Exam key will be posted on the class website this afternoon'

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Dr. Stuart Reichler
Exam key will be posted on the class website this
afternoon. Lecture slides will also be posted on
the class website.
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Plants respond to the direction of light
CB 39.0
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Light quality is different in shademore far-red
direct light
shade
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Plants respond to touch
touched
not touched
CB 39.26
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Another touch response
CB 39.27
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Bad touch Herbivory
Protease Inhibitors
Protease Inhibitors
Protease Inhibitors
Jasmonic acid
Protease Inhibitors
sytemin
Protease Inhibitors
Protease Inhibitors
Ive got indigestion!
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Cells and organisms must monitor and respond to
the environment.
Is there
anybody
out there?
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(No Transcript)
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Signal Transduction
External
Stimulus
Internal
Effector
Effector
Effector
Effector
Response
Perception (by receptor)
Stimulus
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Signal transduction step by step Perception
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Signal transduction step by step Transduction
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Signal transduction step by step Response
such as changes in cellular components or
production of new cellular components
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Transduction can involve activation or
inactivation of proteins.
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Cellular responses may involve changes in the
expression of genes.
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Blood sugar levels as an example of cellular
responses to the environment
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Perception, Transduction, Response
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Why so many steps?
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Multiple steps allow for signal specificity.
Different relay molecules lead to different
responses
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Calcium is a common effector. Cytoplasmic
calcium levels are normally low.
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General model of Ca signaling
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Ca is involved in many responses
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Ca is involved in signal transduction for
responses of

• in Plants
• Development
• Cold
• Guard cell closing
• Osmotic shock
• Light
• Fungal infection
• Touch
• Pollen tube growth
• Wounding

• in Animals
• Neurons
• Muscle movement
• Wounding
• Development
• Fertilization
• Hormones

How can there be specificity?
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General model of Ca signaling
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Multiple steps allow for signal
amplification Calcium is a simple method of
amplifying signals
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Multiple steps allow for signal specificity.
Different relay molecules lead to different
responses
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Everything has its place