Unit 3 Energy and Metabolism (12-16%)

Free Energy

used for organization, growth and reproduction. Loss of it results in death.

more Free Energy than needed will

be stored for growth (roots, glycogen, fat)

Matter and Energy are NOT created but

CHANGE form (1st law of thermo; sun energy to bond energy in glucose)

Entropy is increasing in

disorganization of energy (heat released by cell respiration)

Reactions can be coupled to maintain a system

ex. Photosynthesis and Cellular Respiration

more organized or built up compounds have means

more free energy and less entropy (glucose)

less organized or built up compounds have means

less energy and more entropy (carbon dioxide)

Cellular Respiration (C6H12O6 + 6O2 → 6CO2 + 6H2O)

makes ATP for cell use; uses glucose and oxygen makes waste product of carbon dioxide and water; occurs in mitochondria, NADH is electron carrier used

Glycolysis (location and process)

CR; (1) occurs in cytoplasm, anaerobic (2) rearranges the bonds in glucose molecules, releasing free energy to form ATP from ADP through substrate-level phosphorylation resulting in production of pyruvate.

Krebs (Citric Acid) Cycle (location and frequency)

CR; (1) occurs in mitochondrial matrix (2) occurs twice per molc of glucose

Electron Transport Chain (ETC) and Chemiosmosis

CR; (1) captures electrons, pumping H+ ions into the inner-membrane space of mitochondria. (2) Electrons are captured by O2 molc forming H2O. (3) Concentration of H+ builds up within inner-membrane lowering the pH and ions rush through ATP Synthase into the mitochondria matrix. Rush of ions spins ATP synthase, causing ADP an Pi to joing, forming ATP by oxidative phosphorylation.

Photosynthesis (6CO2 + 6H2O → C6H12O6 + 6O2)

Photosynthetic organisms capture free energy present in sunlight and use water and carbon dioxide to make carbon products and free oxygen

Light Dependent reactions - Photophosphorylation (process)

PS; (1) Photostems I and II (cholopyll and proteins) are embedded in the internal membranes of chloroplasts (thylakoids and grana). They pass electrons through an electron transport chain (ETC) and electrons are passed that allow hydrogen ions (protons) across the thylakoid membrane.

Krebs (Citric Acid) Cycle (process)

PS; (3) Pyruvate is oxidized further and carbon dioxide is released; ATP is synthesized from ADP and inorganic phosphate via substrate level phosphorylation and electrons are captured by coenzymes (NAD+ and FAD) (4) NADH and FADH2 carry electrons to the ETC

Light Dependent reactions - Photophosphorylation (electrons)

PS; (2) are passed to NADP+ to make NADPH (electron carrier)

Light Dependent reactions - Photophosphorylation (products, byproduct, light)

PS; (5) energy converted from sun into chemical energy of ATP and NADPH to be used in building of sugar - Calvin Cycle (3) H2O is used and O2 released (4) Red and Blue light works best since green is reflected typically

Light Independent Reactions - Calvin Cycle

PS; (1) cabron fixation occurs (carbons of CO2 used to make sugar) (2) occurs in stroma of chloroplasts (3) ATP and NADPH generate by light-dependent reactions are used to assemble glucose (Glycolysis)

Anaerobic Fermentation

PS; No O2, cell only goes through glycolysis followed by fermentation, which recycles NAD needed to start glycolysis, very insufficient (ex: alchohol w/ yeast cells - glucose → CO2 + NAD+ or lactic acid /muscle cells - glucose → lactic acid + NAD+)

Absorption Spectrum

A graph showing the wavelengths of light absorbed by a pigment.

Chloroplast

An organelle in plant and algae cells where photosynthesis occurs.

NAD/NADH

NAD is an electron carrier; NADH is the reduced form, carrying electrons and hydrogen ions.

Acetyl CoA

A molecule formed from pyruvate before entering the Krebs cycle; important for energy production.

Citric Acid/Krebs Cycle

A series of reactions in the mitochondria that breaks down acetyl CoA to produce energy carriers (NADH, FADH₂) and CO₂.

NADP/NADPH

NADP is an electron carrier in photosynthesis; NADPH is its reduced, energy-carrying form.

Anabolism

Metabolic pathways that build larger molecules from smaller ones, requiring energy.

Electron Transport Chain (ETC)

A series of proteins in a membrane that transfer electrons and pump protons to create a proton gradient for ATP production.

Oxidative Phosphorylation

The process of producing ATP using energy from the redox reactions of the electron transport chain.

Anaerobic Metabolism

The creation of energy without oxygen, often producing lactic acid or ethanol.

FAD/FADH

FAD is another electron carrier; FADH₂ is its reduced form, carrying electrons for the ETC.

Photolysis

The splitting of water molecules using light energy, producing oxygen, electrons, and protons in photosynthesis.

ATP (Adenosine Triphosphate)

The main energy-carrying molecule in cells.

Feedback Inhibition

A process where the end product of a pathway inhibits an earlier step to regulate the pathway

Photosynthesis

The process where plants, algae, and some bacteria convert light energy into chemical energy (glucose)

ATP Synthase

An enzyme that uses a proton gradient to make ATP from ADP and inorganic phosphate.

Fermentation

A type of anaerobic metabolism where cells make ATP by glycolysis and convert pyruvate into waste products like alcohol or lactic acid.A type of anaerobic metabolism where cells make ATP by glycolysis and convert pyruvate into waste products like alcohol or lactic acid.

Photosystem I (PSI)

A protein-pigment complex in the thylakoid membrane that absorbs light for the second part of the light-dependent reactions; it helps produce NADPH.

Autotroph

An organism that makes its own food, usually through photosynthesis or chemosynthesis.

Glycolysis

The first step of cellular respiration; it breaks glucose into two pyruvate molecules, producing a small amount of ATP and NADH.

Photosystem II (PSII)

A protein-pigment complex that absorbs light to start the light-dependent reactions; it splits water and generates an electron flow.

Calvin Cycle

The cycle of light-independent reactions in photosynthesis where CO₂ is used to build glucose.

Light Dependent Reactions

The part of photosynthesis that captures light energy to make ATP and NADPH.

Pyruvate

A 3-carbon molecule produced from glucose in glycolysis; it enters the mitochondrion for further energy extraction.

Cellular Respiration

A process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.

Light Independent Reactions

The part of photosynthesis (Calvin cycle) that uses ATP and NADPH to fix carbon into sugars.Stroma

Stroma

The fluid-filled space inside the chloroplast, surrounding the thylakoids; where the Calvin cycle occurs.

Chemiosmosis

The movement of protons across a membrane to drive the formation of ATP via ATP synthase.

Metabolic Pathway

A series of chemical reactions in a cell that build or break down molecules for a specific purpose.

Substrate-Level Phosphorylation

Direct formation of ATP by transferring a phosphate group to ADP during a chemical reaction.

Chlorophyll

The green pigment in plants that absorbs light energy for photosynthesis.

Mitochondrion

An organelle where cellular respiration happens to produce ATP.

Thylakoid Membrane

The membrane inside chloroplasts where light-dependent reactions take place; it contains chlorophyll.