AP Biology Vocab Test #1

Active Transport

the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy

Adhesion

the action or process of sticking to a surface or object

antiparallel

the opposing orientations of the two strands in a DNA double helix

aquaporin

a family of channel proteins that facilitate the rapid transport of water across cell membranes

carbohydrate

organic compounds composed of carbon, hydrogen, and oxygen atoms

cohesion

the tendency of water molecules to stick together due to hydrogen bonding, forming a cohesive force that allows them to resist separation

concentration gradient

the difference in the concentration of a substance, like ions or molecules, between two different areas

contractile vacuole

a specialized, membrane-bound organelle in many microorganisms, like protists, that regulates water balance by expelling excess water from the cell

dehydration reaction

a chemical reaction that results in the formation of a larger molecule from smaller subunits (monomers) by the removal of a water molecule

denaturation

the process where a protein or nucleic acid (like DNA or RNA) loses its characteristic three-dimensional structure, leading to a loss of its biological function

diffusion

the passive movement of molecules from an area of higher concentration to an area of lower concentration, down their concentration gradient

endocytosis

a cellular process where the cell membrane surrounds and engulfs substances, bringing them into the cell

Endosymbiotic Theory

an evolutionary theory which posits the eukaryotic cells arose from prokaryotic cells

eukaryotic cells

cells containing membrane-bound organelles and are the basis for both unicellular and multicellular organisms

exocytosis

a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane

facilitated diffusion

transport of substances across a biological membrane from an area of higher concentration to an area of lower concentration

flaccid

plant tissue that has become soft and less rigid than normal because the cytoplasm within its cells has shrunk and contracted away from the cell

fluid mosaic model

describes the structure of the plasma membrane as a mosaic of components

glycoprotein

any of a class of proteins that have carbohydrate groups attached to the polypeptide chain

hydrogen bond

a weak electrostatic attraction the occurs between a partially positive hydrogen atom and a highly electronegative atom (like oxygen) in another molecule or a different part of the same molecule.

hydrolysis

the chemical breakdown of a compound due to reaction with water

hydrophilic

the tendency to mix with water

hydrophobic

tending to repel or fail to mix with water

hypertonic solution

a solution with a higher concentration of solutes compared to another

hypotonic solution

has a lower solute concentration than the solution it’s compared to

integral protein

a type of membrane protein that is permanently embedded within the lipid bilayer of a cell membrane

isotonic solution

has the same concentration of solutes as the fluid in a cell, leading to no net movement of water into or out of the cell

lipid

fatty acids that are insoluble in water but soluble in organic solvents. includes natural oils, waxes, and steroids

monomer

a molecule that can be bonded to other identical molecules to form a polymer

nucleic acid

a large essential biomolecule composed of repeating nucleotide units that carries and transmits genetic information

nucleotide

the fundamental building block of nucleic acids (like DNA and RNA) consisting of a nitrogenous base, a five-carbon sugar, and a phosphate group

osmoregulation

the biological process by which an organism actively maintains homeostasis by regulating and balancing the water and electrolyte concentrations within its body fluids

osmosis

the passive diffusion of water across a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration

passive transport

the movement of molecules across a cell membrane down their concentration gradient (from high to low concentration) without the cell expending ATP

peripheral protein

proteins that are attached to the surface of cell membranes but do not penetrate or embed within the lipid bilayer

phagocytosis

the process where a cell engulfs and consumes large particles, such as microorganisms, foreign substances, or dead cells, by forming membrane extensions called pseudopodia

phospholipid

a lipid molecule that is a principal component of cell membranes, forming a lipid bilayer. consists of hydrophilic head and two hydrophobic tails

pinocytosis

a type of endocytosis where a cell takes in small molecules and fluids from its environment by forming a pocket in the cell membrane that pinches off to create a small, membrane-bound sac called a vesicle

plasma membrane

the thin, flexible, semipermeable barrier that surrounds all cells, separating the cell’s interior from its external environment

plasmolysis

the process where a plant cell loses water when placed in a hypertonic solution, causing the protoplast to shrink and detach from the rigid cell wall

polar molecule

a molecule with an uneven distribution of electric charge resulting in a permanent electric dipole (a positive end and a negative end)

polymer

a large molecule (macromolecule) composed of many smaller, repeating units called monomers, which are linked together by covalent bonds in a repeating pattern

prokaryotic cell

a single celled organism that lacks a membrane bound nucleus and other membrane-bound organelles

protein

a large, complex molecule that plays essential roles in all living organisms. they are composed of amino acids, which are linked together in long chains

receptor-mediated endocytosis

a cellular process where a cell takes in specific molecules (ligands) by binding them to receptor proteins on the cell membrane, triggering the formation of a vesicle from the membrane that engulfs the receptor-ligand complex and transports it into the cell

selective permeability

the characteristic of a biological membrane that allows some substances to pass through while restricting the passage of others

specific heat

the amount of heat required to raise the temperature of one gram of a substance by one degree Celsius

surface tension

the property of a liquid’s surface to resist an external force, behaving like a stretched elastic membrane

transport protein

specialized proteins embedded in the cell membrane that facilitate the movement of molecules, ions, and nutrients across the membrane

turgid

a plant cell that is swollen and firm due to the internal pressure of water, called turgor pressure, exerted against its cell wall

vesicle

a small, membrane-bound sac that transports, stores, or digests substances within a cell