Biology Cellular and Molecular Flashcards

What is the function of restriction enzymes in molecular biology?

Answer: They cut DNA at specific recognition sequences

Restriction enzymes (endonucleases) recognize and cleave specific short DNA sequences, producing fragments used in cloning and genetic analysis.

Which process allows cells to engulf large particles or other cells by forming membrane vesicles?

Answer: Phagocytosis

Phagocytosis is a form of endocytosis in which the cell membrane engulfs large particles like bacteria, forming a phagosome.

What is epigenetics?

Answer: Heritable changes in gene expression without altering the DNA sequence

Epigenetics refers to changes in gene expression caused by modifications like DNA methylation and histone acetylation that do not change the underlying DNA sequence.

In CRISPR-Cas9 gene editing, what is the role of the guide RNA (gRNA)?

Answer: It directs the Cas9 enzyme to a specific DNA sequence

The guide RNA is complementary to the target DNA sequence and directs the Cas9 nuclease to the correct location in the genome for cleavage.

What is the purpose of the ubiquitin-proteasome pathway?

Answer: Tagging and degrading damaged or misfolded proteins

Ubiquitin molecules are attached to proteins marked for destruction, directing them to the proteasome where they are degraded into peptides.

Which model best explains enzyme-substrate specificity based on conformational flexibility?

Answer: Induced fit model

The induced fit model proposes that the enzyme changes shape upon substrate binding to achieve optimal fit, unlike the rigid lock-and-key model.

What is the primary role of cyclin-CDK complexes in the cell cycle?

Answer: Regulating progression through cell cycle checkpoints

Cyclin-dependent kinase (CDK) complexes phosphorylate target proteins to drive the cell through key transitions such as G1/S and G2/M checkpoints.