che 40 a- major metabolic pathways.pdf

7/29/2019 CHE 40 A- Major Metabolic Pathways.PDF

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METABOLIC PATHWAYS:RESPIRATION AND

PHOTOSYNTHESIS


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What are Metabolic Pathways?

o A series of chemical reactions occurring inthe cells catalyzed by enzymes.


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RESPIRATION


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What is ATP?

o ATP or Adenosine Triphosphate (C10H16N5O13P3) is a nucleotide thatcontains a large amount of chemical energy stored in its phosphate

bonds.

o ATP is produced through respiration from Adenosine Diphosphate orADP (C10H15N5O10P2).


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There are two types of respiration:

1. Aerobic Respiration uses oxygen tobreakdown glucose into ATP.

2. Anaerobic Respiration uses inorganic ororganic molecule other than oxygen tobreakdown glucose into ATP.


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Aerobic respiration consists of threeprocesses:

1. GLYCOLYSIS

2. KREBS CYCLE

3. ETS (ELECTRON TRANSPORT SYSTEM)


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Schematic Diagram of Glycolysis

GLYCOLYSIS

1. The 6-carbon glucose

(C6H12O6) is divided intotwo 3-carbon molecule

known as glyceraldehydes 3 phosphate

2. These glyceraldehydes 3

phosphates will undergofurther reactions to produce

pyruvic acid or pyruvate(CH3COCOOH).

REACTION


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Schematic Diagram ofKrebs cycle

KREBS CYCLE

1. The 3-carbon pyruvic acidformed from glycolysis isbeing reacted to enzymes

to produce 2-carbon acetyl.

2. In the Krebs cycle, theacetyl molecule is

completely oxidized to formCO2.

REACTION


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Schematic Diagram of ETS

ELECTRON TRANSPORT SYSTEM

1. NADH and FADH2 carry hydrogen ions(H+) and electrons (e-) to the

electron transport system located inthe membrane. The energy from theelectron transfers pumps hydrogen

ions across the membrane creating anelectrochemical gradient.

2. As the accumulating hydrogen ionsfollow the electrochemical gradientback across the membrane through

an ATP synthase complex, themovement of the ions provides

energy for synthesizing ATP from ADPand phosphate.

REACTION


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OVERALL REACTION FOR AEROBIC

RESPIRATION


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Anaerobic Respiration

o The final electron acceptor for this process, instead of O2,is inorganic or organic molecules.

o The process in which ATP is produced using organic matteras the final electron acceptor is fermentation.


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PHOTOSYNTHESIS


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What is photosynthesis?

o Photosynthesis is the process of transforming light energyto chemical bond energy.

o The most important chemical reaction on Earth.

o Photosynthesis is essentially the reverse of aerobicrespiration


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Photosynthesis takes place in three stages:

oLight-capturing events Capture energy from the sunlight

oLight-dependent reactions

Using energy to make ATP

oLight-independent reactions Using ATP to power the synthesis of plantmolecules from CO2 in the air.


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Light-Capturing Event

In the light-capturing event, photosynthetic pigments, especiallychlorophyll, absorb photons of light.

This excites some electrons in chlorophyll to the point where they are

passed to molecules in the light-dependent reactions

Reaction:


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Light-Dependent Reactions

In the light-dependent reactions, the energy of some of theseexcited electrons is used to generate ATP.

Some of the energy is used to split H2O into O2 and H+.

Oxygen is released as a waste productThe H+ and excited electrons are loaded onto a carrier, NADP+.

Reaction:


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Light-Independent Reactions

The light-independent reaction, also known as the Calvin Cycleis where CO2 is used to synthesize plant molecules

The end product is sugar, a food source for the plant. Thismakes the plant an autotroph.

Reaction:


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OVERALL REACTION FORPHOTOSYNTHESIS

che 40 a- major metabolic pathways.pdf

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