Intracellular communication and signal transduction Flashcards

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1
Q

Cell communication

A

A signalling cell releases signalling molecules therefore the responding cell has receptor proteins that bind to the signalling molecule

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2
Q

Intracellular signalling molecules

A

paracrines
NTs
Hormones
Neurohormones

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3
Q

Signal Transduction

A

A transducer converts energy forms (e.g., pressure to electrical signal).
Signal transduction transmits an incoming signal through the cell membrane to produce a cellular response.
Second messenger systems amplify the original signal through multiplying steps

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4
Q

Messenger Responses

A

Extracellular messenger (1st messenger) binding to receptors causes:
FAST: Opens/closes ion channels, causing EPSPs or IPSPs.
SLOW: Activates a second messenger system.

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5
Q

Hormone Responses

A

Hormones can elicit responses through:
Direct gene activation of steroid hormones.
Activation of G-protein coupled receptors.
G-proteins bind GTP (active) and GDP (inactive).
Involved in cyclic AMP and intracellular Ca²⁺ second messenger systems.

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6
Q

Types of hormones

A

Hydrophilic
Lipophilic

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7
Q

What are lipophilic hormones?

A

Lipid soluble and water insoluble
Combine with intracellular receptors and activate specific genes to cause the formation of new intracellular proteins
Time taken to response= several hours
Duration of response= depends on how quickly protein is degraded
Examples might include thyroid hormone- amine hormone derived from the amino acid tyrosine

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8
Q

What are hydrophilic hormones?

A

Extracellular domain
Transmembrane domain
Cytoplasmic domain
water soluble and lipid insoluble
combine with a protein receptor on outside of membrane + activate a second messenger system= altering the activity of pre-existing intracellular proteins; usually proteins
time to response= few mins
duration of response- after hormonal trigger = depends on how quickly the enzyme is inactivated
examples; insulin= peptide hormones

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9
Q

receptors with dynamic structures

A

Sometimes target cells can form more receptors in response to rising blood levels of that specific hormone
This is called up-regulation
Sometimes prolonged exposure to high concentrations of a hormone desensitizes the target cells so that the cell responds less vigorously.
This involves the loss of receptors and is called down-regulation

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