Cellular Respiration Competencies 1 differentiate aerobic from anaerobic

Cellular Respiration

Competencies 1. differentiate aerobic from anaerobic respiration. STEM_BIO 11/12 -IIa-j-6 2. explain the major features and sequence the chemical events of cellular respiration - STEM_BIO 11/12 -IIa-j-7 3. distinguish major features of glycolysis, Krebs cycle & electron transport system- STEM_BIO 11/12 -IIa-j-8 4. describe the role of oxygen in respiration and describe pathways of electron flow in the absence of oxygen. STEM_BIO 11/12 -IIa-j-10 5. compute the number of ATPs needed or gained in respiration. STEM_BIO 11/12 -IIa-j-11

Cellular Respiration Harvesting Chemical Energy C 6 H 12 O 6 + 6 O 2 6 H 2 O + 6 CO 2 + ATP

What is Cellular Respiration? • The process in which organisms take molecules broken down from food and release the chemical energy stored in the chemical bonds of those molecules • The energy that is released from chemical bonds during cellular respiration is stored in molecules of ATP.

What types of organisms undergo cellular respiration? • While only autotrophs undergo photosynthesis both Heterotrophs AND Autotrophs Undergo cellular respiration.

What types of molecules are broken down? • Any food (organic) molecule, or nutrient, including carbohydrates, fats/lipids, and proteins can be processed and broken down as a source of energy to produce ATP.

What will the ATP be used for? • ATP will release energy for cellular metabolic processes. • Examples: 1) Active transport of molecules across the cell membrane. 2) Protein synthesis 3) Muscle contractions

Functions of ATP: 1. mechanical work 2. electrical work 3. active transport 4. bioluminescence 5. heat 6. anaerobic activities

The Cellular Respiration Equation C 6 H 12 O 6 + 6 O 2 Glucose oxygen 6 CO 2 + 6 H 2 O + energy (ATP) carbon dioxide water

REDOX Reactions • A chemical reaction in which there is the transfer of one or more electrons from one reactant to another. Oxidation is the loss of electrons and Reduction is the addition of electrons. • Because the electron transfer requires a donor and an acceptor, oxidation and reduction always go together.

oxidation C 6 H 12 O 6 + 6 O 2 6 CO 2 + H 2 O reduction

Where does cellular respiration occur?

Cellular Respiration in Detail

Cellular Respiration Cellular respiration breaks down into these major steps. 1. Glycolysis (anaerobic) 2. Krebs Cycle (aerobic) 3. Electron Transport Chain (aerobic)

The Aerobic Pathway

Pathway to the Krebs Cycle (citric acid cycle) Glycolysis Pyruvic Acid Acetyl Co. A Krebs Cycle/Citric Acid/Tri. Carboxyl Acid

Glycolysis Splits a Glucose molecule into 2 - 3 Carbon molecules called PYRUVATE products: 2 ATP, 2 NADH and Pyruvate

GLYCOLYSIS GLUCOSE (6 C) ---- 1. HIXOKINASE GLUCOSE 6 PHOSPHATE -----2. PHOSPHOGLUCOISOMERASE FRUCTOSE 6 PHOSPHATE ----3. PHOSPHOFRUCTOKINASE FRUCTOSE 1, 6 DIPHOSPHATE ----4. ALDOLASE GLYCERALDEHYDE PHOSPHATE ----5. TROSEPHOSPHATE DEHYDROGENASE DIPHOSPHOGLYCERATE ----6. PHOSPHOGLYCERATE KINASE 3 PHOSPHOGLYCERIC ACID ----7. PHOSPHOGLYCEROMUTASE 2 PHOSPHOGLYCERIC ACID C ----8. ENOLASE PHOSPHOENOLPYRUVIC ACID -----9. PYRUVATE KINASE 2 PYRUVIC ACID (3 C EACH)

Glycolysis

Pre-Krebs Cycle (Acetyl- Co. A) • Before pyruvic acid enters the Krebs Cycle, it combines with an enzyme called Coenzyme A (Co. A). • This reaction produces a molecule of Acetyl Co. A. • Acetyl Co. A is a molecule produced by almost all nutrients (carb. , protein, lipids) before entering the Krebs cycle.

Preparation for the Citric Acid Cycle C The pyruvate looses a carbon leaving the 2 carbon molecule C Acetyl Co. A CO 2 products: CO 2, Acetyl Co. A and NADH

Krebs Cycle (Citric Acid Cycle) • Named after Hans Krebs who won the Nobel Prize for the pathway he discovered in cellular respiration.

The Citric Acid Cycle Products: CO 2, 1 ATP, 3 NADH, 1 FADH

The TCA Cycle The tricarboxylic acid cycle (TCA cycle) is a series of enzyme-catalyzed chemical reactions that form a key part of aerobic respiration in cells. This cycle is also called the Krebs cycle and the citric acid cycle. The greatly simplified cycle below starts with pyruvate, which is the end product of gylcolysis, the first step of all types of cell respiration.

(3) Electron Transport Chain • The ETC is a series of proteins located in the mitochondrial membrane. • It uses high energy electrons from the NADH and FADH 2 provided by the Krebs Cycle to move H+(protons) across the concentration gradient. • These protons pass back down the concentration gradient through ATP synthase to form 1 ATP. Very much like the ETC in the light reactions of photosynthesis.

ETC • Oxygen is used as the final electron acceptor at the end of the ETC. • Oxygen receives electrons and H+(hydrogen ions) and produces a molecule of water.

Electron Transport The mitochondria has two membranes--the outer one and the inner membrane which is convoluted. The H+ which are brought to mitochondria accumulate between these two membranes.

ETC Product Summary • 34 ATP • H 2 O Usable energy Byproduct • Legend: 1 NAD --- 3 ATP 1 FAD --- 2 ATP • NAD – Nicotinamide adenine dinucleotide • FAD – Flavin adenine dinucleotide

Overview of Aerobic Respiration NADH FADH 2 Pyruvic Acid

Anaerobic Pathways Fermentation

What happens to the products of glycolysis when O 2 isn’t present?

Fermentation • Breathing provides enough oxygen for your body to carry out normal activities. • When you are conducting a high level of activity, breathing doesn’t supply enough air for your cell’s activities.

• If oxygen is not present, the products of glycolysis (pyruvic acid and NADH) will enter an alternative process called fermentation. • Fermentation provides enough ATP and recycles NADH into NAD+ so that glycolysis may continue until more oxygen becomes available.

Where does fermentation occur? • Cytosol of the cell

Two Types of Fermentation • Lactic Acid • Alcoholic

Lactic Acid Fermentation • Occurs in muscle cells in the body. • Lactic acid is a waste product of fermentation that will build up and cause your muscles to “burn” during hard exercise.

Lactic Acid Fermentation • Lactic acid fermentation also occurs in some bacteria and molds. • Waste products of the fermentation process give cheese different flavors. • Yogurt is another product of lactic acid fermentation.

Alcoholic Fermentation • Alcoholic fermentation is a process used by many yeasts and plants. • Also uses the products of glycolysis (NADH and pyruvic acid) to provide enough NAD+ and ATP for glycolysis to continue.

Alcoholic Fermentation • Alcoholic fermentation is used to make bread or dough rise and is also used for beer and wine.

Fermentation • Bacteria that rely upon fermentation play a very important role in digestive systems of animals. • They breakdown molecules by taking undigested material for their needs. • Without these bacteria we’d be unable to fully digest food.

1. 2. 3. 4. 5. 6. Questions What is the real benefit of fermentation? What is the cellular respiration equation? What factor determines the pathway that pyruvic acid takes after leaving glycolysis? What is the importance of cellular respiration to us? Explain how cellular respiration complements photosynthesis. What is the ultimate end product of cellular respiration?