MCB181R

Mutation

a change in any of the nucleotides in our DNA

denaturation (PCR)

- 90 degrees celcius or above to break H bonds but not phosphodiester bonds

To have communication between cells, you must have a: - signaling molecule - all of these choices are correct - receptor - responding cell

- all of these choices are correct

Applications of PCR

- cloning - the mutagenesis in research labs -medical diagnostic and forensics

A protein on a cell surface that binds to a signaling molecule is an example of which element of cellular communication? - a responding cell - a signaling cell - a signaling molecule - None of the other answer options is correct - a receptor protein

A receptor protein

When a ligand binds to a G protein-coupled receptor, which of the answer choices would you expect to happen before any of the others? - None of the other answer options are correct. - Adenylyl cyclase activity increases. - Upon a G protein-coupled receptor binding a ligand, G protein α subunit binds GTP, which activates adenylyl cyclase, which then produces cAMP that binds to protein kinase A, which in turn phosphorylates other proteins. The signal response is terminated by GTPase activity, phosphodiesterase activity, which breaks down cAMP, and phosphatase activity. - Protein kinase activity increases. - Phosphodiesterase activity to break down cAMP increases. - The amount of cAMP in the cytoplasm increases.

Adenylyl cyclase activity increases.

Which of the events are listed in the correct order of G protein-coupled signaling? - Protein kinase A (PKA) phosphorylates adenylyl cyclase, which then synthesizes cAMP from ATP. - Adenylyl cyclase catalyzes the formation of cAMP, which activates protein kinase A (PKA). - cAMP activates adenylyl cyclase, which activates protein kinase A (PKA).

Adenylyl cyclase catalyzes the formation of cAMP, which activates protein kinase A (PKA).

Ligand binding to a receptor kinase results in - binding of cytoplasmic signaling molecules - phosphorylation of the cytoplasmic domain of the receptor - All of these choices are correct - receptor dimerization.

All are correct

Which of the answer choices is part of the general response of cells during cellular communication? - An activated cell-surface receptor transfers the signal to the interior of the cell - Receptors on the outside of the cell bind to specific signal molecules - All of these choices are correct - A cell-surface receptor molecule becomes activated by binding to a molecular signal - The signal is transmitted inside the cell and amplified as a series of proteins are activated in sequence, affecting cellular activities according to the type of signal involved.

All of these are correct

The extent and duration of a cellular response to a signal depend on the: - All of these choices are correct. - level of expression of the genes encoding the signal transduction proteins. - level of expression of the genes encoding the proteins that terminate the response. - binding affinity of the receptor to the signaling molecule. - concentration of the signaling molecule in the vicinity of the receptor.

All of these choices are correct.

What happens to the α (alpha) subunit of a G protein when bound GTP is replaced with GDP? - It re-associates with the G protein-coupled receptor. - It reassembles with the β (beta) and γ (gamma) subunits. - It no longer activates an effector protein. - All of these choices are correct. - When GTP bound to G proteins is hydrolyzed to GDP, the G protein loses its ability to activate its target and returns to binding with the other G proteins and the receptor.

All of these choices are correct.

Which of the answer choices is a cellular response to signal transduction? - All of these choices are correct. - Signal transduction can produce many changes in the cell, ranging from changes in gene expression to the release of signals to communicate with other cells. - the release of signaling molecules from the cella change in the proteins found in the cytosol - a change in the activity of an enzyme

All of these choices are correct.

In cell communication, which one of the answer choices is a requirement of the responding cell? - It must express receptor proteins. - For cells to respond to a signal, there must be some kind of receptor that binds to the signal to activate a response. - It must be a eukaryotic cell. - It must produce signaling molecules. - It must be a prokaryotic cell.

It must express receptor proteins.

polymerase chain reaction (PCR)

Makes millions of copies of both strands of a target double stranded DNA sequence

Why are some mutations of Ras associated with cancer? - Ras alters ion flow across the cell membrane. - Ras binds to growth factor receptors. - Ras is a type of second messenger. - Ras activates the MAP kinase signal transduction pathway that regulates cell division. - Ras mutations associated with cancer block the GTPase activity and prevent Ras from hydrolyzing GTP to GDP and turning off. Thus, mutant Ras is constantly "on" and activates the MAP kinase pathway, resulting in increased rates of cell division.

Ras activates the MAP kinase signal transduction pathway that regulates cell division.

Why don't steroid hormones bind to transmembrane cell-surface receptors? - Steroid hormones are nonpolar and therefore cannot bind to receptors. - Steroid hormones are not signaling molecules. - Steroid hormones are nonpolar and therefore are able to cross the cell's plasma membrane, binding to receptors inside the cell. - Steroid hormones are nonpolar and can pass through the cell membrane. - They do bind to receptors in the cytoplasm or in the nucleus. - Steroid hormones don't require receptors because they bind directly to DNA.

Steroid hormones are nonpolar and can pass through the cell membrane.

Why do the functions of many receptor kinases depend on the fluid nature of the plasma membrane? - Binding of ligand to the receptor requires a fluid membrane. - The generation of cAMP requires a fluid membrane. - Phosphorylation requires a fluid membrane. - The receptor monomers must move together and dimerize to be activated. - For protein kinase receptor monomers to dimerize upon ligand binding, they must be able to move laterally in the plasma membrane.

The receptor monomers must move together and dimerize to be activated.

What is the very first effect of ligand binding to a G protein-coupled receptor? - an exchange of GTP in place of GDP on the α (alpha) subunit of the G protein - the release of the α (alpha) subunit of the G protein - a conformational change in the cytoplasmic domain of the receptor - When ligands bind to G protein-coupled receptors, they cause a change in the shape of the cytoplasmic domain and release of the G proteins, which then become activated by exchange of GDP for GTP in G protein α (alpha) subunit. - the activation of an effector protein

a conformational change in the cytoplasmic domain of the receptor

A cell that responds to an environmental condition by the release of a chemical is an example of which element of cellular communication? - a receptor protein - a responding cell - None of the other answer options is correct. - a signaling cell - a signaling molecule

a signaling cell

Annealing (PCR)

cooling down to 55-60 degrees celcius for 1 min - use DNA primers - bond complementary and antiparallel - Primers are essential as they provide a free 3'OH to begin DNA synthesis BUT are NOT removed at the end of PCR like they are in a cell

Ras is a type of G protein because it: - triggers the formation of cyclic AMP (cAMP). - is only active when it binds GTP. - All of these choices are correct. - responds to the activation of G protein-coupled receptors.

is only active when it binds GTP.

In many signaling pathways, once a signaling molecule binds to a receptor, the receptor becomes phosphorylated. This initial phosphorylation step best demonstrates: - either cellular response or signal transduction. - cellular response. - signal transduction. - termination. - receptor activation. - When receptors bind to their signaling molecules, receptor activation results from a change in shape of the receptor that activates enzyme activity of the receptor or allows binding of other proteins to the receptor.

receptor activation.

GTP binding occurs on which subunit of a G protein? - the γ (gamma) subunit - the α (alpha) subunit - the β (beta) subunit - GTP binds both β (beta) and γ (gamma) subunits.

the α (alpha) subunit

What is the function of adenylyl cyclase? - to form protein kinase A (PKA) - to convert ATP into cyclic AMP (cAMP) - to phosphorylate protein kinase A (PKA) - to phosphorylate cyclic AMP (cAMP)

to convert ATP into cyclic AMP (cAMP)