Exam 4 - POSSIBLE REVIEW INFO from 22 Flashcards
Metabolism involves
catabolic reactions that break down large, complex molecules to provide energy and smaller molecules.
anabolic reactions that use ATP energy to build larger molecules.
break down large, complex molecules to provide energy and smaller molecules.
catabolic reactions
use ATP energy to build larger molecules.
anabolic reactions
Catabolic reactions are organized in stages
Stage 1, 2, 3?
Stage 1: Digestion and hydrolysis break down large molecules to smaller ones that enter the bloodstream.
Stage 2: Within the cells, degradation breaks down molecules to two- and three-carbon compounds.
Stage 3: Oxidation of small molecules in the citric acid cycle and electron transport provides ATP energy.
Catabolic reactions
Stage 1:
Digestion and hydrolysis break down large molecules to smaller ones that enter the bloodstream.
Catabolic reactions
Stage 2:
Within the cells, degradation breaks down molecules to two- and three-carbon compounds.
Catabolic reactions
Stage 3:
Oxidation of small molecules in the citric acid cycle and electron transport provides ATP energy.
The ATP molecule, composed of
the base adenine, a ribose sugar, and three phosphate groups, hydrolyzes to form ADP and AMP along with a release of energy.
A. used in anabolic reactions
B. the energy-storage molecule
C. combined with energy-requiring reactions
ATP
What are the Important Coenzymes in Metabolic Pathways?
NAD+
NADP+
FAD
Coenzyme A
Coenzyme A (CoA) is made up of several components:
pantothenic acid (vitamin B5), phosphorylated ADP, and aminoethanethiol.
NAD+
nicotinamide adenine dinucleotide
is an important coenzyme in which the vitamin niacin provides the nicotinamide group, which is bonded to ribose and the nucleotide adenosine diphosphate (ADP).
NAD+
is required in dehydrogenation reactions that produce carbon–oxygen double bonds, such as the oxidation of alcohols to aldehydes and ketones.
NAD+
NADP+
nicotinamide adenine dinucleotide phosphate
is used in anabolic reactions, such as lipid and nucleic acid synthesis.
is reduced to form NADPH
NADP+
Used in phosphate pentose pathway… a coenzyme only used here…
NADP+ or NADPH
FAD name?
flavin adenine dinucleotide
contains ADP and riboflavin (vitamin B2).
undergoes reduction when the two nitrogen atoms in the flavin part of the FAD coenzyme react with two hydrogen atoms (2H+ + 2 e−), reducing it to FADH2.
Coenzyme FAD, flavin adenine dinucleotide
The coenzyme FAD (flavin adenine dinucleotide) made from riboflavin (vitamin B2) and adenosine diphosphate is reduced to
FADH2 by adding two hydrogen atoms.
participates in reactions that produce a carbon-carbon double bond.
is reduced to FADH2 with the aide of enzyme succinate dehydrogenase.
Think Succinate —> Fumarate
FAD, flavin adenine dinucleotide
is derived from a phosphorylated ADP and pantothenic acid bonded by an amide bond to aminoethanethiol, which contains the —SH reactive part of the molecule.
Coenzyme A
Important functions of coenzyme A include
preparation of small acyl groups such as acetyl for reactions with enzymes.
production of the energy-rich thioester acetyl CoA.
which steps for all pathways do we need FAD?
What about NAD?
What about NADP?
If you can’t think of every cycle then go back and look
complex II of ETC?
Complex II consists of the enzyme succinate dehydrogenase from the citric acid cycle.
In complex II,
CoQ obtains hydrogen and electrons directly from FADH2. This produces CoQH2 and regenerates the oxidized coenzyme FAD, which becomes available to oxidize more substrates.
Difference between ETC and oxidative phosphorylation?
Complexes I through IV are ETC, but the oxidative phosphorylation is complex V
In the chemiosmotic model,
H+ cannot move through the inner membrane but returns to the matrix by passing through a fifth protein complex in the inner membrane called ATP synthase (also called complex V).
the flow of H+ from the intermembrane space through the ATP synthase generates energy that is used to synthesize ATP from ADP and Pi.
***This process of oxidative phosphorylation couples the energy from electron transport to the synthesis of ATP.
In the liver, hexoses ___ and ____ are converted to glucose, the primary energy source for muscle contractions, red blood cells, and the brain.
fructose and galactose
takes place in the cytosol of the cell.
is a metabolic pathway that uses glucose, a digestion product.
degrades six-carbon glucose molecules to three-carbon pyruvate molecules.
Glycolysis
where does glycolysis occur?
cytosol
Where do we see NAD in Glycolysis?
In reaction 6, oxidation and phosphorylation,
the aldehyde group of each glyceraldehyde-3-phosphate is oxidized to a carboxyl group.
NAD+ is reduced to NADH and H+.
a phosphate group is transferred to each of the new carboxyl groups, forming two molecules of 1,3-bisphosphoglycerate.
sometimes to regenerate the NAD needed for step 6 in glycolysis…. what is one mechanism our body can do this anaerobically?
Anaerobic metabolism of pyruvate into Lactate… this allows for NADH + H+ —-> NAD+
High levels of NADH activates
lactate dehydrogenase molecule to make lactate (out of pyruvate)
What is step 1 of glycolysis, i.e. ___ turns Glucose into ____
The enzyme hexokinase catalyzes the phosphorylation of glucose to glucose-6-phosphate (G6P)
Glycolysis is regulated by three enzymes…. name them
In reaction 1, hexokinase is inhibited by high levels of glucose-6-phosphate, which prevents the phosphorylation of glucose.
In reaction 3, phosphofructokinase, an allosteric enzyme, is inhibited by high levels of ATP and activated by high levels of ADP and AMP.
In reaction 10, pyruvate kinase, another allosteric enzyme, is inhibited by high levels of ATP or acetyl CoA.
In glycolysis, there is a net gain of
two ATPs and two NADHs.
In glycolysis, there is a net gain of
two ATPs and two NADHs.
In reaction 1, hexokinase is inhibited by high levels of ___ which prevents…
glucose-6-phosphate, which prevents the phosphorylation of glucose
In reaction 3, phosphofructokinase, an allosteric enzyme, is inhibited by ___ and activated by ____
inhibited by high levels of ATP and activated by high levels of ADP and AMP.
In reaction 10, pyruvate kinase, another allosteric enzyme, is inhibited by ___ or ___.
In reaction 10, pyruvate kinase, another allosteric enzyme, is inhibited by high levels of ATP or acetyl CoA.
GLYCOLYSIS finish the Rxn below from one glucose molecule:
Glucose + 2 NAD+ + 2 ADP + 2Pi —->
Glucose + 2 NAD+ + 2 ADP + 2Pi
—->
Pyruvate + 2 NADH + 2 ATP + 4H+ + 2H2O
glycogen synthase - synthesis
glycogen phosphorylase - break down
Glycogenesis: Rxn 3 remember that GLYCOGEN SYNTHASE catalyzes the breaking of the phosphate bond to glucose in UDP-glucose so glucose can be added to the glycogen chain
In glycogenolysis, glycogen is broken down to glucose.
• glucose molecules are phosphorylated by glycogen
phosphorylase
glycogen phosphorylase cleaves α(1 4)-links until only oneglucose remains bonded to the main chain.
In muscles and kidneys, fructose is phosphorylated to
_____, which enters glycolysis in
reaction 3.
fructose-6-phosphate
Galactose reacts with ATP to yield galactose-1-
phosphate, which is converted to ______,
which then enters glycolysis at reaction 2.
glucose-6-phosphate
Pathways for Pyruvate
aerobic conditions
anaerobic conditions
anaerobic - fermentation or lactate
- fermentation: pyruvate –> ethanal + CO2 –> Ethanol (don’t forget NADH + H+ helps ethanal become ethanol and makes NAD+)
- lactacte: pyruvate (NADH + H+ to NAD+) –> Lactate
aerobic - acetyl
Pyruvate —> HS-COA + Pyruvate + (NAD+ to NADH) —> Acetyl CoA + CO2 AKA Acetyl-S-CoA + CO2
Under aerobic conditions, oxygen is available to convert
pyruvate to
acetyl coenzyme A (acetyl CoA) and CO2.
When oxygen levels are low, pyruvate is reduced to
lactate.
Under aerobic conditions (oxygen present), pyruvate
moves from the __ to the ___
is oxidized when a carbon atom is removed as CO2 as….
cytosol into the mitochondria to be oxidized further.
…the coenzyme NAD+ is reduced.
under aerobic conditions… The resulting two-carbon acetyl group is attached to CoA, producing….
…acetyl CoA, an important intermediate in many metabolic pathways.
Under anaerobic conditions (without oxygen),
- pyruvate is reduced to lactate and NAD+ by ___.
- NAD+ is used to oxidize ____ in the glycolysis pathway, producing a small amount of ATP.
lactate dehydrogenase
glyceraldehyde-3-phosphate
produced during anaerobic conditions
lactate
B. reaction series that converts glucose to
glycolysis pyruvate
C. metabolic reactions that break down large molecules to smaller molecules + energy
catabolic reactions
D. substances that remove or add H atoms in oxidation and reduction reactions
coenzymes
Glycogenesis
- is the metabolic process of converting glucose molecules into glycogen.
- produces ___ in this step of glycolysis
glucose-6-phosphate in reaction 1 of glycolysis.
Glycogenesis
- is the metabolic process of converting glucose molecules into glycogen.
- produces ___ in this step of glycolysis
glucose-6-phosphate in reaction 1 of glycolysis.
activated by low levels of blood glucose
glycogenolysis
B. converts glucose-1-phosphate to glucose-6-phosphate
glycogenolysis
C. activated by high levels of glucose-6-phosphate
glycogenesis
D. glucose + UTP UDP-glucose + Ppi
glycogenesis
• is a polymer of glucose with α(1 4)-glycosidic bonds and multiple branches attached by α(1 6)-glycosidic
bonds.
Glycogen
is formed when high levels of glucose-6-phosphate are
formed in the first reaction of glycolysis.
Glycogen
is not formed when energy stores (glycogen) are full,
which means that additional glucose is converted to
triacylglycerols and stored as body fat
Glycogen
Glycogenesis
1) G6P
2) G1P
3) UDP-Glucose
4) Glycogen
What is the regulatory enzyme?
Glycogen synthase
–Activated by insulin
–Inhibited by glucagon (liver) and epi (muscle)
Glycogenesis rxn steps?
which step adds uridine?
1) G6P
2) G1P
3) UDP-Glucose
4) Glycogen
Step 2 going to step 3 releases energy with enzyme pyrophosphorylase to transfer high energy UTP adding UMP to G1P
Glycogenolysis: Reactions 1 and 2
______ cleaves α(1 4)-links until only one glucose remains bonded to the main chain.
glycogen phosphorylase
Glycogenolysis:
is also the regulatory enzyme?
Activated by?
Regulated by?
glycogen phosphorylase
Activated by glucagon (liver) and epic (muscle)
Regulated by insulin
what helps activate glycogen synthesis and is also added to the end of the glycogen chain
UTP or Uridine Tri Phosphate
To protect the brain, hormones with opposing actions control blood glucose levels such as
- glucagon,
- insulin,
- epinephrine.
Gluconeogenesis: Glucose Synthesis
Where?
For which organs use it as their main energy source?
Glucose is synthesized in the tissues of the liver and kidneys.
Tissues that use glucose as their main energy source are the brain, skeletal muscles, and red blood cells.
If our glycogen stores are depleted,
• liver cells synthesize glucose by gluconeogenesis.
• glucose is synthesized in the cytosol of the liver cells,
and some is synthesized in the kidneys.
To begin gluconeogenesis, carbon atoms from noncarbohydrate food sources are converted to
pyruvate.
To start the synthesis of glucose from pyruvate,
• two catalyzed reactions are needed to replace reaction
10 in glycolysis to bypass the irreversible rxn
pyruvate carboxylase uses the energy of ATP hydrolysis
to catalyze the addition of CO2 to pyruvate and produce
oxaloacetate.
• phosphoenolpyruvate carboxykinase converts
oxaloacetate to phosphoenolpyruvate.
• phosphoenolpyruvate molecules now use enzymes to
form fructose-1,6-bisphosphate.
Gluconeogenesis new steps as far as new names of enzymes
- Pyruvate Carboxylase
- Phosphoenolpyruvate carboxykinase
- Fructose 1, 6 Biphosphatase
- Glucose-6-Phosphate
The second irreversible reaction in glycolysis is bypassed when fructose-1,6-bisphosphatase cleaves a phosphate group from fructose-1,6-bisphosphate to continue step 9 of Gluconeogenesis
F 1,6 B to F6P
Gluconeogenesis
In the final irreversible reaction, the phosphate group of glucose-6-phosphate is hydrolyzed by a different enzyme, ______, to form glucose.
glucose-6-phosphatase
Energy Cost of Gluconeogenesis
• The pathway consists of seven reversible reactions of
glycolysis and four new reactions that replace the three
irreversible reactions.
• Overall, glucose synthesis requires four ATPs, two GTPs, and two NADHs.
what do you start and finish with in the Krebs cycle?
oxaloacetate
Tell me about the Krebs cycle or Citric Acid Cycle and I mean EVERYTHING
Which steps turn NAD to NADH+H?
Which steps make FADH2?
Which steps turn GTP in to ATP?
Acetyl CoA + O-CIASSFMO for products
CAIASSFM for enzymes
Remember we switched your cycle up to start with what you ended before Central is now preceded by Only and for enzymes Army is now preceded by Cookies!
NADH+H+ made in steps 3, 4, and 8
GTP turned to ATP in step 5
FADH2 made in step 6
- an acetyl group bonds with oxaloacetate to form citrate.
- two decarboxylations remove two carbons as two CO2.
- four oxidations provide hydrogen for three NADHs and one In the citric acid cycle, FADH2.
- a direct phosphorylation forms GTP (ATP).
In the citric acid cycle
what are the products of the citric acid cycle total?
CoA + 3NADH + 3H + FADH2 + GTP + 2CO2
Regulation of the Citric Acid Cycle
The reaction rate for the citric acid cycle
• increases when ____ activate isocitrate
dehydrogenase.
• decreases when high levels of __ or ___ inhibit citrate synthase (first step in cycle).
low levels of ATP
ATP or NADH
3 regulating enzymes of the citric acid cycle?
1) Citrate synthase
3) Isocitrate dehydrogenase
4) A-Ketoglutarate dehydrogenase
3 regulating enzymes of the citric acid cycle, what activates and down regulates each?
1) Citrate synthase
3) Isocitrate dehydrogenase
4) A-Ketoglutarate dehydrogenase
1) Citrate synthase
ADP activates
NADH, ATP, and Citrate down regulates
3) Isocitrate dehydrogenase
ADP activates
NADH and ATP down regulates
4) A-Ketoglutarate dehydrogenase
ADP activates
NADH and Succinyl CoA down regulates
Ho w many of each of the following are produced in one turn of the citric acid cycle?
A. _ CO2 B. _ NADH
C. _ FADH2 D. _ GTP
A. 2 CO2
B. 3 NADH
C. 1 FADH2
D. 1 GTP
Cytochrome c carries one electron when
Fe 3+ is reduced to Fe2+ (orange sphere).
Electron transport AKA
Occurring in the matrix between the inner and outer membrane of the mitochondria and stepping high energy molecules down. All of these are oxygen dependent!!
respiratory chain
Th e reduced coenzymes NADH and FADH2 produced from glycolysis, oxidation of pyruvate, and the citric acid cycle are
oxidized to provide the energy for the synthesis of ATP.
In electron transport or the respiratory chain,
• hydrogen ions and electrons from NADH and FADH2 are
passed from one electron acceptor or carrier to the next
until they combine with…
• energy released during electron transport is used to
synthesize ATP from ADP and Pi during ____
…oxygen to form H2O.
oxidative
phosphorylation.
How many ATP are made from Glycolysis, Citric Acid Cycle Results?
How about in terms of ATP and Reduced Coenzymes?
32 ATP total
Glycolysis: 2 ATP, 2 NADH
Oxidation of pyruvate: 2 NADH
Citric acid cycle w/ 2 acetyl-CoA: 2 ATP, 6NADH, 2 FADH2
when you add all these up you get 4 ATP, 10 NADH, and 2 FADH2 which adds up after converting to 32 TOTAL ATP!
what is citrate synthase?
In the first reaction of the citric acid cycle,
catalyzes the condensation of an acetyl group (2C) from acetyl CoA with oxaloacetate (4C) to yield
citrate (6C) and coenzyme A.
the energy to form citrate is provided by the hydrolysis of
the high-energy thioester bond in acetyl CoA.
what turns on and off the citric acid cycle for all intensive purposes?
citrate synthase
two electron carriers, ___ and ____, attached to the inner
membrane of the mitochondrion, carry
electrons among these protein complexes
bound to the inner membrane.
coenzyme Q (CoQ) and cytochrome c
in the ETS what’s being pumped across the membrane (not passed along but actually travels through)?
Protons (H+) travel through DUE to the electrons being transported down the chain
In electron transport, the oxidation of __ and___provides hydrogen ions and electrons that eventually react with oxygen to form water.
NADH and FADH2
electron transport begins when hydrogen ions and electrons are transferred from
NADH to complex I.
loss of hydrogen from NADH regenerates NAD + to oxidize more substrates in
oxidative pathways such as the citric acid cycle.
hydrogen ions and electrons are transferred
to the mobile electron carrier CoQ, forming
CoQH 2.
CoQH2 carries electrons from complexes I
and II to complex III.
Complex I
During electron transfer,
• H+ ions are pumped through complex I into the intermembrane space, producing a reservoir of H+ (hydrogen ion gradient).
for every two electrons that pass from NADH to CoQ,
4H+ are pumped across the mitochondrial membrane,
producing a charge separation on opposite sides of the
membrane.
All true
What allows FADH2 and NADH to be oxidized and return to the citric acid cycle?
The electron transport Chain or system
Complex II consists of the enzyme ____ from the citric acid cycle.
succinate dehydrogenase
In complex II,
• CoQ obtains hydrogen and electrons directly from
This produces CoQH2 and regenerates the oxidized
coenzyme….
FADH2.
….FAD, which becomes available to oxidize more substrates.
In complex II,
• CoQ obtains hydrogen and electrons directly from
FADH2 and becomes CoQH2.
• two electrons are transferred from the mobile carrier
CoQH2 to a series of iron-containing proteins called
cytochromes.
• electrons are then transferred to two cytochrome c,
which can move between complexes III and IV.
all true
- contains Fe3+/Fe2+, which is reduced to Fe2+ and oxidized to Fe3+.
- generates energy from electron transfer to pump 4H+ from the matrix into the intermembrane space, increasing the hydrogen ion gradient.
Cytochrome c
Energy is coupled with the production of ATP in a process called
oxidative phosphorylation.
chemiosmotic model
• links the energy from electron transport to a hydrogen
ion gradient that drives the synthesis of ATP.
• allows complexes I, III, and IV to act as hydrogen ion
pumps, producing a hydrogen ion gradient.
• equalizes pH and electrical charge between the matrix
and intermembrane space that occurs when H+ must
return to the matrix.
all true
In the chemiosmotic model,
• H+ cannot move through the inner membrane but returns to the matrix by passing through a fifth protein complex in the inner membrane called….
called ATP synthase (also called complex V).
• the flow of H+ from the intermembrane space through the ATP synthase generates energy that is used to synthesize
ATP from ADP and Pi.
This process of oxidative phosphorylation couples the energy from
electron transport to the synthesis of ATP.
What regulates electron transport?
- is regulated by the availability of ADP, Pi, oxygen (O2), and NADH.
- decreases with low levels of any of these compounds and decreases the formation of ATP.
What regulates electron transport?
- is regulated by the availability of ADP, Pi, oxygen (O2), and NADH.
- decreases with low levels of any of these compounds and decreases the formation of ATP.
When a cell is active and ATP is consumed rapidly, the elevated levels of ADP will
activate the synthesis of ATP.
The activity of electron transport is strongly dependent on the availability of
ADP for ATP synthesis.
Ma tch each with its function: CoQ cyt c
A. a mobile carrier between complexes II and III
B. carries electrons from complexes I and II to
complex III
C. accepts 2H+ and 2 electrons from FADH2
Match each with its function: CoQ cyt c
A. a mobile carrier between complexes II and III - cyt c
B. carries electrons from complexes I and II to
complex III - CoQ
C. accepts 2H+ and 2 electrons from FADH2 -
CoQ
- CO 2
A. citric acid cycle B. electron transport chain - FADH2
A. citric acid cycle B. electron transport chain - NAD+
A. citric acid cycle B. electron transport chain - NADH
A. citric acid cycle B. electron transport chain - H2O
A. citric acid cycle B. electron transport chain
- CO2 A. citric acid cycle
- FADH2 A. citric acid cycle
- NAD+ B. electron transport chain
- NADH A. citric acid cycle
- H2O B. electron transport chain
At complex IV,
- four electrons from four cytochrome c are passed to other electron carriers.
- electrons combine with….
- energy is used to pump H+ from the mitochondrial matrix into the intermembrane space, further increasing the hydrogen ion gradient.
….hydrogen ions and oxygen (O2) to form two molecules of water.
Look at table 23.1 again for ATP from Oxidation of Glucose
DO IT DUDE
The _____ transfers the energy stored in NADH to transporters that move from the cytosol into the mitochondrial matrix where NADH is regenerated for use in electron transport
malate–aspartate shuttle
catalyzes the reaction of
oxaloacetate and NADH to yield malate and NAD+.
malate dehydrogenase
a transporter binds the malate and carries it across the
membrane into the matrix, where malate dehydrogenase
oxidizes malate back to
oxaloacetate.
The oxidation to oxaloacetate provides hydrogen ions and electrons that are used to reduce NAD+ to NADH, which can now enter
electron transport to synthesize ATP.
Be cause the oxaloacetate produced in the matrix cannot cross the mitochondrial membrane, it
- is converted back to aspartate;
- moves out of the matrix back into the cytosol; and
• undergoes transamination, which converts it to
oxaloacetate.
The resulting NAD+ can participate again in glycolysis in the cytosol.
ALL TRUE
The complete oxidation of glucose to CO2 and H2O yields a maximum of
32 ATPs.
stores 85% of the total energy available in the body.
Adipose tissue (made of adipocytes)
What is the function of bile salts in fat digestion?
Bile salts break down fat globules, allowing pancreatic lipases to hydrolyze the triacylglycerol.
How is glycerol utilized?
Glycerol adds a phosphate and is oxidized to an intermediate of the glycolysis and gluconeogenesis pathways.
In the digestion of fats (triacylglycerols),
___break fat globules into smaller particles called micelles in the small intestine.
bile salts
In the digestion of fats (triacylglycerols),
____ hydrolyze ester bonds to form monoacylglycerols and fatty acids, which recombine in the intestinal lining.
pancreatic lipases
In the digestion of fats (triacylglycerols),
__ and ___ coat the fats, forming ____, which are transported to the cells of heart, muscle, and adipose tissues.
phospholipids and proteins
chylomicrons
In the digestion of fats (triacylglycerols),
lipases hydrolyze triacylglycerols, forming glycerol and free fatty acids, which are
oxidized to acetyl CoA molecules for ATP synthesis.
The digestion of fats begins in the small intestine when bile salts….
…emulsify fats that undergo hydrolysis to monoacylglycerols and fatty acids.
the hormones glucagon and epinephrine are secreted into the bloodstream, where they bind to receptors on the membrane of adipose tissue.
When blood glucose is depleted and glycogen stores are low
a hormone-sensitive lipase within the fat cells catalyzes the hydrolysis of triacylglycerols to glycerol and free fatty acids.
When blood glucose is depleted and glycogen stores are low,
glycerol and fatty acids diffuse into the bloodstream and bind with plasma proteins to be transported to the tissues, muscles, and fat cells.
When blood glucose is depleted and glycogen stores are low,
glycerol and fatty acids diffuse into the bloodstream and bind with plasma proteins to be transported to the tissues, muscles, and fat cells.
When blood glucose is depleted and glycogen stores are low,
Metabolism of Glycerol
from fat digestion
3 main points?
adds a phosphate from ATP to form glycerol-3-phosphate.
undergoes oxidation of the —OH group to dihydroxyacetone phosphate (thereby forming NADH + H as a byproduct)
becomes an intermediate in glycolysis and gluconeogenesis.
steps of glycerol metabolism
1) Glycerol to G3P (w/ ATP to ADP)
2) G3P to DHP (w/ NAD+ to NADH + H+)
3) DHP enters glycolysis or Gluconeogenesis
Where is glycerol converted to DHP?
What is the significance?
in the liver
it’s an intermediate for glycolysis and gluconeogenesis
A large amount of energy is obtained when fatty acids undergo
oxidation in the mitochondria to acetyl CoA.
A large amount of energy is obtained when fatty acids undergo what? How does this occur?
beta oxidation (β oxidation), which removes two-carbon segments containing the alpha and beta carbon from the carboxyl end of the fatty acid.
A cycle in β oxidation
produces
an acetyl CoA and a fatty acid that is shorter by two carbons.
A cycle in β oxidation repeats until the original fatty acid is
completely degraded to two-carbon units that form acetyl CoA, which enters the citric acid cycle.
where does Fatty acid activation occur?
it begins in the cytosol as fatty acids are transported into the inner mitochondrial membrane to undergo β oxidation
Fatty Acid Activation
a fatty acid is combined with CoA to yield
a high-energy fatty acyl CoA.
Fatty Acid Activation
energy is released by the hydrolysis of ATP to AMP and used to
drive the reaction.
fatty acid + ATP + CoA to yield Fatty acyl CoA + AMP + 2Pi + H2O
fatty acid + ATP + CoA to yield?
Fatty acyl CoA + AMP + 2Pi + H2O
A transport system called the ______ carries fatty acids into the mitochondria from the cytosol.
carnitine shuttle
Transport of Fatty Acyl CoA
________catalyzes the transfer of a fatty acyl group to the hydroxyl group of carnitine to produce fatty acyl carnitine.
_______ then passes through the inner mitochondrial membrane into the matrix.
Carnitine acyltransferase
Fatty acyl carnitine
Transport of Fatty Acyl CoA (continued):
In the matrix, another carnitine acyltransferase
catalyzes the reverse reaction that transfers the ___ to ___-
releases the carnitine and returns to the cytosol.
fatty acyl group to CoA to reform fatty acyl CoA.
Thus, the carnitine shuttle moves fatty acyl CoA from the cytosol into the matrix, where
the fatty acid can undergo β oxidation.
Look at ch 24 slide 15 to draw the carnitine shuttle system…
do IT!
Oxidation of Unsaturated Fatty Acids
What’s the significance?
No FADH2 produced in first cycle because we already have the double bond and they can skip oxidation step and go straight to hydration … therefore less energy!
How many acetyl CoA groups are produced by the complete β oxidation of palmitic acid (C16)?
1) 16 2) 8 3) 7
How many oxidation cycles are necessary to completely oxidize palmitic acid (C16)?
1) 16 2) 8 3) 7
How many acetyl CoA groups are produced by the complete β oxidation of palmitic acid (C16)?
2) 8 (16 C/2 = 8)
How many oxidation cycles are necessary to completely oxidize palmitic acid (C16)?
3) 7 (16 C/2 – 1 = 7)
Four steps of β oxidation simplified?
OHOC
1) Oxidation with enzyme Acyl CoA deydrogenase and FAD to FADH2 (C=C created)
2) Hydration with Enoyl CoA hydrase (H2O added so B carbon has OH
3) Oxidation with enzyme 3-Hydroxyacyl CoA dehydrogenase and NAD+ to NADH + H+ (to make a C=O bond)
4) Cleavage (β-Ketoacyl CoA thiolase to cleave off two carbons each time and creates Acetyl CoA each time from the Fatty acyl CoA)
Match the reactions of β oxidation with each of the following:
Water is added. FADH2 forms. A two-carbon unit is removed. A hydroxyl group is oxidized. NADH forms.
1) oxidation 1
2) hydration
3) oxidation 2
4) acetyl CoA cleaved
Match the reactions of β oxidation with each of the following:
Water is added. 2) hydration
FADH2 forms. 1) oxidation 1
A two-carbon unit is removed. 4) acetyl CoA cleaved
A hydroxyl group is oxidized. 3) oxidation 2
NADH forms. 3) oxidation 2
ATP from β Oxidation, Capric Acid?
10 carbon Fatty acid
Math is on page 29
Total of 64 ATP
What is the total ATP produced from the β oxidation of stearic acid (C18)?
A. 108 ATP
B. 120 ATP
C. 148 ATP
What is the total ATP produced from the β oxidation of stearic acid (C18)? B. 120 ATP Activation –2 ATP 9 Acetyl CoA × 10 ATP 90 ATP 8 NADH × 2.5 ATP 20 ATP 8 FADH2 × 1.5 ATP 12 ATP 120 ATP
What’s the difference between Type I and Type II diabetes?
Type 1, insulin-dependent diabetes - Little to NO insulin produced
In type 2, insulin-resistant diabetes - insuline produced but RECEPTORS aren’t responsive… WON’T RESPOND TO INSULIN THERAPY!!!
WHICH DIABETES TYPE WILL NOT RESPOND TO INSULIN THERAPY?!?
type 2, insulin-resistant diabetes - insuline produced but RECEPTORS aren’t responsive
Ketogenesis acronym?
Cons
Hate
Home
Depot
Condensation
Hydrolysis
Hydrogenation
Decarboxylation
2 questions from this section…. slow down turbo
If carbohydrates are not available,
fatty acids break down to meet energy needs.
acetyl CoA molecules combine to form ketone bodies.
When large quantities of fatty acids are degraded,
too much ____ is produced.
high levels of acetyl CoA accumulate in the ____.
acetyl CoA molecules combine in a pathway known as…
acetyl CoA
liver
…ketogenesis to form compounds called ketone bodies.
What is the reason for ketogenesis?
The oxidation of large amounts of fatty acids causes high levels of acetyl CoA which undergoes ketogenesis
In ketogenesis,
how many molecules of acetyl CoA combine to form acetoacetyl CoA and HS—CoA?
two molecules of acetyl CoA
combine to form acetoacetyl CoA and HS—CoA.
When the body has met all its energy needs AND the glycogen stores are full,
acetyl CoA from the breakdown of carbohydrates and fatty acids is used to synthesize….
two-carbon acetyl units are linked to form a ____, in the pathway called lipogenesis.
this whole thing is so we can do what?!?!?!
new fatty acids in the cytosol.
16-carbon fatty acid, palmitic acid
Fatty Acid Synthesis!!!!
Where does lipogenesis occur? (not a reversal of B oxidation)
using which coenzyme?
occurs in the cytosol using the reduced coenzyme NADPH instead of occurring in the mitochondria, where oxidation takes place using FAD and NAD+.
synthesis of fatty acids occurs where?
cytosol
