Topic 5: Energy for Biological Processes

Respiration 5.1 Aerobic respiration I Know that cellular respiration yields ATP which is used as a source of energy for metabolic reactions, and the process also generates heat. II Know the different stages in aerobic respiration, including: Glycolysis in the cytoplasm Link reaction Krebs Cycle Oxidative phosphorylation in mitochondria Starter: Write out the word and symbol equation for aerobic respiration?

5.2 Glycolysis Understand the conversion of monosacharides to pyruvate during glycolysis in the cytoplasm, including: The phosphorylation of hexose molecules by ATP Breakdown of glycerate 3-phosphate (GP) Production of reduced coenzyme (NADH) and ATP

ATP – The energy currency in cells The ultimate goal of releasing energy in a controlled way is to trap the released energy in the form of ATP molecules. If a cell does not have glucose available, other organic molecules may be substituted, such as fatty acids or amino acids. Cell respiration is the controlled release of energy from organic compounds in cells to form ATP (adenosine triphosphate)

Glycolysis is the first step in respiration Glycolysis is the breakdown of one molecule of glucose (6C) into two molecules of pyruvate (2 x 3C) with a small net yield of ATP (2 molecules of ATP) This process also results in the reduction of two hydrogen acceptors (NAD+) to form 2 molecules of NADH + H+ 2ATP 2 ADP Energy to get reactions started pyruvate 3C glucose 6C pyruvate 3C 2ATP 2 ADP 2 ADP 2ATP

Glycolysis (HL) Two molecules of ATP are used to begin glycolysis. Phosphates from the ATPs phosphorylate glucose to form fructose-1,6-bisphosphate.

Glycolysis 2. The 6-carbon phosphorylated fructose is split into two 3-carbon sugars called glyceraldehyde-3-phosphate (G3P). This process is called lysis

Glycolysis 3. Oxidation phase is entered involving ATP formation and production of the reduced coenzyme NAD. Each G3P molecule undergoes oxidation to form a reduced molecule of NAD+ which is NADH. A phosphate group is added to each G3P which is then removed and added to 2 x ADP to form 2 x ATP.

Summary 2 ATPs are used to start the process 4 ATPs are produced at the end – net gain of 2 ATPs 2 molecules of NADH are produced Involves substrate level phosphorylation, lysis, oxidation and ATP formation. Happens in cytoplasm of the cell Controlled by enzymes. If ATP levels are high, feedback inhibition occurs to control the process. 2 pyruvate molecules are present at the end of the process.

1. Of the following products, which is produced by both anaerobic respiration and aerobic respiration in humans? I. Pyruvate II. ATP III. Lactate A. I only B. I and II only C. I, II and III D. II and III only (Total 1 mark)

1. Of the following products, which is produced by both anaerobic respiration and aerobic respiration in humans? I. Pyruvate II. ATP III. Lactate A. I only B. I and II only C. I, II and III D. II and III only (Total 1 mark) B

2. How many ATP molecules (net yield) are produced per molecule of glucose as a direct result of glycolysis? A. 2 B. 4 C. 10 D. 38

2. How many ATP molecules (net yield) are produced per molecule of glucose as a direct result of glycolysis? A. 2 B. 4 C. 10 D. 38 A

3. Humans can respire aerobically and anaerobically 3. Humans can respire aerobically and anaerobically. Which are products of both aerobic cell respiration and anaerobic cell respiration in humans? A. Pyruvate and ATP B. Pyruvate and lactate C. ATP and carbon dioxide D. Lactate and carbon dioxide

3. Humans can respire aerobically and anaerobically 3. Humans can respire aerobically and anaerobically. Which are products of both aerobic cell respiration and anaerobic cell respiration in humans? A. Pyruvate and ATP B. Pyruvate and lactate C. ATP and carbon dioxide D. Lactate and carbon dioxide A

C

5.

5. D

6.

C

7. Where in eukaryotic cells is glucose broken into pyruvate, to release energy for use in the cell? A. Chloroplast B. Cytoplasm C. Mitochondrion D. Nucleus (Total 1 mark)  

7. Where in eukaryotic cells is glucose broken into pyruvate, to release energy for use in the cell? A. Chloroplast B. Cytoplasm C. Mitochondrion D. Nucleus (Total 1 mark)   B