AP Biology Unit 2 Review

Tonicity

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

Isotonic Solution

A solution where the concentration of nonpenetrating solutes is equal inside and outside the cell, resulting in no net movement of water.

Hypertonic Solution

A solution where the concentration of nonpenetrating solutes is higher outside the cell, causing cells to lose water and shrivel.

Hypotonic Solution

A solution where the concentration of nonpenetrating solutes is lower outside the cell, causing cells to gain water and swell.

Osmoregulation

The ability of cells to regulate their solute concentrations and maintain water balance.

Plasmolysis

The shrinkage of the vacuole and pulling away of the plasma membrane from the cell wall due to loss of water in a hypertonic solution.

Water Potential

A physical property that predicts the direction of water flow, influenced by solute concentration and physical pressure.

Water Potential Formula

Y = Ys + Yp; where Y represents water potential, Ys represents solute potential, and Yp represents pressure potential.

Solute Potential Formula

Y_s = -iCRT; where 'i' is the ionization constant, 'C' is the molar concentration, 'R' is the pressure constant, and 'T' is temperature in Kelvin.

Pressure Potential

The physical pressure on a solution that can be positive or negative relative to atmospheric pressure.

Selective Permeability

A property of cell membranes that allows certain substances to cross more easily than others.

Passive Transport

The movement of molecules across a membrane without the use of energy, moving down their concentration gradient.

Facilitated Diffusion

The process of transporting molecules across a membrane via specific transport proteins, without using energy.

Osmosis

The diffusion of water across a selectively permeable membrane, moving from areas of low solute concentration to high solute concentration.

Active Transport

The movement of molecules across a membrane that requires energy, moving against their concentration gradient.

ATP (Adenosine Triphosphate)

The primary energy carrier in cells, used to fuel active transport processes.

Electrogenic Pumps

Proteins that generate voltage across membranes, contributing to the electrochemical gradient.

Cotransport

The coupling of the favorable transport of one substance with the unfavorable transport of another.

Exocytosis

The process by which a cell secretes materials via vesicles that fuse with the plasma membrane.

Endocytosis

The process by which a cell takes in materials through vesicles that fuse with the plasma membrane.

Phagocytosis

A type of endocytosis in which a cell engulfs large particles, which are then digested by lysosomes.

Pinocytosis

A form of endocytosis where cells take in extracellular fluid and dissolved molecules.

Receptor-Mediated Endocytosis

A selective uptake mechanism where cells target specific molecules via receptors on the plasma membrane.

SA:V ratio

The ratio of surface area to volume, a high ratio in small cells optimizes material exchange, while a low ratio in large cells decreases efficiency.

Small cell characteristics

Possess a high SA:V ratio, which optimizes the exchange of materials at the plasma membrane.

Large cell characteristics

Have a lower SA:V ratio, leading to reduced efficiency in material exchange, increased cellular demand for resources, and decreased rate of heat exchange.

Phospholipid

A primary component of the plasma membrane, an amphipathic molecule composed of a hydrophilic head and two hydrophobic tails.

Hydrophilic Head

The water-loving component of a phospholipid, often containing a phosphate group and glycerol, oriented towards aqueous environments.

Hydrophobic Tail

The water-fearing component of a phospholipid, composed of hydrocarbon chains, facing inwards away from aqueous environments.

Plasma Membrane

A selectively permeable boundary primarily composed of phospholipids, separating the internal cell environment from the external environment.

Amphipathic

A descriptor for molecules, like phospholipids, that possess both hydrophilic (water-loving) and hydrophobic (water-fearing) regions.

Selective Permeability

The ability of the plasma membrane to regulate which substances can enter and exit the cell.

Fluid Mosaic Model

A model describing the cell membrane as a fluid structure with various proteins and other macromolecules embedded in or associated with a phospholipid bilayer.

Fluid (membrane property)

Refers to the membrane's characteristic of being held together by weak hydrophobic interactions, allowing phospholipids and proteins to move and shift.

Mosaic (membrane property)

Refers to the membrane's composition of many different macromolecules, including various proteins, lipids, and carbohydrates.

Unsaturated hydrocarbon tails

Kinked phospholipid tails that prevent tight packing, helping to maintain membrane fluidity, especially at low temperatures.

Cholesterol (membrane)

A lipid embedded in the membrane that helps maintain fluidity by reducing movement at high temperatures and reducing tight packing of phospholipids at low temperatures.

Integral proteins

Proteins that are embedded into the lipid bilayer, also known as transmembrane proteins, and are amphipathic.

Transmembrane proteins

Another term for integral proteins, indicating they span across the entire lipid bilayer.

Peripheral proteins

Proteins that are not embedded into the lipid bilayer but are loosely bonded to the surface of the membrane.

Membrane Carbohydrates

Molecules (glycolipids and glycoproteins) found on the cell membrane surface that are important for cell-to-cell recognition.

Glycolipids

Carbohydrates bonded to lipids, found on the external surface of the plasma membrane.

Glycoproteins

Carbohydrates bonded to proteins, found on the external surface of the plasma membrane.

Cell wall

An extracellular structure found in plant cells (not animal cells) composed of cellulose, providing shape, structure, protection, and regulating water intake for the cell.

Plasmodesmata

Hole-like structures in plant cell walls filled with cytosol that connect adjacent plant cells, facilitating material exchange and communication.

Ose ending

Always carbs

Ase ending

Always proteins

Nine ending

Always nucleic acids

Microfilaments (Actin)

Thin, solid rods of actin that help maintain cell shape, bear tension, and, with myosin, drive muscle contraction and cell movement; also participate in cytokinesis.

Contractile ring

A ring of actin filaments that constricts to form the cleavage furrow during cytokinesis, dividing the cell.

Cleavage furrow

Indentation that forms as the contractile ring tightens, leading to cytoplasmic division in animal cell cytokinesis.

Intermediate Filaments

Fibrous proteins that are permanent structural elements; maintain cell shape; anchor the nucleus and organelles; form the nuclear lamina and line the nuclear envelope.

Nuclear lamina

A network of intermediate filament proteins lining the inner surface of the nuclear envelope, providing structural support to the nucleus.

Chloroplast

Organelle in plant cells where photosynthesis occurs; contains chlorophyll and enzymes and is bounded by a double membrane.

Thylakoid

Flattened membrane-bound sacs inside chloroplasts; organize into stacks called grana; site of light-dependent reactions.

Grana

Stacks of thylakoids within the chloroplasts.

Stroma

Fluid-filled space surrounding the thylakoids in chloroplasts; location of the Calvin Cycle.

Calvin Cycle

Light-independent reactions of photosynthesis that build sugars using CO2, ATP, and NADPH; occurs in the stroma.

Chloroplast ribosomes

Ribosomes within chloroplasts that synthesize chloroplast-encoded proteins.

Chloroplast enzymes

Enzymes present in chloroplasts that participate in photosynthetic reactions.

Cytoskeleton

Network of protein fibers in the cytoplasm that provides structural support, anchors organelles, and enables movement.

Centrosome

Organizethe near the nucleus that organizes microtubules during cell division (microtubule organizing center).

Microtubules

Hollow, rod-like filaments made of tubulin; grow from the centrosome and aid in movement and cell shape. Aid in microtubule assembly

Microfilaments

Thin actin filaments involved in supporting cell shape and facilitating movement.

Intermediate filaments

Rope-like cytoskeletal elements that provide mechanical strength.

Motor proteins

Proteins that move along cytoskeletal filaments to transport vesicles and organelles.

Movement of the cytoskeleton

Movement occurs when the cytoskeleton interacts with motor proteins.

Endosymbiont Theory

Theory that mitochondria and chloroplasts originated as free-living prokaryotes engulfed by a primitive eukaryotic cell and later became part of a single functional organism.

Mitochondria

Energy organelle and site of cellular respiration; contains a double membrane.

Double membrane

Mitochondria have two membranes: an outer smooth membrane and an inner membrane.

Outer mitochondrial membrane

The smooth outer membrane surrounding the mitochondrion.

Inner mitochondrial membrane

The membrane with folds called cristae that increases surface area for reactions.

Cristae

Folds of the inner mitochondrial membrane that increase surface area for ATP production.

Mitochondrial matrix

The inner compartment inside the inner membrane; location of the Krebs cycle and contains enzymes, mitochondrial DNA, and ribosomes.

Krebs Cycle

Series of reactions in cellular respiration occurring in the mitochondrial matrix that produces ATP.

Mitochondrial DNA

Circular DNA located in mitochondria, separate from nuclear DNA.

Ribosomes (mitochondrial)

Ribosomes located in mitochondria; enable mitochondrial protein synthesis and allow some independence from the nucleus.

Enzymes of cellular respiration

Enzymes in mitochondria that catalyze cellular respiration and help produce ATP.

Metabolic activity and mitochondrial number

The number of mitochondria in a cell correlates with its metabolic activity; more mitochondria in high-energy-demand cells.

Lysosome

Membranous sac containing hydrolytic enzymes that digest macromolecules in animal cells; participates in autophagy by recycling organelles.

Autophagy

Cellular process that recycles its own organelles by enveloping them in a membrane to form an autophagosome, which fuses with a lysosome for digestion.

Peroxisome

Membrane-bound organelle similar to a lysosome; catalyzes oxidation reactions producing H2O2, which is then broken down to water by its enzymes.

Vacuole

Large vesicle derived from the ER and Golgi; involved in selective transport and storage; comes in multiple types.

Food vacuole

Vacuole formed via phagocytosis that is digested by lysosomes.

Contractile vacuole

Vacuole that maintains water balance in cells by expelling excess water.

Central vacuole

Plant cell vacuole that stores water and inorganic ions and helps generate turgor pressure.

Turgor pressure

Hydrostatic pressure within plant cells that keeps cells firm.

Phagocytosis

Process by which a cell engulfs solid particles to form a food vacuole.

Endoplasmic Reticulum (ER)

A network of membranous sacs and tubules that synthesizes membranes from components of free ribosomes and compartmentalizes the cell to keep proteins formed in the rough ER separate.

Rough Endoplasmic Reticulum (RER)

ER region with ribosomes bound to its membrane.

Smooth Endoplasmic Reticulum (SER)

ER region that contains no ribosomes.

Ribosomes (bound vs free)

Ribosomes bound to the ER synthesize membrane and secretory proteins; free ribosomes reside in the cytosol.

Golgi Complex

Golgi apparatus that synthesizes lipids, metabolizes carbohydrates, detoxifies the cell, and modifies, sorts, and packages materials received from the ER.

Cisternae

Flattened membranous sacs of the Golgi; each cisterna is not directly connected to others and the sacs are arranged with directionality.

Cis face

The side of the Golgi that receives vesicles from the ER.

Trans face

The side of the Golgi that sends vesicles to the cytosol or to the plasma membrane for secretion.

Protein folding/modification in Golgi

Golgi modifies and ensures newly formed proteins are folded correctly or modified before packaging into transport vesicles.

ER membrane synthesis

The ER synthesizes membranes from components produced by free ribosomes.

Compartmentalization

Separation of different metabolic reactions into distinct organelle locations, increasing surface area for reactions and preventing interference between processes.

Cell wall

Rigid layer outside the plant cell membrane that provides structure and protection.