AP Biology Unit 3- Cellular Energetics Vocab

Enzyme

macromolecules that catalyze (speed up) reactions by lowering the activation energy

Substrate

the substance that is acted upon by an enzyme

Enzyme-Substrate Complex

a substrate that is bound into the enzyme

Active Site

an area for substrate to bind to in the enzyme

Activation Energy

the amount of energy that is needed for a reaction to occur

Catalyst

a substance that initiates or accelerates a chemical reaction without itself being affected

pH

a measure of the acidity of a solution

Denature

destroy the characteristic properties of a protein by heat, acidity, or other effects that change its shape

ATP

molecule that organisms use as a source of energy to perform work

Kinetic Energy

energy associated with motion

Potential Energy

stored energy

Free Energy

used to determine the likelihood of reactions in organisms, or if the reactions are energetically favorable

Exergonic Reaction

reactions that release energy
ΔG＜0
reaction is spontaneous

Endergonic Reaction

reactions that absorb energy
ΔG>0
Reaction is not spontaneous

Catabolic Pathway

Pathways that release energy by breaking down complex molecules into simpler compounds

Anabolic Pathway

Pathways that consume energy to build complicated molecules from simpler compounds

Entropy

the measure of disorder in the universe

Energy

the ability to do work

First Law of Thermodynamics

Energy cannot be created or destroyed. Energy can be transferred or transformed

Second Law of Thermodynamics

Energy transformation increases the entropy (disorder) of the universe

C4 Plant

Plants that have their stomata collect and fix carbon to be delivered to the bundle sheath cells and used in photosynthesis.

NADPH

Electron carrier molecule that is used in photosynthesis

Stomata

pores in leaves that allow CO2 in and O2 out

Stroma

aqueous internal fluid of the chloroplast

Thylakoid

form stacks known as grana

Chlorophyll

green pigment in thylakoid membranes

Redox Reactions

reaction involving complete or partial transfer of one or more electrons from one reactant to another

Oxidation

loss of e-

Pigments

molecules that are able to absorb visible light

Photosynthesis

the conversion of light energy to chemical energy

Photons

particles of energy that make up light

Reduction

gain of e-

Heterotrophs

Organisms unable to make their own food so they live off of other organisms

Calvin Cycle

cyclic electron flow that produces G3P

Light Reactions

Converts solar energy to chemical energy

Chloroplast

organelle for the location of photosynthesis

Photosystems

protein complexes found in the thylakoid membrane that contain chlorophyll to collect energy from the sun

Mesophyll

the cells that make up the interior tissue of the leaf

Photorespiration

On very hot days plants close their stomata to stop water loss

G3P

a 3 carbon sugar that is produced during photosynthesis and can be turned into glucose

CAM Plant

Open stomata at night and close during the day then carbon dioxide is incorporated into organic acids and stored in vacuoles

Cellular Respiration

Cells harvest chemical energy stored in organic molecules and use it to generate ATP

NAD+

Electron acceptor molecule that is used in cellular respiration. Used in Glycolysis and Krebs Cycle

FADH+

Electron acceptor molecule that is used in cellular respiration. Used in Krebs Cycle

Glycolysis

-Starting point of cellular respiration
-Occurs in the cytosol
-Splits glucose (6C) into 2 pyruvates (3C)

Pyruvate Oxidation

If oxygen is present, the pyruvate enters the mitochondria (eukaryotic cells) where it is oxidized into acetyl-coA

Krebs Cycle (Citric Acid Cycle)

-Occurs in the mitochondrial matrix
-Turns acetyl CoA into citrate
-Releases CO2
-ATP synthesized
-Electrons transferred to NADH and FADH2

Chemiosmosis

H+ ions flow down their gradient through ATP synthase and produce ATP molecules

ATP Synthase

Protein imbedded in the inner membrane of the mitochondria that uses the power from chemiosmosis to produce ATP

Anaerobic Respiration

generates ATP using an ETC in the absence of oxygen
-The final electron acceptors: sulfates or nitrates

Fermentation

generates ATP without an ETC or oxygen. It is an extension of glycolysis.

Autotroph

Organisms that produce their own food (organic molecules) from simple substances in their surroundings