AP Biology Unit 3

AP Biology Unit 3 Flashcard

Metabolism

All of the chemical reactions in an organism

Metabolic Pathways

Series of chemical reactions that either build complex molecules or break down complex molecules

Catabolic Pathways

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

Anabolic Pathways

Pathways that consume energy to build complicated molecules from simpler compounds

Thermodynamics

the study of energy transformations in matter

1st Law of Thermodynamics

Energy cannot be created or destroyed, only transformed from one form to another.

2nd Law of Thermodynamics

Energy transformation increases the entropy of the universe. During energy transfers or transformations some energy is unusable and often lost as heat.

Exergonic Reactions

Reactions that release energy

Endergonic Reactions

Reactions that absorb energy

Mechanical

movement

Transport

pumping substances across membranes against spontaneous movement

Chemical

Synthesis of molecules

Adenosine Triphosphate

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

Phosphorylation

the released phosphate moves to another molecule to give energy

Enzymes

macromolecules that catalyze reactions, lowering the activation energy

Induced Fit

Enzyme will change the shape of their active site to allow the substrate to bind better

Optimal Conditions

The conditions (temperature and pH) that allow enzymes to function optimally

Cofactors

non-protein molecules that assist in enzyme function

Holoenzyme

an enzyme with the cofactor attached

Coenzymes

Organic cofactors

Enzyme Inhibitors

Reduce the activity of specific enzyme

Competitive Inhibitors

Reduce enzyme activity by blocking substrates from binding to the active site.

Noncompetitive Inhibitors

Bind to an area other than the active site which changes the shape of the active site prevents substrates from binding

Allosteric Regulations

molecules bind (noncovalent allosteric interactions) to an allosteric site which changes the shape and function of the active site

Allosteric Inhibitor

Substrate binds to allosteric site and stabilizes the enzyme shape so that the active sites are closed

Cooperativity

Substrate binds to one active site (on an enzyme with more than one active site) which stabilizes the active form

Feedback Inhibition

Sometimes the end product of a metabolic pathway can act as the inhibitor to an early enzyme in the same pathway

Autotrophs

Organisms that produce their own food from simple substances in their surroundings

Heterotrophs

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

Cyanobacteria

early prokaryotes capable of photosynthesis

Photosynthesis Formula

6CO2+6H2O+Light Energy —→ C6H12O6+6O2

Redox Reaction

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

Oxidation

Loss of electrons

Reduction

Gain of electrons

Light

Electromagnetic energy

Wavelength

the distance from the crest of one wave to the crest of the next

Photorespiration

On very hot days plants close their stomata to stop water loss. Causes less Carbon Dioxide to be present and more oxygen. Rubisco binds to oxygen and uses ATP

C4 Plants

Spatial separation of steps. Stomata partially close to conserve water. Mesophyll cells fix Carbon dioxide into a 4-C molecule. Transferred to bundle sheath cells.

CAM Plants

Open stomata at night and close during the day. Carbon dioxide is incorporated into organic acids and stored in vacuoles. During the day, light reactions and Carbon dioxide is released from the organic acids and incorporated into the Calvin Cycle.

Electron Transport Chain

a sequence of membrane proteins that shuttle electrons down a series of redox reactions

Glycolysis

1. Starting point of cellular respiration

2. Occurs in the cytosol

3. Splits glucose (6C) into pyruvates (3C)

Energy Investment Stage

the cell uses ATP to phosphorylate compounds

Energy Payoff Stage

Energy is produced by substrate level phosphorylation.
Net energy yield per one glucose: 2 ATP @ NADH

Citric Acid Cycle

1. Also known as the Krebs cycle

2. Occurs in the mitochondrial matrix

3. Turns acetyl CoA into Citrate. Releases CO2 ATP synthesized; electrons transferred to NADH and FADH2

ATP Synthase

The enzyme that makes ATP from ADP+
1. Uses energy from the H+ gradient across the membrane
2. H+ ions flow down their gradient through ATP synthase.

Anaerobic Respiration

Generates ATP using an ETC in absence of oxygen. Takes place in prokaryotic organisms that live in environments with no oxygen.

Fermentation

Generates ATP without an ETC. Extension of glycolysis. Recycless NAD+

Alcohol Fermentation

Pyruvate is converted to ethanol

Lactic Acid Fermentation

Pyruvate is reduced directly by NADH to form lactate