AP Biology Unit 2: Cell Structure and Function Review

VOCABULARY style flashcards covering cell organelles, membrane transport, and water potential formulas based on the AP Biology Unit 2 review notes.

Ribosomes

Non-membrane bound structures made of ribosomal RNA ($rRNA$) and proteins that are the site of protein synthesis in all life forms.

Rough Endoplasmic Reticulum

An organelle directly attached to the nucleus and studded with ribosomes; its job is to synthesize proteins that sit in the membrane or are secreted from the cell.

Smooth Endoplasmic Reticulum

The part of the endoplasic reticulum responsible for detoxification of the cell and lipid synthesis, including steroids.

Golgi Complex

A membrane-bound organelle that packages and modifies materials, correctly folds proteins, and handles trafficking molecules around the cell.

Mitochondria

The site of the Krebs cycle and oxidative phosphorylation in cellular respiration; it features a double membrane and highly folded inner membranes called cristae to synthesize $ATP$.

Lysosomes

Sacks containing hydrolytic enzymes used for intracellular digestion, breaking down macromolecules, or programmed cell death ($apoptosis$).

Vacuoles

Membrane-bound sacks used for various storage and regulation purposes, including food vacuoles, contractile vacuoles for water balance, and central vacuoles for plant turgor pressure.

Chloroplasts

Organelles found in plants and algae that perform photosynthesis; they contain thylakoid membranes where light reactions occur.

Endosymbiotic Theory

The theory that mitochondria and chloroplasts originated as prokaryotes, evidenced by their double membranes, circular DNA, and their own ribosomes.

Surface Area to Volume Ratio

A critical cell dimension where a large ratio (typical of smaller cells) allows for more efficient nutrient intake and waste elimination.

Phospholipid Bilayer

The primary structural component of the plasma membrane, consisting of hydrophilic phosphate heads facing outward and hydrophobic hydrocarbon tails facing inward.

Cholesterol

A steroid molecule embedded in the plasma membrane that acts as a temperature buffer to maintain membrane fluidity.

Glycoproteins and Glycolipids

Sugar molecules attached to proteins or lipids on the cell exterior that function in cell-to-cell communication and identification.

Simple Diffusion

A type of passive transport where small, non-polar molecules like $CO_2$, $O_2$, and $N_2$ move directly across the membrane down a concentration gradient without energy.

Facilitated Diffusion

Passive transport that uses specific channel or carrier proteins to move polar or charged materials, such as water through aquaporins or sodium ions through sodium channels.

Active Transport

The process of moving solutes against a concentration gradient (low to high concentration) requiring a transport protein and metabolic energy ($ATP$).

Sodium Potassium Pump

A specific active transport mechanism that pumps three sodium molecules ($Na^+$) out of the cell and two potassium molecules ($K^+$) into the cell.

Exocytosis

A form of bulk transport where internal vesicles fuse with the plasma membrane to release materials, such as insulin, out of the cell.

Tonicity

The ability of an extracellular solution to make water move into or out of a cell by osmosis; classified as hypotonic, hypertonic, or isotonic.

Hypertonic Solution

A solution with a high solute concentration and low free water, causing water to flow out of the cell into the surroundings.

Hypotonic Solution

A solution with a low solute concentration and high free water, causing water to rush into the cell, which may lead to osmotic lysis in animal cells.

Water Potential ($\Psi$)

A measure of the potential for water to move, calculated as the sum of pressure potential ($\Psi_P$) and solute potential ($\Psi_S$); water always moves from high to low potential.

Solute Potential Formula

Represented by $\Psi_S = -iCRT$, where $i$ is the ionization constant, $C$ is the molar concentration, $R$ is the pressure constant ($0.0831\,L\cdot bar\,mol^{-1}\cdot K^{-1}$), and $T$ is temperature in Kelvin.