AP Biology - Unit 3 Part 2

ATP

main energy source that cells use for most of their work

ADP

molecule that ATP becomes when it gives up one of its three phosphate groups

free energy

Chemical energy available to do work

substrate level phosphorylation

the enzyme-mediated direct transfer of phosphate from another molecule (the substrate) to ADP

NAD+

a coenzyme that is an electron carrier

cellular respiration

The catabolic pathways by which electrons are removed from various molecules and passed through intermediate electron carriers to O2, generating H2O and releasing energy.

aerobic

Requiring oxygen in the form of O2

pyruvate oxidation

pyruvate molecules are oxidized and produce acetyl-CoA, CO2, and NADH

Krebs Cycle

In cellular respiration, a set of chemical reactions whereby acetyl CoA is oxidized to carbon dioxide and hydrogen atoms are stored as NADH and FADH2. Also called the citric acid cycle

energy-investing reactions

endergonic stage of glycolysis in which glucose is converted into G3P

energy-harvesting reactions

exergonic stage of glycolysis in which G3P is converted into two molecules of pyruvate

pyruvate

Three-carbon compound that forms as an end product of glycolysis.

NADH

reduced electron carrier molecule formed in glycolysis

acetyl CoA

molecule formed from the oxidation of pyruvate

FADH2

a reduced coenzyme similar to NADH; an electron carrier

anaerobic

Occurring without the use of molecular oxygen, O2.

fermentation

(1) Speaking specifically about energy metabolism, the anaerobic breakdown of a substance such as glucose to smaller molecules such as lactic acid or alcohol with the extraction of energy.

(2) Speaking generally, metabolic processes that occur in the absence of O2.

lactic acid fermentation

Anaerobic series of reactions that convert glucose to lactic acid, in some bacteria and animal cells.

alcoholic fermentation

Anaerobic series of reactions that convert glucose to ethyl alcohol (ethanol) and carbon dioxide in some plants and yeast cells.

photosynthesis

Metabolic processes carried out by green plants and cyanobacteria, by which visible light is trapped and the energy used to convert CO2 into organic compounds.

light reactions

The initial phase of photosynthesis, in which light energy is converted into chemical energy.

pigment

A substance that absorbs visible light.

chlorophyll

Any of several green pigments associated with chloroplasts or with certain bacterial membranes; responsible for trapping light energy for photosynthesis.

absorption spectrum

A graph of light absorption versus wavelength of light; shows how much light is absorbed at each wavelength.

light-harvesting complex

in photosynthesis, a group of different molecules that cooperate to absorb light energy and transfer it to a reaction center. Also called antenna system.

photosystem

A light-harvesting complex in the chloroplast thylakoid composed of pigments and proteins.

cyclic electron transport

in photosynthetic light reactions, the flow of electrons that produces ATP but no NADPH or O2.

noncyclic electron transport

In photosynthesis, the flow of electrons that forms ATP, NADPH, and O2.