Campbell Biology in Focus - Chapters 6 to 9 Vocabulary Flashcards

Vocabulary flashcards covering metabolism, cellular respiration, photosynthesis, and the cell cycle from Campbell Biology in Focus, Chapters 6 through 9.

Metabolism

The totality of an organism's chemical reactions, arising from orderly interactions between molecules.

Catabolic Pathways

Metabolic pathways that release energy by breaking down complex molecules into simpler compounds.

Anabolic Pathways

Metabolic pathways (also called biosynthetic pathways) that consume energy to build complex molecules from simpler ones.

Bioenergetics

The study of how energy flows through living organisms.

Kinetic Energy

Energy associated with motion.

Thermal Energy

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

Heat

Thermal energy in transfer from one object to another.

Potential Energy

Energy that matter possesses because of its location or structure.

Chemical Energy

Potential energy available for release in a chemical reaction.

Thermodynamics

The study of energy transformations.

First Law of Thermodynamics

The principle stating that the energy of the universe is constant; energy can be transferred and transformed, but it cannot be created or destroyed.

Second Law of Thermodynamics

The principle stating that every energy transfer or transformation increases the entropy (disorder) of the universe.

Entropy

A measure of molecular disorder, or randomness.

Spontaneous Process

A process that occurs without energy input and leads to an increase in the entropy of the universe.

Free Energy

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

Exergonic Reaction

A spontaneous chemical reaction that proceeds with a net release of free energy ($\Delta G < 0$).

Endergonic Reaction

A nonspontaneous chemical reaction that absorbs free energy from its surroundings ($\Delta G > 0$).

Energy Coupling

The use of an exergonic process to drive an endergonic one.

ATP (Adenosine Triphosphate)

A molecule composed of ribose, adenine, and three phosphate groups that acts as the primary energy source for cellular work.

Phosphorylation

The transfer of a phosphate group from ATP to another molecule, such as a reactant.

Phosphorylated Intermediate

A recipient molecule that receives a phosphate group from ATP, making it more reactive than the original molecule.

Catalyst

A chemical agent that speeds up a reaction without being consumed by the reaction.

Enzyme

A macromolecule (typically a protein) that acts as a catalyst to speed up metabolic reactions.

Activation Energy ($E_A$)

The amount of energy required to start a reaction by contorting reactant molecules so their chemical bonds can break.

Substrate

The reactant molecule on which an enzyme acts.

Active Site

The specific region on an enzyme to which the substrate binds.

Induced Fit

The change in shape of an enzyme's active site due to chemical interactions with the substrate to bring active site chemical groups together.

Cofactors

Nonprotein molecules that help carry out processes that are difficult for amino acids during enzyme catalysis.

Coenzyme

An organic cofactor, such as vitamins or vitamin derivatives.

Competitive Inhibitors

Enzyme inhibitors that bind directly to the active site of an enzyme and prevent the substrate from binding.

Noncompetitive Inhibitors

Enzyme inhibitors that bind to an alternate site on the enzyme, causing the active site to change shape and become less effective.

Allosteric Regulation

The process in which a protein's function at one site is affected by the binding of a regulatory molecule to a separate site.

Cooperativity

A form of allosteric activation where the binding of one substrate molecule to the active site of one subunit locks all other subunits into the active shape.

Feedback Inhibition

A metabolic pathway regulation method where the end product shuts down the pathway by inhibiting an enzyme that functions early in the pathway.

Fermentation

A catabolic process that partially breaks down organic molecules without using $O_2$ or an electron transport chain.

Aerobic Respiration

The most efficient catabolic pathway, which consumes $O_2$ and organic molecules to produce ATP.

Anaerobic Respiration

A catabolic pathway similar to aerobic respiration that consumes electronegative compounds other than $O_2$ as the final electron acceptor.

Redox Reactions

Chemical reactions that transfer electrons between reactants (oxidation-reduction reactions).

Oxidation

The loss of electrons from a substance during a redox reaction.

Reduction

The gain of electrons by a substance during a redox reaction.

Reducing Agent

The electron donor in a redox reaction, which reduces the electron acceptor.

Oxidizing Agent

The electron acceptor in a redox reaction, which oxidizes the electron donor.

NAD+

Nicotinamide adenine dinucleotide, a coenzyme that functions as an electron carrier and oxidizing agent during cellular respiration.

Electron Transport Chain

A sequence of electron carrier molecules that shuttle electrons down a series of redox reactions that release energy used to make ATP.

Glycolysis

A series of reactions in the cytosol that splits a 6-carbon glucose molecule into two 3-carbon pyruvate molecules.

Citric Acid Cycle

An 8-step chemical cycle that completes the metabolic breakdown of glucose molecules by oxidizing acetyl CoA to $CO_2$ in the mitochondrial matrix.

Oxidative Phosphorylation

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

Substrate-Level Phosphorylation

The enzyme-catalyzed formation of ATP by the direct transfer of a phosphate group from an intermediate substrate molecule to ADP.

Chemiosmosis

An energy-coupling mechanism that uses energy stored in an $H^+$ ion gradient across a membrane to drive cellular work, such as ATP synthesis.

ATP Synthase

A protein complex that uses the exergonic flow of $H^+$ ions down their concentration gradient to drive the phosphorylation of ADP into ATP.

Proton-Motive Force

The potential energy stored in an $H^+$ electrochemical gradient across a membrane.

Alcohol Fermentation

A process of anaerobic metabolism where pyruvate is converted to ethanol in two steps, releasing $CO_2$ and oxidizing NADH to $NAD^+$.

Lactic Acid Fermentation

A process of anaerobic metabolism where pyruvate is reduced directly by NADH to form lactate without releasing $CO_2$.

Obligate Anaerobes

Organisms that carry out only fermentation or anaerobic respiration and cannot survive in the presence of $O_2$.

Facultative Anaerobes

Organisms, such as yeast and many bacteria, that can produce ATP using cellular respiration in the presence of $O_2$ or fermentation when $O_2$ is absent.

Beta Oxidation

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

Autotrophs

Organisms that make organic molecules entirely from non-living materials and act as producers in the biosphere.

Heterotrophs

Organisms that live on compounds produced by other organisms and act as consumers in the biosphere.

Photoautotrophs

Organisms that use light energy plus $CO_2$, water, and minerals to synthesize organic molecules.

Mesophyll

The interior tissue of a leaf where chloroplasts are mainly concentrated.

Stomata

Microscopic pores in leaves through which $CO_2$ enters and $O_2$ exits.

Stroma

The dense fluid surrounded by a double membrane within the chloroplast.

Thylakoids

A third membrane system in chloroplasts consisting of connected membranous sacs suspended within the stroma.

Chlorophyll

A green photosynthetic pigment located in the thylakoid membranes of chloroplasts that absorbs light energy.

Light Reactions

The first stage of photosynthesis occurring in thylakoid membranes that converts solar energy into chemical energy in ATP and NADPH.

Calvin Cycle

The second stage of photosynthesis occurring in the stroma that uses ATP and NADPH to convert $CO_2$ into sugar.

Photophosphorylation

The process of generating ATP from ADP and inorganic phosphate during the light reactions of photosynthesis using chemiosmosis.

Carbon Fixation

The initial incorporation of carbon from $CO_2$ into organic molecules.

Wavelength

The distance between crests of electromagnetic waves.

Photons

Discrete particles of light energy that possess a fixed quantity of energy inversely proportional to wavelength.

Absorption Spectrum

A graph plotting a pigment's light absorption versus wavelength.

Action Spectrum

A graph profiling the relative effectiveness of different wavelengths of radiation in driving photosynthesis.

Chlorophyll a

The primary photosynthetic pigment in plants and algae that absorbs violet-blue and red light.

Carotenoids

Accessory photosynthetic pigments that function in photoprotection by absorbing excessive light that would damage chlorophyll a.

Photosystem

A light-capturing structure in thylakoid membranes consisting of a reaction-center complex surrounded by light-harvesting complexes.

Linear Electron Flow

The primary pathway of electron transfer during the light reactions that uses PS II and PS I to synthesize ATP and NADPH.

Rubisco

RuBP carboxylase/oxygenase, the enzyme that catalyzes carbon fixation in phase 1 of the Calvin cycle.

Photorespiration

A wasteful metabolic process in which rubisco fixes $O_2$ instead of $CO_2$, consuming ATP and organic fuel without producing ATP or sugar.

C4 Plants

Plants that minimize photorespiration by spatially separating carbon fixation in mesophyll cells from the Calvin cycle in bundle-sheath cells.

CAM Plants

Succulent plants adapted to arid climates that temporarily separate carbon fixation at night from the Calvin cycle during the day.

Genome

All the DNA contained within a single cell.

Chromosomes

Cellular structures consisting of DNA molecules packaged with proteins.

Chromatin

The complex of DNA and protein that makes up eukaryotic chromosomes.

Somatic Cells

All nonreproductive cells in a multicellular organism, containing 46 chromosomes in humans.

Gametes

Reproductive cells (sperm and eggs) containing half as many chromosomes as somatic cells.

Sister Chromatids

Joined copies of the original chromosome produced after DNA replication.

Centromere

The specific region on a duplicated chromosome where two sister chromatids are most closely attached.

Mitosis

The division of the genetic material in the eukaryotic nucleus.

Cytokinesis

The division of the cytoplasm that produces two separate daughter cells.

Interphase

The long cell cycle stage (about 90% of the cycle) consisting of $G_1$, S, and $G_2$ phases, during which the cell grows and copies its DNA.

Mitotic Spindle

A structure made of microtubules and associated proteins that controls chromosome movement during mitosis.

Centrosome

A subcellular microtubule organizing center that duplicates in interphase to form the spindle poles in animal cells.

Kinetochores

Protein complexes assembled on centromeric regions of DNA where spindle microtubules attach.

Metaphase Plate

An imaginary structure midway between the spindle's two poles where centromeres align at metaphase.

Cleavage Furrow

A shallow groove in the cell surface near the old metaphase plate that forms during cytokinesis in animal cells.

Cell Plate

A structure formed by vesicles during cytokinesis in plant cells that develops into a new cell wall.

Binary Fission

A method of asexual reproduction in prokaryotes where a single chromosome replicates starting at the origin of replication and the cell splits into two.

G0 Phase

A nondividing state entered by cells that do not receive a go-ahead signal at the $G_1$ checkpoint.

Growth Factors

Proteins released by certain cells that stimulate other cells to divide.

Density-Dependent Inhibition

A phenomenon in which crowded animal cells stop dividing.