ALL AP BIO VOCAB

study these terms for the ap biology exam

Enzyme

A protein that acts as a catalyst - a chemical agent that speeds up a reaction without being consumed by the reaction.

Substrate

A specific reactant acted upon by an enzyme

Activation Energy

the minimum amount of energy required to start a chemical reaction

enzyme mediated reactions

with these type of reactions the rate of product formation is greatly influenced by the concentrations of the reactants

Active Site

a region on an enzyme that binds to a protein or other substance during a reaction.

Induced Fit

The change in shape of the active site of an enzyme so that it binds more snugly to the substrate, induced by entry of the substrate.

Denaturation

In proteins, a process in which a protein unravels and loses 3D structure, thereby becoming biologically inactive.

pH

hydrogen ion concentration

Inhibitor

A substance that slows down or stops a chemical reaction

Competitive Inhibitor

A substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics.

Noncompetitive Inhibitor

A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing its conformation so that it no longer binds to the substrate.

Enzyme

A protein that acts as a catalyst - a chemical agent that speeds up a reaction without being consumed by the reaction.

Substrate

A specific reactant acted upon by an enzyme

Energy

The ability to rearrange a collection of matter

Metabolism

All of the chemical reactions that occur within an organism

System

The matter under study

Surroundings

everything outside the system

Thermodynamics

The study of energy transformations that occur in a collection of matter.

1st law of thermodynamics

Energy cannot be created or destroyed

2nd law of thermodynamics

Every energy transfer or transformation increases the entropy of the universe.

Entropy

A measure of disorder or randomness.

Spontaneous Process

A process that occurs without an overall input of energy; a process that is energetically favorable.

Exergonic Reaction

A spontaneous chemical reaction in which there is a net release of free energy.

Endergonic Reaction

A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings.

Equilibrium

A state of balance - equilibrium = dead

Energy Coupling

The use of an exergonic process to drive an endergonic one.

ATP

(adenosine triphosphate) main energy source that cells use for most of their work

phosphorylated intermediate

A molecule (often a reactant) with a phosphate group covalently bound to it, making it more reactive (less stable) than the unphosphorylated molecule.

the energy stored in bonds

The potential energy that can be released when new bonds are formed after the original bonds break, as long as the products are of lower free energy than the reactants

Metabolic pathway

series of chemical reactions in which the product of one reaction is the substrate for the next reaction

Anabolic Pathway

A metabolic pathway that consumes energy to synthesize a complex molecule from simpler compounds.

Catabolic Pathway

A metabolic pathway that releases energy by breaking down complex molecules to simpler compounds.

photosynthesis

process by which plants and some other organisms use light energy to convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars and starches

cyanobacteria

Photosynthetic, oxygen-producing bacteria (formerly known as blue-green algae).

autotroph

an organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide.

photoautotroph

organism that uses energy from sunlight to convert carbon dioxide and water to carbon compounds

Light independent reactions

set of reactions in photosynthesis that do not require light; energy from ATP and NADPH is used to build high-energy compounds such as sugar; also called the Calvin cycle

Light dependent reactions

reactions of photosynthesis that use energy from light to produce ATP and NADPH

chloroplast

An organelle found in plant and algae cells where photosynthesis occurs

thylakoid

A flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy.

granum

stack of thylakoids

stroma

fluid portion of the chloroplast; outside of the thylakoids

ATP

(adenosine triphosphate) main energy source that cells use for most of their work

NADPH

An electron carrier involved in photosynthesis. Light drives electrons from chlorophyll to NADP+, forming NADPH, which provides the high-energy electrons for the reduction of carbon dioxide to sugar in the Calvin cycle.

Excited state

when an atom absorbs energy, its electrons move to a higher energy level

chlorophyll

Green pigment in plants that absorbs light energy used to carry out photosynthesis

photosystem

cluster of chlorophyll and proteins found in thylakoids

photosystem I

One of two light-harvesting units of a chloroplast's thylakoid membrane - uses electrons from photosystem II to create NADPH

photosystem II

One of two light-harvesting units of a chloroplast's thylakoid membrane - uses electrons from splitting water to supply electrons to photosystem I

photophosphorylation

The process of generating ATP from ADP and phosphate by means of a proton-motive force generated by the thylakoid membrane of the chloroplast during the light reactions of photosynthesis.

Cellular Respiration

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

Fermentation

Process by which cells release energy in the absence of oxygen

Glycolysis

first step in releasing the energy of glucose, in which a molecule of glucose is broken into two molecules of pyruvic acid

substrate-level phosphorylation

The enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism.

Pyruvate

Organic compound with a backbone of three carbon atoms. Two molecules form as end products of glycolysis

Link reaction

a decarboxylation reaction that occurs in the mitochondrion between glycolysis and the Krebs cycle.

Acetyl CoA

the entry compound for the citric acid cycle in cellular respiration, formed from a fragment of pyruvate attached to a coenzyme

Kreb's Cycle

second stage of cellular respiration, in which pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions

FADH2

A molecule that stores energy for harvest by the electron transport chain.

NADH

An energy-carrying coenzyme produced by glycolysis and the Krebs cycle. NADH carries energy to the electron transport chain, where it is stored in ATP.

Electron Transport Chain

A sequence of electron carrier molecules (membrane proteins) that shuttle electrons during the redox reactions that release energy used to make ATP.

Mitochondrial Matrix

The compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the Krebs cycle.

inner mitochondrial membrane

The inner mitochondrial membrane is the innermost membrane of the mitochondria. Oxidative phosphorylation and chemiosmosis take place at the inner mitochondrial membrane, which produces ATP via the flow of protons across the membrane.

intermembrane space

the fluid filled space between the inner and outer mitochondrial membranes

Chemiosmosis

A process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme.

oxidative phosphorylation

The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration.

alcoholic fermentation

anaerobic process in which cells convert pyruvic acid into carbon dioxide and ethyl alcohol; carried out by many bacteria and fungi such as yeasts

lactic acid fermentation

The conversion of pyruvate to lactate (lactic acid) with no release of carbon dioxide.

Autocrine

A cell secretes a hormone or second messenger that binds to receptors on the same cell.

Target Cell

Cells that are receptive to a secreted hormone

Paracrine Signaling

A cell sends a local signal to a nearby cell

Endocrine Signaling

A cell sends a chemical signal to another cell that is far away in the body

cell communication

the process through which cells can detect and respond to signals in their environment

Plasmodesmata

channels through cell walls that connect the cytoplasms of adjacent cells

Quorum sensing

The ability of bacteria to sense the presence of other bacteria via secreted chemical signals.

Antigen-presenting cells (APCs)

cells that process protein antigens and present them on their surface in a form that can be recognized by lymphocytes (white blood cells)

Killer T cells (cytotoxic T cells)

kill infected cells

Helper T lymphocytes

initiate immune response

cell-to-cell contact signaling

a type of short signaling where the signal never has to leave the cell that produced it

local signaling

signaling between adjacent cells (paracrine, autocrine, and synaptic)

long distance signaling

signaling between cells separated by some distance (exocrine)

gap junctions

provide cytoplasmic channels between adjacent animal cells

desmosomes

Anchoring junctions that prevent cells from being pulled apart

tight junctions

Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid

synaptic signaling

a nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell

Neurotransmitter

chemical used by a neuron to transmit an impulse across a synapse to another cell

Morphogen

Morphogen is a chemical substance released by organizer cells that moves form one tissue to the target tissue, helping with induction in a developing embryo.

Hormone

Chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another

Insulin

A protein hormone synthesized in the pancreas that regulates blood sugar levels by facilitating the uptake of glucose into tissues

Human Growth Hormone

is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals.

Thyroid hormones

hormones produced by the thyroid gland primarily responsible for regulation of metabolism

Testosterone

the most important of the male sex hormones. Both males and females have it, but the additional testosterone in males stimulates the growth of the male sex organs in the fetus and the development of the male sex characteristics during puberty

Estrogen

A sex hormone, secreted in greater amounts by females than by males. In nonhuman female mammals, estrogen levels peak during ovulation, promoting sexual receptivity.

signal transduction

A series of molecular changes that converts a signal on a target cell's surface to a specific response inside the cell.

reception

The target cell's detection of a signal molecule coming from outside the cell.

transduction

a multistep pathway that involves changes in shape or phosphorylation of proteins to transmit a chemical signal within a cell

response

In cellular communication, the change in a specific cellular activity brought about by a transduced signal from outside the cell.

G-protein coupled receptors

A special class of membrane receptors with an associated GTP binding protein; activation of a G protein-coupled receptor involves dissociation and GTP hydrolysis

GTP

A nucleotide composed of guanine, ribose, and three linked phosphate groups. It is incorporated into the growing RNA chain during synthesis of RNA and used as a source of energy during synthesis of proteins

Ligand gated ion channel