AP Biology Unit 3

Enzymes

These are biological catalysts that are usually composed of proteins in the tertiary stage.

Ribozymes

Enzymes that are composed of RNA instead of proteins.

Substrate

The substance or composition that binds to the active site of an enzyme to kick start a reaction. It must have a specific shape to the active site and compatible charge to the active site.

Active Site

The part of an enzyme where the substrate binds to. It must have a specific shape for the substrate and compatible charge with the substrate.

Competitive Inhibitors

Inhibitors that have the same shape as the substrate and bind to the active site. Increasing substrate concentration can lower the effect of these.

Allosteric Inhibitor

Inhibitors that binds to another part of the enzyme therefore changing the shape of the active site. It functions in feedback mechanisms, suiting changes to environment conditions.

Cofactors

Inorganic molecules that increase the efficiency of enzyme-catalyzed reactions, usually binding to the active site ofr substrate.

Coenzymes

Organic molecules that increase the efficiency of enzyme-catalyzed reactions, usually binding to the active site ofr substrate.

Endergonic Reactions

Reactions that result in a positive net change in free energy, considered energetically unfavorable.

Exergonic Reactions

Reactions that result in a negative net change in free energy, considered energetically favorable.

Activation Energy

The energy input required to kickstart a reaction. Enzymes can lower this by…

1. Bringing substrates into correct orientation.

2. Temporarily binding ionically or covalently with substrates.

3. Bending the bonds of the substrate (destabilizing).

First Law of Thermodynamics

Energy cannot be created or destroyed, but only transfered.

Second Law of Thermodynamics

With each energy transfer, the disorder (entropy) of the universe is always increasing.

Coupled Reactions

Reactions that combine exergonic and endergonic reactions in living organisms.

Heterotrophs

Living organisms that consume other organisms for organic molecules.

Autotrophs

Organisms that produce their own organic molecules through inorganic molecules.

Photoautotrophs

Organisms that use light energy to power their own system.

Photosynthesis

A process in plants (rarely in prokaryotes) that takes place in the chloroplasts, using light energy to produce sugar and oxygen.

Light-dependent Reactions

A process in photosynthesis that occurs in the thylakoids of the chloroplast’s membranes.

Light-independent Reactions

A process in photosynthesis that occurs in the stroma of the chloroplast.

Photophosphorylation

When light energy is used to power the production of ATP.

Photolysis

When light energy is used to separate water molecules into oxygen, protons, and electrons.

Chemiosmosis

The process where ATP synthase and the proton gradient work together to create ATP.

Fixation

A process where something is transformed from unusable to usable.

Reduction

In photosynthesis in the light-independent reaction, the process where G3P is produced.

Regeneration

The process in photosynthesis found in the light-independent reaction where 5 G3P molecules form 3 RuBP molecules (using more ATP formed from the light-dependent reactions).

NADP+ Reductase

The enzyme in the light-dependent reaction that is used to form NADPH using protons and electrons.

Photosystem 1

The second photosystem in the light-dependent reaction chain, absorbing light energy of around 700nm.

Photosystem 2

The first photosystem in the light-dependent reaction chain, absorbing light energy of around 680nm.

Rubisco

The enzyme that catalyzes CO2 by adding it to a 5-carbon RuBP to form a 6 carbon intermediate.

RuBP

A 5 carbon molecule that is used to bond to CO2 to create a 6-carbon intermediate in the Calvin Cycle.

Cellular Respiration

The process that produces CO2, H2O, and ATP

Anaerobic Organisms

These organisms do not require oxygen and can only perform glycolysis and fermentation.

Aerobic Organisms

These organisms can and don’t have to use oxygen. They can also perform glycolysis and fermentation, but much more as well.

Glycolsis

The process of cellular respiration that occurs in the cytosol and uses glucose, 2NAD+, and 2ATP to produce 4ATP, 2NADH, and 2 pyruvates.

Oxidation of Pyruvate

The process of cellular respiration that occurs in the mitochondria of the cell where 1 pyruvate is oxidized, NAD+ is reduced into NADH, CO2 is released, and one acetyl group remains. Happens twice for one cycle of cellular respiration.

Kreb’s Cycle

The process of cellular respiration that occurs in the matrix of the mitochondria where 1 ATP, 1 FADH2, 3NADH, and 2CO2 is produced.

Substrate-Level-Phosphorylation

The formation of ATP using a phosphate group and ADP without a electron transport chain or chemiosmosis.

Oxidative Phosphorylation

The process of cellular respiration that occurs in the matrix of the mitochondria where 34 ATP is produced as NADH and FADH2 are oxidized.

Fermentation

The process when oxygen is not present in cellular respiration and therefore oxidative phosphorylation cannot occur. Occurs in the cytosol.

Alcoholic Fermentation

The type of fermentation where the pyruvate and NADH produce CO2, NAD+, and ethanol (2C).

Lactic Acid

The type of fermentation where the pyruvate and NADH produce NAD+ and lactic acid (3C).