Cell signalling

Question 1

Different combinations of ______ ______ mediated by _____ ________ lead to the cell undergoing _________ ____ _____

Answer 1

distinct signals __different receptors__different cell fates.

Question 2

Different cell fates

Answer 2

Survivie/ Differentiate/ Divide/ Die

Question 3

Key cell survival signalling pathway

Answer 3

IGF1 > IGF1R > PI 3-kinase > Protein kinase B (PKB/Akt) > Inactivates death proteins and promotes survival functions

Question 4

Death signals are mediated by

Answer 4

Specific extracellular ligands that bind to specific cell surface receptors and initiate intracellular signals.

Question 5

Cell growth

Answer 5

• Involves an increase in cell size without and increase in cell number.
• Synthesis of new proteins, membrane lipids.
• Increase numbers of organelles.
• May involve replication of DNA but not necessary.

Question 6

Cell growth is controlled by

Answer 6

• Growth factors
• Contact with adjacent cells
• Nutrient availability

Question 7

Cell Proliferation

Answer 7

• Involves replication of DNA and division to produce two cells.
• Usually follows on from a cell growth phase.
• If not a reductive division will occur resulting in one or more smaller cells.

Question 8

There are both positive and negative

growth/proliferation signals T/F

Answer 8

True

Question 9

Growth stimulating pathway

Answer 9

• Growth factor signal bind to the Tyrosine- kinase receptor ( at the extracellular surface) - ATP phosphorlyated with receptor to ADP and activated G protein (Ras) with GTP.
• [Hyperactive Ras protein (product of oncogene) issues signals on its own]
• Protein kinases (phosphorylation cascade)
• (Activate) Transcription factor (activator) in the nucleus and (turn on) gene expression
• Synethesis protein that stimulates the cell cycle

Question 10

Growth inhibiting pathway

Answer 10

Growth inhibiting factor bind to the receptor ( at the extracellular surface) and activated G protein with GTP.

• Protein kinases (phosphorylation cascade)
• (Activate) Transcription factor (such as P53) in the nucleus and (turn off) gene expression
• Synethesis protein that inhibits the cell cycle
• [Defective or missing transciption factor such as p53, cannot activate transcription

Question 11

The cell cycle checkpoint control_______

Answer 11

blocks the cell cycle and have to be removed to allow the cycle to proceed

Question 12

Signal transduction pathways when activated _________

Answer 12

remove the blocks and allow cell cycle to proceed

Question 13

The cell cycle checkpoint control has

Answer 13

G1 checkpoint ( nearly the end of G1- cell growth)
G2 checkpoint ( at the end of G2 - gap 2)
M checkpoint ( in the middle of M - Mitosis)

Question 14

Cell differentiation

Answer 14

• The process by which cells become specialised cell types

- Usually but not always involves them ceasing to proliferate.

Question 15

Cultured stem cells can be obtained from

Answer 15

Adult stem cells from bone marrow/ Embryonic stem cells (Earky human embryo at blastocyst stage (mammalian equivalent of blastula)