Cell Structure and Function AP Biology Exam Review

Flashcards to review cell structure and function, including prokaryotes, eukaryotes, subcellular components, and transport.

Compare prokaryotes and eukaryotes.

Prokaryotes are smaller, simpler cells without a nucleus or other membrane-bound organelles. Eukaryotes are larger, more complex cells with a nucleus and membrane-bound organelles.

Why do scientists think that eukaryotes evolved from prokaryotes (endosymbiosis theory)? Provide at least two pieces of evidence.

The endosymbiosis theory suggests that mitochondria and chloroplasts were once independent prokaryotic organisms that were engulfed by ancestral eukaryotic cells. Evidence includes their independent replication, double lipid bilayer, prokaryotic-like ribosomes, and their own DNA.

Ribosome (also found in prokaryotes)

rRNA + protein; Translate mRNA into proteins

Endoplasmic Reticulum

Folded lipid membrane;Rough ER: ribosomes on surface; package proteins for secretion, send transport vesicles to Golgi, make replacement membrane. Smooth ER: no ribosomes on surface, synthesize lipids, metabolize carbs, detox drugs & poisons, store Ca2+

Golgi Apparatus

Lipid membrane sacs; synthesis & packaging of materials (small molecules) for transport (in vesicles); produce lysosomes

Mitochondrion

Double membrane; Cell Respiration: Pyruvate Oxidation, Krebs Cycle and Electron Transport Chain of cellular respiration

Lysosome

Contains hydrolytic enzymes; intracellular digestion; recycle cell’s materials; programmed cell death (apoptosis

Vacuole

Membrane-bound vesicles; storage of materials (food, water, minerals, pigments, poisons); Plants: large central vacuole -- stores water, ions; retains water for turgor pressure

Chloroplast

Contains chlorophylls (pigments) for capturing sunlight energy; Photosynthesis

Nucleus

Contains DNA (& mRNA); control center of cell

Why is it important that cells exchange materials with their environment? Give two examples.

To bring in nutrients and remove waste.

Why are cells small?

Cells must be small to maintain a large surface area to volume ratio. Large S.A. allows increased rates of chemical exchange between cell and environment

Bigger cells have higher or lower SA/V ratios. Explain.

Lower. Bigger cells have a smaller surface area to volume ratio. Therefore, they are less efficient in exchanging materials.

Identify the areas that are hydrophobic and hydrophilic in a phospholipid bilayer.

Hydrophilic heads and hydrophobic tails.

What is the purpose of cholesterol in the cell membrane?

Helps maintain fluidity/flexibility of membrane.

Why do we have embedded proteins in the cell membrane?

Transport

Why is a cell membrane considered selectively permeable? What items can move across the membrane with ease?

a cell membrane is selectively permeable because only certain materials are able to enter and exit. Non polar molecules are able to pass with ease.

What is a cell wall made of in these organisms: Bacteria, Archaea, Plants, Fungi

Bacteria: Peptidoglycan, Archaea: Other carbohydrates, Plants: Cellulose, Fungi: Fungi

What is passive transport? How do the molecules move across the membrane with passive transport?

Passive transport is the movement of materials across the membrane without the cell using energy. Energy comes from the concentration gradient; materials move from an area of high concentration to an area of low concentration. Facilitated diffusion – ions and polar molecules require a protein channel as they will not be able to pass through they hydrophobic tails of the membrane.

What is active transport? How do the molecules move across the membrane with active transport?

Energy is required; molecules move AGAINST their concentration gradient.

Compare endocytosis to exocytosis.

Endocytosis – bulk movement of materials INTO the cell; exocytosis – bulk movement of materials out of the cell.

How does the sodium potassium pump work?

Pump Na+ out, K+ into cell – used in Nerve transmission

What is an aquaporin’s purpose?

Protein channel for the facilitated diffusion of water (osmosis)

What is osmosis? How does it work?

Osmosis is the diffusion of water across a selectively permeable membrane (water moves with its concentration gradient).

What is water potential? How is it calculated?

Water potential is the potential energy of water. Water potential = solute potential + pressure potential.

How does cell compartmentalization help a cell? Explain.

Compartmentalization allows a cell to isolate processes and increase efficiency; this leads to a cells ability to specialize.