Reactions of Photosynthesis Biology Chapter 8 1 Cellular

Reactions of Photosynthesis Biology - Chapter 8 1

Cellular Respiration Biology - Chapter 8 2

Cellular Respiration Biology - Chapter 8 3

Cellular Respiration Biology - Chapter 9 4

Cellular Respiration Biology - Chapter 9 5

Biology - Chapter 9 6

Photosynthesis and Respiration: process of converting food energy into a form of energy usable by the cell · All life activities require energy · Source of energy is food (organic molecules) o More specifically, the energy is stored in chemical bonds. Ex. Glucose is the most common food molecule Biology - Chapter 9 7

Photosynthesis Vs. Respiration Biology - Chapter 9 8

ATP – adenine triphosphate · Molecule that temporarily stores energy for the cells to use Biology - Chapter 9 9

ATP – adenine triphosphate • Break bonds release energy • Make bonds store energy • ATP ADP + energy (releasing energy) • ADP + energy ATP (storing energy) Biology - Chapter 9 10

Cellular Respiration • Glucose is broken down, energy is released and stored in ATP. H 2 O (water) and CO 2 (carbon dioxide) are waste products. • Respiration occurs in the mitochondria • Know this: C 6 H 12 O 6 + O 2 CO 2 + H 2 O + energy (ATP) Biology - Chapter 9 11

Biology - Chapter 9 12

Cellular Respiration This Photo by Unknown Author is licensed under CC BYSA-NC Biology - Chapter 9 13

Cellular Respiration Biology - Chapter 9 14

Stages of Cellular Respiration Biology - Chapter 9 15

3 Stages of Cellular Respiration 1. Glycolysis 2. Krebs Cycle 3. Electron Transport Chain Biology - Chapter 9 16

Stage 1: Glycolysis is the first series of reactions that break glucose apart to liberate the energy. Glycolysis occurs in both aerobic (with oxygen) and anaerobic (does not need oxygen) respiration! Biology - Chapter 9 17

Glycolysis Biology - Chapter 9 18

Stage 2: Krebs Cycle Biology - Chapter 9 19

Biology - Chapter 9 20

Cellular Respiration 2 Stages of Respiration 1. Anaerobic Respiration 2. Aerobic Respiration Anaerobic Respiration (fermentation) · Occurs in cytoplasm · Simple organisms (unicellular) Biology - Chapter 9 21

Anaerobic Respiration (fermentation) 2 ATP Glucose 2 Pyruvic Acids Lactic Acid Alcohol and CO 2 Biology - Chapter 9 22

Anaerobic Respiration (fermentation) Examples: Bacteria Sauerkraut Yogurt Vinegar Buttermilk Cheese Yeast Bread Alcohol – beer/wine Biology - Chapter 9 23

Anaerobic Respiration Example: Bread Yeast Bread yeast, or baker’s yeast, reproduces by a process called budding. Bread yeast causes bread to rise by releasing carbon dioxide, which gets trapped in the dough. Biology - Chapter 9 24

Fermentation Inside a Modern Brewery The huge brew kettles shown are used in a vital stage of the beer-brewing process. Hops, cone-like flowers derived from hop vines, give beer its bitter flavour and help prevent the growth of certain bacteria. Biology - Chapter 9 25

Aerobic Respiration In the absence of oxygen, fermentation reactions produce alcohol or lactic acid but no additional ATP. Biology - Chapter 9 26

Aerobic Respiration (mitochondria) Biology - Chapter 9 27

Aerobic Respiration (mitochondria) Same beginning as anaerobic respiration • 2 Pyruvic acid molecules go through • Krebs Cycle • Electron Transport Chain The molecules are broken down further and more energy is released - 36 ATP Last step: H 2 + O 2 = H 20 (waste) Net gain = 36 ATP Aerobic Respiration is 18 X more efficient than anaerobic respiration Biology - Chapter 9 28

Lactic Acid There is a definite limit to anaerobic respiration because of the lactic acid. The acid is what makes your muscles hurt. Lactic acid builds up in the muscle tissue and causes the fatigue and soreness you feel in your exercising muscles. Biology - Chapter 9 29

Cellular Respiration 1. Glycolysis occurs in the cytosol. 2. The Krebs cycle takes place in the matrix of the mitochondria. 3. Oxidative phosphorylation via the electon transport chain is carried out on the inner mitochondrial membrane. In the absence of oxygen, respiration consists of two metabolic pathways: glycolysis and fermentation. Both of these occur in the cytoplasm.

Step 1: Glycolysis In glycolysis, the 6 -carbon sugar, glucose, is broken down into two molecules of a 3 -carbon molecule called pyruvate. This change is accompanied by a net gain of 2 ATP molecules and 2 NADH molecules.

Step 2: The Krebs Cycle The Krebs cycle occurs in the mitochondrial matrix and generates a pool of chemical energy (ATP, NADH, and FADH 2) from the oxidation of pyruvate, the end product of glycolysis.

Step 3: The Electron Transport Chain The electron transport chain allows the release of the large amount of chemical energy stored in reduced NAD+ (NADH) and reduced FAD (FADH 2). The energy released is captured in the form of ATP (3 ATP per NADH and 2 ATP per FADH 2).

Fermentation complements glycolysis and makes it possible for ATP to be continually produced in the absence of oxygen. By oxidizing the NADH produced in glycolysis, fermentation regenerates NAD+, which can take part in glycolysis once again to produce more ATP.

Glucose & Energy Each molecule of glucose can generate 36 -38 molecules of ATP in aerobic respiration but only 2 ATP molecules in respiration without oxygen (through glycolysis and fermentation).

Photosynthesis Overview · Carried out by Autotrophs · Occurs only during daylight · Light energy is used to combine H 2 O and CO 2 into glucose (C 6 H 12 O 6) (light energy is now stored in chemical bonds). Know this (forever): Light energy + 6 CO 2 + 6 H 2 O (chlorophyll) C 6 H 12 O 6 + 6 O 2 (Notice that this is the complete opposite to cellular respiration) Photosynthesis is broken up into 2 stages: Chloroplast: Light reactions (light-dependent reactions) Mitochondria: Dark reactions (light-independent reactions) Biology - Chapter 9 38

Photosynthesis Overview Biology - Chapter 9 39

Light Dependent Reactions Light Reactions (light-dependent reactions): · White light ROYGBIV · Colors that are most important in photosynthesis: RED and BLUE · Photosynthetic pigments absorb light energy and convert it into a form usable by the cell. · · · Chlorophyll – major photosynthetic pigment Carotene – accessory pigment (orange) Xanthophyll - accessory pigment (yellow) Biology - Chapter 9 40

Light Dependent Reactions 1. 2. 3. 4. Light strikes chlorophyll and excites it Energy released and it splits H 2 O into H 2 and O 2 goes into the atmosphere Energy and H 2 goes to dark reactions Biology - Chapter 9 41

Light Dependent : Krebs Cycle Biology - Chapter 9 42

Dark Reactions: Mitochondria Dark Reactions (light-independent reactions): 1. H 2 and energy (from light reactions) 2. H 2 + CO 2 ADP + PGAL 3. PGAL molecule that forms glucose and other food molecules 4. H 2 O released Biology - Chapter 9 43

Photosynthesis Vs. Respiration Comparison Chart for Photosynthesis versus Respiration Photosynthesis Respiration What happens to energy? It is stored It is released Wastes produced O 2 and C 6 H 12 O 6 CO 2 and H 2 O, ATP Sunlight Food (glucose) Light chemical Chemical ATP Autotrophs & Heterotrophs During daylight 24 hours per day (all the time!) Energy Source Energy Conversion Who does it? When is it done? Biology - Chapter 9 44

Anaerobic Vs. Aerobic Comparison Chart for Anaerobic Vs. Aerobic Respiration Anaerobic Aerobic Does it need O 2 (oxygen)? None Needs O 2 Amount of energy needed to start 2 ATP Net gain of energy 2 ATP 36 ATP Occurs in cytoplasm? Yes No Occurs in mitochondria? No Yes Does it need enzymes? Yes Alcohol, CO 2 OR Lactic acid CO 2, H 2 O Wastes produced Biology - Chapter 9 45