Biology Chapters 6+7 Key terms

Key terms off pearson

alcohol fermentation

Glycolysis followed by the reduction of pyruvate to ethyl alcohol, regenerating NAD+ and releasing carbon dioxide.

ATP synthase

A cluster of several membrane proteins that function in chemiosmosis with adjacent electron transport chains, using the energy of a hydrogen ion concentration gradient to make ATP.

cellular respiration

The aerobic harvesting of energy from food molecules; the energy-releasing chemical breakdown of food molecules, such as glucose, and the storage of potential energy in a form that cells can use to perform work; involves glycolysis, pyruvate oxidation and the citric acid cycle, and oxidative phosphorylation (the electron transport chain and chemiosmosis).

chemiosmosis

An energy-coupling mechanism that uses the energy of hydrogen ion (H+) gradients across membranes to drive cellular work, such as the phosphorylation of ADP; powers most ATP synthesis in cells.

citric acid cycle

The chemical cycle that completes the metabolic breakdown of glucose molecules begun in glycolysis by oxidizing acetyl CoA (derived from pyruvate) to carbon dioxide. The cycle occurs in the matrix of mitochondria and supplies most of the NADH molecules that carry electrons to the electron transport chains. Together with pyruvate oxidation, the second major stage of cellular respiration.

electron transport chain

A series of electron carrier molecules that shuttle electrons during a series of redox reactions that release energy used to make ATP; located in the inner membrane of mitochondria, the thylakoid membranes of chloroplasts, and the plasma membranes of prokaryotes.

glycolysis

A series of reactions that ultimately splits glucose into two molecules of pyruvate; the first stage of cellular respiration in all organisms; occurs in the cytosol.

intermediate

One of the compounds that form between the initial reactant and the final product in a metabolic pathway, such as between glucose and pyruvate in glycolysis.

kilocalorie (kcal)

A quantity of heat equal to 1,000 calories. Used to measure the energy content of food, it is usually called a "Calorie."

lactic acid fermentation

Glycolysis followed by the reduction of pyruvate to lactate, regenerating NAD+.

NAD+

Nicotinamide adenine dinucleotide; a coenzyme that can accept electrons during the redox reactions of cellular metabolism. It cycles between oxidized (NAD+) and reduced (NADH) states.

oxidation

The loss of electrons from a substance involved in a redox reaction; always accompanies reduction.

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.

photosynthesis

The process by which plants, algae, and some protists and prokaryotes convert light energy to chemical energy that is stored in sugars made from carbon dioxide and water.

pyruvate oxidation

The oxidation of pyruvate to acetyl CoA, with the release of CO2 and production of NADH. Preparatory reaction to the citric acid cycle.

redox reaction

Short for reduction-oxidation reaction; a chemical reaction in which electrons are lost from one substance (oxidation) and added to another (reduction).

reduction

The gain of electrons by a substance involved in a redox reaction; always accompanies oxidation.

substrate-level phosphorylation

The formation of ATP by an enzyme directly transferring a phosphate group to ADP from an organic molecule (for example, one of the intermediates in glycolysis or the citric acid cycle).

autotroph

An organism that makes its own food (often by photosynthesis), thereby sustaining itself without eating other organisms or their molecules. Plants, algae, and numerous bacteria are autotrophs.

C3 plant

A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate.

C4 plant

A plant in which the Calvin cycle is preceded by reactions that incorporate CO2 into a four-carbon compound, which then supplies CO2 for the Calvin cycle.

Calvin cycle

The second of two stages of photosynthesis; a cyclic series of chemical reactions that occur in the stroma of a chloroplast, using the carbon in CO2 and the ATP and NADPH produced by the light reactions to make the energy-rich sugar molecule G3P.

CAM plant

A plant that uses an adaptation for photosynthesis in arid conditions in which carbon dioxide entering open stomata during the night is converted to organic acids, which release CO2 for the Calvin cycle during the day, when stomata are closed.

carbon fixation

The incorporation of carbon from atmospheric CO2 into an organic compound. During photosynthesis in a C3 plant, carbon is fixed into a three-carbon sugar as it enters the Calvin cycle. In C4 and CAM plants, carbon is first fixed into a four-carbon sugar.

chlorophyll

A green pigment located within the chloroplasts of plants and algae and in the membranes of certain prokaryotes. Chlorophyll a participates directly in the light reactions, which convert solar energy to chemical energy.

climate change

Increase in temperature and change in weather patterns all around the planet, due mostly to increasing atmospheric CO2 levels from the burning of fossil fuels. The increase in temperature, called global warming, is a major aspect of global climate change.

electromagnetic spectrum

The entire spectrum of electromagnetic radiation ranging in wavelength from less than a nanometer to more than a kilometer.

greenhouse effect

The warming of Earth due to the atmospheric accumulation of CO2 and certain other gases, which absorb infrared radiation and reradiate some of it back toward Earth.

heterotroph

An organism that obtains organic food molecules by eating other organisms or substances derived from them; a consumer or a decomposer in a food chain.

light reactions

The first of two stages in photosynthesis; the steps in which solar energy is absorbed and converted to the chemical energy of ATP and NADPH, releasing oxygen in the process.

mesophyll

Leaf cells specialized for photosynthesis; a leaf's ground tissue system.

NADP+

Nicotinamide adenine dinucleotide phosphate, an electron acceptor that, as NADPH, temporarily stores energized electrons produced during the light reactions.

photoautotroph

An organism that obtains energy from sunlight and carbon from CO2 using the process of photosynthesis.

photon

A fixed quantity of light energy. The shorter the wavelength of light, the greater the energy of a photon.

photophosphorylation

The production of ATP by chemiosmosis during the light reactions of photosynthesis.

photorespiration

In a plant cell, a metabolic pathway that consumes oxygen, releases CO2, and decreases photosynthetic output. Photorespiration generally occurs on hot, dry days, when stomata close, O2 accumulates in the leaf, and rubisco fixes O2 rather than CO2. Photorespiration produces no sugar molecules or ATP.

photosynthesis

The process by which plants, algae, and some protists and prokaryotes convert light energy to chemical energy that is stored in sugars made from carbon dioxide and water.

photosystem

A light-capturing unit of a chloroplast's thylakoid membrane, consisting of a reaction-center complex surrounded by numerous light-harvesting complexes.

stoma (plural, stomata)

A microscopic pore surrounded by guard cells in the epidermis of a leaf. When stomata are open, CO2 enters a leaf, and H2O and O2 exit. A plant conserves water when its stomata are closed.

stroma

The dense fluid within the chloroplast that surrounds the thylakoid membrane. Sugars are made in the stroma by the enzymes of the Calvin cycle.

thylakoid

A flattened membranous sac inside a chloroplast. Thylakoid membranes contain chlorophyll and the molecular complexes of the light reactions of photosynthesis. A stack of thylakoids is called a granum.

wavelength

The distance between crests of adjacent waves, such as those of the electromagnetic spectrum.