Download Khan Academy 15min cell respiration

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CELL RESPIRATION AND FERMENTATION
Khan Academy 15min cell respiration
Bozeman biology
What is cellular respiration?
Stepwise oxidation of high energy food
molecules to low energy molecules: CO2 + H2O
organic mol. + O2 ----- CO2 + H2O + Energy
Fire is an oxidation rxn but unlike living systems it
releases Energy all at once.
Living systems respiration occurs in a series of
controlled steps releasing food energy a little at a
time.
AEROBIC RESPIRATION: ( 38atp/glucose)
W/ OXYGEN
(CH2O)n + O2 --- CO2 + H2O + Energy
ANAEROBIC RESPIRATION ( FERMENTATION)
w/o oxygen ( 2atp/glucose )
Breakdown of food using organic mol. Instead
of Oxygen as an oxidizer. ( much less efficient )
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-Fermentation ( anaerobic) : only breaks down food
molecules(glucose) part way.
-Energy stored as chemical potential energy
-There are other metabolic pathways for proteins
and lipids that feed molecules into the respiratory
pathway.
OVERVIEW OF THE BREAKDOWN OF GLUCOSE
UNDER AEROBIC CONDITIONS:
1.
Glucose ( C6H12O6) is broken down to
Carbon dioxide and water in a long series of
exergonic rxns.
2. Some of the energy stored in the glucose
molecules chem. Bonds is used to make
ATP.
3. Most of the energy transfer occurs as
hydrogen atoms removed from glucose are
passed through a pathway called the electron
transport system in a series of redox rxns.
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COENZYMES: (NAD+ , FAD+2)
1. Organic molecules that help to carry
substances from one rxn to another.
( in this case: specifically hydrogen atoms)
NADH , FADH2
2. Many coenzymes are made from vitamins
3. Coenzymes are reuseable:
a.NAD nicotinamide adenine dinucleotide
b. FAD flavin adenine dinucleotide
OVERALL OXIDATION OF ONE GLUCOSE DURING
CELL RESPIRATION:
4 BASIC PARTS:
1.
Glycolysis
2. Preparation for the CAC ( citric acid cycle)
( also known as the kreb cycle)
3. Citric acid Cycle
4. e- transport and chemiosmotic ATP
synthesis
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1.
GLYCOLYSIS:
a. Breaks down GLUCOSE into 2 PYRUVATE
Molecules
b. A small amount of ATP is made (2ATP)
c. NAD is reduced to NADH that then
takes the hydrogen to the e- transport
chain.
2NAD+ + H2 +2e- ---- 2NADH
1. GYLCOLYSIS
INPUTS:
1. GLUCOSE ( 6 C)
2. 2 ATP
OUTPUTS:
1. PYRUVATE (3C )
2. 4 ATP
3. 2NADH
-Many organisms survive solely on ATP mad
during glycolysis when O2 is not available .
-Occurs in the Cytosol.
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-The first half of Glycolysis uses energy
2ATP’s
- Each ATP donates a phosphate group to a 3
carbon molecule
-The 2nd half of glycolysis nets
4ATP’s -- direct energy use
2NADH ---- chemiosmosis
2 ( 3carbon pyruvates) -- CAC
- Pyruvate and NADH formed during glycolysis
move into the mitochondria
- The folded inner membrane of the
mitochondria forms a closed compartment
called the mitochondrial matrix. It is protein
rich.
Copyright 2004 by Alberts, Bray, Johnson, Lewis, Raff, Roberts, Walter.
Garland Publishing: Taylor Francis Group.
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The stepwise oxidation of sugars begins with glycolysis.
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2. PREPARATION FOR THE CITRIC ACID CYCLE
( KREB CYCLE)
- Each 3 carbon Pyruvate gives up one carbon
atom as CO2 leaving a two carbon Acetyl
group. Hydrogens released are picked up by
NAD+ forming NADH. ( NADH will go to etransport chain)
INPUTS :
2 PYRUVATE MOLECULES (3 CARBON)
Structural Formula
C3H3O3pyruvate ion
OUTPUTS:
- 2 CO2
- 2 Aceytl CoA
- 2 NADH
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-
Structure of NAD+/NADH
-
3. CITRIC ACID CYCLE: ( Kreb Cycle)
- The two carbon Acetyl groups are broken down
into 2CO2 molecules
- INPUTS
Acetyl CoA
-OUTPUTS:
1. ATP (2)
2. NADH (6)
3.FADH2 (2)
4.CO2
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In the CAC , Citric acid is recycled by the
attachment of a 2 carbon Acetyl group to
Oxaloacetate (4C) .
mitochondrion
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One Turn of the Cycle
Acetyl-CoA + 3 NAD+ + FAD + GDP + Pi --- 3 NADH + FADH2 + CoA-SH + GTP
>
+ 3 H2O
+ 3 CO2
Acetyl-CoA
Oxaloacetate
Citrate
Malate
Isocitrate
Fumarate
a-Ketoglutarate
Succinate
Succinyl-CoA
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4.ELECTRON TRANSPORT CHAIN AND
CHEMIOSMOTIC ATP SYNTHESIS
NADH + FADH2 produced in glycolysis and the citric
acid cycle pass hydrogens they carry to a system of
electron transport molecules housed in the
membrane.
Here the hydrogen is separated into H+ and e- and
the hydrogen ion is pushed from the matrix to the
intermembrane space setting up a hydrogen ion
gradient across the inner membrane.
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-The H+ Gradient provides energy to join ADP + Pi
forming ATP
-Some electron transport molecules in the chain
carry hydrogen atoms while others only carry
electrons
-The first molecule in the chain lies on the inner
surface of the mitochondrial membrane. It can
accept two hydrogen atoms from NADH + H+ and
transports them through the membrane to the
outer surface.
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H+ builds up on the outside membrane
1 glucose = 64 H+ moved to the outside
Note: most energy is made in the e- transport chain
via chemiosmotic ATP synthesis.
OXYGEN’S ROLE IN RESPIRATION:
1. Oxygen is breathed into the lungs where it
enters the bloodstream via the alveoli.
2. It is attached to rbcs on the heme group
3. It goes to each cell in your body via blood
4. Oxygen diffuses into the cell and into the
mitochondria
5. e- arriving at the end of the ETC have given
up most of their energy. These electrons
plus some H+ ions are taken by O2 forming
H2O.
O2 + 4e- + 4H+ ---- 2H2O
Note: w/o oxygen the carrier proteins can’t get rid
of the e- so the system backs up
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Dissociation of water into hydrogen ion and
hydroxide ion
H2O ---- H+ + OHElectron transport chain lies on the inner
membrane of the mitochondria
Pg 119 old book KNOW LAST TWO PARAGRAPHS
Uncouplers : Substances that permit hydrogen
ions to leak through the membrane without going
through channels where their energy is used by ATP
synthetase.
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(a) In the presence of excess phosphate and substrate and intact
mitochondria, oxygen is consumed only when ADP is added.
When all of the added ADP has been convertedinto ATP, electron
transport stops and oxygenconsumption ceases. (b) The addition of
2,4-dintrophenol uncouples electron transfer fromATP synthesis. The
oxygen is completelyconsumed in the absence of ADP.
Uncouplers Enable Organisms to Generate Heat.
The uncoupling of oxidative phosphorylation from electron
transport generates heat.
Hibernating animals and new borne animals (including human
beings) contain brown adipose tissue. The adipose
tissue is brown due to the high mitochondria content of the
tissue. A protein called thermogenin uncouples ATP synthesis
from electron transport by opening up a passive proton channel
(UCP-1) through the inner mitochondrial membrane. The
collapse of the pH gradient generates heat.
Proton Motive Force Drives Transport
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The primary purpose of the proton gradient is to generate ATP
by oxidative phosphorylation. The potential energy of the
gradient can also be used for active transport. The inner
mitochondrial membrane is impermeable to charged molecules.
Dinitrophenols used for diet supplement s until
several people ran out of ATP and died.
Many antibiotics are uncouplers . ex Gramicidin
Know steps pg 120 first 2 paragraphs
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FERMENTATION: (AKA: ANAEROBIC RESPIRATION)
2 TYPES: (Both pathways use glycolysis which nets
2ATP and 2 pyruvates)
1. LACTATE: Bi-product = lactate (lactic acid)
2. ALCOHOL: Bi-product = ethanol
- If a cell runs out of oxygen all the transport
molecules are soon stuck holding electrons
and the chain stops running , the proton
gradient runs out, the CAC also backs up and
stops . Organisms can still produce small
amounts of energy via Anaerobic respiration.
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ATP SYNTHASE ENZYME (F0 F1 complex)
Structure of ATP synthase, the FO proton channel and rotating stalk are shown in blue, the F1 synthase domain in
red and the membrane in grey.
An ATP synthase (EC 3.6.3.14) is a general term for an enzyme that can synthesize adenosine
triphosphate (ATP) from adenosine diphosphate (ADP) and inorganic phosphate by using some form of
energy. This energy is often in the form of protons moving down an electrochemical gradient, such as
from the lumen into the stroma of chloroplasts or from the inter-membrane space into the matrix in
mitochondria. The overall reaction sequence is:
ADP + Pi → ATP
These enzymes are of crucial importance in almost all organisms, because ATP is the common "energy
currency" of cells.
The antibiotic oligomycin inhibits the FO unit of ATP synthase.
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The electron transport chain in the mitochondrion is the site of oxidative
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The similarity between intracellular mitochondria and free-living bacteria is striking. The known
structural, functional, and DNA similarities between mitochondria and bacteria provide strong evidence
that mitochondria evolved from intracellular prokaryotic symbionts that took up residence in primitive
eukaryotic cells. (endosymbiont theory)
[edit] Mitochondrial redox carriers
Prokaryotes similar to Mitochondria / plastids
Cyclic DNA
Cyclic DNA
Small ribosomes
Small ribosomes
Plasma membrane
Plasma membrane
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FATS AND PROTEINS MAY ENTER THE METABOLIC
PATHWAYS OF CELL RESPIRATION.
-Both fats and proteins enter cell respiration at the
Acetyl level. They can then be used to power cell
respiration.
Proteins Are de-aminized
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Your body uses approx. 1 LB of ATP per minute
That is just less than one mole of ATP /minute
6.02 X 1023
A person will use up their bodyweight in ATP in about 24hrs