AP Bio Flashcards Unit 2

Q: What is the structure and function of ribosomes?

Structure: Made of rRNA and proteins.

Function: Synthesize proteins according to the mRNA sequence

Q: What are the features and functions of the rough ER?

Structure: Membrane-bound with ribosomes.

Function: Compartmentalizes cell, synthesizes and transports proteins, provides mechanical support.

Q: What are the features and functions of the smooth ER?

Structure: Membrane-bound, no ribosomes. 

Function: Lipid synthesis, detoxification, carbohydrate metabolism, calcium ion storage.

Q: What does the Golgi complex do?

Correct folding, chemical modification, and packaging of proteins for trafficking.

Q: What is the structure and function of mitochondria?

Structure: Double membrane; inner folded (cristae). 

Function: Cellular respiration—ATP production.

Q: What are vacuoles used for?

Storage and regulation.

Plant cells: Water storage, turgor pressure.

Animal cells: Pump out water (contractile), store food, waste removal.

Q: What is the function of vesicles?

Transport materials within or out of the cell.

Q: What is the structure and function of chloroplasts?

Structure: Three membranes with thylakoids and stroma.

Function: Photosynthesis—light reactions (thylakoid/grana), Calvin cycle (stroma).

Q: What do lysosomes do?

Contain hydrolytic enzymes for digestion, recycling, and apoptosis (programmed cell death).

Q: What does the nucleus do?

Contains DNA, controls cell activity, and transcripts DNA into RNA that guides protein synthesis. Enclosed by double membrane (nuclear envelope).

Q: What is the nucleolus?

A: Site of rRNA synthesis and ribosome assembly.

Q: What are peroxisomes?

Structure: Specialized metabolic compartment bounded by a single membrane. Contains hydrogen peroxide.

Function: Break down fatty acids, amino acids, and alcohol; produce hydrogen peroxide.

Q: What are the parts and roles of the cytoskeleton?

Microtubules – shape, organelle movement, chromosome separation.

Microfilaments – cell movement (pseudopodia).

Intermediate filaments – structure and anchoring organelles.

Q: What are centrioles?

Microtubule structures in animal cells that organize spindle fibers during cell division.

Q: What are cilia and flagella?

Cilia: Short projections for movement or material transport.

Flagella: Long projections for cell propulsion.

Q: What does the plasma membrane do?

Selective barrier controlling movement of substances in/out of the cell.

Q: What is the cell wall’s function?

Provides structure and protection; made of cellulose (plants) or peptidoglycan (bacteria).

Q: What are phospholipids composed of?

Hydrophilic phosphate head and hydrophobic fatty acid tails.

Q: Describe the fluid mosaic model.

Membrane is a fluid phospholipid bilayer with embedded proteins, cholesterol, glycoproteins, and glycolipids.

Q: How does structure influence selective permeability?

Small nonpolar molecules (O₂, CO₂, N₂) pass freely; polar or charged molecules need transport proteins.

Q: What is passive transport?

Movement from high to low concentration without energy; imports materials and exports waste.

Q: What is active transport?

Movement from low to high concentration using ATP and transport proteins.

Q: What is exocytosis?

Vesicles fuse with plasma membrane to secrete materials out of the cell.

Q: What is endocytosis?

A cellular process where the cell membrane engulfs external substances, forming a vesicle to bring them into the cell's interior.(Bulk Transport requires Energy)

Q: What do aquaporins do?

Facilitate water movement across membranes. (Facilitated diffusion)

Q: What does the Na⁺/K⁺ ATPase pump do?

Maintains membrane potential by pumping Na⁺ out and K⁺ in using ATP

Q: Define tonicity.

The ability of a solution to cause a cell to gain or lose water.

Q: What happens in a hypotonic solution?

Cell gains water and may burst (lysis).

Q: What happens in a hypertonic solution?

Cell loses water and shrivels.

Q: In which direction does water move?

From high water potential (low solute) to low water potential (high solute).

Q: Why do eukaryotic cells have compartmentalization?

To separate reactions, increase efficiency, and minimize interference between processes.

Q: What are examples of membrane-bound organelles?

Nucleus, ER, Golgi apparatus, mitochondria, chloroplasts.

Q: How do prokaryotic and eukaryotic cells differ in compartmentalization?

Prokaryotes lack membrane-bound organelles but have specialized regions; eukaryotes have internal membranes dividing functions.

Q: What is endosymbiotic theory?

Eukaryotic organelles (mitochondria & chloroplasts) evolved from free-living prokaryotes.

Q: What evidence supports endosymbiotic theory?

Double membranes

Own circular DNA

Divide by binary fission

Own ribosomes similar to bacteria

Similar transcription/translation to bacteria

How does SA:V ratio affect cells?

Smaller cells have higher SA:V ratio, making exchange of materials more efficient.

Q: What happens as cells get larger?

SA:V decreases, slowing exchange; cells may develop folds to increase surface area.

Q: Give examples of adaptations that improve exchange efficiency.

Microvilli in intestines, root hair cells in plants.

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?

Mitochondria have double membranes and Chloroplasts have triple membranes, both own DNA, ribosomes, and can replicate independently, and are similar in size to bacteria.