Cells Memory Jogger 1. What is the process called when a phosphate is added? 2. ATP stands for ___________ ___________. 3. What does ‘lysis’ generally mean at the end of a word? 4. Which organelle is the ‘powerhouse of a cell’? 5. What does ‘aerobic’ mean?

Cells Memory Jogger 1. What is the process called when a phosphate is added? 2. ATP stands for ___________ ___________. 3. What does ‘lysis’ generally mean at the end of a word? 4. Which organelle is the ‘powerhouse of a cell’? 5. What does ‘aerobic’ mean? phosphorylation Adenosine triphosphate to split or break apart mitochondria requires oxygen

Respiration

The Chemistry of Respiration energy and mitochondria clip

The role of ATP review ► ATP stores the energy in the third bond of the molecule ► The energy is released when that bond is broken to release the third inorganic phosphate. ► ► Pi= the phosphoric acid

P adenosine PP + Energy released to do work ATP ADP Enzymes adenosine PPP

Summary ATP ADP + Pi energy (out) energy (in) cellular respiration cell activities ATP energy (out) cellular respiration cell activities The whole process is an enzyme controlled reaction.

► The process by which food molecules (ex: glucose) are broken down to produce ATP. ► Takes place in the mitochondria of plants and animals. ► There are 3 stages of respiration: 1. Glycolysis 2. Krebs Cycle 3. Electron Transport Chain ► Chemical Equation: C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + Energy Cell Respiration

breathing and respiration breathing and respiration intro. click (aerobic resp.)

Aerobic respiration = respiration with oxygen

Aerobic respiration happens in 3 stages: Stage 1 – Glycolysis Stage 1 – Glycolysis glyco lysis glucose splitting glucose splitting 2 ATP needed to start reaction, 4 ATP are produced thus the net gain is 2 ATP from glycolysis.

In glycolysis, a glucose molecule is broken down into two molecules of pyruvic acid. energy released to make small quantity of ATP (2 molecules) series of enzyme controlled reactions pyruvic acid glucose Glycolysis does not require oxygen

In both eukaryotes and prokaryotes, this process occurs in the cytosol of the cell. The cytosol is the portion of the cytoplasm not contained within membrane-bound organelles. Cytosol makes up about 70% of the cell volume and is composed of water, salts and organic molecules.

Breakdown of Pyruvic acid The pyruvic acid made in glycolysis (stage1) still contains a lot of energy It can only be broken down to release the rest of the energy in the presence of oxygen. It can only be broken down to release the rest of the energy in the presence of oxygen.

Stage 2: Krebs Cycle ► Pyruvic acid molecules then move into the mitochondria to begin the next stage of cellular respiration: the Krebs Cycle. ► During the Krebs Cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions. ► Citric Acid is created in this cycle thus giving it the nickname Citric Acid cycle. ► Net ATP Production is 2 ATP from the Krebs Cycle.

Mitochondrial structure Krebs cycle takes place in the matrix.

Stage 2: Krebs Cycle ► The enzyme involved in this stage is referred to as acetyl-CoA ► The citric acid is broken down into a 5- carbon compound, then into a 4-carbon compound. Energy is being released along the way. ► Electron carriers in the form of NADH and FADH2 are produced, which transport energized electrons along the electron transport chain in the mitochondria.

Stage 3: Electron Transport Chain ► The electron transport chain uses the high- energy electrons from the Krebs Cycle to convert ADP to ATP. ► Same idea as in photosynthesis: energized electrons from Citric Acid Cycle are passed from protein to protein, losing energy as they go. ► The energy is used to make ATP.

Stage 3: Electron Transport Chain ► Takes place in the mitochondria in the cristae or inner membrane. ► Requires oxygen to assist in passing the electrons from protein to protein. ► Water is formed. ► Net ATP Gain: 32 ATP from the electron transport chain.

So why do we need oxygen? ► Oxygen serves as the final electron acceptor of the electron transport chain. Therefore, oxygen is essential for getting rid of low-energy electrons and hydrogen ions, the wastes of cellular respiration.

Cell Respiration Summary ► Total process (Glycolysis, Citric Acid Cycle, and Electron Transport Chain) produces 36 ATPs. ► All of this is from 1 molecule of glucose! ► This happens in 1 mitochondrion (liver cells may have 2500 mitochondria each!) ► Cells and organisms require a HUGE amount of energy!!

Anaerobic Respiration (in animals) anaerobic = in the absence of oxygen

In low oxygen conditions or during heavy exercise, when not enough oxygen can be supplied, muscle cells swap to anaerobic respiration

Lactic Acid Fermentation ► Glycolysis still takes place but is followed by this type of fermentation. ► Fermentation: releases energy from food molecules in the absence of oxygen

glycolysis still happens as it does not require oxygen in absence of oxygen pyruvic acid is turned into lactic acid. pyruvic acid lactic acid glucose 2 ADP + 2 Pi 2 ATP

A build up of lactic acid produces muscle fatigue. Muscle fatigue makes muscles ache and contract less powerfully. A recovery period is needed. During this time more oxygen is taken in to convert the lactic acid back into pyruvic acid again. 2 ATP’s are produced.

Summary oxygen debt e.g. during hard exercise oxygen debt repaid during recovery time glucose pyruvic acid lactic acid

Anaerobic Respiration in plants The same process occurs in plants and yeast in low oxygen conditions, e.g. muddy, flooded soils.

Alcoholic Fermentation ► Used most commonly by yeast. ► CO 2 + ethyl alcohol are produced from 2 pyruvic acids. ► 2 ATPs are produced ► These processes (fermentation) are not ideal, because they are not as efficient at producing energy, and so they occur in lower organisms, or under distress.

glycolysis still happens, producing 2 ATP molecules This time in absence of oxygen, pyruvic acid is turned into carbon dioxide and ethanol glucose pyruvic acid ethanol + carbon dioxide This is irreversible 2 ADP + 2 Pi 2 ATP

Energy & Exercise ► Quick energy – Lactic Acid fermentation is used to get quick energy and gives off lactic acid as a by product, thus the muscle pain. ► Long-Term Energy – Use cellular respiration to produce energy. Exercising or activities that last for at least 15 to 20 minutes. Best form for weight control.

Comparison of aerobic and anaerobic respiration Aerobic respiration Anaerobic Respiration in animals in plants and yeast Oxygen required? yesnono Glycolysis occurs yesyesyes ATP yield 36ATP2ATP2ATP Glucose completely broken down? yesnono End products Carbon dioxide and water Lactic acid Ethanol and carbon dioxide

Comparing Photosynthesis & Respiration Photosynthesis Cellular Respiration Function Energy Storage Energy Release LocationChloroplastsMitochondria Reactants CO 2 and H 2 O C 6 H 12 O 6 and O 2 Products CO 2 and H 2 O Equation 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O

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