energy and life energy is the force that makes it possible to do work
DESCRIPTION
ENERGY CONVERSION PROCESSES. ENERGY AND LIFE Energy is the force that makes it possible to do work. Almost everything that a cell does require energy. Living things can only use chemical energy to carry out their life functions. Living things rely on the chemical energy stored in their food. - PowerPoint PPT PresentationTRANSCRIPT
ENERGY AND LIFE• Energy is the force that makes it
possible to do work.• Almost everything that a cell does
require energy.• Living things can only use chemical
energy to carry out their life functions.• Living things rely on the chemical
energy stored in their food.
Carbohydrates are the foods most commonly broken down for energy.
The release of the energy stored in food goes on inside the cells in both autotrophs and heterotrophs.
This energy releasing process is called cellular respiration.
The energy released during cellular respiration is stored in the molecules of certain compounds.
One such compound is called ATP or adenosinetriphosphate.
AA TT PPADENOSINE TRIPHOSPHATE
It is the universal immediate source of energy in all living things.
Adenine – Ribose – P ~ P ~ P
Adenosine Triphosphate
~
~
• High energy bonds are shown with wavy line.
Hydrolysis of ATPHydrolysis of ATP
ATP + H2O ADP + Pi + Energy (7,3 kcal/mol)
enzyme
When the third phosphate in ATP is removed and bonded to another compound, it transfers its energy to the other compound. This transfer of energy is called “phosphorylation”.
In some processes, ADP’s second phosphate is used as a source of energy.
Ex: during polypeptide synthesis
ATP + H2O AMP + 2 Pi + Energy
REGENERATION OF ATPREGENERATION OF ATP There is continuous use
and regeneration of ATP in the cells.
The energy required for the regeneration is obtained from the oxidation of food stuff (cellular respiration) and in photosynthesis (during light reactions)
Regeneration of ATP involves phosphorylation reactions.
ADP – ATP CycleADP – ATP Cycle
ATP
ADP
Chemical energy for life used in
PiPiEnergy
gained by
Cellular respiration
Anaerobic
Aerobic
Biosynthesis
Movement
Active transport of materials
Muscle contraction
Transmission of nerve impulse
Bioluminescence
Exothermic processes
Endothermic processes
During cellular respiration, the energy released by the gradual breakdown of food molecules is used to attach a third phosphate to ADP.
Gradual release of energy from food is important because if all of the energy were released in a single burst, it would be too much for the cell to handle.
Oxidation-Reduction ReactionsOxidation-Reduction Reactions
Oxidation reduction reactions involve a transfer of energy
These reactions play a key role in cellular respiration.
When an atom is oxidized the other is reduced. A reaction of this kind is called oxidation-reduction reaction.
Oxidation-Reduction ReactionsOxidation-Reduction Reactions
Reduction involves a chemical change in which an atom or a molecule gains electrons or hydrogen.
The substance that is reduced gains energy.
Oxidation involves a chemical change in which an atom or a molecule loses electrons or hydrogen.
The substance that is oxidized usually loses energy.
HYDROGEN ACCEPTORSHYDROGEN ACCEPTORS
Each of the oxidation- reduction reactions requires the action of a specific enzyme. In turn, each enzyme requires a coenzyme to act as the hydrogen acceptor.
NAD and FAD are two of the coenzymes that act as hydrogen acceptors in cellular respiration. Each of these molecules can accepts two hydrogen atoms.
The coenzymes are reduced and gain energy temporarily.
Oxidation of coenzymes leads to production of ATP.
Oxygen or another substance acts as the final acceptor of hydrogen.
HYDROGEN ACCEPTORSHYDROGEN ACCEPTORS
NAD+ + 2H NADH + H+
NADH + H+ leads to production of 3ATP
FAD + 2H FADH2
FADH2 leads to production of 2ATP
TYPES OF RESPIRATIONTYPES OF RESPIRATION
ANAEROBIC RESPIRATIONANAEROBIC
RESPIRATIONAEROBIC
RESPIRATIONAEROBIC
RESPIRATION
glucose is not completely oxidized into CO2 and water
occurs in the absence of oxygen.
less energy is produced
glucose is completely oxidized to CO2 and water
requires free oxygen
more energy is produced
SUMMARY OF GLYCOLYSIS:
Glucose+ 2 ATP + 4Pi+ 4ADP+ 2NAD+
2 pyruvic acids +4ATP +2(NADH + H+ )+2H2O
enzymes
TOTAL ATP : 4 ATP NET GAIN: 2 ATP
1. Alcoholic Fermentation:
Glucose 2 pyruvic acid+2ATP 2 acetaldehyde
2 ethyl alcohol
2CO2
glycolysis
2NADH2 2NAD+
Replenishment of NAD
(to glycolysis)(from glycolysis)
ALCOHOLIC FERMENTATIONALCOHOLIC FERMENTATIONWhich type of cells perform alcoholic fermentation?
Where does it take place?
What is the energy yield of this process?
Yeast (Yeast are facultative anaerobes. They are eukaryotes and unicellular fungi. They can also carry out aerobic respiration.) Some type of bacteria
In cytoplasm
No energy is produced and used after glycolysis.
ALCOHOLIC FERMENTATIONALCOHOLIC FERMENTATIONWhat type of phosphorylation (ATP production) is seen?
Why the amount of energy harvested is less than aerobic respiration:
Are the microorganisms affected by the end-products?
Substrate level phosphorylation
Less energy produced because the end products still contain energy in their structure.
If the concentration of ethyl alcohol is more than 18% bacteria would die.
Why is pyruvic acid converted into end products after glycolysis?
ALCOHOLIC FERMENTATIONALCOHOLIC FERMENTATION
In order to replenish the oxidized NAD+ molecules.
Why is the end product a 2-carbon molecule (ethyl alcohol)?
ALCOHOLIC FERMENTATIONALCOHOLIC FERMENTATION
During the formation of acetaldehyde, CO2 is released.
2. LACTIC ACID FERMENTATION2. LACTIC ACID FERMENTATION
Glucose 2 pyruvic acid+2ATP 2lactic
acid
glycolysis2NADH2 2NAD+
Replenishment of NAD
(from glycolysis) (to glycolysis)
LACTIC ACID FERMENTATIONLACTIC ACID FERMENTATIONWhich type of cells perform lactic acid fermentation?
Where does it take place?
What is the energy yield of this process?
Skeletal muscle cells,
Yoghurt bacteria,
Certain fungi
In cytoplasm
No energy is produced and used after glycolysis.
Products such as wine, salami, cheese, sourdough bread, pickles, yogurt, cocoa, and coffee are all enhanced by LAB, which ferment six-carbon sugars, or hexoses, to produce lactic acid. (Image courtesy of DOE/Joint Genome Institute)
LACTIC ACID FERMENTATIONLACTIC ACID FERMENTATIONWhat type of phosphorylation (ATP production) is seen?
Why the amount of energy harvested is less than aerobic respiration:
Substrate level phosphorylation
Less energy produced because the end products still contain energy in their structure.
Accumulation of lactic acid in muscle cells causes muscle fatique (kas yorgunluğu). That’s why it needs to be broken down.
The amount of oxygen needed to get rid of lactic acid is called oxygen debt (oksijen borcu).
LACTIC ACID FERMENTATION IN LACTIC ACID FERMENTATION IN SKELETAL MUSCLE CELLSSKELETAL MUSCLE CELLS
LACTIC ACID FERMENTATION IN LACTIC ACID FERMENTATION IN SKELETAL MUSCLE CELLSSKELETAL MUSCLE CELLS
There are two mechanisms to get rid of lactic acid:
1. In the muscle cells lactic acid is converted to pyruvic acid during resting and pyruvic acid is used during aerobic respiration.
2. Lactic acid is also released into blood circulation and transported to the liver. In the liver it is converted back into glucose.
Lactic pyruvic glucose glycogen acid acid (for storage)
LACTIC ACID FERMENTATION IN LACTIC ACID FERMENTATION IN SKELETAL MUSCLE CELLSSKELETAL MUSCLE CELLS
LACTIC ACID FERMENTATION IN LACTIC ACID FERMENTATION IN SKELETAL MUSCLE CELLSSKELETAL MUSCLE CELLS
Comparison Of Lactic Acid Fermentation And Comparison Of Lactic Acid Fermentation And Alcoholic FermentationAlcoholic Fermentation
ALCOHOLIC FERMENTATION CO2 is released
End product is a 2- carbon compound (ethyl alcohol)
LACTIC ACID FERMENTATION No CO2 is released
End product is a 3-carbon compound (lactic acid)
Fermentation end products are variable, because organisms have different enzymes that produce different substances.
EXAMPLES
1. A cell hydrolyzes a polysaccharide containing 19 glycoside bonds. Calculate the total and net gain of ATP when the hydrolysis products of this molecule are used in glycolysis.
n -1= 19 so 20 monosaccharides
Total 20 x 4 =80 ATP
Net 20 x 2 =40 ATP
2. Calculate the total and net gain of ATP when a bacterium uses two molecules of glucose monophosphate during fermentation.
Total 8 net 6
3. A yeast cell uses 2 molecules of maltose. After hydrolysis these molecules are used in fermentation. Calculate the total and net gain of ATP.
Maltose = 2 glucose
Total = 4 x 4 = 16
Net = 4 x 2 =8
4. What will be the total and net gain of ATP in fermentation when a cell uses one molecule of fructose diphosphate?
4
FACTORS AFFECTING THE RATE OF FERMENTATION
FACTORS AFFECTING THE RATE OF FERMENTATION
Some of these factors are:
Amount of glucose Temperature The amount of end products
As all the reactions in fermentation are enzyme-catalyzed, any factor that affects enzyme activity also affects the rate of fermentation.
When the third phosphate in ATP is removed and bonded to another compound, it transfers its energy to the other compound. This transfer of energy is called “phosphorylation”.
TYPES OF PHOSPHORYLATION
TYPES OF PHOSPHORYLATION1. PHOSPHORYLATION AT SUBSTRATE LEVEL
X P + ADP ATPenzyme
Activated compound or substrate
2. PHOTOPHOSPHORYLATION
Chlorophyll ETS 2é
High energy electrons
light energy 2é
ATP
ADP + P i
All living things
Photosynthetic organisms
(Plants, cyanobacteria)
3. OXIDATIVE PHOSPHORYLATION
X ETS 2H + + 2é 2é
ADP + P i
ATP
½ O
2H + O -2
H 2 O4. CHEMOSYNTHETIC PHOSPHORYLATION
Chemosynthetic organisms
Ex: Iron, sulfur, nitrifying bacteria
Non-pigmented sulfur bacteria
2H 2 S + O2
oxidation
2H 2 O + S + ENERGY
ATP
ADP + P i
Organisms which do aerobic respiration
STAGES OF AEROBIC CELLULAR RESPIRATION IN EUKARYOTES
1.GLYCOLYSIS Breaking down of (6C) into two (3C)
molecules (It is the splitting of glucose) It occurs in the cytoplasm It is the metabolic pathway that occurs in
every living cell with the same enzymes. It is the common stage for both aerobic
and anaerobic cellular respiration.
SUMMARY OF GLYCOLYSIS:
Glucose+ 2 ATP + 4Pi+ 4ADP+ 2NAD+
2 pyruvic acids +4ATP +2(NADH + H+ )+2H2O
enzymes
TOTAL ATP : 4 ATP NET GAIN: 2 ATP 2NADH +2 H+ to the ETS
2. FORMATION OF ACETYL Co-A FROM PYRUVIC ACID
Pyruvic acid Acetyl Co A
CO 2
Co A
NAD + NADH + + H+
2 pyruvic acid+ 2CoA + 2 NAD + 2AcetylCoA + 2NADH + 2 H + + 2CO 2
ETSDiffuses out
Krebs cycle
3. KREBS CYCLE (C pathway) In eukaryotes it occurs in mitochondria matrix
In prokaryotes it occurs in cytoplasm
Krebs cycle occurs two times for each glucose molecule that enters glycolysis.
CO2 is released during the reactions.
Substrate level phosphorylation takes place. (2 ATP)
SUMMARY:
2 Acetyl CoA + 6NAD + + 2FAD +2 ADP+ 2Pi + 6 H 2 O
4 CO 2 + 6 NADH + 6 H + + 2 FADH 2 + 2ATP + 2CoA
Diffuse out
ETS RECYCLED
3. KREBS CYCLE (C pathway)
2 AcetylCoA (2C)
2H2 O
2CoA
2 citric acid (6C)2 oxaloacetic acid (4C)
2 NADH + 2H +
2 NADH + 2H +
2 NADH + 2H +
2 NAD+
2 NAD
2 NAD+
2α- ketoglutaric acid (5C)
2(4C) compound
2CO 2
2CO 2
2(4C) compound2H2 O
2 ATP 2 ADP + 2Pi
2(4C) compound
2(4C) compound
2FADH2
2FAD
(Substrate level phosphorylation)
2H2 O
(ETS)
(ETS)
(ETS)
(ETS)
4. ETS
(Respiratory Chain / H- Pathway / Oxidative phosphorylation) • ETS involves a series of oxidation reduction reactions.
• Most of the ATP created from the energy stored in glucose is produced by oxidative phosphorylation when NADH2 and FADH2 donate their electrons to a system of electron carriers embedded in the mitochondrial cristae.
• ETS consists of a series of increasingly electronegative components.
• The final electron acceptor of the chain is oxygen which is very electronegative.
• The components of the chain receive electrons from NADH2 and FADH2 and shift between reduced and oxidized states, passing electrons down an energy gradient to oxygen, which then picks up a pair of hydrogen ions and forms water.
4. ETS
(Respiratory Chain / H- Pathway / Oxidative phosphorylation)
12 pairs of high energy hydrogens are transferred to coenzymes NAD+ and FAD. The energy releasing reactions are carried out by the ETS which is a highly organized system of enzymes and coenzymes located in the inner membrane of the mitochondria (cristae).
4. ETS • Coenzymes FAD, NAD+ and
coenzyme Q can accept and transfer a pair of protons and electrons at a time ( 2H+ + 2e- )
But,
• a cytochrome molecule can accept and transfer only one electron at a time.
Therefore;
1. Protons (H+) are released after the coenzyme level of the system
2. Each ETS contains 2 molecules of each cytochrome
2 H + + 2é NAD +
ADP + Pi ATP
FAD
Coenzyme Q
2Cyt b
2Cyt c
2Cyt a3
2Cyt a
ADP + Pi ATP
ADP + Pi ATP
H2O
2H+
½ O2O -2 (Last electron acceptor)
Transfer of a Pair Of Protons and Electrons by NAD and FAD
NADH2 + 3 ADP + 3 Pi + ½ O NAD + 3ATP + H2 O
1.
2.
FADH2 + 2 ADP + 2 Pi + ½ O FAD + 2ATP + H2 O
Oxidative phosphorylation
Substrate
(oxidized)
Substrate
NADH2
NAD+
ADP+ Pi
ATP
FAD
FADH2
Reduced
Oxidized
CoQ
2Fe+3
2Fe+2
2 Cytb
ATP
ADP+ Pi
2 Cytc
2Fe+3
2Fe+2 2Fe+3
2Fe+2
ATP
ADP+ Pi
2 Cyta
2Fe+3
2Fe+2
2 Cyta3
½ O2
O-2
H2O2H+
2H+ + 2é
STAGESATP EXPENDED
ATP PRODUCTION
AT SUBSTRATE LEVEL
THE NUMBER OF HYDROGENS RELEASED AND THE AMOUNT OF
ATP PRODUCED IN ETS(OXIDATIVE
PHOSPHORYLATION)
H2OPRODUCE
D
Glycolysis
2 ATP 4 ATP2NADH2 4H ETS 4 or 6 ATP 2
Pyruvic Acid
Acetyl CoA
___ ___
2NADH2 4H ETS 6 ATP 2
Krebs Cycle and ETS
___ 2 ATP 6NADH2 12H ETS 18 ATP
2FADH2 4H ETS 4 ATP
6
2
TOTAL 2 ATP 6 ATP 10 NADH2
24 H 32 or 34 ATP2 FADH2
12
TOTAL NUMBER OF ATP PRODUCED IN AEROBIC RESPIRATION = 38 OR 40 (Depending on the type of eukaryotic cell)
NET GAIN = 36 or 38 ATP
ENERGY PRODUCTION IN AEROBIC RESPIRATION DURING BREAKDOWN OF ONE MOLECULE OF GLUCOSE
FUELS FOR CELLULAR RESPIRATION• Polysaccharides, fats, and proteins are digested
into monosaccharides, fatty acids, glycerol and amino acids that can be used in cellular respiration.
• Fermentation uses only monosaccharides as fuels.
• Aerobic respiration can use all three kinds of fuels.
• In addition to normal fuels, aerobic respiration can use the alcohol in alcoholic beverages.
FUELS FOR CELLULAR RESPIRATION• Monosaccharides enter aerobic respiration at glycolysis.
• Fatty acids enter as Acetyl-CoA.
• Glycerol enters as PGAL.
• Amino acids enter either pyruvic acid, or Acetyl-CoA or a molecule of the Krebs cycle . Most of the amino acids that enter the process from the Krebs cycle enter through α-ketoglutaric acid.
FUELS ADVANTAGES DISADVANTAGESMonosaccharides • used in both
fermentation and aerobic respiration• forms ATP rapidly•no toxic wastes
• limited stores in animals
Fatty Acids • large amount of energy per molecule • large stores in animals•normally no toxic wastes
• used only in aerobic respiration• forms ATP slowly• may lower blood pH
Amino acids • large amounts in animals (in muscles)
• used only in aerobic respiration• break down the muscles• nitrogenous wastes
COMPARISON OF FUELS USED IN CELLULAR RESPIRATION
AEROBIC CELLULAR RESPIRATIONAEROBIC CELLULAR RESPIRATION
C6H12O 6+ 6 H 2O + 6 O 2 6 C O 2 + 12 H 2 O + ENERGY
When the oxygen of glucose labelled with O18, it was released in the CO2
produced.
When the oxygen of the molecular oxygen was labelled, it was released in the water produced
AEROBIC RESPIRATION
ANAEROBIC RESPIRATION
Organic molecules are completely degraded into inorganic molecules. End products are carbon dioxide and water
Organic molecules are partially degraded. Ex: ethyl alcohol, carbon dioxide, lactic acid are the end products
• In prokaryotic cells, the complete process takes place in the cytoplasm.• In eukaryotic cells, the process begins in the cytoplasm and completed in the mitochondria
Takes place in the cytoplasm of prokaryotic and eukaryotic cells.
Involves substrate level and oxidative level phosphorylation
Involves substrate level phosphorylation only
AEROBIC RESPIRATION
ANAEROBIC RESPIRATION
It is more efficient.
Net gain of ATP from one glucose is 36 or 38.
It is less efficient.
Net gain of ATP from one glucose is 2.
Energy efficiency from one glucose
36 X 7.3
683
38 X 7.3
683
Energy efficiency from one glucose
2 X 7.3
683X 100 = 38.5 %
X 100 = 40%
X 100 = 2%