Proteins and their Functions

Question 1

What is transcription?

Answer 1

When DNA acts as a template for RNA

Question 2

What is primary structure

Answer 2

sequence of amino acids

Question 3

what is secondary structure

Answer 3

the foldings of the primary sequence- alpha helixes, beta pleated sheets, hydrogen bonds, VDW

Question 4

what is tertiary structure

Answer 4

3D confirmation- further folding of the protein

Question 5

what is quaternary structure

Answer 5

multiple polypeptide chains

Question 6

what protein structure is an enzyme

Answer 6

globular- for secretion

Question 7

describe the structure of haemoglobin

Answer 7

4 polypeptide chains with a haem group

Question 8

how are proteins directed to the correct site in the cell

Answer 8

via a sorting signal

Question 9

how do proteins move into organelles

Answer 9

They move from the cytosol into organelles via transporters located in the membrane

Question 10

where are proteins modified

Answer 10

endoplasmic reticulum and are further modified in the golgi apparatus

Question 11

what is cystic fibrosis

Answer 11

a mutated membrane protein- deletion of F508

Question 12

How is the Na+ electrochemical gradient maintained?

Answer 12

1. 3 Na+ bind to sites on catalytic subunit, ATPase is activated
2. ATP hydrolysis takes place to produce ADP and a phosphate which attaches to pump
3. Phosphorylation of catalytic subunit causes conformational change
4. Causing Na+ to be release to exterior of cell and 2 K+ to bind
5. Binding of K+ triggers removal of phosphate group causing pump to revert to original shape
6. K+ ions are released to inside of cell

Question 13

what is a symport coupled transporter

Answer 13

moves solutes in the same direction e.g NA/glucose transporter

Question 14

what is an antiport coupled transporter

Answer 14

moves solutes in opposite directions e.g Na/Ca pump moves Ca out of cell to decrease muscle contraction