Cell Energetics

enzyme

protein that acts as a biological catalyst

substrate

The reactant on which an enzyme works.

enzyme-substrate complex

enzyme binds to its substrate

active site

the region on the enzyme where the substrate binds

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.

enzyme specificity

each enzyme catalyzes only one kind of reaction

activation energy (EA)

Energy needed to get a reaction started

cofactors

nonprotein enzyme helpers

coenzymes

organic cofactors

inhibitors

used to slow down a chemical reaction

competitive inhibition

Inhibitor competes with substrate for active site.

noncompetitive inhibition

inhibitor binds elsewhere on the enzyme; alters active site so that the substrate cannot bind

allosteric regulation

When a protein's function at one site is affected by the binding of a regulatory molecule to a separate site.

irreversible inhibition

active site is made unavailable for prolonged period of time or enzyme is permanently altered

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.

catabolic reaction

any chemical reaction that breaks down complex molecules into simpler molecules

anabolic reactions

build up large chemicals and require energy

substrate-level phosphorylation

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

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.

atp synthase

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

cellular respiration equation

C6H12O6 + 6O2 --> 6CO2 + 6H2O + ATP

cellular respiration where?

cytoplasm and mitochondria of each cell of the body

cellular respiration input

glucose and oxygen

cellular respiration output

carbon dioxide, water, and energy (ATP)

cellular respiration is oxygen required?

YES, All aerobic cells require oxygen to perform aerobic cellular respiration

glycolysis

the breakdown of glucose by enzymes, releasing energy and pyruvic acid.

citric acid/krebs cycle

The second stage of aerobic respiration in which many coenzymes form as pyruvate from glycolysis is fully broken down to CO2 and H2O. Two ATP also form. Occurs only in mitochondria.

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.

anaerobic respiration why does it happen?

when a cell does not have enough oxygen to perform normal aerobic respiration

anaerobic respiration difference from aerobic respiration?

Unlike aerobic respiration, oxygen is not necessary for anaerobic respiration to take place

anaerobic respiration input

glucose

anaerobic respiration output

lactic acid in animal muscle cells, while in plant cells it is ethanol (alcohol)

Equation for Photosynthesis

6CO2 + 6H2O ------> C6H12O6 + 6O2

mesophyll cells

cells that contain many chloroplasts and host the majority of photosynthesis

cuticle

The waxy, waterproof layer that covers the leaves and stems of most plants.

stomata (stoma)

Small openings on the underside of a leaf through which oxygen and carbon dioxide can move

guard cells

The two cells that flank the stomatal pore and regulate the opening and closing of the pore.

inner membrane

The membrane of the mitochondria that is the site of electron transport and chemiosmosis.

outer membrane

The outer membrane is the outermost membrane in the mitochondria that protects and holds the form of the organelle.

stroma

fluid portion of the chloroplast; outside of the thylakoids

thylakoid

A flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy.

granum

stack of thylakoids

thylakoid membrane

membrane in a chloroplast where the light reactions of photosynthesis occur

thylakoid space

space inside thylakoid