Chpt. 12: Respiratio

n

Two types of respiration

External Respiration Internal respiration-is the process by which - is the controlled organisms exchange gases release of energywith their environment, from food.e.g. occurs in lungs of mammals, gills of fish.

Internal Respiration• controlled by enzymes.• normally involves the breakdown of glucose.• Energy that is released is trapped in the form of ATP:

EnzymesGlucose Energy

(ATP)

•Two types of internal respiration:1 Aerobic respiration.2 Anaerobic respiration.

Internal RespirationAerobic Respiration: is the release of energy from food within cells using oxygen.

Aerobes – living organisms which get their energy from aerobic respiration.

Brief explanation of aerobic respiration:

• Energy stored in bonds of glucose molecule released and used to make ATP.•When ATP breaks down it supplies energy for all metabolic reactions in the cell, e.g. growth, production of new cells etc.

Internal RespirationProcess of aerobic respiration can be represented by the balanced equation:

Enzyme

Glucose + Oxygen Carbon Dioxide + Water + Energy

C6H12O6 + 6O2 = 6CO2 + 6H2O + Energy

Internal Respiration

Detailed explanation of aerobic respiration (O.L.):

Aerobic respiration is a two stage process:

Stage 1: A process called glycolysis occurs in the cytosol (liquid in cell that surrounds the cell organelles) of the cell.Glycolysis does not use oxygen – anaerobic process.This process releases very little energy!!!Glycolysis involves the splitting of glucose with 6 carbon molecules (C6) into two 3 carbon molecules (C3).

Internal RespirationStage 1: At the same time a small number of ATP

molecules are released.

Glycolysis:

Glucose two 3 carbon + small amount molecules of energy

Note: stage 1 does not require oxygen and releases a small amount of energy!!!

Internal RespirationStage 2: takes place in the mitochondria. requires oxygen – aerobic respiration. releases a lot of energy – it produces many ATP molecules.This stage involves the complete breakdown of the two C3 molecules releasing a large amount of energy which is used to form a large amount of ATP molecules.Carbon dioxide and water (contain very little energy) are the end products of stage 2 and subsequently aerobic respiration.

Internal Respiration

Aerobic Respiration (O.L)

Glucose (6 carbons)

Two 3 – carbon molecules

Carbon Dioxide and Water

Small energy release

Large energy release

Stage 1

Anaerobic

Stage 2 Aerobic

Internal RespirationAnaerobic Respiration: is the release of energy from food without using oxygen.

Anaerobes: living organisms which get their energy from anaerobic respiration.

Brief explanation of anaerobic respiration: occurs in the cytoplasm of the cell. Glycolysis occurs breaking glucose (C6) into two 3 – carbon molecules (C3)

This process releases very little energy!!! As a result this process is far less efficient process than aerobic respiration as glucose only partially broken down.

Internal Respiration

Anaerobic respiration also known as fermentation

Two types of fermentation

Lactic Acid Fermentation Alcohol Fermentation

Internal Respiration

Lactic Acid Fermentation (Anaerobic Respiration): occurs in some bacteria and fungi and in mammal muscle (humans) when it is short of oxygen. This process can be represented by the equation:

Glucose 2 Lactic Acid + Small amount of energy

Internal Respiration

Alcohol Fermentation:occurs in some bacteria, fungi (such as yeast) and in plants when they are deprived of oxygen.This process can be represented by the equation:

Glucose 2 ethanol + 2 carbon dioxide +

small amount of energy

Micro Organisms in Industrial Fermentation• Biotechnology (bioprocessing): is the production of useful products using living cells or their parts (cells, enzymes).

• Biotechnology: involves the use of plants, animals and (mainly) micro-organisms.

• Fermentation: in industry means the production of useful products by micro-organisms with or without the use of oxygen.

Industrial Fermentation – Production MethodNote: Bioreactor – vessel in which the biological reactions take place (pg. 117).

• Micro – organisms – placed in bioreactor with suitable substrate.•Mixture – stirred or agitated to ensure contact between micro –organisms and substrate.• Foam – ,which is produced as a result of mixing, removed by foam breaker.•Culture Medium – liquid in which micro-organisms grow.

Industrial Fermentation – Production Method• Air is pumped into bioreactor to ensure adequate amount of oxygen dissolved in culture medium. • Sparger – forms small air bubbles which dissolve more readily into culture medium.• Other important factors during production:

1. correct nutrients and micro – organisms.2. suitable temperature and pH.3. sterile environment.

Micro – Organisms used in Bio processingWide range of micro – organisms used to produce a huge range of useful chemicals and materials:

• Fungi (yeast) - used in beer and wine production.

- used to supply carbon dioxide to cause dough to rise.

• Bacteria and yeasts – manufacturing yoghurt, cheese, vinegar,

antibiotics.

• Genetically altered bacteria, yeasts, fungi – solvents, amino acids, vitamins, drugs, food additives, enzymes.

Aerobic Anaerobic

Location Cytoplasm and Lumen and Cristae of mitochondria

Cytoplasm

Oxygen Requirements

Uses O2 Does not use O2

End Products CO2 + H2O Ethanol +CO2

or

Lactic acid

Energy Produced Lots of energy(38 ATP)

Little energy(2 ATP)

Differences between Aerobic and Anaerobic Respiration

Detailed Study of Aerobic RespirationHigher Level

Stage 1: Glycolysis (small amount of energy produced)

- occurs in cytosol of cell.

- enzymes speed up the process.

- glucose which is a 6-carbon (C6) sugar is converted to two 3-carbon (C3) sugars called pyruvic acid.

-This is neutral molecule which may be found as the negatively charged ion pyruvate.

- No oxygen is required some of the energy released forms 2 ATP molecules more of the energy is used to form NADH.

Stage 1:

Starch in plants Glycogen in animals

Glucose (C6)

ADP + P

ATP

NAD+

NADH

PYRUVIC ACIDC3

PYRUVIC ACIDC3

NAD+

NADH

ADP + P

ATP

Stage 1:

Glucose (C6) 2 Pyruvic + 2ATP Acids (C3)

Stage 2:In stage 2 a complex series of reactions take place

• If oxygen is present the 2 pyruvic acids enter the lumen(matrix) of the mitochondria and the following processes take place:

A) Formation of acetyl coenzyme A• Pyruvic acid (3C) is converted to acetyl coenzyme A (2C) by the

removal of CO2 and 2 e-

• NAD+ is an electron acceptor and it will combine with the 2e- and a H+ proton to produce NADH:

NAD+ + 2e- + H+ NADH

Note: this NADH enters an electron transport system (ETC) to produce H2O and ATP – discuss later

Stage 2:

B) Krebs Cycle• Acetyl coenzyme A now enters a series of reactions

called Krebs Cycle

• Acetyl coenzyme A is broken down to CO2, H+ protons and 2e- by a series of reactions.

• 2e- and H+ combine with NAD+ to form NADH (goes to ETC)

• One ATP (phosphorylation) is made in each cycle.

Stage 2:

B) Krebs Cycle

Please be familiar with diagram representing this cycle

Pyruvic Acid (3C)

CO2NAD+

2e- NADH

Acetyl coenzyme A (2C)

CO2

6e-

3NAD+

3NADH

ADP + PATP + water

CO2

2e-

NADH

NAD+

Electron Transport System

Electron Transport System

Stage 2:

C) Electron Transport Chain (ETC)• Electron transport chains are located on the inner

membrane (cristae –folds) of the mitochondria.

• Each electron transport chain consists of electron carrier proteins in an orderly sequence in the cristae of the mitochondria.

• High energy electrons are passed from NADH to the first of these protein molecules.

• As electrons pass from molecule to molecule within each chain they lose some of their energy.

Stage 2:C) Electron Transport Chain (ETC):• Some of the energy released by the electrons is

used to form ATP (oxidative phosphorylation) and the rest is lost as heat.

• At the end of each chain , low energy electrons are removed by combining with oxygen and hydrogen to form water.

Stage 2:Electron Transport Chain (Oxidative Phosphorylation)

NADH (From Krebs Cycle)

H+ and NAD+

2e-

Carrier Enzyme 1ADP + P

ATP

Carrier Enzyme 2 ADP + P

ATP

Carrier Enzyme 3ADP + P

ATP

2e- + 2H+ + ½ O2 H2O

2e-

2e-

2e-

Low energy electrons

High energy electrons

Summary of Aerobic Respiration

Stage 1:• Glycolysis - anaerobic respiration

- releases very little energy - occurs in cytosol

Stage 2:• Krebs Cycle rxns and Electron Transport Chains• aerobic respiration• release large amount of energy• occurs in lumen and cristae of mitochondria

Anaerobic RespirationGlycolysis (small amount of energy produced)

- occurs in cytosol of cell.- glucose which is a 6-carbon (C6) sugar is converted to two 3-carbon (C3) sugars called pyruvic acid.

-This is neutral molecule which may be found as the negatively charged ion pyruvate.

- No oxygen is required some of the energy released forms 2 ATP molecules more of the energy is used to form 2 NADH molecules.

Anaerobic Respiration

• In the absence of oxygen the two NADH molecules break down to release 2e- and a proton.

• The 2e- and the proton are then added to pyruvic acid forming either:

- lactic acid (lactic acid fermentation)- ethanol and CO2 (alcohol fermentation)

This addition of electrons is a process called Reduction

Krebs Cycle Diagram Krebs Cycle Theory

Glycolysis Diagram Glycolysis Theory

ETC Diagram ETC Theory