AP BIO: Unit 3: Cellular Energetics

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

Metabolic Pathway system

Substrate → intermediate → intermediate → Product

Catabolic Pathways

Type of metabolic pathways that release energy by breaking down complex molecules into simpler compounds

Anabolic Pathways

Type of metabolic pathways that consume energy to build complicated molecules from simpler compounds.

Energy

The ability to do work

Survive and function

Organisms need energy to?

death

A loss of energy flow results in?

Kinetic Energy

Energy associated with motion

Thermal energy

Energy associated with the movement of atoms or molecules

Potential Energy

Stored energy

Chemical Energy

Potential energy available for release in a chemical reaction

Thermodynamics

The study of energy transformations in matter

1st Law of Thermodynamics

Energy cannot be created or destroyed

Energy can be transferred or transformed

2nd law of thermodynamics

Energy transformation increases the entropy (disorder) of the universe.

Heat

During energy transfers or transformations, some energy is unusable and often lost as?

Free energy

Scientists use this concept since law of thermodynamics apply to the universe as a whole. This concept is used to determine the likelihood of reactions in organisms, or if the reactions are energetically favorable.

Spontaneous reaction

Reaction where no outside input of energy is required

Exergonic Reactions

Reactions that release energy

Ex: Cellular Respiration

and occur spontaneously, often resulting in a negative change in free energy.

Endergonic Reactions

Reactions that absorb energy

Ex: Photosynthesis

Not spontaneous and absorbs free energy.

equilibrium

Living cells have a constant flow of materials in and out of the membrane meaning they’re not at?

Mechanical cell work

Movement (beating cilia, movement of chromosomes, contraction of muscle cells)

Transport cell work

Pumping substances across membranes against spontaneous movement

Chemical Cell work

Synthesis of molecules (building polymers from monomers)

Adenosine Triphosphate (ATP)

Molecule that organisms use as a source of energy to perform work
Couples exergonic reactions to endergonic reactions to power cellular work

2nd and 3rd phosphate

Organisms obtain energy by breaking the bond between which phosphates in a hydrolysis reaction?

ATp → ADP

Phosphorylation

The released phosphate moves to another molecules to give energy

ATP Cycle

ADP can be regenerated to ATP via?

Enzymes

Macromolecule that catalyze reactions by lowering the activation energy

• Not consumed by reactoin

• Type of protein

• Names end in -ase

1000 years

How long would the hydrolysis of sucrose to glucose take to happen spontaneously?

Substrate

Enzymes act on reactants called?

Active Site

Area for substrate to bind

Induced Fit

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

Enzyme Catabolism

Enzyme helps break down complex molecules

Enzyme Anabolism

Enzyme helps build complex molecules

Temp, pH, chemicals

Enzymes efficiency can be affected by?

Optimal Conditions

Conditions that allow enzymes to function optimally

hydrogen bonds

Being outside the normal pH range can cause _____ _____ in the enzyme to break changing the shape of the enzyme.

Cofactors

Non-protein molecules that assist enzyme function

• Inorganic consist of metals

• Can be bound loosely or tightly

Holoenzyme

Enzyme with the cofactors attached

Coenzymes

Organic cofactors

Ex: Vitamins

Enzyme Inhibitors

Reduce the activity of specific enzymes

• Can be permanent or reversible

Permanent Inhibitor

Inhibitor binds with covalent bonds

Ex: Toxins and poisons

Reversible Inhibitor

Inhibitor binds with weak interactions

Competitive inhibitors

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

• Can be reversed with increased substrate concentrations

Noncompetitive inhibitors

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

• Type of allosteric inhibition

Control where and when enzymes are active

Switch genes that code for enzymes on or off

How does a cell regulate its metabolic pathways?

two (1 active, 1 allosteric)

How many binding sites do allosteric enzymes have?

Allosteric regulation

Molecules bind to an allosteric site which changes the shape and function of the active site

• May result in inhibition or stimulation of the enzymes activity

Allosteric activator

Substrate binds to allosteric site and stabilizes the shape of the enzyme so that the active sites remain open

Allosteric inhibitor

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

Cooperativity

Substrate binds to one active site which stabilizes the active form.

• Considered allosteric regulation since binding at one site changes the shape of the other sites

Feedback inhibition

When the end product of a metabolic pathway acts as an inhibitor to an early enzyme in the same pathway.