AP Bio Unit 2

Phospholipid

A molecule made up of a glycerol backbone, two fatty acid tails, and a phosphate group

Function: Forms the structural foundation of cell membranes, creating a semi-permeable barrier

Bilayer

Two layers of phospholipids arranged tail-to-tail

Function: Forms the basis of the cell membrane. allowing selective permeability

Cell membrane

A semi-permeable membrane made of a phospholipid bilayer and proteins

Function: Regulates what enters and exists the cell

Ribosome

A complex of RNA and protein

Function: Synthesizes proteins from mRNA in both prokaryotes and eukaryotes

Chloroplast

Definition: Organelles found in plant cells and some protists

Function: Conducts photosynthesis to convert light energy into chemical energy

Mitochondria

Double-membraned organelles found in eukaryotic cells

Function: Produces ATP through cellular respiration

Cytoskeleton

A network of fibers made of proteins like actin, tubulin, and intermediate filaments

Function: Provides structural support and helps with cell movement

Endoplasmic Reticulum (Smooth & Rough)

A network of membranes within the cell

Function: Rough ER- Synthesizes proteins (ribosome-studded) Smooth ER: Synthesizes lipids, detoxifies, and stores calcium ions

Golgi Complex

A series of flattened membrane sacs

Function: Modifies, sorts, and packages proteins and lipids for transport

Nucleus

The membrane-bound organelle containing DNA in eukaryotic cells

Function: Controls cell activities and contains genetic material

Vacuole

A large membrane-bound organelle

Function: Stores nutrients, waste products, and maintains turgor pressure in plant cells

Lysosome

Membrane-bound organelles containing digestive enzymes

Function: Breaks down waste materials and cellular debris

Cell Wall

A rigid outer layer found in plant cells, fungi, and bacteria

Function: Provides structural support and protection

Prokaryote

A single-celled organism without a nucleus or membrane-bound organelles

Ex. Bacteria and archea

Eukaryote

Organisms whose cells contain a nucleus and membrane-bound organelles

Ex. Animals, plants, fungi, and protists

Cellulose

A polysaccharide composed of glucose units

Function: Forms the structural component of plant cell walls

Cellular Respiration

A process that converts glucose into ATP with the help of oxygen

Equation: C6H12O6+ 6O2 —> 6CO2 + 6H2O+ ATP

Photosynthesis

A process in plants and some protists that converts light energy into chemical energy stored in glucose

Equation: 6CO2 + 6H2O +light —> C6H12O6 +6O2

Thylakoid

Membrane-bound sacs inside chloroplasts

Function: Contain chlorophyll and are site of the light-dependent reactions of photosynthesis

Granum

Stacks of thylakoids

Function: Increase surface area for light-dependent reactions in photosynthesis

Stroma

The fluid-filled space surrounding the thylakoids in a chloroplast

Function: Site of the light-independent reactions (Calvin Cycle) in photosynthesis

Inner Membrane (Mito)

The inner layer of the mitochondrion

Function: Contains the enzymes for the electron transport chain and ATP synthesis

Outer Membrane (Mito)

Definition: The outer layer of the mitochondrion.

Function: Encloses the mitochondrion and provides structure.

Matrix (Mito)

Definition: The inner liquid-filled space inside the mitochondrion.

Function: Contains enzymes for the Krebs cycle.

Surface Area

Definition: The total area of the cell's outer surface.

Function: Affects the rate of diffusion and other cellular processes.

Inter-membrane space (Mito & Chloro)

Definition: The region between the inner and outer membranes of mitochondria and chloroplasts.

Function: Houses protons (H⁺) during the electron transport chain.

Volume

Definition: The three-dimensional space inside a cell or structure.

Function: Affects the metabolic rate of a cell and the demand for resources.

Solute

Definition: The substance dissolved in a solution.

Example: Salt in saltwater.

Solvent

Definition: The substance that dissolves the solute.

Example: Water in saltwater.

Solution

Definition: A homogeneous mixture of solute and solvent.

Diffusion

Definition: The movement of molecules from an area of high concentration to an area of low concentration.

Example: Oxygen moving into cells.

Osmosis

Definition: The diffusion of water across a selectively permeable membrane.

Example: Water entering a plant cell.

Polar

Definition: Molecules with an unequal distribution of charge.

Example: Water.

Nonpolar

Definition: Molecules with an equal distribution of charge.

Example: Lipids.

Hydrophillic

Definition: Substances that are water-loving or dissolve easily in water.

Example: Salt.

Hydrophobic

Definition: Substances that repel water or do not dissolve in water.

Example: Oil.

Aquaporin

Definition: A transport protein in the cell membrane that facilitates water movement.

Function: Helps water move quickly into or out of a cell.

Vesicle

Definition: A small membrane-bound sac within a cell.

Function: Transports materials within the cell.

Transport protein

Definition: Membrane proteins that help move substances across the cell membrane.

Function: Can facilitate active or passive transport.

Active Transport

Definition: The movement of molecules against their concentration gradient, requiring energy (ATP).

Example: Sodium-potassium pump.

Passive Transport

Definition: The movement of molecules down their concentration gradient, without the use of energy.

Example: Diffusion.

Facilitated Diffusion

Definition: The passive transport of molecules via a transport protein.

Example: Glucose transport through a membrane.

Integral Proteins

Definition: Membrane proteins that span the entire lipid bilayer.

Function: Involved in transport and communication.

Peripheral Proteins

Definition: Membrane proteins that are attached to the surface of the lipid bilayer.

Function: Involved in cell signaling and maintaining the cell's shape.

Surface Area to Volume Ratio

Definition: The ratio of the surface area of a cell to its volume.

Function: A higher ratio improves the cell's efficiency in exchanging materials with its environment.

Ion

Definition: An atom or molecule with a net electrical charge due to the loss or gain of electrons.

Example: Na⁺ or Cl⁻.

Concentration Gradient

Definition: The difference in concentration of a substance across a space.

Function: Determines the direction of diffusion.

Equilibrium

Definition: The state in which the concentrations of a substance are equal throughout a system.

Function: No net movement of molecules occurs at equilibrium.

Water Potential

Definition: A measure of the potential energy of water in a system.

Function: Determines the direction of water movement.

Solute Potential

Definition: The potential of a solution to take up water due to the presence of solutes.

Function: More solutes = lower solute potential.

Pressure Potential

Definition: The physical pressure exerted on water in a plant cell.

Function: Can be positive (turgor pressure) or negative (tension in xylem).

Positive Pressure

Definition: Pressure exerted on water inside a plant cell that pushes against the cell wall.

Function: Helps maintain cell shape and rigidity.

Negative Pressure

Definition: Pressure exerted in the xylem during transpiration.

Function: Pulls water upward in plants.

Stomata

Definition: Small pores on plant leaves that regulate gas exchange.

Function: Allow CO₂ in and O₂ out, while controlling water loss.

Molarity

Definition: A measure of the concentration of a solution, expressed in moles of solute per liter of solution.

Example: 1 M NaCl solution.

Cholesterol

Definition: A lipid molecule found in the cell membrane.

Function: Helps maintain membrane fluidity and stability

Exocytosis

Definition: The process by which cells expel materials using vesicles.

Example: Release of neurotransmitters.

Endocytosis

Definition: The process by which cells take in materials via vesicle formation.

Example: Phagocytosis in immune cells.

Turgid/ Turgor Pressure

Definition: The pressure within a plant cell due to water intake.

Function: Helps maintain cell shape and prevents wilting.

Flaccid

Definition: A state of plant cells when they are not turgid.

Function: Occurs when water is lost, causing the cell to shrink.

Cell Compartmentalization

Definition: The process by which cells use membranes to divide the cell into distinct functional regions.

Function: Increases efficiency by isolating different biochemical processes.

Endosymbiosis

Definition: The theory that mitochondria and chloroplasts originated as free-living prokaryotes that were engulfed by a host cell.

Function: Explains the similarities between these organelles and prokaryotes.

DNA

Definition: Deoxyribonucleic acid, the molecule that carries genetic information.

Function: Directs cell activities and inheritance.

ATP

Definition: Adenosine triphosphate, the main energy carrier in cells.

Function: Provides energy for cellular processes.

Cytosol

Definition: The fluid portion of the cytoplasm, excluding organelles.

Function: Site for many cellular processes, like glycolysis.

Permeable/ Semi-Permeable

Definition:

- Permeable: Allows all substances to pass.

- Semi-permeable: Allows only certain substances to pass through.

Hydrolysis

Definition: The breakdown of a molecule using water.

Example: Breaking down polymers into monomers.

Enzymes

Definition: Proteins that catalyze biochemical reactions.

Function: Speed up reactions by lowering activation energy.

pH

Definition: A measure of how acidic or basic a solution is. High is basic, low is acidic

Function: Influences the shape and function of enzymes and cellular activities.