3) Unit 1 - Hydrophobic & Hydrophillic Interactions, Influencing The Location of Cellular Proteins

Question 1

what are membranes made of

Answer 1

bilayar of phospholipids and proteins

Question 2

why can the membrane be described as semi-permeable

Answer 2

only allows certain molecules enter and exit the cell

Question 3

why do R groups at the surface of a protein determine its location

Answer 3

the R groups interact with the proteins environment

Question 4

Describe the nature of R groups of proteins in the cytoplasm

Answer 4

• proteins in the cytoplasm will have hydrophillic R groups on their surface as the cytoplasm is a hydrophillic environment
• In these soluble proteins, their hydrophobic R groups will cluster at their center, making a globular structure

Question 5

identify the hydrophobic regions of the membrane

Answer 5

tails of phospholipids

Question 6

identify the hydrophillic regions of the membrane

Answer 6

heads of phospholipids

Question 7

describe integral proteins and give examples

Answer 7

proteins that span the width of the membrane

e.g. transmembrane proteins such as channels and transporters

Question 8

describe peripheral proteins

Answer 8

partially embedded in the membrane

Question 9

how are integral proteins held in the membrane

Answer 9

integral proteins have hydrophobic R groups on their surface which interact with the hydrophobic tails of the membrane, holding them in place.

Question 10

describe what a channel and transporter is

Answer 10

channel:
allows the movement of molecules from one side of the membrane to the other without energy

transporter:
transports molecules across the membrane by conformational change

Question 11

how many hydrophobic R groups do peripheral proteins have in comparison to integral

AND

how are they held in place in the membrane

Answer 11

• fewer interacting with the phospholipids

* held in place by charged, polar or hydrophobic interactions