Overview of Cell Signalling & Transcription Regulation in Cell

Question 1

What are the main types of extracellular signals that cells in multicellular organisms respond to?

Answer 1

1. Extracellular signalling molecules
2. Signals derived from cell-cell contact

Question 2

Explain the concept of INDUCTION in cellular development

Answer 2

The mechanism whereby one cell population influences the development of neighbouring cells

Question 3

What are the three major classes of cell-surface receptor proteins?

Answer 3

1. Ion-Channel-Coupled Receptors
2. G-Protein-Coupled Receptors
3. Enzyme-Coupled Receptors

Question 4

How do Receptor Tyrosine Kinases (RTKs) function in signal transduction?

Answer 4

Activated Receptor Tyrosine Kinases (RTKs) phosphorylate themselves and bind to SH2 domain containing signalling proteins

Question 5

Describe the process of RTK activation and autophosphorylation

Answer 5

1. Signal protein binds inactive RTKs
2. RTKs autophosphorylate each other and activate tyrosine kinase domains
3. Autophosphorylation generates sites for SH2 domain containing signalling proteins
4. Activated signalling proteins relay signal downstream

Question 6

What factors influence the speed of a cellular response to signals?

Answer 6

• Turnover of signalling molecules
• Positive and negative feedback
• Control by protein alteration and degradation

Question 7

Explain how cells can adjust their sensitivity to a signal

Answer 7

• Receptor sequestration
• Receptor down-regulation
• Receptor inactivation
• Inactivation of signalling protein
• Production of inhibitory protein

Question 8

How are specific and precise signals relayed in a crowded cytoplasm?

Answer 8

Liquid-Liquid Phase Separation at plasma membrane

Question 9

What are the 6 stages that gene expression can be controlled in cells?

Answer 9

1. Transcriptional Control
2. RNA Processing Control
3. RNA Transport and Localisation Control
4. Translation Control
5. mRNA Degradation Control
6. Protein Activity Control