9.1 Cellular Respiration: An Overview Lesson Overview 9.1 Cellular Respiration: An Overview

THINK ABOUT IT You feel weak when you are hungry because food serves as a source of energy. How does the food you eat get converted into a usable form of energy for your cells?

Chemical Energy and Food Food provides living things with the chemical building blocks they need to grow and reproduce. Food molecules contain chemical energy that is released when its chemical bonds are broken.

Chemical Energy and Food Energy stored in food are calories. A Calorie is the amount of energy needed to raise the temperature of 1 gram of water by 1 degree Celsius. 1000 calories = 1 kilocalorie, or Calorie. Cells use the energy from fats, proteins, and carbohydrates.. Cells break down food molecules to make ATP

Comparing Photosynthesis and Cellular Respiration What is the relationship between photosynthesis and cellular respiration?

PHOTOSYNTHESIS AND RESPIRATION Mitochondria Chloroplast

How ATP is Produced: Cellular Respiration IN Out Mitochondrion Glucose Carbon Dioxide Oxygen Water ADP ATP Free Phosphate (P) The ATP can be used directly to power life processes

Capturing Light Energy: Photosynthesis Requirements and products of photosynthesis Out IN Chloroplast Glucose Carbon Dioxide Oxygen Water Water Light Energy

Overview of Cellular Respiration What is cellular respiration? Cellular respiration is the process that releases energy from food in the presence of oxygen. In symbols: 6 O2 + C6H12O6  6 CO2 + 6 H2O + Energy In words: Oxygen + Glucose  Carbon dioxide + Water + Energy

Adenosine Triphosphate What forms of energy? ATP Adenosine Triphosphate

How ATP provides energy… ATP links Anabolism (building molecules) and catabolism (breaking down molecules)!!!!!

Stages of Cellular Respiration The three main stages of cellular respiration are … Glycolysis, the Krebs cycle, the Electron Transport Chain. WE START HERE!!

Glycolysis Glycolysis produces only a small amount of energy. Glycolysis takes place in the cytoplasm of a cell. Gylcolysis is an anaerobic process (no O2 needed)

Glycolysis Cytoplasm

Glycolysis During glycolysis, we start with… 1 molecule of glucose We end with… 2 ATP 2 NADH 2 molecules of pyruvic acid (these 2 will be used for the Krebs cycle)

Glycolysis ATP production 2 ATP are used to get it started 4 ATP are produced during Glycolysis SO, a total of 2 ATP are produced for each molecule of glucose that enters glycolysis…

NADH Production 2 NADH molecules are produced for every molecule of glucose that enters glycolysis. During glycolysis, the electron carrier NAD+ (nicotinamide adenine dinucleotide) accepts a pair of high-energy electrons and becomes NADH. - Electrons are carried by NADH to the electron transport chain to make more ATP.

The Advantages of Glycolysis Glycolysis produces ATP very fast, which is an advantage when the energy demands of the cell suddenly increase. Glycolysis does not require oxygen, so it can quickly supply energy to cells when oxygen is unavailable.

NET PRODUCTION OF ATP = 2

Stages of Cellular Respiration What molecule is entering the Kreb’s Cycle? 2 Pyruvic Acid Molecules During the Krebs cycle, a little more energy is generated from pyruvic acid.

Stages of Cellular Respiration Glycolysis – takes place in cytoplasm and requires no oxygen Krebs Cycle – takes place in mitochondria and requires oxygen Electron Transport Chain – takes place in mitochondria, requires oxygen and produces A LOT of energy

The Process of Cellular Respiration Kreb’s Cycle The Process of Cellular Respiration

The Krebs Cycle During the Krebs cycle, pyruvic acid is broken down into CO2 The Krebs Cycle is also known as the citric acid cycle due to the citric acid that is formed…

Citric Acid Production pyruvic acid enters the mitochondria.. NADH, CO2 and acetyl-CoA form from electrons and carbon atoms. Acetyl-CoA combines with a 4-carbon molecule to produce citric acid.

Energy Extraction Citric acid breaks down into a 5-carbon compound and a 4-carbon compound. The 4-carbon compound can then start the cycle again by combining with acetyl-CoA.

Energy Extraction Breaking bonds causes a release of energy. ATP, NADH, and FADH2 catch and store this released energy.

Energy Extraction Remember! Each molecule of glucose results in 2 pyruvic acids.. 2 pyruvic acids = two complete “turns” of the Krebs cycle. 2 pyruvic acids make…. 6 CO2 2 ATP 8 NADH 2 FADH2

2 pyruvic acids enter the Krebs Cycle, but what would only ONE pyruvic acid produce? 3 CO2 1 ATP 4 NADH 1 FADH2

Electron Transport and ATP Synthesis How does the electron transport chain use high-energy electrons from glycolysis and the Krebs cycle? The electron transport chain uses the high-energy electrons from glycolysis and the Krebs cycle to convert ADP into ATP.

Electron Transport NADH and FADH2 bring their high-energy electrons to electron carrier proteins in the electron transport chain.

Electron Transport At the end of the ETC, electrons combine with H+ ions and oxygen to form water.

Electron Transport Energy from the ETC moves H+ ions up the concentration gradient into the intermembrane space. H+ ions are building up…

ATP Production H+ ions pass back quickly across the mitochondrial membrane through the ATP synthase This causes ATP synthase molecule to spin. With each rotation, the ATP synthase makes 1ATP. For every glucose molecule, ATP synthase will spin 34 times and 34 ATP are produced.

Fermentation

Fermentation How do organisms generate energy when oxygen is not available? In the absence of oxygen, fermentation releases energy from food molecules by producing ATP.

Fermentation Fermentation is a process by which energy can be released from food molecules in the absence of oxygen. Fermentation occurs in the cytoplasm of cells.

Fermentation Under anaerobic conditions, fermentation follows glycolysis. During fermentation, cells convert NADH produced by glycolysis, which allows glycolysis to continue producing ATP.

Alcoholic Fermentation Yeast and a few other microorganisms use alcoholic fermentation that produces ethyl alcohol and carbon dioxide. This process is used to produce alcoholic beverages and causes bread dough to rise.

Alcoholic Fermentation Chemical equation: Pyruvic acid + NADH  Alcohol + CO2 + NAD+

Lactic Acid Fermentation Most organisms, including humans, carry out fermentation using a chemical reaction that converts pyruvic acid to lactic acid. Chemical equation: Pyruvic acid + NADH  Lactic acid + NAD+

Energy and Exercise How does the body produce ATP during different stages of exercise? For short, quick bursts of energy, the body uses ATP already in muscles as well as ATP made by lactic acid fermentation. For exercise longer than about 90 seconds, cellular respiration is the only way to continue generating a supply of ATP.