Enzymes and Cellular Processes

Flashcards reviewing key concepts about enzymes, photosynthesis, and cellular respiration.

Enzymes are typically __.

Proteins (though some RNAs can act as enzymes)

Enzymes catalyze reactions by lowering the __.

Activation energy

Enzymes exhibit high specificity due to their __ complementing the shape and charge of their substrate.

Active site

Enzymes possess secondary, tertiary, and quaternary structures stabilized by __.

Hydrogen bonds, ionic bonds, hydrophobic clustering

Environmental changes can lead to __, which is when the enzyme's shape changes, reducing or eliminating its function.

Denaturation

Enzymes have a __ at which they function most efficiently.

pH optimum

Up to a certain point, enzyme activity increases with temperature due to increased __.

Kinetic energy

Restoration of optimal conditions restores the enzyme's function in __.

Reversible denaturation

The enzyme's shape is permanently changed, and its catalytic ability is destroyed in __.

Irreversible denaturation

Eventually, a __ is reached where all enzymes have their active sites engaged with the substrate, leading to a peak in the reaction rate.

Saturation point

In competitive inhibition, the inhibitor binds to the __.

Active site

In non-competitive inhibition, the inhibitor binds to the __.

Allosteric site

Organisms that produce their own food are called __.

Autotrophs

Organisms that obtain energy by consuming organic compounds are called __.

Heterotrophs

A linked series of enzyme-catalyzed chemical reactions occurring within a cell is a __.

Metabolic pathway

Reactions that release energy are called __.

Exergonic reactions

Reactions that require energy are called __.

Endergonic reactions

The linking of an exergonic reaction to an endergonic reaction is known as __.

Energy coupling

During photosynthesis, plants use light energy to combine __ to create carbohydrates.

Carbon dioxide and water

Photosynthesis is an __ reaction because it converts low-energy inputs into a high-energy product.

Endergonic

The two phases of photosynthesis are __.

Light reactions and Calvin cycle

__ is the pigment that absorbs light energy in photosynthesis.

Chlorophyll

The light reactions of photosynthesis occur in the __.

Thylakoids

The Calvin cycle occurs in the __ of the chloroplast.

Stroma

__ are complex assemblies of proteins with embedded chlorophyll molecules that convert light energy into a flow of electrons.

Photosystems

Protons diffuse through the __ channel, an enzyme that uses their kinetic energy to power the endergonic reaction of turning ADP and phosphate into ATP.

ATP synthase

Electrons flow through the electron transport chain of photosystem one to __, an enzyme that reduces NADP+ into NADPH.

NADP+ reductase

The __ is a graphical representation of the light reactions, showing electron energy.

Z scheme

The three phases of the Calvin cycle are __.

Carbon fixation, energy investment and harvest, regeneration of RuBP

Carbon dioxide is combined with RuBP, a reaction catalyzed by the enzyme __.

Rubisco

This yields __, also known as PGAL.

Glyceraldehyde-3-phosphate (G3P)

The phases of cellular respiration, in order, are __.

Glycolysis, link reaction, Krebs cycle, electron transport chain

Glycolysis occurs in the __.

Cytoplasm

The end product of glycolysis is __.

Pyruvic acid (pyruvate)

Pyruvate enters the __ and is converted into acetyl CoA.

Mitochondrial matrix

Enzymes oxidize the two carbons in acetyl CoA in the __.

Krebs cycle

The electron transport chain (ETC) is located in the __.

Inner mitochondrial membrane

Protons flow down the electrochemical gradient through __, an enzyme-channel.

ATP synthase

Hormones induce the formation of __ (also known as UCP, uncoupling protein), a protein channel in the inner mitochondrial membrane.

Thermogenin

Aerobic respiration generates __ per glucose molecule.

Approximately 32 ATP

Anaerobic respiration generates __ per glucose molecule.

2 ATP

__ is glycolysis followed by reactions that regenerate NAD+.

Fermentation

The products of alcohol fermentation are __.

Ethanol and CO2

The product of lactic acid fermentation is __.

Lactic acid