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AP Bio Final
| Question | Answer |
|---|---|
| What is a local regulator in terms of cell communication? | chemical signals that travel over short distance by diffusion |
| What are the three steps of a signal transduction pathway? | Reception, transduction, and response |
| What is a ligand? | a chemical messenger released by one cell to signal either itself or a different cell; highly specific to particular receptors |
| What are the two types of messengers (or receptors)? | Membrane receptors and cytosolic (intracellular) receptors |
| What are the special properties of each of the two types of messengers (or receptors)? | Membrane receptors are found on the surface of the cell (in the plasma membrane - have polar ligands) and intracellular receptors are found inside of the cell (in the cytoplasm or nucleus - have nonpolar ligands) |
| What is quorum sensing in bacteria? | the regulation of gene expression in response to fluctuations in cell-population density |
| Describe the process of a G protein-coupled receptor. | Ligand binds w/ GPCR (alters receptor's shape slightly) -> G Protein activated by GCPR & released (GDP -> GTP) -> G Protein dephosphorylates GTP -> GDP (inactivating itself) -> ligand concentration drops, ligand dissociates from receptor (deactivated) |
| How can a hormone act as a messenger? | It travels through the bloodstream to reach its target cells in another part of the body. A variety of cells in the body receive the signal but not all of them are compatible to act on it. |
| What is a neurotransmitter | A chemical messenger that sends signals between cells. They travel down neurons and across the synapse to send these signals to its receptors. |
| What are the possible cellular responses to a messenger? | A message can be received and you end up with a phosphorylation cascade (part of transduction before cellular response) and protein modification can occur (the change of a protein) |
| What is is a protein kinase? | It transfers phosphates from ATP to a protein (phosphorylates ). It is made up of subunits of protein (2 catalytic and 2 regulatory subunits); it is inactivated when these 2 subunits are attached and is also targeted by secondary messengers. |
| Describe a signal transduction pathway. | It is a way to send signals and get the desired reaction. It is a chemical message that is transduced into actions within a cell and can be amplified. They sometimes modify a protein or change the shape or conformation of it. |
| What is a secondary messenger? Give an example. | A secondary messenger is a small, nonprotein, water-soluble molecule/ion that is spread throughout the cell by diffusion. They participate in pathways initiated by GPCRs. Ex) cAMP |
| What is apoptosis? | It is the programmed cell death (occurs by extracellular death, DNA damage, protein misfolding in ER); components of cell packaged into vesicles -> digested by scavenger cells - prevents enzymes from leaking out of dying cell/damaging neighboring cells |
| Give an example of how signal transduction can alter a phenotype. | Y-chromosomal SRY gene activation - the signal that is received from the signal transduction pathway results in the response that determines whether you're biologically a male or female |
| Reception | Occurs when a signal molecule (ligand) binds to a receptor protein --> altering receptor's shape |
| Transduction | Conformational change in receptor (relay in cell by proteins) - Multistep pathways: amplify signal; provide more opportunities for coordinators & regulation of cellular response - signal transmitted by cascade of protein phosphorylations |
| Response | Cell signaling -> regulation of transcription/cytoplasmic in nature; cell's response can be fine-tuned by amplifying signal; specificity of response; overall efficiency of response (enhanced by scaffolding proteins); termination of signal |
| Nuclear responses | Regulate the synthesis of enzymes or other proteins, usually by turning genes on/off in the nucleus; the final activated molecule in the signaling pathway may function as a transcription factor |
| Cytoplasmic responses | Often regulate the activity of enzymes rather than their synthesis |
| Ligand-Gated Ion Channels | Acts as a gate when the receptor changes shape; when a signal molecule binds as a ligand to the receptor, the gate allows specific ions (Na+ or Ca2+) through a channel in the receptor |
Created by:
Sofia.D
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