Bio unit 2

Kinectic energy

• energy of an active movement

Potential energy

• energy stored in an object based on its position and chemical structure

• In cells, it exists in chemical bonds or across membranes

Oxidation reactions

• atom or molecule loses an electron or hydrogen

• always coupled

Reduction reactions

• atom or molecules gains an electron or hyrdogen

• always coupled

First Law of Thermodynamics

• energy cannot be created or destroyed only transformed

Second Law Thermodynamics

• every energy transfer increases entropy (disorder)

• Biological systems maintain order by coupling energy-requiring processes to energy-releasing ones

Negative ΔG

• spontaneous

• exergonic

Postive ΔG

• non spontaneous

• endergonic

How is free energy related to the outcome of chemical reactions

• ΔG depends on enthalpy, entropy, and reactant/product concentrations

Enzyme

• lower activation energy, increasing reaction rate without altering ΔG or equilibrium

Uncatalyzed reactions

• proceed slowly because fewer molecules reach the transition state

Catalyzed reactions

• stabilize the transition state and provide an alternative reaction pathway

Enzyme as a biological catalysts

• accelerate biochemical reactions by binding substrates, orienting them correctly, and stabilizing transition states

• often require cofactors or coenzymes

• enable metabolism to occur at physiological temps

What influences enzyme catalyzed reaction rates?

• temperature, ph, substrate concentration, enzyme concentration

• extreme temps and ph can cause denaturation

Competitive inhibitors

• bind the active site and compete with substrate

Noncompetitive inhibitors

• bind to an allosteric site, altering enzyme conformation

Biochemical pathways

• organize reactions into regulated sequences

• prevents wasteful overproduction and maintains metabolic balance

Feedback inhibition

• occurs when the end product binds an enzyme early in the pathway, reducing activity

• Prevents wasteful overproduction and maintains metabolic balance

What is the role of ATP in short term energy storage

• stores energy in high energy bonds

• hydrolysis releases energy that drives cellular work

• rapidly regenerated through cellular respiration

• is the cells immediate energy currency

How is ATP related to control of protein activity

• ATP often regulates proteins through phosphorylation

• Kinases transfer phosphate groups from ATP to target proteins, altering shape and activity

• Controls signaling pathways, enzyme activity, and cellular responses

Autotrophs

• generate organic molecules from inorganic carbon (CO2) using light energy (photoautotrophs) or chemical energy (chemoautotrophs)

• They form the foundation of ecosystems by producing biomass

Heterotrophs

• cannot fix for carbon

• they must consume organic molecules produced by organisms

• they rely on external sources for both energy and carbon skeletons

Electrons

• carry chemical energy through redox reactions

• as substrates are oxidized, high energy electrons transferred to carries

  • ex. NAD+, FAD forming NADH and FADH2

Electron Carriers

• deliver electrons to electron transport chain where sequential redox reactions release energy used to pump protons and drive ATP synthesis via oxidative phosphorylation

Glycolysis

• 1st in reactions

• In the cytosol

• 2 ATP (net) molecules by substrate - level phosphorylation

• 2 NADH produced by the reactions of NAD+

Pyruvate Oxidation

• 2nd in reactions

• Occurs in the mitochondrial matrix of eukaryotes

• Plasma membrane of prokaryotes

• CO2 reduces NAD to NADH and attaches to CoA to form acetyl- CoA

Pyruvate

• is oxidized in the presence of oxygen

Krebs Cycle

• 3rd in reactions

• Oxidizes the acetyl group from pyruvate

• Occurs in the mitochondrial matrix

• Acetyl-CoA enters the cycle and releases two CO2 per acetyl group

• cycle generates 3 NADH, 1 FADH2, and 1 ATP per acetyl-CoA via substrate-level phosphorylation

Electron transport chain/ chemiosis

• 4th in reactions

• occurs in inner membrane

What is happening with this Redox reaction?

A: + B → A+ + B-

• A is oxidized; B is reduced

For an endergonic reaction is the level of reactants more or less than the energy level of the products.

• less

For an exergonic reaction is the level of reactants more or less than the energy level of the products.

• more

What type of inhibitory molecule binds to an enzymes’s active sight

• competitive inhibitor

What type of inhibitory molecule binds to the enzyme at a location that is not the active sight

• allosteric inhibitor

OIL RIG

• oxidation is loss

• reduction is gained

What is an example of First Law of thermodynamics

• cells convert chemical energy in food into ATP and heat

Why is the Second Law of thermodynamics important

• cells release some energy as heat, increasing entropy (disorder)

What is an active site

• the region of an enzyme wher ethe substrate binds the reactions occurs

What is a substrate

• the reactant molecule upon which an enzyme acts

How do enzymes lower activation energy

• by properly orienting substrates and stabilizing the transitions state

What is biochemical pathway

• a series of enzyme-controlled reactions where the product of one step becomes the substrate fpr the next

What is feedback inhibition

• when the final product of a pathway inhibits an earlier enzyme pathway

What does ATP stand for

• Adenosine Triphosphate

Why is ATP a short term energy storage

• it stores small amounts of readily available energy that cells can use quickly

What happens what ATP is hydrolyzed

• ATP loses a phosphate groups

How does ATP regulate protein activity

• ATP transfers a phosphate group to proteins through phosphorylation

What is phosphorylation

• the addition of a phosphate group to a molecule, often a protein

Why is ATP important for cell signaling

• ATP-driven phosphorylation is major way cells regulate protein activity and communication

What effect can phosphorylation have on proteins

• it can activate, deactivate, or alter p proteins function

What organisms process of glycolysis to generate energy

• all organism

What uses photosynthesis to generate organic molecules and ATP

• Autotrophs

Plants and green algae

• autotrophs

Humans and fungi

• heterotrophs

NADH+ is __ to NADH as a result of the _ _ of electron

• reduced; gain

What is required for the complex oxidation of glucose

• Glycolysis, Krebs cycle, pyruvate oxidation

Where does the electron transport chain occur in the eukaryotic cells

• the inner mitochondrial membrane

What molecules donate electrons to the electron trasnport chain

• NADH and FADH2

What is the first electron carrier that receives electrons from NADH

• complex 1

What happens to electrons as they move through the ETC

• they pass from one carrier protein to another and lose energy

How is the energy released by electron used

• to pump H+ ions (protons) across the inner mitchondrial membrane

What is the final electron acceptor in aerobic respiration

• oxygen

What is formed when oxygen accepts electrons and hydrogen ions

• Water (h2o)

Electron flow diagram

• NADH/FADH2 → ETC proteins → Oxygen → Water

What is chemiosmosis

• the movement of H+ ions across a membrane to drive ATP production

What is proton gradient

• the difference in H+ concentration across a membrane

Where are protons pumped during electron transport

• because they move down their concerntration gradient

Through what protein do protons re-enter the matrix

• ATP synthase

What does ATP synthase do

• uses proton flow to produce ATP and ADP and phosphate

What is oxidative phosphorlyation

• ATP production powered by electron transport chemiomisis

What directly powers ATP synthase

• the flow of H+ ions through the enzyme

Chemiosmosis diagram

• ETC pumps H+ out → H+ gradient forms → H+ flows through ATP synthase →ATP produced

What is the purpose of cellular respiration?

• to harvest energy from glucose and convert it into ATP

What is the net ATP yield from glycolysis

• 2 ATP

How many NADH are produced during glycoysis

• 2 NADH

How many ATP are produced during the pyruvate oxidation

• 0 ATP

How many NADH are produced during pyruvate oxidation

• 2 NADH per glucose

What is the ATP yield from the krebs cycle

• 2 ATP per glucose

How many NADH are produced from the Krebs cycle

• 6 NADH

How many FADH2 are produced from the Krebs cycle

• 2 FADH2

Which state produces the most ATP

• oxidative phosphorylation (ETC)

Approximately how much ATP is produced by oxidation phosphorylation

• about 26-28 ATP

Total ATP produced from one glucose molecule during aerobic resperation

• about 30-32 ATP

What is aerobic respiration

• cellular respiration that requires oxygen as the final electron acceptor

What is anaerobic respiration

• respiration that uses an electron acceptor other than oxygen

What is fermintaion

• an anaerobic process that regenerates NAD+ without using an electron transport chain

Which process produces the most ATP

• aerobic respiration

How much ATP does fermentation produce per glucose

• 2 ATP (from glycolysis only)

What is the main function of fermination

• Regenerate NAD+ so glycolysis can continue

What are two types of fermentation

• Lactic acid and alcoholic fermentation

WHat does catabolism mean

• the breakdown of large molecules to release energy

How are fats used for energy

• triglycerides are broken into glycerol and fatty acids

What happens to glycerol

• it enters glycolysis

What happens to fatty acids

• they are broken down by beta-oxidation into acetyl-CoA

Where does acetyl-CoA go

• into the krebs cycle

Why do fats provide so much energy

• they contain many high energy electron and produce large amounts of ATP

How are proteins used for energy

• Proteins are broken into amino acids

What must happen before amino acids enter respiration pathways

• their amino group must be removed (deamination)

Where can amino acids carbon skeletons enter cellular respiration

• Glycolysis, pyruvate oxidation, or krebs cycle

Which energy source is usually used first?

• carbohydrates

Why are proteins generally used as a last resort energy source

• because proteins are needed for important cellular respiration structures and functions