Biology- Cells

AS91156 2.4

Activation Energy

minimum amount of energy required to trigger a chemical reaction

Active Site

the site on an enzyme that attaches to a substrate

Active Transport

movement of molecules through protein channels in the membrane from low to high concentration requiring energy (ATP)

Adenine

nitrogen base found in DNA and RNA; pairs with thymine in DNA and with uracil in RNA

ADP (Adenosine Diphosphate)

the compound that remains when a phosphate group is removed from ATP, releasing energy

Aerobic

respiration that requires oxygen

Anaerobic

respiratory process that does not require oxygen

ATP (Adenosine Triphosphate)

main energy source that cells use for most of their work

Catalyst

a substance that initiates or accelerates a chemical reaction without itself being affected

Cell Membrane

thin, flexible barrier around a cell; regulates what enters and leaves the cell

Cell Wall

a rigid structure that surrounds the cell membrane and provides support to the cell

Cellular Respiration

process that releases energy by breaking down glucose and other food molecules in the presence of oxygen

Cellulose

hard, nonliving material that makes up the cell wall of a plant cell

Chloroplast

organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy

Co-enzyme

a small molecule (not a protein but sometimes a vitamin) essential for the activity of some enzymes

Co-factor

inorganic compound required for the proper functioning of an enzyme

Concentration Gradient

a difference in the concentration of a substance across a distance

Cristae

infoldings of the inner membrane of a mitochondrion that houses the electron transport chain and the enzyme catalyzing the synthesis of ATP

Cytoplasm

a jellylike fluid inside the cell in which the organelles are suspended

Cytosine

nitrogen base that pairs with guanine

Denature

enzyme destroyed by high temperatures and shape changes so that it no longer functions properly

Enzyme

protein that acts as a biological catalyst

Glycolysis

a metabolic process that breaks down carbohydrates and sugars through a series of reactions to either pyruvic acid or lactic acid and releases energy for the body in the form of ATP

Grana

a stack of thylakoids within a chloroplast

Guanine

nitrogen base that pairs with cytosine

Induced Fit Model

change in the shape of an enzyme's active site that enhances the fit between the active site and its substrate(s)

Lactic Acid

produced in muscle cells from the reduction of pyruvate under anaerobic conditions

Phospholipid Bilayer

double-layered sheet that forms the core of nearly all cell membranes

Lock and Key Theory

this theory says that the enzyme's active site is exactly complementary to the structure of the substrate

Mitochondria

powerhouse of the cell, organelle that is the site of ATP (energy) production

Nucleolus

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

Nucleotide

monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

Osmosis

diffusion of molecules through a semipermeable membrane from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal

Passive Transport

transport of a substance across a cell membrane by diffusion

Phagocytosis

process in which phagocytes engulf and digest microorganisms and cellular debris

Pinocytosis

process by which certain cells can engulf and incorporate droplets of fluid

Plasmolysis

when a cell is in a hypertonic environment, the cell will lose water to its surroundings, shrink, and its plasma membrane will pull away from the wall

Ribosome

site of protein synthesis

Semi-permeable Membrane

a membrane (as a cell membrane) that allows some molecules to pass through but not others

Stroma

the dense colorless framework of a chloroplast

Substrate

the reactant on which an enzyme works

Thymine

nitrogen base that pairs with adenine

Turgor

a cell's swelling against its cell wall caused by the pressure of the cell's contents

Vacuole

cell organelle that stores materials such as water, salts, proteins, and carbohydrates

Vesicle

small membrane-bound sac that functions in moving products into, out of, and within a cell

Pyruvate

three-carbon compound that forms as an end product of glycolysis

Krebs Cycle

a series of biochemical reactions that convert pyruvic acid into carbon dioxide and water; it is the major pathway of oxidation in animal, bacterial, and plant cells, and it releases energy

Enzyme Inhibitor

any substance or molecule that slows down the rate of an enzyme-controlled reaction by affecting the enzyme molecule in some way