Unit C

• Electromagnetic Radiation

  Photons - EMR energy packets

  Photons are small units of energy of a specific wavelength
• Chlorophyll

  Green pigment absorbing photons from solar energy

  Two types: blue-green vs. yellow-green

  Blue-green is primary light absorber

  Yellow-green is backup light absorber (accessory pigment)

  Carotenoids - Also act as accessory pigments

  In fall, chlorophyll breaks down, making yellow, red, and brown
• Chloroplasts

  Two membranes before reaching middle

  Stroma - Organelle filling, protein-rich

  Thylakoids - Membrane sacs

  Grana - Column stacks of thylakoids

  Lamellae - Thylakoids bridging grana

  Photosynthesis happens in stroma and thylakoid membrane

  Thylakoid lumen - Thylakoid juice (water) to bloat thylakoid membrane and increase surface area
• Adenosine Tri/Diphosphates

  ATP - Immediate energy for cell functions

  After using ATP, it gets split back into ADP and phosphate

  ADP + phosphate = ATP
• Nicotinamide Dinucleotide Phosphate and friends

  NADP+ combines with one hydrogen and two electrons to make NADPH

  NADPH donates electrons to other molecules, becoming NADP+ again
• Photosynthesis in steps

  Solar energy caught, some makes ATP, some goes to electrons

  Electrons + NADP = NADPH

  ATP + NADPH electrons forms big molecules i.e. glucose

  Steps 1 & 2 are light-dependent reactions, requiring chlorophyll and thylakoids

  Step 3 is carbon fixation in stroma using Calvin cycle (light-independent reaction)
• Pigments capturing solar energy

  Photosystems - Pigment clusters in thylakoids

  Pigment molecule absorbs photon, exciting atom electrons

  Electron transport chain - Electrons transported across molecules

  Photolysis - Absorbed photons used to break down water into hydrogen ions (1+) and oxygen, happens in thylakoid lumen

  Extra hydrogen electron replaces the moving electrons' positions

  Two water molecules consumed for every four electrons transported
• Electron Transport Chain

  Excited electrons slowly releases energy, forming ATP

  Remaining energy used to form other compounds i.e. glucose
• Oxidation-Reduction Reactions

  Oxidation - Reaction when atoms/molecules lose electrons

  Reduction - Reaction when atoms/molecules gain electrons

  Electron transfer involves both oxidation and reduction

  NADPH oxidizes and loses hydrogen nucleus and two electrons

  NADP reduces and gains hydrogen nucleus and two electrons

  Energy released when NADP becomes NADPH
• Light-dependent reaction steps

  Electrons transferred across thylakoid membrane to inner surface

  Some electron energy used to pull hydrogen ions, positive charge buildup in lumen

  Electrons transferred to chlorophylls to refill energy

  Ions and electrons become ingredients for NADPH
• Chemiosmosis

  ATP Synthase Complex - Protein filtering hydrogen ions to leave lumen, creating ATP from resulting energy

  Chemiosmosis - Energy from hydrogen ion gradient used to create ATP
• Calvin Cycle and Carbon Fixation

  ATP and NADPH electrons make G3P (sugar to make glucose)

  Glucose production supplied by CO2 and hydrogen from light-dependent reactions

  Three ATP and two NADPH are consumed for every CO2 that enters
• Cellular respiration intermediate products

  NADH - Reduced form of NAD+ (nicotinamide adenine dinucleotide)

  FADH - Reduced form of FAD+ (flavin adenine dinucleotide)

  Electrons transport through these low-energy compounds

  Eventually reaches to ADP and P which forms ATP
• Purpose of ATP

  Most cellular processes use the energy from ATP

  Average human has one billion molecules of ATP

  Constantly broken down as an exothermic reaction to be put together again
• Active transport

  Sodium-potassium pump - Potassium and sodium ions go through cell membranes with this
• ATP Uses

  Contracts fibers in muscles to move

  Powers active transport

  Energy used to build large molecules

  Controls certain molecular functions
• ATP and Glucose

  Glucose carries more energy than ATP, but glucose needs to be converted into ATP to be used

  Glucose better suited for long-term storage and transportation

  Only thirty-six percent of glucose energy turned into ATP

  The rest is used as heat for bodies
• Aerobic cellular respiration

  Releases carbon dioxide, water, and thirty-six ATP molecules

  Involves four stages:

  Glycolysis

  Pyruvate Oxidation

  Krebs Cycle

  Electron transport and chemiosmosis
• Anaerobic cellular respiration

  Two stages: Glycolysis and fermentation

  Products either involve ethanol and carbon dioxide, or lactic acid

  Only two ATP produced for every glucose
• Glycolysis

  Anaerobic process in the cytoplasm

  Breaks down glucose into two pyruvate (C3H4O3) and hydrogen atom

  Two ATP molecules used and four produced

  Hydrogen atom used by NAD+ to make NADH
• Glycolysis steps

  Two ATP molecules used in the first stage (investment of energy)

  Oxidation-reduction reactions let NAD+ take hydrogen atoms from glucose to become NADH; The other two released into cytoplasm

  Enough energy released to create four ATP molecules

  Net production of two ATP, two NADH, and two pyruvate

  Glucose + 2 ADP + 2 P + 2 NAD = 2 Pyruvate + 2 ATP + 2 NADH + 2 H
• Glycolysis efficiency

  Glucose has 90 times more energy than ATP

  Only 2.2% of the energy converted into ATP

  Most multicellular organisms need more
• Mitochondria Structure

  Scattered throughout cytoplasm

  Produces ATP with oxygen

  Double membrane (smooth outer, zigzag inner)

  Intermembrane space filled with fluid

  Mitochondrial matrix - Protein-rich liquid inside inner membrane
• Pyruvate Oxidation

  Carbon dioxide removed and wasted from each pyruvate

  NAD+ molecules take two hydrogen ions from pyruvate, leaving acetic acid group to remain

  Coenzyme A (CoA) attaches to acetic acid group, forming acetyl-CoA
• Krebs Cycle

  Acetyl-CoA condenses with oxaloacetate to make citrate

  Coenzyme A is released from acetyl-CoA to be used for the next pyruvate

  Three NAD+ and one FAD is reduced to NADH and FADH

  One ATP is formed

  Two carbon atoms originally in glucose thrown away as carbon dioxide

  Krebs Cycle happens twice for every glucose
• Electron Transport and Chemiosmosis Pt. 1

  NADH and FADH transfer their hydrogen to proteins in the mitochondria's inner membrane

  NADH releases two electrons at the beginning of transport chain and one hydrogen ion into matrix

  Electrons release energy as they are passed on

  Energy used to force hydrogen ions across inner membrane
• Electron Transport and Chemiosmosis Pt. 2

  Electrochemical potential energy - Charged particles on one side of insulator i.e. batteries

  Ions gain electrochemical potential energy when moving through proton pumps

  At the end of transport chain oxygen takes the electrons and bonds with hydrogen ions to make water

  FADH has lower energy than NADH