Packet 6 Cellular Energy ATP cellular energy Why

Packet 6 Cellular Energy

ATP: cellular energy

Why do cells need energy? • Cells carry out three kinds of energy-requiring work: – Chemical – Mechanical – Transport

Making ATP: Aerobic cellular respiration

Glycolysis (Stage 1) • Breaking down glucose – “glyco – lysis” (splitting sugar) glucose pyruvate 2 x 3 C 6 C – Occurs in the cytoplasm – A little ATP energy is harvested, – but it’s inefficient • generate only 2 ATP for every 1 glucose

Overview 10 reactions – convert glucose (6 C) to 2 pyruvate (3 C) – produces: 4 ATP & 2 NADH – consumes: 2 ATP – net yield: 2 ATP & 2 NADH Substrate-level phosphorylation

Products of glycolysis move on to stage 2 or 3

Mitochondria — Structure • Double membrane – – – smooth outer membrane highly folded inner membrane intermembrane space Matrix DNA, ribosomes enzymes outer intermembrane inner space membrane cristae matrix mitochondrial DNA

Stage 2: Pyruvate grooming and the Kreb’s Cycle This happens twice for each glucose molecule that started glycolysis…wh y?

Cellular respiration

Electron Transport Chain and Chemiosmosis: ATP payoff! • Electron Transport Chain – series of proteins built into inner mitochondrial membrane

Remember the Electron Carriers? Glycolysis 2 NADH Time to break open the piggybank! Krebs cycle 8 NADH 2 FADH 2

Electron Transport Chain What powers the proton (H+) pumps? … Electronegativity!

Chemiosmosis and oxidative phosphorylation

Cellular respiration 2 ATP + ~3 8 A 34 ATP TP

Summary of cellular respiration C 6 H 12 O 6 + 6 O 2 • • 6 CO 2 + 6 H 2 O +~34 -38 ATP Where did the glucose come from? Where did the O 2 come from? Where did the CO 2 go? Where did the H 2 O come from? Where did the ATP come from? What is recycled for use again? Why do we breathe?

Taking it beyond… • What is the final electron acceptor in Electron Transport Chain? O 2 § So what happens if O 2 unavailable? § ETC backs up nothing to pull electrons down chain u NADH & FADH 2 can’t unload H u § ATP production ceases § cells run out of energy

Anaerobic respiration Making ATP without oxygen

• • All cells carry out glycolysis: prokaryotes and eukaryotes. Eukaryotes and many prokaryotes also carry out oxidative phosphorylation (remember this requires oxygen). How can some bacteria carry out aerobic respiration if they don't have mitochondria? FUN FACT: many bacteria have ETC’s in their cell membranes.

Reminders! A net of 2 ATP is generated in glycolysis. NAD+ must be present available for this process. New considerations For aerobic organisms this is not a problem, NAD+ is regenerated by the ETC. Not all organisms can use oxygen, they are anaerobic Anaerobic organisms use glycolysis only to make ATP They regenerate , NAD+ through fermentation processes

Alcohol fermentation

Lactic acid fermentation

Review: Answer all of the following questions in your notebook. • What are the products of pyruvate grooming for 1 molecule of glucose? • What are the products of the citric acid cycle for 1 molecule of glucose? • After glycolysis, pyruvate grooming, and the citric acid cycle, what are your net products? • What is phosphorylation? • What is substrate-level phosphorylation? • What is the main goal for stages 1 -3?

Review: Answer all of the following questions in your notebook • What is the summary equation for cellular respiration? • If oxidation is a loss of electrons (in the form of hydrogen atoms) and reduction is the gain of electrons (in the form of hydrogen atoms), – what is oxidized during cellular respiration? – what is reduced during cellular respiration? • How does glucose get to your cells for cellular respiration? • What is the point of cellular respiration? • What are the net molecular products of glycolysis?

Where does glucose come from for cellular respiration? Photosynthesis!

Photosynthesis

Leaf structure Mesophyll cells Stomate Guard cells Vascular tissue

Chloroplast structure Grana Thylakoid Stroma Double membrane

Stage 1: Lightdependent reactions Light energy is converted to chemical energy (as NADPH and ATP). Stage 2: Calvin cycle Glucose is made from CO 2 and hydrogens carried by NADPH using ATP energy.

Calvin cycle

SUMMARY What factors might affect the rate of photosynthetic reactions?