Post on 14-Nov-2014
Advanced BiologyAdvanced Biology
Cellular RespirationCellular Respiration
Energy FlowEnergy Flow
Energy flows into Energy flows into an ecosystem as an ecosystem as sunlight and sunlight and leaves as heatleaves as heat
Light energy
ECOSYSTEM
CO2 + H2O
Photosynthesisin chloroplasts
Cellular respirationin mitochondria
Organicmolecules
+ O2
ATP
powers most cellular work
Heatenergy
Cellular RespirationCellular Respiration
C6H12O6 + 6O2 6CO2 + 6H2O + Energy
Stored in ATP
In cellular respiration the mitochondria break In cellular respiration the mitochondria break down (reduce) glucose releasing its stored energy down (reduce) glucose releasing its stored energy and producing and producing CO2 and and H2O as wastes
The energy is then stored in ATP molecules
Monosaccharide produced
by plants
Oxygen produced by plants during photosynthes
is
Waste CO2 is used by plants to
make more sugars 6.1
Redox ReactionsRedox Reactions
Redox reactionsRedox reactions– Transfer electrons from one reactant to Transfer electrons from one reactant to
another by oxidation and reductionanother by oxidation and reduction In In oxidationoxidation
– A substance A substance loses electronsloses electrons, or is , or is oxidizedoxidized
In In reductionreduction– A substance A substance gains electronsgains electrons, or is , or is
reducedreduced6.2
Redox ReactionsRedox Reactions Examples of redox reactions:Examples of redox reactions:
C6H12O6 + 6O2 6CO2 + 6H2O + Energy
becomes oxidized
becomes reduced
Na + Cl Na+ + Cl–
becomes oxidized(loses electron)
becomes reduced(gains electron)
#1
#2
6.2
Cellular RespirationCellular Respiration
Cellular respiration Cellular respiration oxidizes glucose in a oxidizes glucose in a series of stepsseries of steps
NADNAD+ + accepts accepts electrons from the electrons from the oxidation of glucoseoxidation of glucose
NADH is the reduced NADH is the reduced form of NADform of NAD+ +
NAD+
H
O
O
O O–
O
O O–
O
O
O
P
P
CH2
CH2
HO OHH
HHO OH
HO
H
H
N+
C NH2
HN
H
NH2
N
N
Nicotinamide(oxidized form)
N
6.3
Electron Transport ChainsElectron Transport Chains
From food via NADH
Uncontrolled Reaction Cellular Respiration6.4
Making ATPMaking ATP
Oxidative phosphorylationOxidative phosphorylation – – ATP is ATP is made as the result of an electron transport made as the result of an electron transport chainchain
Substrate-level phosphorylationSubstrate-level phosphorylation – ATP – ATP is made directly when an enzyme transfers is made directly when an enzyme transfers a P (phosphate) to ADPa P (phosphate) to ADP
6.5
ReviewReview
What particles store the energy in What particles store the energy in glucose?glucose?
What molecule carries electrons?What molecule carries electrons? What molecule gains and stores the What molecule gains and stores the
energy from the electrons?energy from the electrons?
The CellThe Cell
Cell Membrane
Cytoplasm
Golgi Apparatus
EndoplasmicReticulum
Nucleus
Mitochondria
3 Phases of Cellular 3 Phases of Cellular RespirationRespiration
GlycolysisGlycolysis– Breaks down glucose into two molecules Breaks down glucose into two molecules
of pyruvateof pyruvate The citric acid cycleThe citric acid cycle
– Completes the breakdown of glucoseCompletes the breakdown of glucose Oxidative phosphorylationOxidative phosphorylation
– Is driven by the electron transport chainIs driven by the electron transport chain– Generates ATPGenerates ATP
6.6
3 Phases of Cellular 3 Phases of Cellular RespirationRespiration
Electronscarried
via NADH
Glycolysis
Glucose Pyruvate
ATP
Electrons carried via NADH and
FADH2
Citric acid cycle
Oxidativephosphorylation:electron transport
andchemiosmosis
ATPATP
Mitochondrion
6.6
GlycolysisGlycolysis
Occurs in the cytoplasm of the cell Occurs in the cytoplasm of the cell
Means “splitting of sugar”Means “splitting of sugar”
Breaks down glucose into pyruvateBreaks down glucose into pyruvate1 6-Carbon glucose 1 6-Carbon glucose
2 3-Carbon sugar 2 3-Carbon 2 3-Carbon sugar 2 3-Carbon pyruvatespyruvates
6.7
ATP is required as activation energy to begin the reactions of glucolysis
ATP is then produced in the payoff phase along with 2NADH
Investment and Payoff
6.8
#1 – Two ATP are added to glucose to produce fructose 1,6-bisphosphate
#2 – Fructose 1,6-bisphosphate is split into two molecules of Glyceraldehyde 3-Phosphate
#3 – The two G3P’s are further oxidized producing 4 ATP (2 Net) and 2 NADH
#4 – G3P has now been completely oxidized to pyruvate
Glycolysis – In Detail
6.9
Before the citric acid cycle can begin Before the citric acid cycle can begin pyruvate must first be converted to acetyl pyruvate must first be converted to acetyl CoACoA
CYTOSOL MITOCHONDRION
NADH+ H+NAD+
2
31
CO2 Coenzyme A
PyruvateAcetyl CoA
S CoA
C
CH3
O
Transport protein
O–
O
O
C
C
CH3
3C 2C
CO2 NADH6.10
= ATP
The Citric Acid CycleThe Citric Acid Cycle Products Products
from one from one acetyl acetyl CoACoA– 3 NADH3 NADH– 1 ATP1 ATP– 1 FADH1 FADH– 2 CO2 CO
6.11
2
2
ReviewReview
How many carbons are left from 1 How many carbons are left from 1 glucose at the beginning of the citric glucose at the beginning of the citric acid cycle?acid cycle?
Electron TransportElectron Transport
NADH and FADH NADH and FADH provide electrons provide electrons for the chainfor the chain
The electrons The electrons transfer is transfer is exergonic because exergonic because they lose energy at they lose energy at each stepeach step
Where does this Where does this energy go?energy go?
2
Electronslide
6.12
Electrons from NADH and FADH are Electrons from NADH and FADH are passed to oxygen, forming waterpassed to oxygen, forming water
Electron transfer causes protein Electron transfer causes protein complexes to pump Hcomplexes to pump H++ from the from the mitochondrial matrix to the mitochondrial matrix to the intermembrane spaceintermembrane space
The resulting HThe resulting H++ gradient gradient– Stores energyStores energy– Drives chemiosmosis in ATP synthaseDrives chemiosmosis in ATP synthase– Is referred to as a proton-motive forceIs referred to as a proton-motive force
Electron TransportElectron Transport 6.12/6.13
The YieldThe Yield
There are three main processes in this metabolic enterpriseThere are three main processes in this metabolic enterprise
Electron shuttlesspan membrane
CYTOSOL 2 NADH
2 FADH2
2 NADH 6 NADH 2 FADH22 NADH
Glycolysis
Glucose
2Pyruvate
2AcetylCoA
Citricacidcycle
Oxidativephosphorylation:electron transport
andchemiosmosis
MITOCHONDRION
by substrate-levelphosphorylation
by substrate-levelphosphorylation
by oxidative phosphorylation, dependingon which shuttle transports electronsfrom NADH in cytosol
Maximum per glucose:About
36 or 38 ATP
+ 2 ATP + 2 ATP + about 32 or 34 ATP
or
6.14
Making ATP without OxygenMaking ATP without Oxygen
Cellular respirationCellular respiration– Relies on oxygen to produce ATP using Relies on oxygen to produce ATP using
the electron transport chainthe electron transport chain FermentationFermentation
– Allows cells to produce ATP in the Allows cells to produce ATP in the absence of oxygenabsence of oxygen
6.15
Fermentation or Fermentation or Respiration?Respiration?
Pyruvate is a key juncture in catabolismPyruvate is a key juncture in catabolismGlucose
CYTOSOL
Pyruvate
No O2 presentFermentation
O2 present Cellular respiration
Ethanolor
lactate
Acetyl CoA
MITOCHONDRION
Citricacidcycle
Alcohol Fermentation
Lactic Acid Fermentation
aerobicanaerobic
2 ADP + 2 P1 2 ATP
GlycolysisGlucose
2 NAD+ 2 NADH
2 Pyruvate
2 Acetaldehyde 2 Ethanol
H
H OH
CH3
C
O –
OC
C O
CH3
H
C O
CH3
CO22
2 ADP + 2 P1 2 ATP
GlycolysisGlucose
2 NAD+ 2 NADH
2 Lactate
O–
C O
C O
CH3O
C O
C OHH
CH3
2 Pyruvate
Alcohol fermentation– Pyruvate is converted Pyruvate is converted
to ethanol in two steps, to ethanol in two steps, one of which releases one of which releases COCO22
Lactic acid fermentationLactic acid fermentation– Pyruvate is reduced, using Pyruvate is reduced, using
NADH, to form lactate as a NADH, to form lactate as a waste productwaste product
6.16
Amino acids
Sugars Glycerol Fattyacids
GlycolysisGlucose
Glyceraldehyde-3- P
Pyruvate
Acetyl CoA
NH3
Citricacidcycle
Oxidativephosphorylation
FatsProteins Carbohydrates Glycolysis and the Glycolysis and the citric acid cycle citric acid cycle connect to many connect to many other metabolic other metabolic pathwayspathways
These pathways These pathways funnel electrons from funnel electrons from many kinds of organic many kinds of organic molecules into molecules into cellular respirationcellular respiration
Organisms use these Organisms use these organic molecules to organic molecules to build other build other substances or to substances or to make ATPmake ATP
6.17