membrane transport and cell signalling

Question 1

What molecules can passively diffuse across the membrane?

Answer 1

Small
Hydrophobic
Non polar
Uncharged

Question 2

What are the different types of channel proteins?

Answer 2

Ligand gated

Voltage gated

Question 3

What does a concentration gradient represent?

Answer 3

A chemical potential/energy potential

Question 4

What are the two types of active transporters?

Answer 4

Primary ATP driven pumps

Secondary coupled transporters(electrochemical gradient)

Question 5

What are the 3 types of Primary ATP pumps?

Answer 5

P-type pump
F-type and V-type proton pump
ABC transporter

Question 6

What are the 3 types of secondary coupled transporters?

Answer 6

Uniport
Symport
Antiport

Question 7

How do co-transporters work?

Answer 7

The electrochemical potential of one molecule, is used to move another molecule against its chemical gradient (from low to high).
Uses active transport.

Question 8

‘Co-transporters’ symporter vs antiporter.

Answer 8

A symporter carries two different ions or molecules, both in the same direction. An antiporter also carries two different ions or molecules, but in different directions

Question 9

What are the 4 phases of action potentials?

Answer 9

Resting potential -70mv of cell exists:
Depolarisation
Depolarisation 
Hyperpolarisation
Return to resting potential

Question 10

Compare ion concentration in vs out of cell of:
Na+
K+
Mg2+
Ca2+
Cl-

Answer 10

Na+ (in cell: 5-15mM, out cell 145mM)
K+ (in cell: 140mM, out cell 5mM)
Mg2+ (in cell: 0.5mM, out cell 1-2mM)
Ca2+ (in cell: 10'-4'mM, out cell 1-2mM)
Cl- (in cell: 5-15mM, out cell 110mM)

Question 11

How do cells communciate?

Answer 11

Signals are transmitted via soluble molecules.

Question 12

What are the 5 different modes of cell signalling?

Answer 12

• Contact dependent (contact between signalling and target cell).
• Paracrine (signal molecule sent to neighbour cells).
• Synaptic.
• Endocrine (hormones secreted by endocrine cells too target cells).
• Autocrine (self signalling cell via signalling molecule to cell receptor).

Question 13

Agonist ligands vs antagonist ligands.

Answer 13

A ligand is a molecule that binds to a receptor.
Agonist induce a responce.
Antagonists repress a responce.

Question 14

What are the 2 locations of receptors?

Answer 14

Cell surface, activated by hydrophilic signal molecules.

Intracellular, activated by small hydrophobic ligands on a carrier protein.

Question 15

What are the 4 types of receptors?

Answer 15

.Ligand-gated ion channels
.G-protein-coupled receptors
.Receptor tyrosine kinases
.Intracellular receptors

Question 16

What is the structure of RTK’s

Answer 16

• Transmembrane protein
• Consists of a dimer (two came together proteins)
• ‘extracellular ligand’ binding site
• Intracellular kinase domain

Question 17

What’s a kinase?

Answer 17

Phosphorylating enzyme, add a phosphate group to hydroxyl group on amino acids.
This phosphorylation causes activation.

Question 18

What are the 3 main amino acids that can be phosphorylated?

Answer 18

• Serine
• Threonine
• Tyrosine

Question 19

How are GTPases used as molecular switches?

Answer 19

G protein GEF activates the GTPase, GAP deactivates.

GTP binds to GTPase in active form, in unactive form GDP binds.

Question 20

What reverses phosphorylation?

Answer 20

Phosphatase’s