AP Biology Unit 1-3 Midterm Review

Enzymes

proteins that act as biological catalysts

chemical energy

A form of potential energy that is stored in chemical bonds between atoms.

kinetic energy

the energy an object has due to its motion

thermal energy

The total energy of motion in the particles of a substance

heat

thermal energy in transfer from one body of matter to another

first law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

second law of thermodynamics

when energy is changed from one form to another, some useful energy is always degraded into lower quality energy (usually heat) entropy

Law of Conservation of Energy

the law that states that energy cannot be created or destroyed but can be changed from one form to another

Exergonic

Chemical reactions that release energy

Endergonic

A chemical reaction that requires the input of energy in order to proceed.

Metabolism

the combination of chemical reactions through which an organism builds up or breaks down materials

Catabolism

Metabolic pathways that break down molecules, releasing energy.

Anabolism

Metabolic pathways that construct molecules, requiring energy.

Catalytic proteins (enzymes)

speed up chemical reactions without being consumed themselves. work by decreasing the activation energy required.

energy of activation

The amount of energy that reactants must absorb before a chemical reaction will start

transition state

a high-energy intermediate state of the reactants during a chemical reaction that must be achieved for the reaction to proceed

-ase

suffix of enzymes

cofactors and coenzymes

-non protein, small molecules that can bind to the active site of an enzyme and participate in catalyzing the reaction (use ionization, protonation, deprotonation)

cofactors

usually inorganic molecules or metal ions

coenzymes

small organic groups such as vitamins or NAD, FAD, CoA

competitive inhibition

substance that resembles the normal substrate competes with the substrate for the active site

noncompetitive inhibitors or allosteric regulators

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.

allosteric

describes a region of an enzyme that can bind a regulatory molecule and is not the active site

ATP

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

Glycolysis

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

A series of anaerobic chemical reactions using pyruvic acid that supplies energy when oxygen is scarce

Citric Acid Cycle (Krebs Cycle)

A chemical cycle involving eight steps that completes the metabolic breakdown of glucose molecules begun in glycolysis. The second major stage in cellular respiration. - 2 Pyruvates enter the mitochondrion

* releases 2 ATP, 6NADH, and 2 FADH2 for each glucose

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. The third major stage of cellular respiration

oxidative phosphorylation

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

reduction reaction

A reaction in which a substance gains at least one electron; becoming more negative in charge

Oxidation reaction

a chemical reaction in which a reactant loses one or more electrons such that the reactant becomes more positive in charge

redox reaction

A chemical reaction involving the transfer of one or more electrons from one reactant to another; also called oxidation-reduction reaction.

Pyruvate (pyruvic acid)

An end product of glycolysis; in aerobic metabolism, pyruvate is sent to the Krebs cycle to aid in the production of ATP; in anaerobic metabolism, pyruvate is converted to lactic 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.

Mitochondrion (Mitochondria)

Cell organelle that converts the chemical energy stored in food (glucose) into compounds that are more convenient for the cell to use (ATP)

Outer Compartment (Mitochondria)

space outside the cristae membrane. Where H ions set up a concentration gradient. Labelled C in picture

Acetyl-CoA

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

NADH

the reduced form of the coenzyme NAD+ (nicotinamide adenine dinucleotide); an electron-carrying molecule that functions in cellular respiration. A molecule that stores energy for harvest by the electron transport chain.

FADH2

the reduced form of the coenzyme FAD (flavin adenine dinucleotide); an electron-carrying molecule that functions in cellular respiration. A molecule that stores energy for harvest by the electron transport chain.

Electron Transport Chain (ETC)

uses the high-energy electrons from the Krebs cycle to convert ADP into ATP in the cristae of the mitochondria

proton pump

An active transport protein in a cell membrane that uses ATP to transport hydrogen ions out of a cell against their concentration gradient, generating a membrane potential in the process.

Chemiosmosis

A process for synthesizing ATP using the energy of an electrochemical gradient and the ATP synthase enzyme. Also known as oxidative phosphorylation

Oxygen

Final electron acceptor in the ETC

electronegativity

the tendency to attract electrons to form a chemical bond

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.

FADH2

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

exergonic flow

movement of electrons towards oxygen that provides energy for endergonic flow

endergonic flow

takes in energy to pump protons against their concentration gradient into the outer compartment of the mitochondria

oxidative phosphorylation

The production of ATP using energy derived from the redox reactions of an electron transport chain; the last stage of cellular respiration. also known as chemiosmosis.

proton gradient

The product of the electron transport chain. A higher concentration of protons outside the inner membrane of the mitochondria than inside the membrane is the driving force behind ATP synthesis.

mitochondrial matrix

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

ATP synthase

enzyme that catalyzes the reaction that adds a high-energy phosphate group to ADP to form ATP

Water

waste product created when oxygen picks up spent electrons and protons in ETC

substrate-level phosphorylation

The enzyme-catalyzed formation of ATP by direct transfer of a phosphate group to ADP

36-38 ATP

Total number of ATP produced per glucose molecule during cellular respiration

32-34 ATP

Total Number of ATP made by E.T.C. & Oxidative Phosphorylation

anaerobic respiration

Respiration that does not require oxygen

Fermentation

A catabolic process that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.

facultative anaerobes

Bacteria that can live with or without oxygen

alcoholic fermentation

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

lactic acid fermentation

anaerobic process of glucose breakdown that produces lactic acid and NAD+; carried out by bacteria, yeasts and ourselves

light-dependent reactions

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

Light Independent Reactions (Calvin Cycle)

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

photosynthetic pigments

Chemicals that absorb light energy and use it to carry out photosynthesis. Contained in thylakoid membranes in chloroplast. Examples are chlorophyll a, chlorophyll b, carotenoids, xanthophylls, and phycobilins.

chlorophyll a and chlorophyll b

A green pigment found in the chloroplasts of plants, algae, and some bacteria. Absorbs light energy

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.

Stroma

fluid portion of the chloroplast; outside of the thylakoids

Photosystem

light-collecting units of the chloroplast

photosystem I (PS1)

One of two light-harvesting units of a chloroplast's thylakoid membrane; it uses the P700 reaction-center chlorophyll.

Photosystem II (PS2)

One of two light-harvesting units of a chloroplast's thylakoid membrane; it uses the P680 reaction-center chlorophyll.

Photolysis

In the thylakoid membranes of a chloroplast during light-dependant reactions, two molecules of water are split to form oxygen, hydrogen ions, and electrons.

Chemiosmosis

the use of energy in a H+ gradient to drive cellular work

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.

NADP+

oxidized carrier molecule that transfers high-energy electrons from chlorophyll to other molecules

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.

cyclic photophosphorylation

The synthesis of ATP during photosynthesis, coupled to the cyclic passage of electrons to and from P700, the specialized form of chlorophyll a which is involved in photosystem I, using a series of carrier molecules.

carbon fixation

The initial incorporation of carbon from CO2 into an organic compound by an autotrophic organism (a plant, another photosynthetic organism, or a chemoautotrophic prokaryote).

Rubisco

Ribulose carboxylase, the enzyme that catalyzes the first step of the Calvin cycle (the addition of CO2 to RuBP, or ribulose bisphosphate).

stomata (stoma)

Small openings on the underside of a leaf through which oxygen and carbon dioxide can move

Photorespiration

A metabolic pathway that consumes oxygen, releases carbon dioxide, generates no ATP, and decreases photosynthetic output; generally occurs on hot, dry, bright days, when stomata close and the oxygen concentration in the leaf exceeds that of carbon dioxide.

fluid mosaic model

Structural model of the plasma membrane where molecules are free to move sideways within a lipid bilayer.

phospholipid bilayer

a two-layered arrangement of phosphate and lipid molecules that form a cell membrane, the hydrophobic lipid ends facing inward and the hydrophilic phosphate ends facing outward.

integral membrane proteins

A protein embedded in the lipid bilayer of a cell. These are typically cell surface receptors, channels, or pumps.

peripheral membrane proteins

proteins associated with but not embedded within the plasma membrane

amphipathic

having both a hydrophilic region and a hydrophobic region

active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

passive transport

Requires NO energy, Movement of molecules from high to low concentration, Moves with the concentration gradient

Glycoproteins

Membrane carbohydrates that are covalently bonded to proteins.

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Osmosis

Diffusion of water through a selectively permeable membrane

facilitated diffusion

process of diffusion in which molecules pass across the membrane through protein channels

gated channels

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

Solvent

A liquid substance capable of dissolving other substances

Solute

A substance that is dissolved in a solution.

Solution

A mixture that forms when one substance dissolves another.

Isotonic

when the concentration of two solutions is the same

Hypertonic

Having a higher concentration of solute than another solution.

Hypotonic

Having a lower concentration of solute than another solution