Membranes

Question 1

What is the role of membranes

Answer 1

-to define the limits of the cell and its organelles
-to receive and transmit chemical or electrical signals
-to regulate the transport of solutes
-to provide a surface area for reactions to take place on

Question 2

How is membrane fluidity regulated

Answer 2

The length of the fatty acids tails (longer tails are less fluid)
Cholesterol (higher levels of cholesterol make the membrane more rigid)

Question 3

What are flippases

Answer 3

Proteins than flip lipids back to their correct leaflet

Question 4

What are the 3 types of membrane protein

Answer 4

Anchored proteins
Peripheral membrane proteins
Integral membrane proteins

Question 5

What are the 3 types of cell signaling

Answer 5

Paracrine (signal acts on a local set of cells)
Autocrine (signal acts on the secreting cell)
Endocrine (long range signals moving through the blood stream)

Question 6

How do cell signals enter the cell

Answer 6

The signal can pass straight through the plasma membrane (steroids and retinoids)

The signal activated a membrane receptor that produces a secondary messenger

Question 7

What are nuclear receptors

Answer 7

Proteins in the cytoplasm that receive signals that passed straight through the plasma membrane. They then form a complex and enter the nucleus to activate genes

Question 8

What are G protein linked receptors

Answer 8

When a signal binds to a G protein it releases GDP and takes up GTP.
Part of the G complex dissociates and activates secondary messengers e.g. cAMP
GTP is then hydrolysed back to GDP and the G protein recombines