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Cell Communication CHAPTER 11.

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Presentation on theme: "Cell Communication CHAPTER 11."— Presentation transcript:

1 Cell Communication CHAPTER 11

2 An Example of Cell Communication: Fight or Flight Response

3 Cell Signaling Animal cells communicate by:
Direct contact (gap junctions) Secreting local regulators (growth factors, neurotransmitters) Long distance (hormones) Chemical and Electrical signals

4 Types of Communication:
Autocrine- receptor on same cell (growth factors telling tumor cells to keep growing) Paracrine- neighboring cell is near signal releasing cell (two neurons) Juxtacrine- target and releasing cells are in physical contact (quorum sensing in bacteria, gap junctions) - Endocrine- chemicals that need to travel long distances (hormones)

5 Signal Transduction Pathway
Series of steps by which a signal on a cell’s surface is converted to a specific cellular response Signaling can be short distance or long distance

6 3 Stages of Cell Signaling:
Reception: A signal molecule (ligand) binds to a receptor protein causing it to change shape Transduction: series of molecules interactions that relay signal from receptor to target molecule Response: regulation of transcription or cytoplasmic activities

7 1. Reception Binding between signal molecule (ligand) + receptor is highly specific. Receptors found in: Intracellular receptors (cytoplasm, nucleus) hydrophobic ligands Eg. testosterone or other hormones turning on and off certain genes Plasma membrane receptor water-soluble ligands

8 G-Protein-Coupled Receptor
2 min

9 Tyrosine Receptor Kinase
1 min

10 Ligand-Gated Ion Channel
2 minutes

11 Plasma Membrane Receptors
G-Protein Coupled Receptor (GPCR) Tyrosine Kinase Ligand-Gated Ion Channels 7 transmembrane segments in membrane Attaches (P) to tyrosine Signal on receptor changes shape G protein + GTP activates enzyme  cell response Activate multiple cellular responses at once Regulate flow of specific ions (Ca2+, Na+)

12 2. Transduction Cascades of molecular interactions relay signals from receptors  target molecules; “dominoes effect” Protein kinase: enzyme that phosphorylates and activates proteins at next level Phosphorylation cascade: enhance and amplify signal

13

14 Second Messengers small, nonprotein molecules/ions that can relay signal inside cell Eg. cyclic AMP (cAMP) and Ca2+ - cAMP is made when adenyl cyclase converts ATP to cAMP - cAMP activates protein kinase A which phosphorylates other proteins

15 3. Response Regulate protein synthesis by turning on/off genes in nucleus (gene expression) Regulate activity of proteins in cytoplasm

16 G-Protein-coupled Receptors
Figure 6-11: The G protein-coupled adenylyl cyclase-cAMP system

17 Transduction Reviewed
Figure 6-14: Summary of signal transduction systems


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