is the structure of Haemoglobin

Answer 11

Quaternary Structure (2 or more connected polypeptide subunits)

Question 12

What are the components of Haemoglobin?

Answer 12

Has a prosthetic group (non-protein) called haem

- Haem binds with oxygen

Question 13

What lowers the affinity of HB for O2?

Answer 13

Decrease in pH and increase in temperature

Question 14

Give an example of Reduced Affinity of Haemoglobin for O2?

Answer 14

when cells are respiring (heat generated) there is reduced binding of oxygen to haemoglobin and therefore increases oxygen deliver to tissues that need it!

Question 15

what can kind changes can a phosphate group addition or removal cause?

Answer 15

conformational change of a protein

Question 16

Protein Kinase & Phosphate

Answer 16

transfers a phosphate to a protein. Terminal phosphate from ATP (last phosphate on ATP) is transferred to the R group of the protein

Question 17

Protein phosphatases & Phosphate

Answer 17

remove a phosphate from protein

Question 18

Activation of a protein (enzymes) by Phosphorylation

Answer 18

activated by phosphorylation (adding a phosphate)

Question 19

Removing a phosphate from an activated protein

Answer 19

deactivated by removing a phosphate.