Figure 11.0 Yeast

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Figure 11.0 Yeast
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Figure 11.1 Communication between mating yeast
cells

• Cell Communication
• Between separate organisms
• Between cells within an organism

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Figure 11.2 Communication among bacteria
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Figure 11.3 Local and long-distance cell
communication in animals
Communicating cells can be close together or far
apart.
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• Paracrine Signaling
• Histamine released by mast cells.
• Inflammation of nearby tissue
• Increased secretion of stomach acid

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Figure 11.4 Communication by direct contact
between cells
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Three Stages of Cell Signaling

1. Reception detection of signal
2. Transduction signal converted to form that
   yields cellular response
3. Response

Earl Sutherland
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Figure 11.5 Overview of cell signaling (Layer 1)
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Figure 11.5 Overview of cell signaling (Layer 2)
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Figure 11.5 Overview of cell signaling (Layer 3)
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Signal Reception

• Receptors
• Membrane protein
• On surface of cell
• Specific
• Ligand binds receptor causing a change in
  conformation
• Signal transduction pathway initiated
• Types of membrane receptors
• G-Protein Linked Receptors
• Tyrosine kinase receptors
• Ion-channel receptors

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Figure 11.6 The structure of a G-protein-linked
receptor
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Figure 11.7 The functioning of a
G-protein-linked receptor
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Figure 11.8 The structure and function of a
tyrosine-kinase receptor
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Figure 11.9 A ligand-gated ion-channel receptor
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Figure 11.10 Steroid hormone interacting with
an intracellular receptor
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Signal Transduction Pathways

• Process of relaying signal to produce response.
• Often several steps/processes
• Amplification
• Involves second messengers
• Cyclic AMP (cAMP), Ca2
• Protein Kinase Enzyme that transfers phosphate
  from ATP to a protein
• Protein Phosphatase enzyme that removes
  phosphate from a protein.

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Figure 11.11 A phosphorylation cascade
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Figure 11.12 Cyclic AMP
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Figure 11.13 cAMP as a second messenger
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Examples of Hormone-induced Cellular Responses
Mediated by cAMP
Target Tissue Hormone Major Response
Thyroid gland TSH TH synthesis/secretion
Muscle Adrenaline Glycogen breakdown
Heart Adrenaline Increase heart rate/force of contract
Liver Glucagon Glycogen breakdown
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Figure 11.14 The maintenance of calcium ion
concentrations in an animal cell
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Figure 11.15 Calcium and inositol triphosphate
in signaling pathways (Layer 1)
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Figure 11.15 Calcium and inositol triphosphate
in signaling pathways (Layer 2)
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Figure 11.15 Calcium and inositol triphosphate
in signaling pathways (Layer 3)
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Some Cellular Responses Mediated by
G-Protein-linked Receptors Coupled to Inositol
Phospholipid Signaling Pathway
Target Tissue Signaling Molecule Major Response
Liver Vasopressin Glycogen breakdown
Pancreas Acetylcholine Amylase secretion
Smooth Muscle Acetylcholine Contraction
Mast cells Antigen Histamine secretion
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Figure 11.16 Cytoplasmic response to a signal
the stimulation of glycogen breakdown by
epinephrine
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Figure 11.17 Nuclear response to a signal the
activation of a specific gene by a growth factor
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Amplification of Signal Response
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Figure 11.18 The specificity of cell signaling
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Figure 11.19 A scaffolding protein