Title: Cell Communication
Course: Question Banks

Q: In ________ signaling, a cell targets itself.
- endocrine (Incorrect. Endocrine signaling occurs when a cell targets a distant cell using the bloodstream)
- paracrine (Incorrect. Paracrine signaling involves signaling to a nearby cell.)
- autocrine (Correct. This one should be easy to remember because of ‘auto’!)
A: autocrine

Q: A synaptic signal is the ________ that travels between nerve cells.
- electrical signal (Incorrect. The nerve impulse is the electrical signal.)
- microtubule path (Incorrect. There are no microtubule paths between signaling nerve cells.)
- chemical trigger (Correct. A synaptic signal is a chemical message between nerve cells.)
A: chemical trigger

Q: ________ are small molecules that diffuse between cells directly connected by gap junctions.
- Nerve impulses (Incorrect. A nerve impulse is actually an electrical signal.)
- Synaptic signals (Incorrect. A synaptic signal is a chemical message between nerve cells.)
- Intracellular mediators (Correct. These small molecules pass easily using the physical connections between adjacent cells’ plasma membranes.)
A: Intracellular mediators

Q: ________ are one type of small hydrophobic ligands used in cellular signaling.
- Peptides (Incorrect. Peptides are usually water-soluble ligands.)
- Large ions (Incorrect. Because they are ions (have a charge), these molecules are usually hydrophilic.)
- Steroid hormones (Correct. Steroid hormones are small hydrophobic molecules that act as ligands.)
A: Steroid hormones

Q: Peptides are one type of ________ used in cellular signaling.
- small hydrophobic ligands (Incorrect. Peptides are not hydrophobic ligands.)
- hydrophilic ions (Incorrect. Peptides are hydrophilic but they are not ions.)
- water-soluble ligands (Correct. Peptides are usually water-soluble ligands.)
A: water-soluble ligands

Q: ________ is a gas that serves as a ligand that acts to dilate blood vessels.
- Nitroglycerin (Incorrect. Nitroglycerin triggers the ligand but is not itself a ligand.)
- Carbon monoxide (Incorrect. Carbon monoxide is not a ligand but is in fact a potentially deadly gas.)
- Nitric oxide (Correct. NO is a small gas ligand that triggers dilation of blood vessels.)
A: Nitric oxide

Q: Cells use protein molecules called receptors to receive signals, and the two types of receptors are ________ and cell-surface receptors.
- gap junction (Incorrect. There are no ‘gap junction’ receptors.)
- external (Incorrect. This is not the term used for the other type of signal receptor.)
- internal (Correct. Internal receptors are the other type of receptors.)
A: internal

Q: ________ receptors respond to hydrophobic molecules that easily cross the plasma membrane.
- Gap junction (Incorrect. This is not the receptor type that binds to hydrophobic molecules.)
- Cell-surface (Incorrect. Cell-surface receptors do not bind hydrophobic molecules that easily cross the plasma membrane.)
- Internal (Correct. Internal receptors bind to hydrophobic ligands.)
A: Internal

Q: Many ________ are able to disrupt G-protein-linked receptors.
- viruses (Incorrect. Viruses are not particularly known for disrupting G-protein-linked receptors.)
- fungi (Incorrect. Fungi are not particularly known for disrupting G-protein-linked receptors.)
- infectious bacteria (Correct. Many infectious bacteria target G-protein-linked receptors.)
A: infectious bacteria

Q: After a ligand binds to a cell-surface receptor, a series of ________ steps occurs that integrates the events eventually leading to a change in the cellular environment.
- signaling stream (Incorrect. This is not what the process is called to integrate cellular changes in response to a ligand.)
- enzymatic cascade (Incorrect. Enzymatic cascades may amplify the process but this is not the process name itself.)
- signaling cascade (Correct. A signaling cascade is the chain of events that ultimately triggers a change in the cell’s environment.)
A: signaling cascade

Q: Multiple receptors may merge activity to trigger ________ during signal integration.
- a larger response (Incorrect. Multiple receptors do not need to merge activity to trigger a larger response.)
- a smaller response (Incorrect. Multiple receptors do not need to merge activity to trigger a smaller response.)
- the same response (Correct. Signal integration allows a cell to receive multiple signals before a response is generated.)
A: the same response

Q: The variation in responses from different cells to the same ligand is due to differences in ________.
- receptor types (Incorrect. The same receptor will often bind to the same ligand regardless of cell type.)
- signal amplification (Incorrect. While some signals are amplified by enzymatic cascades, this is not the basis of variation in how different cells respond to a signaling ligand.)
- protein expression (Correct. Cell type-specific responses are triggered by differences in protein expression in different cells.)
A: protein expression

Q: Choose the best definition of signal transduction.
- When a cell both secretes and responds to a signal (Incorrect. This is not signal transduction.)
- The chemical communication that takes place within a cell (Incorrect. This is not signal transduction.)
- The process used by a cell to convert a ligand bound to a receptor into some sort of change in the cell. (Correct. This defines ‘signal transduction’.)
A: The process used by a cell to convert a ligand bound to a receptor into some sort of change in the cell.

Q: The phosphorylation of a target is used to ________ a signal within a cell.
- respond to (Incorrect. Phosphorylation of a target is not generally the first response to a signal.)
- initiate (Incorrect. Phosphorylation is not generally used to initiate a signal within a cell.)
- propagate (Correct. Phosphorylation is often used to propagate a signal within a cell.)
A: propagate

Q: A ________ catalyzes addition of phosphate groups during signal transduction.
- phosphatases (Incorrect. This is not the enzyme type that adds phosphate groups.)
- phosphorylators (Incorrect. This is not the enzyme type that adds phosphate groups.)
- kinase (Correct. A kinase is the name of the enzyme that adds phosphate groups.)
A: kinase

Q: Phosphorylation of serine is often used to ________.
- create a binding site (Incorrect. Phosphorylation of serine does not create binding sites.)
- inhibit enzymes (Incorrect. Phosphorylation of serine does not generally inhibit enzymes.)
- activate enzymes (Correct. Phosphorylation of serine and threonine is often used to activate enzymes in signal transduction pathways)
A: activate enzymes

Q: Choose a common response used to propagate a signal within a cell.
- Enzyme cleavage (Incorrect. Enzyme cleavage is not a common response used to propagate a signal within a cell.)
- Dephosphorylation of a target (Incorrect. Dephosphorylation is not used to propagate a signal within a cell.)
- Triggering of a second messenger (Correct. Second messengers are a common response used to propagate a signal within a cell.)
A: Triggering of a second messenger

Q: Calcium ions are a widely used ________ in signal transduction.
- phosphate group (Incorrect. Calcium ions are not phosphate groups.)
- cell signaling cascade (Incorrect. Calcium ions are not a signaling cascade themselves.)
- second messenger (Correct. Calcium ions are widely used as second messengers in signal transduction.)
A: second messenger

Q: ________ is used to activate an enzyme that in turn regulates many metabolic pathways.
- Inositol phospholipid (Incorrect. Inositol phospholipid is a common second messenger but it does not work in signal transduction of metabolic pathways.)
- Calcium ion (Incorrect. Calcium ions are used as second messengers but do not work only on metabolic pathways.)
- cAMP (Correct. cAMP is used to activate cAMP-dependent kinase, which in turn phosphorylates serine and threonine residues on targets to activate them.)
A: cAMP

Q: cAMP is used to activate an enzyme that in turn ________.
- initiates cell signalling (Incorrect. cAMP is not used to initiate cell signaling.)
- activates protein kinase C (PKC) (Incorrect. cAMP activates cAMP-dependent kinase.)
- regulates many metabolic pathways (Correct. cAMP is used to activate cAMP-dependent kinase, which in turn phosphorylates serine and threonine residues on targets to activate them.)
A: regulates many metabolic pathways

Q: The activation of β-adrenergic receptors in muscle cells by adrenaline is an example of ________ as a cellular response to a signal.
- gene expression regulation (Incorrect. Activation of β-adrenergic receptors by adrenaline is not a gene expression regulation response.)
- cell growth (Incorrect. Activation of β-adrenergic receptors by adrenaline is not a cell growth response.)
- an increase in metabolism (Correct. Activation of β-adrenergic receptors by adrenaline is a cellular response that increases metabolism.)
A: an increase in metabolism

Q: ________ is triggered by growth factor ligands that usually bind to cell-surface receptors.
- Epidermal growth factor (EGF) (Incorrect. EGF is a growth factor ligand.)
- Adrenaline (Incorrect. Adrenaline triggers cell response that increases metabolism.)
- Cell division (Correct. Cell division will be triggered by growth factor ligands binding to cell-surface receptors.)
A: Cell division

Q: Signal transduction pathways that influence gene expression do so by ________.
- Influencing DNA copy number (Incorrect. Gene expression is not regulated through DNA copy numbers.)
- degrading proteins (Incorrect. Regulating translation of proteins will regulate gene expression, but not degrading proteins already translated.)
- regulating RNA transcription (Correct. Gene expression can be controlled by regulating transcription of RNA.)
A: regulating RNA transcription

Q: Cells may ________ signals by degrading the signaling molecule.
- initiate (Incorrect. Cells do not initiate signals by degrading the signaling molecule.)
- propagate (Incorrect. Cells do not propagate signals by degrading the signaling molecule.)
- terminate (Correct. Cells terminate signals by degrading the ligand.)
A: terminate

Q: T-cells that incorrectly respond to “self proteins” are targeted for ________ to prevent damage to the organism.
- reprogramming (Incorrect. T-cells are not reprogrammed when they incorrectly target self.)
- necrosis (Incorrect. Necrosis is not the response used to prevent T-cells from damaging the organism.)
- apoptosis (Correct. Programmed cell death can be used to destroy cells that will potentially damage the organism, as would immune cells that target ‘self’.)
A: apoptosis

Q: A signaling cascade between a cell and the extracellular matrix prevents cells from ________.
- being targeted for destruction by the immune system (Incorrect. Cascades between cells and the extracellular matrix is not what prevents destruction by the immune system.)
- degrading ligands (Incorrect. Cascades between cells and the extracellular matrix is not what prevents ligands from being degraded when needed.)
- traveling through the body and growing uncontrollably (Correct. A signaling cascade prevents uncontrolled growth in cells that leave their natural location.)
A: traveling through the body and growing uncontrollably

Q: ________ secrete mating factors in preparation for sharing genetic material with another of their species.
- Fungi (Incorrect. Fungi do not secrete mating factors in preparation for sexual reproduction.)
- Bacteria (Incorrect. Bacteria secrete conjugation factors in order to share genetic material.)
- Yeasts (Correct. Mating factors serve as signal molecules between haploid yeast cells in preparation of yeast mating.)
A: Yeasts

Q: When yeasts prepare to mate, a signaling cascade initiates which includes ________.
- G-proteins (Incorrect. G-proteins are used by animal cells, not fungal cells.)
- mating factors (Incorrect. Mating factors trigger the signaling cascade but are not part of it themselves.)
- GTP-binding proteins (Correct. GTP-binding proteins are similar to G-proteins and function in yeast mating cascades.)
A: GTP-binding proteins

Q: Yeast cells appear to have no ________.
- GTP-binding proteins (Incorrect. GTP-binding proteins was used to initiate yeast mating cascades.)
- phosphatases (Incorrect. Yeast do have phosphatases.)
- tyrosine kinases (Correct. Yeast cells appear to have no tyrosine kinases; these is thought to control more sophisticated functions found in multicelled eukaryotes.)
A: tyrosine kinases

Q: Bacterial signaling is termed ________ because it appears based on cell density in the environment.
- pack behavior (Incorrect. Pack behavior is the complex interactions of higher eukaryotes that live in large groups.)
- crowdsourcing (Incorrect. Crowdsourcing is not a term used in biology.)
- quorum sensing (Correct. The term relates to the ‘quorum’ required in politics to vote on an issue.)
A: quorum sensing

Q: Autoinducers in bacteria are functionally similar to ________ in eukaryotic cells.
- paracrine signals (Incorrect. Paracrine signals are between nearby cells, so this seems logical but it not functionally similar to what occurs in bacteria.)
- endocrine signals (Incorrect. Endocrine signaling occurs within the body of a single organism, so it is not functionally similar to what occurs in bacteria.)
- autocrine signals (Correct. Autoinducers are used in quorum signaling and are functionally similar to autocrine signals in eukaryotes because they are signals between the same type of bacteria.)
A: autocrine signals

Q: Bacterial biofilms help bacteria ________.
- scavenge for food effectively (Incorrect. This is not why bacteria form biofilms.)
- evade predators (Incorrect. This is not why bacteria form biofilms.)
- minimize the effects of antibiotics (Correct. The density of some biofilms help protect the bacteria from antibiotics meant to kill them.)
A: minimize the effects of antibiotics