Cellular Respiration 1. g. Students know the role of the mitochondria in making stored chemical-bond energy available to cells by completing the breakdown of glucose to carbon dioxide. Mitochondria consist of a matrix where three-carbon fragments originating from carbohydrates are broken down (to CO2 and water) and of the cristae where ATP is produced. Cell respiration occurs in a series of reactions in which fats, proteins, and carbohydrates, mostly glucose, are broken down to produce carbon dioxide, water, and energy. Most of the energy from cell respiration is converted into ATP, a substance that powers most cell activities. 1. i.* Students know how chemiosmotic gradients in the mitochondria and chloroplast store energy for ATP production. Enzymes called ATP synthase, located within the thylakoid membranes in chloroplasts and cristae membranes in mitochondria, synthesize most ATP within cells. The thylakoid and cristae membranes are impermeable to protons except at pores that are coupled with the ATP synthase. The potential energy of the proton concentration gradient drives ATP synthesis as the protons move through the ATP synthase pores. The proton gradient is established by energy furnished by a flow of electrons passing through the electron transport system located within these membranes.

What is Cellular Respiration?

Cellular Respiration Is a series of reactions where fats, proteins, and carbohydrates, mostly glucose, are broken down to make CO2, water, and energy. C6H12O6 + 6O2  6CO2 + 6H2O + energy

Mitochondria The matrix where 3-carbon pieces that came from carbohydrates are broken down to (CO2 and water) The cristae is where ATP is made

ATP = Adenosine triphosphate Most of the energy from cell respiration is converted into ATP ATP is a substance that powers most cell activities.

Releasing energy from ATP

Creates ADP – Adenosine Diphosphate

chemical changes in cells cell division Some examples of the use of energy in organisms 10 muscle contraction Respiration supplies the energy for germination chemical changes in cells cell division These are only a few examples. Every living process in living organisms needs energy from respiration

One example of respiration in ourselves 15 One example of respiration in ourselves 2. The lungs absorb oxygen from the air 1. Air taken in 1.Food taken in 2.The stomach and intestine digest food. One of the products is glucose 3.The blood stream carries glucose and oxygen to the muscles The water produced as a waste product of respiration is picked up by the blood stream and may be lost in sweat, water vapour from the lungs or in urine Glucose and oxygen react to produce energy for muscle contraction 4 RESPIRATION 5 Carbon dioxide is carried to the lungs by the blood

Question 1 What is the most important point about respiration? 16 Question 1 What is the most important point about respiration? (a) it uses oxygen (b) It produces energy (c) It produces carbon dioxide (d) It needs food and air

17 Question 2 In which part of the human body is respiration most likely to be occurring? (a) The lungs (b) The heart (c) The muscles (d) All of these Respiration will be occurring in all parts of the human body that consists of living cells. Fingernails, toenails and hair do not contain living cells and so will not be respiring

Question 3 Which of these are waste products of respiration? 18 Question 3 Which of these are waste products of respiration? (a) Carbon dioxide (b) Water (c) Oxygen (d) Nitrogen

Question 4 Which of the following statements are correct? 20 Question 4 Which of the following statements are correct? (a) We breathe in air (b) We breathe in oxygen (c) We breathe out air (d) We breathe out carbon dioxide Air is a mixture of nitrogen, oxygen, carbon dioxide and a small proportion of other gases. We cannot selectively breathe in only oxygen and breathe out only carbon dioxide. The lungs absorb oxygen from the air we breathe in and give out carbon dioxide. So the air we breathe out contains less oxygen and more carbon dioxide than the air we breathe in.

Vocabulary Cellular Respiration – the transfer of energy from an organic compound into ATP Fermentation – the breakdown of carbohydrates by enzymes, bacteria, yeasts, or mold in the absence of oxygen Pyruvate- an ion of a three-carbon organic acid called pyruvic acid.

Cellular Respiration Cellular Energy The Stages of Cellular Respiration Cellular respiration has two stages. Glycolysis The first stage of cellular respiration is called glycolysis. Aerobic and Anaerobic Respiration The second stage of cellular respiration is either aerobic respiration (in the presence of oxygen) or anaerobic respiration (in the absence of oxygen). A large amount of ATP is made during aerobic respiration. NAD+ is recycled during the anaerobic process of fermentation. 12

Cellular Respiration Stage One: Breakdown of Glucose Glycolysis Glucose is broken down to pyruvate during glycolysis, making some ATP. 13

Cellular Respiration Stage Two: Production of ATP Krebs Cycle The Krebs cycle is a series of reactions that produce energy-storing molecules during aerobic respiration. Electron Transport Chain During aerobic respiration, large amounts of ATP are made in an electron transport chain. 14

Cellular Respiration Fermentation in the Absence of Oxygen Fermentation When oxygen is not present, fermentation follows glycolysis, regenerating NAD+ needed for glycolysis to continue. Lactic Acid Fermentation In lactic acid fermentation, pyruvate is converted to lactate. 15

Anaerobic Respiration 23 Anaerobic respiration is involved at some stage in the preparation of these foodstuffs

24 In anaerobic respiration, glucose is still broken down to carbon dioxide with the release of energy, but without the involvement of oxygen The glucose is not completely broken down to CO2 and H2O but to CO2 and alcohol (ethanol).

30 Fermentation One form of anaerobic respiration in bacteria and yeasts is called fermentation. During fermentation, sugar is broken down to alcohol and carbon dioxide Fermentation is involved in brewing and wine-making

31 Wine making Grapes are crushed and the sugar they contain is fermented by yeasts to produce alcohol and carbon dioxide. The carbon dioxide usually escapes but if the wine is bottled before fermentation is complete, the carbon dioxide dissolves and escapes as bubble when the bottle is opened This is the case with ‘sparkling’ wines such as Champagne Different varieties of grape produce different types of wine

Black grapes growing in a vineyard 32 Black grapes growing in a vineyard © Ilan’s Wine Making

Brewing 33 In brewing beer, a sugary product (malt) is dissolved out of germinating barley Yeast is added to this solution and fermentation begins, producing alcohol and carbon dioxide Some of the carbon dioxide escapes but the rest dissolves in the beer when it is bottled or put into casks When the bottles or casks are opened, the dissolved CO2 escapes as bubbles

Beer fermenting 34 ©Stuart Boreham/CEPHAS The carbon dioxide bubbles plus some of the beer constituents produce a dense froth on top of the beer. The fermentation vessel is an old-fashioned open type. ©Stuart Boreham/CEPHAS

Baking 35 In baking, yeast is added to a mixture of flour and water, made into the form of a dough The yeast first changes the flour starch into sugar and then ferments the sugar into alcohol and CO2 The CO2 forms bubbles in the dough which cause it to expand (‘rise’) When the dough is baked, the heat evaporates the alcohol but makes the trapped bubbles expand giving the bread a ‘light’ texture

Dough rising 36 The yeast is mixed with the dough After 1 hour in a warm place the dough has risen as a result of the carbon dioxide produced by the yeast

37 The ‘holes’ in the bread are made by the carbon dioxide bubbles. This gives the bread a ‘light’ texture

cytoplasm mitochondria