third bio exam

Aerobic respiration

Catabolic pathway for organic molecules, using oxygen as the final electron acceptor in an electron transport chain and ultimately producing ATP; most efficient catabolic pathway

Cellular respiration

The catabolic pathways of aerobic and anaerobic respiration, which break down organic molecules and use an electron transport chain for the production of ATP

Redox reaction

Chemical reaction involving the transfer of one or more electrons from one reactant to another

Oxidation

The loss of electrons from a substance involved in a redox reaction

Reduction

The addition of electrons to a substance involved in a redox reaction

Reducing agent

The electron donor in a redox reaction

Oxidizing agent

The electron acceptor in a redox reaction

NADH

The reduced form of nicotinamide adenine dinucleotide which temporarily stores electrons during cellular respiration

Electron transport chain

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

Glycolysis

Series of reactions that splits glucose into pyruvate

Citric acid cycle

Chemical cycle within the mitochondrion involving eight steps that completes the metabolic breakdown of glucose molecules to carbon dioxide

Oxidative phosphorylation

The production of ATP using energy derived from the redox reactions of an electron transport chain

Substrate-level phosphorylation

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

Acetyl CoA

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

Cytochrome

Iron-containing protein that is a component of electron transport chains in the mitochondria and chloroplast

ATP synthase

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

Chemiosmosis

Energy-coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as the synthesis of ATP

Proton-motive force

The potential energy stored in the form of an electrochemical gradient, generated by the pumping of hydrogen ions across membranes during chemiosmosis

Alcohol fermentation

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

Lactic acid fermentation

Glycolysis followed by the reduction of pyruvate to lactate, regenerating NAD+ with no release of carbon dioxide

Obligate anaerobe

Organism that only carries out fermentation or anaerobic respiration

Facultative anaerobes

Organism that makes ATP by aerobic respiration if oxygen is present and switches to anaerobic respiration or fermentation if oxygen is not present

Beta oxidation

Metabolic sequence that breaks fatty acids down to two-carbon fragments that enter the citric acid cycle as acetyl CoA

Mesophyll

Leaf cells specialized for photosynthesis, located between the upper and lower epidermis in C3 and CAM plants and between bundle-sheath cells and the epidermis in C4 plants

Stomata

Microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant

Stroma

Dense fluid within the chloroplast surrounding the thylakoid membrane, containing ribosomes and DNA; involved in the synthesis of organic molecules

Thylakoid

Flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy

Chlorophyll

Green pigment found in chloroplasts that participates in the light reactions

6CO2 + 12H2O + light energy -> C6H12O6 + 6O2 + 6H2O

Chemical equation that summarizes the series of chemical reactions in photosynthesis

Light reactions

Reactions that occur on the thylakoid membranes of the chloroplast that convert solar energy to the chemical energy of ATP and NADPH, releasing oxygen in the process

Calvin cycle

Stage of photosynthesis that involves fixation of atmospheric CO2 and the reduction of the fixed carbon into carbohydrate

NADP+

Oxidized form of nicotinamide adenine dinucleotide phosphate, which acts as an electron carrier that can accept electrons, to become NADPH

Photophosphorylation

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

Carbon fixation

Initial incorporation of carbon into organic compounds

Wavelength

The distance between crests of waves

Electromagnetic spectrum

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

Visible light

Portion of the electromagnetic spectrum that is visible to the human eye as various colors (about 380nm-750nm)

Photon

A quantum of light energy that behaves as if it were a particle

Absorption spectrum

The range of a pigment's ability to absorb various wavelengths of light

Chlorophyll a

Photosynthetic pigment that participates directly in the light reactions

Chlorophyll b

An accessory photosynthetic pigment that transfers energy to chlorophyll a

Action spectrum

Graph that profiles the relative effectiveness of different wavelengths of radiation in driving a particular process

Carotenoid

An accessory pigment, either yellow or orange, in the chloroplasts of plants that absorbs wavelengths of light that chlorophyll cannot and broadens the spectrum of colors that can drive photosynthesis

Photosystem

Light-capturing unit located in the thylakoid membrane consisting of a reaction-center complex surrounded by numerous light-harvesting complexes

Light-harvesting complex

Complex of proteins associated with pigment molecules (including chlorophyll a, chlorophyll b, and carotenoids) that captures light energy and transfers it to reaction-center pigments in a photosystem

Reaction-center complex

Complex of proteins associated with a special pair of chlorophyll a molecules and a primary electron acceptor; triggers the light reactions of photosynthesis where the pair of chlorophylls donate an electron to the primary electron acceptor when excited by light energy

Primary electron acceptor

A specialized molecule that shares the reaction-center complex with a pair of chlorophyll a molecules and accepts an electron from them in the thylakoid membrane

Photosystem I (PS I)

Light-capturing unit in the thylakoid membrane that has two molecules of P700 chlorophyll a at its reaction center

Photosystem II (PS II)

Light-capturing unit in the thylakoid membrane that has two molecules of P680 chlorophyll a at its reaction center

Linear electron flow

A route of electron flow during the light reactions of photosynthesis that involves both photosystems and produces ATP, NADPH, and O2; electron flow is from H2O to NADP+

Glyceraldehyde 3-phosphate (G3P)

Three-carbon carbohydrate that is the direct product of the Calvin cycle

Rubisco

Ribulose bisphosphate carboxylase-oxygenase; enzyme that catalyzes the first step of the Calvin cycle (the addition of CO2 to RuBP)

C3 plant

Plant that fixes carbon with rubisco which incorporates CO2 into organic material, forming a three-carbon compound as the first stable intermediate

Photorespiration

Metabolic pathway that consumes oxygen, releases carbon dioxide, generates no ATP, and decreases photosynthetic output; occurs when stomata close and the oxygen concentration in the leaf exceeds that of carbon dioxide

C4 plant

Plant that fixes carbon with an enzyme in mesophyll cells which incorporates CO2 into a four-carbon compound that moves into bundle-sheath cells to release CO2 for the Calvin cycle; able to make sugars even when stomata are partially closed

Crassulacean acid metabolism (CAM)

Process where a plant takes up CO2 and incorporates it into a variety of organic acids at night so that CO2 can be released from organic acids for use in the Calvin cycle during the day

CAM plant

Plant that opens its stomata at night allowing carbon dioxide to diffuse inward and be converted to organic acids, which then release CO2 for the Calvin cycle during the day, when stomata are closed

Fermentation

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