AP Biology Unit 4 (Topics 4.1, 4.3, 4.4, 4.5, 4.6, and 4.7)

What are local regulators?

• Molecules that act over long distances to influence distant cells.

• Molecules that act over short distances to influence nearby cells, such as neurotransmitters and growth factors.

• Molecules that inhibit the growth of nearby cells.

• Molecules that only function in the bloodstream.

What is paracrine signaling?

• A form of cell signaling where a cell communicates with nearby cells through the release of signaling molecules.

• A type of signaling where cells communicate over long distances using hormones.

• A process where cells directly connect to each other through gap junctions.

• A mechanism of communication that involves the release of neurotransmitters into the bloodstream.

What is signal transduction?

• The process by which a cell responds to external signals through a series of molecular events, leading to a cellular response.

• A method of communication between cells that involves direct contact.

• The mechanism by which cells divide and replicate their DNA.

• A type of signal that is transmitted through electrical impulses in neurons.

What is the role of enzymes in signal transduction?

• Enzymes can modify proteins through phosphorylation or dephosphorylation, altering their activity and function.

• Enzymes serve as receptors that directly bind to signaling molecules.

• Enzymes are responsible for the synthesis of signaling molecules only.

• Enzymes act as transporters to move signals across cell membranes.

What is positive feedback in biological systems?

• A process that enhances or amplifies changes; it pushes a system away from its starting state.

• A mechanism that reduces the output of a system to maintain stability.

• A process that maintains equilibrium within a biological system.

• A method of cellular communication that inhibits further responses.

What role do receptors play in signal transduction?

• Receptors are enzymes that break down signaling molecules.

• Receptors are proteins that bind to signaling molecules (ligands) and initiate the signal transduction pathway.

• Receptors are lipids that store energy for signal transduction.

• Receptors are carbohydrates that provide structural support in cells.

What is a phosphorylation cascade?

• A process where a single protein is modified by adding a phosphate group.

• A series of events where one protein kinase activates another, leading to a rapid amplification of the signal.

• A mechanism that inhibits protein synthesis in cells.

• A method of DNA replication that involves multiple enzymes.

What is negative feedback in biological systems?

• A process that enhances changes, leading to instability in the system.

• A process that counteracts changes, helping to maintain homeostasis by reducing the output or activity of a system.

• A mechanism that only occurs in response to external stimuli.

• A method of increasing the output of a system to achieve a desired effect.

How do cells communicate through direct contact?

• Through gap junctions or cell surface molecules that interact with each other.

• By releasing hormones into the bloodstream.

• Through the process of endocytosis.

• By using electrical signals transmitted through neurons.

What is the significance of mutations in signal transduction pathways?

• Mutations can enhance normal signaling processes, promoting cell growth.

• Mutations can disrupt normal signaling processes, potentially leading to diseases such as cancer.

• Mutations have no effect on signal transduction pathways.

• Mutations only affect the structural proteins involved in signaling.