Download Respiration and Lipid Metabolism Aerobic

Aerobic Respiration - Review
Outline – Respiration and Lipid Metabolism
1. Review of Aerobic Respiration
2. Carbon sources in glycolysis
3. Metabolism of PEP and pyruvate
4. Oxidative pentose phosphate pathway
5. Malate oxidation
6. Electron Transport
Aerobic Respiration - Review
Glycolysis – Carbon sources
Sucrose
6C Sugar
conversion to 5C
sugar
Synthesis of 3C
to 7C sugars
Synthesis of
organic acids
Lipid breakdown
in glyoxysome
UTP
(night)
Glucose
Cytosolic Sucrose synthase
Starch
Chloroplast
Triose phosphates
(day)
UDPGlucose + Fructose
PPi
UTP
Hexokinase
Glucose phosphate
Glucose
Organic acid
synthesis in
mitochondria
Glycolysis
Pyruvate
Gluconeogenesis
in cytoplasm
Pathways to metabolize PEP & Pyruvate
Oxidative Pentose Phosphate Pathway
Glucose-6-P
Glucose
Glycolysis
NADH
Vacuole Æ storage
Mitochondrion Æ degradation
NAD
Pyruvate
P
PE
se
yla
ox
rb
ca
HCO3
ADP
vate e
Pyru xylas
o
arb
dec
2. reduce O2 for ATP
synthesis in mitochondria
6-Phosphogluconate
Oxaloacetate
Malate
Alcohol
dehydrogenase
ATP
Functions
1. supplies NADPH for
biosynthesis
NADP+
NADPH
NADH
NAD
3. Biosynthetic substrates for
RNA & DNA
lignin & flavonoids
aromatic amino acids
CO2
NADP+
NADPH
4. Produce Calvin cycle
intermediates before
greening
Ribulose-5-P
CO2
Fermentative Metabolism
NADH
NAD
Fructose-6-P
1
Citric Acid Cycle oxidation of malate
NAD+
Malate + NAD+
Oxaloacetate + NADH
Malate
dehydrogenase
• Start Mon
NAD+
Malate + NAD+
Pyruvate + CO2 + NADH
malic enzyme
From mitochondrion
Into cytosol
Functions
1. Complete oxidation of Krebs cycle intermediates
2. Regulation of malate levels in cell (malate can be
stored in vacuole … e.g. CAM plants)
Electron Transport Pathway
Electron Transport Pathway in Plants
Electron &
Proton
carrier
FMN &
Fe-S
proteins
e2e-
e-
Fe-S
proteins
Fe - S
proteins
b&c
cytochromes
e-
Cu centers
cytochromes
a1 & a3
1. Multiple NADH dehydrogenases
2. Alternative Oxidase
Outside membrane Oxidize NADH & NADPH
Inside membrane Oxidize NADH & NADPH
Rotenone resistant pathway for NADH oxidation
Cyanide and CO insensitive pathway
Electron Transport Pathway in Plants – Alternative Oxidase
Animal mitochondria – cyanide Æ 100%
Animal mitochondria + cyanide Æ 1% of uninhibited control
Plant mitochondria – cyanide Æ 100%
Plant mitochondria + cyanide Æ 10-100% of uninhibited control
Roles of Alternative oxidase
1. Volatilize chemical attractants
Outline –Lipid Metabolism
1. Functions of lipids in plants
2. Triacylglycerols, glycerophospholipis & glyceroglycolipids
3. Lipid synthesis
2. Adjust rates of ATP synthesis
Low ATP demand Æ high AO activity
4. Lipid degradation
Hi ATP demand Æ low AO activity
Voodoo lily
3. Response to stress
Draining Ubiquinone pool prevents
superoxide/hydroxide buildup
Skunk cabbage
2
Lipid Functions
1. Carbon storage
Seeds e.g. commercial oils: sunflower, soybean, peanut, cotton
Fruits e.g. avocado, olives
2. Energy Storage – same as above
3. Energy harvest – chlorophylls & carotenoids
4. Membranes – phospholipids
5. Protection – waxes
6. Hormones – isopreness Æ precursors to some hormones (ABA & GA)
metabolic products (natural rubber)
sterols & tocopherols
7. Intracellular signalling
linolenic acid Æ jasmonate Æ
activates defenses against
fungal & insect pathogens
anther & pollen development
Lipid Storage
1. Oil bodies store lipids = spherosomes or oleosomes
Half-bilayer membrane
single layer of phospholipids formed from ER
formed within ER membrane bilayer
Oleosin proteins stabilize membrane
Oil Body
11.16 Cycle of fatty acid synthesis in plastids of plant cells
Triacylglycerols
1. Glycerol + 3 fatty acids (acyl groups)
Fatty acids: 12 – 20 carbons, mostly 16-18
Oils ≈ unsaturated fatty acids
Fats ≈ mostly saturated fatty acids
Structural features of triacylglycerols and polar glycerolipids
Glycerophospholipids
Glyceroglycopholipids
Glyceroglycopholipids
Glycerophospholipids
3
Lipid Conversion to Carbohydrates
Β-oxidation of fatty acids
Biosynthesis of Glycerophospholipids & Glyceroglycolipids
Acetyl CoA
Acyl Carrier Protein
Condensation to fatty acids-ACP
Oil
Bodies
100% in
Chloroplast
Oilseed
Germination
Glycerol-3-P
Growth
Glycerophospholipids
Different
Acyl
Carriers
Triacylglycerol hydrolysis to free fatty acids
Fatty acid β oxidation to Acetyl CoA
Glyoxysome
Succinate
Glyoxylate cycle
Sucrose
Glucose
Gluconeogenesis
Mitochondrion
Malate
Oxaloacetate
Cytosol
Glyceroglycopholipids
Lipid Conversion to Carbohydrates
END
Respiration &
Lipid Metabolism
4