AP Bio Unit 2 Vocab

Vacuoles

Structure: Membrane surrounded "bags"; Small in animal cells; Large in plant cells. Function: Storage of food, water, and other materials (food, contractile, and central).

Eukaryote

a cell that contains a nucleus and membrane bound organelles

Plastids

a family of closely related plant organelles (includes chloroplasts)

Thylakoid

a flattened membrane sac inside the chloroplast (inner membrane), used to convert light energy to chemical energy.

Cytoplasm/cytosol

a jellylike fluid inside the cell in which the organelles are suspended; region of the cell between the cell membrane and the nucleus

Glycolipid

a lipid with covalently attached carbohydrate(s).

Ligand

a molecule that binds specifically to another molecule, usually a larger one.

Amphiphatic

a molecule that has both hydrophobic and hydrophilic regions.

Nuclear Lamina

a netlike array of protein filaments lining the inner surface of the nuclear envelope; it helps maintain the shape of the nucleus.

Peripheral Protein

a protein loosely bound to the surface of a membrane and not embedded in the lipid bilayer

Glycoprotein

a protein with one or more carbohydrates covalently attached to it.

Prokaryote

a single-celled organism that does not have a nucleus or membrane-bound organelles; examples are archaea and bacteria

Granum

a stack of membrane-bounded thylakoids in the chloroplast

Integral Protein

a transmembrane protein with hydrophobic regions that completely spans the hydrophobic interior of the membrane

Phagocytosis

a type of endocytosis in which large particulate substances are taken up by a cell

Endoplasmic reticulum

an extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.

Chromatin

combination of DNA and protein molecules, in the form of long, thin fibers, making up the genetic material in the nucleus of a eukaryotic cell

Isotonic

describes a solution whose solute concentration is equal to the solute concentration inside a cell (causes no net change of water into or out of the cell)

Hypertonic

describes a solution whose solute concentration is higher than the solute concentration inside a cell (causes the cell to shrink/shrivel)

Hypotonic

describes a solution whose solute concentration is lower than the solute concentration inside a cell (cell gains water)

Concentration Gradient

difference in concentration of a substance on two sides of a membrane

Stroma

fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water.

Cristae

infoldings of the inner membrane of a mitochondrion that houses the electon transport chain and the enzyme catalyzing the synthesis of ATP (twisted-like spaghetti loops)

Nuclear envelope

layer of two membranes that surrounds the nucleus of a cell

Flaccid

limp. Lacking in stiffness or firmness, as in a plant cell in surroundings where there is no tendency for water to enter the cell

Lysosome

membrane-bound sac containing hydrolytic enzymes that can break down proteins, nucleic acids, and polysaccharides (suicide sacs)

Fluid Mosaic Model

model of cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids.

Facilitated diffusion

movement of specific molecoles across cell membranes through protien channels with no energy expenditure

Nucleolus

organelle where ribosomes are made, synthesized and partially assembled, located in the nucleus

Peroxisomes

organelles containing enzymes that transfer hydrogen atoms from various substances to oxygen, producing and then degrading peroxide (H2O2)

Endocytosis

process by which a cell takes in a substance by surrounding it with the cell membrane

Gated channels

protein channels in a cell membrane that opens or closes in response to a particular stimulus.

Ion channels

protein channels that allows a specific ion to flow across the membrane down its concentration gradient

Glycoproteins

proteins that have carbohydrates covalently attached to them (carbohydrate "flag" or name-tag; lock-key)

Osmoregulation

regulation of solute concentrations and water balance by a cell or organism

Golgi apparatus

stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum ("corrupt fed-ex")

Endomembrane system

the collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles

Mitochondrial matrix

the compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the citric acid cycle as well as ribosomes and DNA

Cotransport

the coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient.

Membrane Potential

the difference in electrical charge (voltage) across a cell's plasma membrane due to the differential distribution of ions.

Electrochemical Gradient

the diffusion gradient of an ion, which is affected by both the concentration difference of the ion across a membrane (a chemical force) and the ion's tendency to move relative to the membrane potential (an electrical force).

Passive transport

the diffusion of substances across a cell membrane without the use of energy

Osmosis

the diffusion of water across a selectively permeable membrane (from high to low)

Active Transport

the movement of materials through a cell membrane using energy

Exocytosis

the process by which a substance is released from the cell through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out

Diffusion

the random movement of a substance down its concentration gradient from a more concentrated to a less concentrated area.

Endosymbiont Theory

the theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by an ancestral eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism.

Plasma Membrane

thin flexible barrier that regulates what enters and exits the cell; composed of two layers of lipids (bilayer)

Transport protein

transmembrane protein that helps a certain substance or class of closely related substances to cross the cell membrane.

Sodium Potassium Pump

transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell.

Turgid

when a plant cell becomes swollen or distended (as a result of hypotonicity)

Plasmolysis

when the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs in plant cells when the cell loses water to a hypertonic environment.