Cell communication

Question 1

Examples of types of signalling

Answer 1

Contact dependent
Paracrine
Endocrine

Question 2

Examples of how cells respond to signalling

Answer 2

Altered metabolism

Altered gene expression

Altered cell shape or movement

Question 3

What is a morphogen gradient with an example?

Answer 3

Different responses occur at different thresholds

E.g Drosophila development, Bicoid mRNA is deposited in anterior of egg, forming a gradient which defines anterior parts of resulting embryo

Question 4

What stages can signalling pathways be regulated?

Answer 4

Extracellular ligand/receptor

Intracellular transduction of signal

Positive/negative feedback

Question 5

How does GTP signalling work?

Answer 5

GTPase hydrolyses GTP to GDP
GEF exchanges GDP to GTP
When GDP is bound = inactive
When GTP bound = active

Question 6

How does phosphorylation signalling work?

Answer 6

ATP dependent
Protein kinase adds phosphate group - active
Protein phosphatase removes phosphate group = inactive

Question 7

Type 1 kinase inhibitor

Answer 7

Binds to active conformation of kinase

Question 8

Type II kinase inhibitor

Answer 8

Bind and stabilise inactive conformation of kinase

Question 9

Type III kinase inhibitor

Answer 9

Occupy allosteric site adjacent to ATP binding pocket

Question 10

Type IV kinase inhibitor

Answer 10

Binds to allosteric pocke