Term
| What is a receptor tyrosine kinase? |
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Definition
a membrane receptor that attaches phosphate to tyrosines
they can trigger multiple signal transduction pathways at once (signal transduction is the conversion of an impulse or stimulus from one physical or chemical form to another. the process by which a cell responds to an extracellular signal) |
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Term
| Receptor Tyrosine Kinases mostly activate what? |
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Definition
Ras which is a small G protein (a monomeric G protein)
It is membrane bound |
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Term
| What pathway does Ras stimulate? |
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Definition
the MAP-kinase system
(mitogen-activated protein-kinase)
which stimulates cell division and growth |
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Term
| Ion-channel coupled receptor |
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Definition
| transmembrane receptor protein or protein complex that forms a gated ion channel that opens in response to the binding of a ligand to the external face of the channel |
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Term
A type of membrane receptor...
Receptor tyrosine kinase |
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Definition
| an enzyme coupled receptor in which the intracellular domain has a tyrosine kinase activity, which is activated by ligand binding to the receptor's extracellular domain |
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Term
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Definition
an ion channel opens when it binds a small molecule such as a neurotransmitter
- it acts as a gate when the receptor changes shape |
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Term
| Ca2+ acts as a ___ ____ in many pathways. Why is it important? |
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Definition
secondary messenger
because cells can regulate its concentration |
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Term
| What other secondary messengers are involved in the pathways that lead to the release of calcium? |
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Definition
| inositol triphosphate (IP3) and diacylglycerol (DAG) |
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Term
| Processing of visual information begins in the _____. |
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Definition
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Term
| the absorption of light triggers ___ ___ ___ in photoreceptor cells. |
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Definition
| signal transduction pathway |
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Term
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Definition
rods are light-sensitive but don't distinguise colors
cones distinguish colors but are not as sensitive to light |
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Term
| what are the visual pigments that each rod and cone made up of? |
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Definition
| a light-absorbing molecule called retinal bonded to a protein called an opsin |
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Term
| what pigment do rods contain? |
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Definition
rhodopsin which is retinal combined with a specific opsin
it changes shape when absorbing light |
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Term
| When light activates rhodopsin what happens? |
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Definition
cyclic GMP breaks down and Na+ channels close
this then hyperpolarizes the cell |
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Term
| Initiation of apopotosis requires the conversion of ______ to mature _______. |
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Definition
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Term
| The proteolytic cascade leads to ____ |
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Definition
| apoptosis - programmed cell death |
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Term
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Definition
| specific cells are not destroyed... webbed fingers |
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Term
| What signals do cells need to avoid apoptosis? |
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Definition
survival factors (stimulate production of Bc12 that blocks apoptosis)
mitogens (A mitogen is a chemical substance that encourages a cell to commence cell division, triggering mitosis
growth factors |
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