Campbell Biology Chapter 8,9,&10

Metabolism

The totality (all) of the chemical reactions that occur within an organism; Manages the material and energy resources of the cell.

Metabolic Pathway

Begins with a specific molecule(s), which is then altered in a series of defined steps, resulting in a certain product(s). Each step in the pathway is catalyzed by a specific enzyme.

Catabolic Pathways

Breaks down complex molecules to simpler compounds; Releases energy. (i.e. cellular respiration)

Anabolic Pathways

Consumes energy to build complicated molecules from simpler ones. (also called biosynthetic pathways) (i.e. synthesizing proteins from amino acids)

Bioenergetics

The study of how energy flows through living organisms; how an organism manages their energy.

Energy

The ability to cause change. Some forms of energy can be used to do work (move matter against opposing forces).

Kinetic Energy

The energy an object has due to its motion.

Heat (Thermal Energy)

Kinetic energy associated with the random movement of atoms or molecules.

Potential Energy

The energy stored by matter as a result of its location or spatial arrangement.

Chemical Energy

Potential energy available for release in a chemical reaction.

Thermodynamics

The study of energy transformations that occur in a collection of matter. Closed systems and Open systems (organisms are Open systems)

First Law of Thermodynamics

The principle of conservation of energy: Energy can be transferred and transformed, but it cannot be created or destroyed.

Entropy

A quantitative measure of disorder or randomness, symbolized by S.

Second Law of Thermodynamics

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

Spontaneous Process

A process that can occur without an input of energy. (For a process to occur without an input of energy it must increase the entropy of the universe.)

Free Energy

The portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system.

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.

A cell's 3 main kinds of work

Chemical, transport, and mechanical.

Energy Coupling

In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction.

ATP is composed of

Ribose, Adenine (nitrogenous base), and 3 phosphate groups.

Activation Energy

The energy needed to start a chemical reaction.

Enzyme's Substrate

The reactant that an enzyme acts on.

Enzyme-Substrate Complex

A temporary complex formed when an enzyme binds to its substrate molecule(s).

Active Site

The specific portion of an enzyme that attaches to the substrate by means of weak chemical bonds.

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.

An enzyme's activity can be affected by

Temperature, pH, and chemicals that influence the enzyme.

Cofactors

Non-protein molecule or ion that is required for the proper functioning of an enzyme, can be permanently bound to the active site or may bind loosely and reversibly along the substrate during catalysis

Coenzyme

An organic molecule serving as a cofactor. Most vitamins function in important metabolic reactions.

Competitive Inhibitors

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

Noncompetitive Inhibitors

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

Allosteric regulation

the binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site.

Cooperativity

A kind of allosteric regulation whereby a shape change in one subunit of a protein caused by substrate binding is transmitted to all the others, facilitating binding of subsequent substrate molecules.

Feedback Inhibition

A method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.

Fermentation

A partial degradation of sugars, or other organic fuel that occurs without the use of oxygen.

Energy Flow and Chemical Recycling in Ecosystem

Energy flows into an ecosystem as sunlight and ultimately leaves as heat, while the chemical elements essential to life are recycled.

Food provides food for cellular respiration exhausting carbon dioxide and water

Organic + Oxygen ---> Carbon + Water + Energy
Compounds Dioxide

Aerobic Respiration

Oxygen is consumed as a reactant along with the organic fuel.

Cellular Respiration

The metabolic processes whereby certain organisms obtain energy from organic molecules; aerobic and anaerobic.

Cellular Respiration Diagram

Summary Equation (Cellular Respiration)

Redox Reactions

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

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.

Oxidizing Agent

The electron acceptor in a redox reaction.

Reducing Agent

The electron donor in a redox reaction.

NAD+

An organic molecule that serves as an electron carrier by being oxidized to NAD+ and reduced to NADH.

NADH

the reduced form of NAD+; an electron-carrying molecule that functions in cellular respiration.

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. (O2 pulls electrons down the chain)

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; first step in cellular respiration.

Citric Acid Cycle (Krebs cycle)

In cellular respiration, series of chemical reactions that break down glucose and produce ATP; energizes electron carriers that pass the energized electrons on to the electron transport chain; second step in cellular respiration.

Oxidative Phosphorylation

The production of ATP using energy derived from the redox reactions of an electron transport chain; generates almost 90% of the ATP; the third major stage of cellular respiration.

Oxidative Phosphorylation

Substrate-level Phosphorylation

The formation of ATP by an enzyme directly transferring a phosphate group to ADP from an intermediate substrate in catabolism; occurs during glycolysis and the citric acid cycle.

Cytochromes

An iron-containing protein that is a component of electron transport chains in the mitochondria and chloroplasts of eukaryotic cells and the plasma membranes of prokaryotic cells.

Acetyl CoA

The entry compound for the citric acid cycle in cellular respiration formed from two-carbon fragment of pyruvate attached to a coenzyme

ATP Synthase

Large protein that uses energy from H+ ions to bind ADP and a phosphate group together to produce ATP.

Chemiosmosis

An energy-coupling mechanism that uses energy stored in the form of a H+ gradient across a membrane to drive cellular work, such as the synthesis of ATP. Most ATP synthesis in cells occurs by chemiosmosis.

Proton-motive Force

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

Alcohol Fermentation

Anaerobic ATP-forming pathway. Pyruvate from glycolysis is degraded to acetaldehyde, which accepts electrons from NADH to form ethanol; NAD+ needed for the reactions is regenerated. Net yield: 2 ATP.

Lactic Acid Fermentation

series of anaerobic chemical reactions in which pyruvic acid uses NADH to form lactic acid and NAD+, which is then used in glycolysis; supplies energy when oxygen for aerobic respiration is scarce; releases no CO2.

Obligate Anaerobes

an organism that only carries out fermentation or anaerobic respiration. Cannot survive in the presence of O2.

Facultative Anaerobes

An organism that makes ATP by aerobic respiration if oxygen is present but that switches to fermentation under anaerobic conditions.

Beta Oxidation

A metabolic sequence that breaks fatty acids down to two-carbon fragments which enter the Krebs cycle as acetyl CoA.

Photosynthesis

The process that converts solar energy into chemical energy.

Autotrophs

Organisms that are able to make their own food

Heterotrophs

organisms that depend on other organisms for their food

Chlorophyll

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

Stomata

Pore-like openings in leaves that allow gases (CO2 enters and O2 exits) and water to diffuse in and out of the leaves.

Mesophyll

the tissue in the interior of the leaf
(30-40 chloroplasts)

Thylakoids

saclike photosynthetic membrane found in chloroplasts. when stacked they are called grana

Stroma

the dense colorless fluid in the chloroplast.

Oxidized in photosynthesis

H2O

Reduced in photosynthesis

CO2

Light reactions

In thylakoids H2o is split, releases O2, reduces NADP+ to NADPH, makes ATP from ADP by photophosphorylation .

Calvin cycle

In stroma forms sugar from CO2 using ATP and NADPH; Begins with carbon fixation.

Carbon fixation

The incorporation of CO2 into organic compounds

Wavelength

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

Electromagnetic spectrum

the entire frequency range of electromagnetic waves

Photons

particles of light.

Spectrophotometer

Measures the ability of a pigment to absorb various wavelengths of light

Absorption spectrum

a graph plotting a pigment's light absorption versus wavelength

Chlorophyll a

A type of blue-green photosynthetic pigment that participates directly in the light reactions.

Action spectrum

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

Chlorophyll b

A type of yellow-green accessory photosynthetic pigment that transfers energy to chlorophyll a.

Carotenoids

accessory pigment; absorb excessive light that would damage chlorophyll

Photosystem

in the thylakoid membranes of chloroplasts, a cluster of chlorophyll and other pigment molecules that harvest light energy for the light reactions of photosynthesis

Reaction-center complex

A complex of proteins associated with a special pair of chlorophyll, a molecule, and a primary electron acceptor. Located centrally in a photosystem, this complex triggers the light reactions of photosynthesis. Excited by light energy, the pair of chlorophylls donates an electron to the primary electron acceptor, which passes an electron to an electron transport chain.

light-harvesting complexes

(pigment molecules bound to proteins) funnel the energy of photons to the reaction center

Primary electron acceptor

A specialized molecule sharing the reaction center with the chlorophyll a molecule; it accepts an electron from the chlorophyll a molecule.

Photosystem ll

functions first and is the best at absorbing a wavelength of 680 nm (P680)

Photosystem l

(P700) occurs 2nd

Linear electron flow

Primary Pathway: involves both photosystems and produces ATP and NADPH using light energy

Cyclic electron flow

uses only photosystem I and produces ATP, but not NADPH

Chemiosmosis

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

Glyceraldehyde-3-phosphate (G3P)

A three-carbon carbohydrate that is the direct product of the Calvin cycle; it is also an intermediate in glycolysis.

3 Phases of the Calvin Cycle

Carbon fixation, Reduction, Regeneration of the CO2 acceptor (RuBP)

Rubisco

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

Photorespiration

a metabolic pathway in plants that consumes oxygen, produces carbon dioxide, generates no ATP, and reduces photosynthesis

Mesophyll cells

more loosely arranged cells between the bundle sheath and leaf surface cells (C4)