AP Bio Unit 2 Flashcards

What is the function of ribosomes?

Protein synthesis; can be free (cytosolic proteins) or bound to rough ER (secreted or membrane proteins).

What is the function of the rough ER?

Modifies and packages proteins, studded with ribosomes.

What is the function of the smooth ER?

Synthesizes lipids, detoxifies drugs, stores calcium

What is the function of the Golgi apparatus?

Modifies, sorts, and ships proteins and lipids (cis → trans face).

What is the function of mitochondria?

Cellular respiration, ATP production, contains its own DNA and ribosomes.

What is the function of chloroplasts?

Photosynthesis; contains thylakoids, grana, and stroma.

What is the function of lysosomes?

Digests macromolecules, recycles cellular components via hydrolytic enzymes.

What is the function of peroxisomes?

Breaks down fatty acids, detoxifies, produces hydrogen peroxide (H₂O₂).

What is the function of the cytoskeleton?

Provides structural support, transport (microtubules, microfilaments, intermediate filaments).

How do organelles work together for protein trafficking?

DNA → mRNA (nucleus) → ribosome (rough ER) → Golgi (modifies) → vesicle → plasma membrane (exocytosis).

What is the structure of a phospholipid?

Hydrophilic phosphate head + hydrophobic fatty acid tails; amphipathic.

What is the fluid mosaic model?

Membrane = mosaic of proteins in a fluid phospholipid bilayer.

What is the role of cholesterol in membranes?

Maintains fluidity at different temperatures.

What is facilitated diffusion?

Passive transport via protein channels or carriers, no ATP needed.

What is active transport?

Movement of molecules against concentration gradient, requires ATP.

What is endocytosis?

Bulk transport of materials INTO cell (e.g., phagocytosis, pinocytosis).

What is exocytosis?

Vesicle fusion with membrane to RELEASE substances out of cell.

What creates a concentration gradient across a membrane?

Uneven distribution of solutes; can be maintained by pumps or channels.

Define water potential (Ψ).

Ψ = pressure potential + solute potential; determines direction of water movement.

What happens to a cell in a hypotonic solution?

Water enters → animal cell lyses, plant cell turgid.

What happens to a cell in a hypertonic solution?

Water leaves → animal cell shrivels, plant cell plasmolyzes.

What happens in an isotonic solution?

No net water movement; animal cells normal, plant cells flaccid.

What is osmolarity regulation (osmoregulation)?

Process of controlling solute concentrations and water balance (e.g., contractile vacuole in paramecium).

What is surface area-to-volume ratio and why is it important?

Smaller cells have larger SA:V ratio → more efficient exchange of materials.

What is compartmentalization?

Use of organelles to isolate processes, increasing efficiency.

Difference between prokaryotes and eukaryotes?

Prokaryotes = no membrane-bound organelles, circular DNA, smaller; Eukaryotes = nucleus + organelles.

What is the endosymbiont theory?

Mitochondria and chloroplasts originated as free-living bacteria engulfed by larger cells.

What evidence supports endosymbiont theory?

Double membranes, own DNA, ribosomes, replicate independently, size similar to bacteria.