Cellular Respiration

1. Cellular Respiration

2. Metabolic reactions

• Many reactions are involved in the metabolism of an
organism:
ANABOLIC-CATABOLIC reactions
• 6CO2 + 6H2O + sunlight= C6H12O6 + 6O2
• C6H12O6 + 6O2 = 6CO2 + 6H2O + Energy
HYDROLYSIS:
• Cleavage (расщепление) of a complex molecule into its
subunits by adding water
ex: maltose + H2O = glucose + glucose
DEHYDRATION:
• Condensation reaction when from smaller molecules or
subunits, complex molecule formed and water is released
ex: glucose + glucose = maltose + H2O

3.

4.

EXOTHERMIC:
• When from reaction among products heat is released
ex: glucose + O2 = H2O + CO2 + energy + heat*
*this reaction passes in our muscles
ENDOTHERMIC:
• When reaction needs heat energy and occurs by taking heat
energy from environment
ex: evaporation of water in order to body to keep normal body
temperature
REDOX reactions
OXYDATION:
When as a result of reaction some atom loses electron
ex: K=K++eREDUCTION:
When as a result of reaction atom accepts electron
ex: Cl2+2e-=2Cl-

5.

6. Electron acceptors

• NAD (Nicotinamide adenine dinucleotide), and FAD
(Flavin adenine dinucleotide) are coenzymes present in
all cells that transfer electrons during the redox
reactions of metabolism.
• NAD + H+ + 2e- = NADH
• FAD + 2H+ + 2e- = FADH2

7. Cellular respiration

• Cellular respiration is a kind of catabolism in which
energy of food molecules, especially glucose is released
as ATP and heat.
• Oxygen in the air we breathe makes the production of
ATP more efficient, although some ATP is made without
oxygen.
• Metabolic processes that require oxygen are called
aerobic.
• Metabolic processes that do not require oxygen are
called anaerobic, which means “without air”.

8. Stages of cellular respiration

• The breakdown of glucose during cellular respiration
can be summarized by the following equation:
C6H12O6 + 6O2 6CO2 + 6H2O + energy
glucose oxygen gas carbon dioxide water
ATP
• Cellular respiration occurs in two stages:
Stage 1 Glucose is converted to pyruvate, producing
a small amount of ATP and NADH.
Stage 2 When oxygen is present, pyruvate and
NADH are used to make a large amount of ATP.
When oxygen is not present, pyruvate is converted
to either lactic acid or alcohol and carbon dioxide.

9. Cellular respiration

10.

11. Stage 1: Breakdown of glucose - GLYCOLYSIS

• The splitting of a glucose into 2
molecules of PYRUVATE is called
glycolysis.
• This step is the same in both aerobic
and anaerobic respiration.
• It takes place in cytoplasm.
Used:
Produced:
• Glucose
• 2 molecules of pyruvate
molecule
• 4 ATP (net gain 2 ATP)
• 2 ATP molecules • 2 NADH are produced
ATP: 2, NADH: 2, FADH: 0

12. Stage 2: Production of ATP

• When oxygen is present, pyruvate produced during
glycolysis enters a mitochondrion and is converted to a
two-carbon compound (Acetyl CoA).
• This process is known as PYRUVATE OXIDATION
Used:
• Pyruvate (*2)
• Oxygen (*2)
Produced
• Acetyl CoA (*2)
• CO2 (*2)
• 1 NADH (*2)
ATP: 2, NADH: 4, FADH: 0

13.

Stage 2: Production of ATP, continued
• After Acetyl CoA is formed, it enters a series cyclic
reactions called the KREBS CYCLE
• It was discovered by Hans Krebs 1937, and in 1953
was given a Nobel prize
Used:
• Acetyl CoA (*2)
Produced:
2 CO2 molecules (*2)
3 NADH molecules (*2)
1 FADH2 molecule (*2)
1 ATP molecule (*2)
ATP: 4, NADH: 10, FADH: 2

14.

15. Electron transport chain

Stage 2: Production of ATP, continued
Electron transport chain
• In aerobic respiration, electrons donated by NADH and
FADH2 pass through an electron transport chain (ETC).
• In eukaryotic cells, the electron transport chain is located in
the inner membranes of mitochondria.
• It is the highly organized system of enzymes and coenzymes
• In here from each NADH molecule 3 ATPs are formed
3*10 NADH = 30 ATPs
• And from each FADH2 molecule 2 ATPs are formed
2*2 FADH2 = 4 ATPs
• The net gain of ATP produced in ETC is equal to 34 ATP
• As a result of whole aerobic respiration, net 38 ATPs are
produced

16.

Electron Transport Chain of Aerobic
Respiration

17.

18.

19. Catabolisation of different compounds

20. Respiration in the absence of oxygen

• The process of energy formation from glucose
molecule in absence of oxygen is called as
FERMENTATION
• In the absence of oxygen only glycolysis occur
• Takes place only in cytoplasm
TYPES OF FERMENTATION
• Lactic acid fermentation
• Alcoholic fermentation

21. Lactic acid fermentation

• Type of fermentation when only lactic acid formed
with no CO2
• Seen in some bacteria and in human body
• Lactic acid fermentation is used in production of
yoghurt and cheese
• During heavy physical activities lactic acid
fermentation is seen in muscles which causes muscle
pain and stimulates brain to stop the activities.
REACTION OF LACTIC ACID FERMENTATION
C6H12O6 + 2ATP 2C3H6O3 + 4ATP + heat
glucose
lactic acid

22. Alcoholic fermentation

• Type of fermentation when ethyl alcohol and CO2
are formed
• Seen in some bacteria and in yeasts
• Alcoholic fermentation is used in production of
bread (yeasts), alcohol, wine, beer.
REACTION OF ALCOHOLIC FERMENTATION
C6H12O6 + 2ATP 2C2H5OH + 2CO2 + 4ATP + heat
glucose
ethyl alcohol carbon dioxide

23. Fermentation types

24. Production of ATP

25. Cellular respiration vs. Fermentation

26.

27. Comparison of aerobic respiration and fermentation

Aerobic respiration
• Uses oxygen
• CO2 and H2O are
produced
• 38 ATP produced
• Controlled by enzymes
• CO2 always produced
• Steps: glycolysis,
pyruvate oxidation,
Krebs cycle, electron
transport chain
• Seen in most organisms
Anaerobic respiration
• Does not use oxygen
• Lactic acid and alcohol
are produced
• 2 ATP produced
• Controlled by enzymes
• CO2 produced only in
alcoholic fermentation
• Steps: glycolysis only
• Seen only in some
bacteria, fungi and
human body