Some Questions to Consider What do we need

Some Questions to Consider What do we need energy for? How do we get energy to do these things?

Cellular Respiration And ATP Formation

Energy can change form • You can’t hold your portable CD player up in the air, and let wind blow through and hear your lovely music playing on it • Yet wind is a form of energy • It is just not the right form of energy to make the CD player work • Wind energy can be transformed into the correct form of energy though

Energy changes form

A wind farm can be used to transform wind energy into a useable form Wind turns the turbines and wind energy is transformed into kinetic energy This is then transformed into electrical energy, which comes through wires to your house and enables the CD player to function.

Wind energy kinetic energy electrical energy

Similarly…. . • Energy in the form of carbohydrates, ( glucose, glycogen) and • Energy in fats • And Energy in the carbon skeleton of amino acids is not in a form that cells can use directly

Transforming energy in simple organic molecules like Glucose into useable energy requires an energy converter In eukaryotic cells mitochondria do most of this trasnformation

General equation for aerobic respiration: C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 H 2 O + 36 ATP Glucose oxygen carbon dioxide water energy transformation hemical ----Chemical glucose) (ATP)

ABOUT ATP • The energy in glucose and other organic compounds is not used directly by cells. It is transferred into molecules of ATP. • ATP is the immediately usable form of energy for the cell. • It is used to drive endergonic (anabolic/build up) reactions.

ABOUT ATP • ATP is used up almost as quickly as it is produced; usually used up within 60 seconds of being formed. ( Yep! Gone in 60 seconds!) • Its production is an ongoing process within body cells. • It is produced using energy made available by the catabolism(breakdown) of organic compounds (usually glucose).

An ATP molecule

Adenosine Triphosphate (ATP)

Building Blocks of ATP Adenosine diphosphate (ADP) Inorganic phosphate

• Production of ATP is said to be COUPLED with the breakdown of glucose. The energy released in one reaction (breakdown of glucose) is used to drive the other (build up of ATP)

ATP Formation (synthesis) Energy from glucose breakdown ? + High energy bond Synthesis: water released

Energy is released from ATP when the high energy bond of the last inorganic phosphate is broken. This reaction is catalysed by an enzyme called ATPase The ADP and P can then be reused to make more ATP

ATP breakdown (hydrolysis) Energy released for cellular use + High energy bond broken (Hydrolysis: water required)

Putting it all together

Lets Summarize

Catabolism of glucose DRIVES…. Anabolism of ATP glucose Catabolism ATP Anabolism Protein

Cellular Respiration

Energy is released step by step ADP+Pi ATP etc, etc ADP+Pi ATP Energy ADP+Pi ATP Energy ADP+Pi Energy H 2 O glucose CO 2 (½) O 2

• Cellular respiration occurs in ALL living organisms (and indeed all living cells) at ALL times. It is essential for the continuation of ALL life. • Cellular respiration is a general term, which refers to the sequential break down of organic compounds by cells, in order to produce a form of energy that is immediately usable by body cells, typically ATP.

• The energy is released from the chemical bonds of the organic molecule that is broken down. • Cellular respiration involves many different reactions, each controlled by its own enzyme. • Cellular respiration usually uses glucose however fats (fatty acids and glycerol) and amino acids can also be used.

TWO TYPES OF RESPIRATION The two types of respiration are: Aerobic (using oxygen) and Anaerobic (not using oxygen).

Aerobic Respiration: • Provides most of the ATP for use in most eukaryotic cells. • Generally it is the breakdown of glucose in the presence of oxygen to provide energy for ATP production. (ATP is then used for cellular activity) • Carbon dioxide and water are produced as waste in this process

General equation for aerobic respiration: C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 H 2 O + 36 AT Glucose oxygen carbon dioxide water energy

Other ways of writing this 36 ADP + 36 pi 36 ATP C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 H 2 O C 6 H 12 O 6 + 6 O 2 + 36 ADP + 36 pi 6 CO 2 + 6 H 2 O + 36 ATP

• Some venoms and toxins can uncouple the reactions of cellular respiration and ATP formation. • When this happens extra energy is released as heat and a fever is experienced. • Apart from fever what other symptom will be experienced? Think …. answer on next slide

• Since less ATP is formed (energy is transformed into heat rather than being used to form as many ATP molecules) you will feel tired and like you have no energy!

Anaerobic Respiration: • Occurs in the absence of oxygen. • Occurs in the cytosol. • Net production of two ATP molecules per glucose molecule • Reduced efficiency, as glucose is not totally broken down. • The process is different in the cells of different organisms due to the different enzymes present within

Anaerobic Respiration in animals cells Glucose lactate + energy (2 ATP) C 6 H 12 O 6 CH 3 CH(OH)COOH + 2 ATP

Anaerobic Respiration in fungi cells Glucose 2 ethanol + 2 carbon dioxide + energy (2 APT) C 6 H 12 O 6 2 CH 3 CH 2 OH + 2 CO 2 +2 ATP

Try to complete the summary table of the two processes and then check the next slide for the answers.

Comparing Aerobic and Anaerobic Respiration Cytosol Where does it occur? When does it occur? Relative speed of ATP production Mitochondria When oxygen is present Relatively slow due to more steps in process When oxygen is absent Net ATP Yield ? 36/38 2 What are the reactants? What are the products? Usually glucose and oxygen Carbon dioxide and water Glucose only Relatively fast due to fewer steps in process Animal cells Lactic acid Plant or fungal cells Ethanol and carbon dioxide