Biology Cell Structure & Function Flashcards
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Read the first 7 Biology Cell Structure & Function flashcards as text
Which of the following is a key structural difference between prokaryotic and eukaryotic cells?
Answer: Eukaryotes have membrane-bound organelles; prokaryotes lack them
Eukaryotic cells have a true nucleus and membrane-bound organelles (mitochondria, ER, Golgi), while prokaryotic cells have no membrane-bound compartments and a nucleoid region instead.
What is the role of cholesterol in the animal plasma membrane?
Answer: It stabilizes membrane fluidity across temperature changes
Cholesterol intercalates between phospholipids, preventing them from packing too tightly at low temperatures and from becoming too fluid at high temperatures, thus buffering membrane fluidity.
Which statement about plant cell walls is correct?
Answer: Primary walls contain cellulose microfibrils embedded in a polysaccharide matrix
Plant primary cell walls consist of cellulose microfibrils cross-linked by hemicellulose and pectin, providing structural support while allowing flexibility for growth.
A researcher observes that a cell has an unusually high number of mitochondria. This cell most likely:
Answer: Has very high energy demands, such as a cardiac muscle cell
Cells with high metabolic demands, like cardiac muscle cells, contain densely packed mitochondria to produce sufficient ATP for continuous contraction.
Tight junctions between epithelial cells serve mainly to:
Answer: Prevent leakage of substances through the paracellular space
Tight junctions (zonula occludens) seal the space between adjacent epithelial cells by fusing their membranes, forcing molecules to pass through cells rather than between them.
Which process allows a cell to break down its own damaged organelles by sequestering them in a double membrane and fusing with lysosomes?
Answer: Autophagy
Autophagy involves the formation of autophagosomes (double-membrane vesicles) that engulf damaged organelles or proteins, then fuse with lysosomes for enzymatic degradation.
The inner mitochondrial membrane is highly folded into cristae primarily to:
Answer: Increase surface area for ATP synthase and electron transport chain complexes
Cristae dramatically increase the inner membrane's surface area, accommodating more copies of the electron transport chain complexes and ATP synthase to maximize ATP production.