Biology Molecular & Cellular Biology Flashcards

Which of the following best describes the function of lysosomes?

Answer: Intracellular digestion of macromolecules using hydrolytic enzymes

Lysosomes contain acid hydrolases that digest worn-out organelles, phagocytized pathogens, and macromolecules in a process called autophagy or phagocytosis.

Which process allows cells to take in large particles by engulfing them with the plasma membrane?

Answer: Phagocytosis

Phagocytosis ('cell eating') involves the plasma membrane extending pseudopods to engulf large particles into a phagosome.

What is the function of telomeres in eukaryotic chromosomes?

Answer: They protect chromosome ends from degradation and prevent end-to-end fusion

Telomeres are repetitive non-coding sequences at chromosome ends that protect chromosomes from degradation and prevent inappropriate recombination.

In the lac operon of E. coli, the operon is induced (turned on) when:

Answer: Lactose is present and glucose is absent

When lactose is present and glucose is absent, allolactose (a lactose derivative) binds the repressor, freeing the operator and allowing transcription.

Which of the following describes a key difference between eukaryotic and prokaryotic cells?

Answer: Only eukaryotes have membrane-bound organelles

Eukaryotic cells contain membrane-bound organelles such as the nucleus, mitochondria, and ER, which are absent in prokaryotes.

What is the primary role of cholesterol in the plasma membrane?

Answer: It modulates membrane fluidity and stability

Cholesterol intercalates between phospholipids to moderate membrane fluidity—preventing it from becoming too rigid at low temperatures or too fluid at high temperatures.

Which event occurs during the G2 checkpoint of the cell cycle?

Answer: The cell verifies that DNA replication is complete and no damage remains before mitosis

The G2 checkpoint ensures that DNA has been replicated accurately and without damage before the cell commits to mitosis.