Ap bio unit 2 concept check

Bigger cells

its surface area to volume ratio decreases, making nutrient exchange slower and less efficient.

Smaller cells

its surface area to volume ratio decreases, making nutrient exchange slower and less efficient.

Eukaryote

Usually have lower SA:V ratios but can efficiently perform complex processes.

Prokaryote

Usually have higher SA:V ratios, allowing fast, simple exchanges.

Compartmentalization

Occurs only in eukaryotes. Organelles separate tasks into compartments, making processes faster and preventing materials from mixing.

Plasma Membrane

Made of a phospholipid bilayer with hydrophilic heads facing outward and hydrophobic tails inward. May contain proteins, cholesterol, and carbohydrates. Controls what enters/exits the cell and maintains homeostasis.

Facilitated Diffusion

Movement of large, polar, or charged molecules through transmembrane proteins from high to low concentration.

Active Transport

Moves molecules against the concentration gradient (low → high) using ATP. Applies to all molecules going against the gradient, even if they usually move by diffusion.

Normal Diffusion

Small, nonpolar molecules move through the membrane without help. Requires ATP only if moving against the gradient.

Endocytosis

The cell engulfs large molecules or particles using a vesicle to bring in materials too big for proteins or channels.

Exocytosis

The cell expels large molecules using vesicles. This process removes waste or secretes hormones/enzymes.

Osmosis

Water moves from areas of low solute concentration to high solute concentration to reach equilibrium.

Hypotonic

Water moves into a cell because the inside has higher solute concentration.

Isotonic

Water does not move; concentrations inside and outside the cell are equal.

Hypertonic

Water moves out of a cell because the outside has higher solute concentration.

Turgid

Occurs in plant cells when water enters, causing them to swell and become firm, supporting structure.

Flaccid

Occurs when plant cells are limp due to equal water concentration (isotonic).

Plasmolysis

Occurs when plant cells shrink and wilt because water leaves the cell (hypertonic), pulling the membrane away from the cell wall.

Water Potential

Predicts the direction water moves. Water moves from high to low potential. Ψ = Ψs + Ψp, where Ψs =

Nucleus

Stores DNA and coordinates cell processes by sending RNA instructions. Has a nuclear envelope that controls entry/exit and pores for transport.

Nucleolus

Inside the nucleus. Assembles ribosomes that later create proteins from amino acids.

Ribosomes

Produce proteins by reading mRNA instructions. Free ribosomes float in the cytoplasm, while bound ribosomes attach to the Rough ER.

Mitochondria

Converts food into ATP. Contains its own DNA and ribosomes, a folded inner membrane, and enzymes for energy production.

Rough ER

Covered in ribosomes; synthesizes proteins for organelles or export.

Smooth ER

Synthesizes lipids, detoxifies substances, and processes carbohydrates. Lacks ribosomes.

Golgi Complex

Receives vesicles, modifies and labels their contents, and sends them to the correct location. Has cis (receiving) and trans (shipping) faces.

Lysosomes

Contain digestive enzymes to recycle organelles, waste, or invading pathogens. Can trigger programmed cell death if the cell is damaged.

Chloroplasts

Convert sunlight into sugar via photosynthesis. Contain DNA and ribosomes. Produced sugar can be converted into ATP by mitochondria.

Central Vacuole

Stores water and macromolecules, isolates waste, and maintains turgor pressure to keep plant cells upright.

Cell Wall

Made of cellulose. Protects against bursting, supports the plant, and helps maintain turgor pressure.