Signal Transduction (6.2) Flashcards
Describe signal transduction
Process of converting the original stimulus signal into a response
State what signal transduction involves
Change in signal form
State what the ability of a multicellular organism to detect and respond to stimuli relies upon
Cells communicating with each other
State what the process involved in a cell detecting and responding to a signalling molecule are referred to as
Signal transdution
State the 3 major steps of the stimulus-response model
- reception
- transduction
- cellular response
Describe reception as part of the stimulus-response model
The detection of the signalling molecule by a receptor
Describe transduction as part of the stimulus-response model
The relay of the signal into the cell
Describe cellular response as part of the stimulus-response model
The activation of cellular activity
State when signal transduction occurs
When a signalling molecule from outside the cell activates a specific receptor located on the cell surface or inside the cell
State 3 locations of the receptor which detects a signalling molecule
- plasma membrane
- cytosol
- nucleus
State what the position of a receptor depends upon
Signalling molecule is hydrophobic or hydrophilic
Describe the specificity of receptors
Receptors are specific
State whether or not receptors will only bind to particular signalling molecules
Yes. Receptors will only bind to specific signalling molecules.
State whether or not all cells are responsive to all signalling molecules.
No. All cells are not responsive to every signalling molecules.
Describe cascades
Multi-step transduction pathway
State the 2 different types of processes in transduction
- one-step
2. multi-step
Describe a one-step process of transduction
A signalling molecule binds to one receptor, producing a response
Describe a multi-step process of transduction
A signalling molecule binds to its receptor, activating different molecules
State what occurs post-transduction
A response is initiated
State 3 cellular responses that may follow transduction
- cellular activity (such as gene transcription)
- activation of enzymes
- secretion of signalling molecules
State the structure of most hydrophobic signalling molecules
Lipid-based molecules
State what hydrophobic signalling molecules are involved in
Gene regulation
State why lipid-based molecules can easily diffuse across the plasma membrane
Lipid soluble
State what hydrophobic signalling molecules bind to inside the target cell
Intracellular receptor
Describe 2 possible locations of an intracellular receptor
- nucleus
2. cytosol
State what steroid hormones are an example of
Lipid-based hydrophobic signalling molecules
State where steroid hormones bind to intracellular receptors
Cytosol
Once steroid hormones are bound to intracellular receptors state where they move to
Move from the cytosol through nuclear pores to the nucleus (final destination)
State what the signalling molecule-receptor acts as in the nucleus
Transcription factor
Provide 1 example of a hydrophobic signalling molecule
- steroid hormones
Provide 3 examples of hydrophilic signalling molecules
- peptide hormones
- neurotransmitters
3 cytokines
State why hydrophilic signalling molecules can diffuse through plasma membranes
Water soluble
State what the first step for all hydrophilic signalling molecules involves
Interaction of receptors on the external surface of the plasma membrane
State what receptors for the hydrophilic signalling molecules are classified as
Transmembrane proteins
State what the transmembrane proteins for hydrophilic signalling molecules are composed of
One or more protein molecules
State the 2 domains of transmembrane receptors
- extracellular domain
2. intracellular domain
State what the extracellular domain of transmembrane receptors is responsible for
Site of binding for the signalling molecule
State what the intracellular domain of transmembrane receptors is responsible for
Transfer of the signalling molecule into the cell
State what occurs when the signalling molecule binds to the extracellular domain
The intracellular domain of the receptor changes shape
Describe an alternative term to describe the change of shape of the intracellular domain of the receptor
Conformational change
State what the conformational change of the transmembrane receptor results in
Activation of molecules inside the cell
State what the transmembrane receptor may initiate
A cellular response
State the 2 types of cellular responses which can be initiated through transduction by hydrophilic signalling molecules
- directly
2. indirectly
Describe the indirect initiation of a response by the receptor in the transduction of hydrophilic signalling molecules
Activation of other molecules such as second messages
Describe second messengers
Intermediate signalling molecules that relay signals
State the 2 types of substances that signal transduction of hydrophilic signalling molecules typically uses
- intermediate proteins
2. other small non-protein molecules
Describe the function of intermediate and small non-protein molecules in signal transduction
Relaying of the signal to its final destination
Provide an alternative term to describe the small non-protein molecules involved in the transduction of hydrophilic signalling molecule
Second messengers
State what the characteristics of the size and solubility of second messengers enable them to do
Diffuse quickly through the cytosol
State what second messengers are responsible for
Triggering and amplifying a response from multiple parts of the cell at once
Describe transduction cascades
Series of events in which a change in one molecule causes a change in another
State what the result of a molecule that is activated by the conformational change of a receptor after binding to a hydrophobic signalling molecule
Trigger of a transduction cascade inside the cell
State what molecules are responsible for the initiation of a transduction cascade
Enzymes, channel protein or cell structure proteins
Different _______ for the same ________ exist in different cells, which may activate different _______________
Receptors, signalling molecule, transduction cascades
State whether or not a signalling molecule can only initiate a response in one cell type
No. Signalling molecules can initiate different responses in different cell types.
State whether or not proteins are specific to particular cells
Proteins are specific to particular cells
State what proteins will lead to in the cells in which they present
Particular response
State in what concentration signalling molecules are usually found
Low concentrations
State what the cascade in a transduction pathway allows for
Amplification of the original signal
State what the amplification of the original signalling molecule as a result of transduction cascades results in
Enough response molecules to have an effect on the cell
State what occurs at the end of a transduction pathway
Initiation of a response
State what alters the response at the end of a transduction pathway
Signalling molecules involved in the pathway
State what responses signalling molecules are involved in initiating within the nucleus
Gene regulation
Describe gene regulation as a response initiated by signalling molecules. State what control is handed to signalling molecules.
Signalling molecules can form a complex (by bonding to their receptor) and so can act as a transcription factor
State in what part of a cell signalling molecules initiate gene regulation as a response
Nucleus
State what responses signalling molecules are involved in initiating within the cytosol
Inhibition/activation of enzymes
Describe inhibition/activation of enzymes as a response initiated by signalling molecules. State what control is handed to signalling molecules.
Enzymes regulate cellular process by catalysing chemical reaction, so by inhibiting/activating this function, effected cellular functions can be controlled
State in what part of a cell signalling molecules initiate inhibition/activation of enzymes as a response
Cytosol
State what responses signalling molecules are involved in initiating on the plasma membrane
Changes in the structure of the plasma membrane
Describe changing the plasma membrane structure as a response initiated by signalling molecules. State what control is handed to signalling molecules.
Some cellular responses involve changes to the plasma membrane that allow certain substances to enter or exit the cell, so changing/not changing structure allows molecules to determine which substances can cross the membrane.
State in what part of a cell signalling molecules are involved in the alteration of plasma membrane structure
Plasma membrane
Describe receptor antagonist in cellular communication
Receptor ligand that blocks a biological response by binding to a receptor
Describe ion channel
Transmembrane protein that allows specific ions to cross the plasma membrane
State what control signalling molecules have over ion channels
Can be opened or closed in response to these molecules
State what types of signalling transduction of a signal carried by the nervous system involves
Electrical/chemical signalling
State the process by which neurotransmitters are released from ion channels
Exocytosis
State what occurs when a neuron is stimulated
Gated sodium and potassium ion channels on its’ membrane are oened
State what the sudden movement of ions into and out of a neuron initiates
Action potential
State what length an action potential travels in a neuron
Axon
Describe action potential
Reversal of the normal potential difference across a cell membrane
State where vesicles containing neurotransmitters are located
Synaptic terminals of the neuron
Provide 2 examples of possible postsynaptic cells
- muscle/gland cell
2. neuron
State what neurotransmitters released form the synaptic terminal will diffuse across
Synaptic gap
State where neurotransmitters will bind to on the postsynaptic cell
Specific receptors
State what occurs when the action potential of a neuron reaches the synaptic terminals of the axon
Ca+2 ion enters the cell
State what the increased concentration of Ca+2 ions in the neuron as a result of the action potential reaching the synaptic terminals of the axon results in
Vesicles will fuse with the nearby membrane to release the neurotransmitters into the synaptic gap
State what the increased concentration of Ca+2 ions in the neuron as a result of the action potential reaching the synaptic terminals of the axon results in
Vesicles will fuse with the nearby membrane to release the neurotransmitters into the synaptic gap
Describe nerve impulse
Wave of electrical change that passes rapidly along an axon membrane
Describe amplification
Process of increasing the strength of a cellular signal
Provide another term for a nerve impulse
Action potential
Describe ligand
Any substance that binds specifically and reversibly to another entity to form a complex
Provide an example of a ligand
Glucagon
State whether or not sex hormones are lipid based
Yes.
State what characteristics allows sex hormones to cross the plasma membrane easily
Share similar structure to cholesterol and can cross the plasma membrane easily to bind to an intracellular receptor
