Cellular Respiration Glycolysis Krebs cycle Electron transport

Learning check This figure represents an overview of the different processes of cellular respiration. Which of the following correctly identifies the different processes? 1. Glycolysis; 2. Electron transport chain; 3. Krebs cycle 1. Glycolysis; 2. Krebs cycle; 3. Electron transport chain 1. Krebs cycle; 2. Electron transport chain; 3. Glycolysis 1. Electron transport chain; 2. Glycolysis; 3. Krebs cycle

What would happen to the flow of electrons if oxygen were not present? The flow of electrons would continue but at a slower rate. The flow would cease and ATP production would stop. The presence of oxygen would have no effect.

Cyanide binds strongly with the last electron carrier in the chain. How would this affect the flow of electrons? The flow of electrons would continue but at a slower rate. The flow would cease and ATP production would stop. The presence of cyanide would have no effect.

How many ATPs?

Cell Respiration Overview Glucose: Stores energy in the molecule Cell respiration: Breaks down the molecules Extracts the contained energy Transfers electrons (from glucose) To hydrogen carriers (e.g., NADH) And to make ATP Giving off waste products (CO2 & H2O) 1st stage: 2nd & 3rd stage: Cytoplasm Mitochondria

1st stage: 2nd stage: 3rd stage: Glycolysis Krebs cycle (or citric acid) Electron transport

Glycolysis, in the cytoplasm Series of steps (but 2 phases) 1. Glucose 2 pyruvic acid molecules As bonds in glucose are broken Electrons (and H+ ions) NAD+ 2. NADH Glucose Is oxidized NAD+ Is reduced Net output is 2 ATP for each glucose molecule But, most of the released energy carried by NADH

Glucose 2 pyruvic acids Phase one 3 carbon 6 carbon 3 carbon

Glycolysis, phase 1 Some ATP is used to start the ‘breakdown’ of glucose Mitochondria Cytoplasm View Activity: Glycolysis

Glycolysis, phase 2 High energy electrons are donated To NAD+ Forming NADH

Glycolysis, phase 2 And, phosphate groups are transferred ATP is made

In-between glycolysis & Krebs Just before (or as) they enter the mitochondria Pyruvic acid molecules are modified And CO2 is released The altered molecule is acetic acid (…vinegar!) Acetic acid is attached to a carrier molecule Called coenzyme A And forms acetyl CoA To the mitochondrion

Learning check 7 3 4 2 6 8 1 5 Name molecule Name of molecule Name the reaction Name of molecule What does the arrow refer to? Where does this take place?

Krebs cycle, in the mitochondria Series of reactions Continues to break down the sugar Present as acetic acid Captures more energy As NADH & FADH2 And more CO2 is released Net output is 2 ATP for each glucose molecule But again, most of the released energy carried by NADH

Krebs (citric acid) cycle & energy production Waste: 2 CO2 Fuel: Acetic acid 3 3 Acceptor molecule View Activity: The Citric Acid Cycle

Electron Transport, in the mitochondria Most of the ATP is produced in the ET And, NADH & FADH donate their electrons to the ET At the end of the chain of steps O2 exerts a strong pull on electrons And combines electrons & H+ ions to form H2O The ‘downhill’ flow of electrons powers an enzyme ATP synthase Which produces ~ 34 ATP

Electron Transport An array of molecules (…proteins) In the inner membrane of the mitochondrion View Activity: Electron Transport

Electrons move from one member to the next The energy given up pumps H+ to inner space Matrix Oxygen captures electrons Hydrogens are added, water forms

The buildup of H+ ions give up energy When they diffuse through a special protein ATP synthase Matrix ATP synthase captures their energy To make ATP

Learning check, name the numbered parts 15 How many? 10 4 7 11 1 6 9 14 2 3 12 8 16 17 5 13 18

Learning check Of the 3 stages of cell respiration, which produces the most ATP per glucose? In glycolysis, _______ is oxidized and _______ is reduced. The final electron acceptor of the electron transport chains in mitochondria is _______.

Learning check Cells can harvest the most chemical energy from which of the following? An NADH molecule A glucose molecule Six carbon dioxide molecules Two pyruvic acid molecules