Chapter 9- Lecture Outline Flashcards
Metabolism II
Flows into an ecosystem as sunlight and leaves as heat
¥ Catabolic Pathways: (3 things)
¥ Yield energy by oxidizing organic fuels
¥ The breakdown of organic molecules is exergonic
¥ Results in the production of ATP
¥ Two types of pathways:
Ð Fermentation
Ð Cellular respiration
¥ Metabolism involves the transfer of electrons
Ð These are oxidation reduction reactions: ____________________
Redox reactions
¥ Molecules can ___________ or ____________ electrons
accept or donate
Ð _____________= accepted electrons
Ð ____________= donated electrons
Reduced
Oxidized
__________________
Ð A molecule is reduced when it gains an electron
Ð A molecule is reduced when it gains a proton and an electron
¥ A hydrogen atom
¥ Reduction
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ Ð Three ways to oxidize a molecule ¥ Losing a hydrogen atom ¥ Losing an electron ¥ By gaining an oxygen atom
¥ Oxidation
Ð Carrier Molecules
Ð Electrons are not bouncing around free in the cytoplasm
¥ Are transferred on carrier molecules
Carrier molecules are usually Usually transferred in the form of a
Hydrogen Atom
Ð Carrier molecules
¥ Nicotinamide adenine dinucleotid (NAD + )
¥ Nicotinamide adenine Dinucleotide phosphate (NADP+)
¥ Flavine adenine Dinucleotide (FAD)
In a Redox reaction the carrier molecule is
NAD+
¥ Respiration is a cumulative function of three metabolic stages
Ð Glycolysis
Ð The Citric Acid Cycle
Ð Electron Transport Chain
The purpose of Cellular Respiration is to make
ATP
=Overview of Cellular Respiration
(Glucose Catabolism)
Glycolysis takes place is the
cytosol
Ð Glycolysis is the first step
¥ This splits glucose into two pyruvate
¥ Produces a net of two ATP
¥ Produces a net of two NADH+ H+
The pyruvate can go to fermentation to produce
acid or alcohol
Ð The Pyruvate can go to the Kreb’s cycle in the ______________
mitochondria ¥ This will produce Ð CO2 Ð NADH+ H+ Ð FADH2
¥ The carrier molecules send electrons to the
—
ETC
Ð The ETC
¥ Takes the electrons
¥ Uses them to pump hydrogen ions across a membrane
¥ Uses this energy for producing ATP
¥ Glycolysis
Ð Means “splitting of sugar”
Ð Breaks down glucose into pyruvate
Ð Occurs in the cytoplasm of the cell
Ð harvests energy by oxidizing glucose to pyruvate
¥ Glycolysis consists of two
(4) major phases
Ð Energy investment phase
Ð Energy payoff phase
Ð Glycolysis energy investment phase
Ð Glucose
¥ Receives a phosphate ¥ Changed to Fructose-6-phosphate ¥ Receives another phosphate Ð Now, Fructose 1,6-phosphate ¥ It is now split Ð G-3-p Ð DHAP Costs 2 ATP
Energy Investment Phase
Each G-3-P gets an inorganic phosphate ¥ Makes 2 NADH in the process ¥ Becomes 1,3 bisphosphoglycerate Ð Phosphate is taken off the 1,3 bisphosphoglycerate ¥ Forms ATP (Two total) ¥ Forms 3-phosphoglycerate Ð 3-phosphoglycerate is changed to 2 phosphoglycerate Ð 2 phosphoglycerate ¥ Loses H2O and becomes phosphopheonolpyruvate Ð Phosphopheonolpyruvate ¥ Loses the Phosphate 2ATP ¥ Forms Pyruvate
¥ The Glycolysis Energy Payoff Phase (Conservation)
¥ The Citric Acid Cycle
Ð Completes the energy-yielding oxidation of organic molecules
Ð Takes place in the matrix of the mitochondrion
¥ Pyruvate is taken to the matrix
¥ Is converted to acetyl CoA
Ð Forms another NADH
Ð Loses a CO2
Ð Acetyl CoA enters the Citric Acid cycle
¥ The Citric Acid Cycle
Ð Completes the energy-yielding oxidation of
organic molecules
Ð Takes place in the matrix of the mitochondrion
¥ Pyruvate is taken to the matrix
¥ Is converted to acetyl CoA
Ð Forms another NADH
Ð Loses a CO2
¥ The Citric Acid Cycle (Kreb‘s Cycle)
Ð Acetyl-CoA Enters the Cycle Ð Loses the CoA Ð The two carbons join the 4 of oxaloacetic acid ¥ This is now Citric Acid Ð This will oxidize the rest of the glucose ¥ Lose Hydrogen Atoms to three NAD+ ¥ Lose Hydrogen atoms to FAD ¥ Gives offs TwoCO2 Make an ATP
¥ After the Citric Acid Cycle
Ð NADH+H+ and FADH2 go to the ETC
Oxidative Phosphorylation Ð During oxidative phosphorylation, chemiosmosis couples electron transport to ATP synthesis Ð NADH and FADH2 ¥ Donate electrons to the electron transport chain ¥ powers ATP synthesis ¥ The Electron Transport Chain Ð A series of redox reactions Ð starts with NADH+ H+ or FADH2 Ð Electrons are passed to membrane bound Carrier molecules ¥ FMN ¥ Coq ¥ Cyt b ¥ Cyt c1 ¥ Cyt c ¥ Cyt a ¥ Cyt a3 ¥ Final electron acceptor is 02 Ð For aerobic Respiration Ð This pumps Hydrogen ions out of a prokaryote
__________________
Ð The Energy-Coupling Mechanism
Ð Uses energy in the form of a H+ gradient across a membrane to drive cellular work
Ð The resulting H+ gradient
¥ Stores energy
¥ Drives chemiosmosis in ATP synthase
¥ Is referred to as a proton-motive force
Ð ATP synthase
¥ H+ Go back to the matrix through ATP synthase
¥ Is the enzyme that actually makes ATP
¥ Net ATP Per Glucose Equals Approximately 36
Ð Chemiosmosis
Ð Two net ATP from Glycolysis
Ð Two ATP from the Citric Acid Cycle
Ð Each NADH =3ATP
¥ Two NADH from Glycolysis
¥ Two NADH fro pyruvate to acetyl CoA
¥ 6 from the Citric Acid cycle
¥ (6+2+2)3=30 ATP
Ð Minus two ATP due to the shuttle for pyruvate
¥ Fermentation
Ð Each FADH2 =2 ATP
¥ Two FADH2 from the citric acid cycle
¥ (2)2=4 ATP
¥ About 40% of the energy
Ð Is transferred to ATP during cellular respiration, making approximately 38 ATP
Ð Actually 36 to 32
¥ Fermentation
Ð When there are no final electron acceptors
¥ Pyruvate goes the other way
Ð The partial oxidation of sugar
Ð Uses an organic molecule to accept electrons
¥ NADH is oxidized to NAD+
Ð This is the main function of fermentation
¥ If a CO2 is lost from pyruvate ethanol is produced
¥ If pyruvate is reduced it becomes lactic acid
Ð The Evolutionary Significance of Glycolysis
__________________
Ð Occurs in nearly all organisms
Ð Probably evolved in ancient prokaryotes before there was oxygen in the atmosphere
¥ Glycolysis
