celullar respiration2
Transcript of celullar respiration2
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CELLULAR RESPIRATION
ENERGY FOR CELLS
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WHAT IS CELLULAR RESPIRATION?
1.Conversion of food into hexosecarbohydrates such as glucose and itssubsequent breakdown
2.May involve breakdown of glucose
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Respiration can be conveniently divided intotwo parts
1. Cellular (internal or tissue) respiration - thebiochemical processes which take placewithin living cells that release the energy from
glucose2. Gaseous exchange (external respiration) -
the processes involved in obtaining oxygenneeded for respiration and the removal of
gaseous waste such as carbon dioxide.
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Three stages in cellular respiration
1.Glycolysis2.Kreb cycle
(tricarboxylic acidcycle)
3.Electron transfersystem
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WHAT ORGANELLE INVOLVED IN THISPROCESSES?
1. Vary in size2. Usually rod shape3. Diameter ~ 1.0 m4. Length ~ 2.5 m
5. The wall - twomembranes
6. Inner membraneforms cristae
7. Most necessaryenzymes attachedto inner membrane
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GLYCOLYSIS
1.The first stage in the breakdown of glucose2.Occurs in cytoplasm of the cell3.Produces two molecules of pyruvates for
each molecule of glucose degraded4.Total energy yield - two ATP directly and six
ATP from two reduced NAD molecules = 8ATP
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Stages of glycolysis
Glucose (6C)
Glucose-P (6C)
Fructose-P (6C)
Fructose bisphosphate (6C)
Triose-P (3C)
Triose phosphate (3C)
Triose-P (3C)
Triose bisphosphate (3C)
Pyruvate (3C)
ATP ADP
ADP ATP
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KREB CYCLE (Citric acid cycle/ TCA cycle)
TCA cycle involves a series of biochemical
reaction
What are the functions TCA cycle?
1.Produce energy by releasing chemical energy in acetyl
CoA (2C) produce reducing power
= NADH , FADH2
2.Produce intermediates
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but : Pyruvate cannot enter TCA cycle directly
it must be converted to Acetyl-CoA
Pyruvate can be produced in Glycolysis
We can get energy from pyruvate, BUT HOW?
Via the process in the TCA cycle
To start TCA cycle:
Acetyl CoA + OAA citrate
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Overview of Krebs cycle
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8 steps in TCA cycle.
1.Introduction of 2C as acetyl-CoA
2.Isomerization of citrate to isocitrate
3.Oxidation of isocitrate
4.Oxidation of-ketoglutarate
5.Cleaving of succinyl-CoA
6.Oxidation of succinate
7.Hydration of fumarate
8.Oxidation of malate
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Importance of Krebs cylce
1. It provides hydrogen atoms which ultimatelyyield the major part of the energy derived fromthe oxidation of s glucose molecule
2. It is a valuable source of intermediates which areused to manufacture other substances, e.g. fattyacids, amino acids, carotenoids
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Connection with otherspathways/reactions
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ELECTRON TRANSFER SYSTEM
1. At the end of Krebs cycle, glucose has beenoxidised completely
2. Much of the energy is in the form of hydrogenatoms which are attached to the hydrogen carriers
NAD and FAD3. Other carriers are iron-containing proteins called
cytochromes4. Allows the production of ATP from ADP = oxidative
phosphorylation
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Energy moleculesproduction
14
3 2
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Electron transport generates
energy.
Aerobic respiration uses
oxygen to generate Energy from
food
Oxygen diffuses easily across
cell membrane
Oxygen is highly reactive so it
accepts electron easily
ELECTRON TRANSPORTCHAIN (ETC)
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In eukaryotic cells
protons are transported from the
matrix of the mitochondria across theinner mitochondrial membrane to theintermembrane space located betweenthe inner and outer mitochondrial
membranes
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Intermembrane space
matrix
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H+ ions that are formed during ETC are transportedfrom the matrix to the intermembrane space
[H+] in the intermembrane space is higher
than in the matrix.
Consequence ?
Proton gradient arise
Proton motive force
Proton must diffuse from high concentration to lowconcentration.
But the inner membrane is impermeable to proton !
How proton will get back into the matrix ?
The chemioosmotic theory
Proton must pass through the inner membrane following the
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Proton must pass through the inner membrane following theconcentration gradient
They pass through a special proton channel = ATP synthase
The flow of proton drives the synthesis of ATP !
matrix
Intermembrane space
Lots of ATP formed !
P d ti f E f Gl
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Production of Energy from Glucose
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QuickTime and a
TIFF (Uncompressed) decompressorare needed to see this picture.
SUMMARY
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ANAEROBIC PATHWAYS
Acetaldehydefermentation
Alcoholicfermentation
Lactic acidfermentation
Produce
pyruvate
Produce
ethanol
Produce
lactateCertainanaerobicbacteria
Yeast andother plants
Higheranimalsespecially in
the muscle
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ASSIGNMENT
Give an example of the application ofaerobic or anaerobic respiration andelaborate the concepts behind it.