Biology Cellular and Molecular Flashcards

What is the role of ATP synthase in cellular respiration?

Answer: Uses the proton gradient to synthesize ATP

ATP synthase harnesses the flow of protons down their electrochemical gradient across the inner mitochondrial membrane to drive ATP synthesis.

Which process describes the movement of water across a selectively permeable membrane from low to high solute concentration?

Answer: Osmosis

Osmosis is the passive movement of water molecules through a semipermeable membrane toward the region of higher solute concentration.

In the lac operon of E. coli, what happens when lactose is absent from the environment?

Answer: The repressor protein binds to the operator and blocks transcription

Without lactose, the repressor protein remains active and binds to the operator, preventing transcription of the lactose-metabolizing genes.

Which cytoskeletal element is primarily responsible for maintaining cell shape in animal cells?

Answer: Microfilaments (actin)

Actin microfilaments form a network beneath the plasma membrane that supports cell shape and enables cell movement.

What is a nucleosome?

Answer: DNA wrapped around a histone octamer

A nucleosome consists of approximately 147 base pairs of DNA wrapped around a core of eight histone proteins, forming the basic unit of chromatin.

Which stage of cellular respiration produces the most ATP per glucose molecule?

Answer: Oxidative phosphorylation

Oxidative phosphorylation (the electron transport chain coupled with chemiosmosis) produces approximately 32–34 of the 36–38 ATP generated per glucose.

What is the function of telomeres?

Answer: Protect chromosome ends from degradation and fusion

Telomeres are repetitive DNA sequences at chromosome ends that protect them from deterioration and prevent chromosomes from fusing with one another.