Chapter 8: Metabolism Flashcards
- all chemical reactions that take place in cells to break down or build molecules
metabolism
- series of linked reactions, each catalyzed by a specific enzyme.
- produce energy and cellular compounds
metabolic pathway
When we eat food, the _ ,_ , _ , are digested to smaller molecules that can be ___.
polysaccharides, lipids, and proteins; absorbed into the cells of our body.
Because we do not use all the energy from our foods at one time, we ___ as high-energy __.
store energy in the cells; adenosine
triphosphate, ATP.
. As the glucose, fatty acids, and amino
acids are broken down further, _
energy is released
ATP is later broken down obtain energy to do work in our bodies:
- contracting muscles
- synthesizing large molecules,
- sending nerve impulses
- moving substances across cell membranes.
use ATP energy to build larger molecules
anabolic reaction
break down large, complex molecules to
provide energy and smaller molecules
catabolic reactions
3 stages of metabolism
- digestion and hydrolysis
- degradation
- oxidation
break down large molecules to smaller ones that enter the bloodstream
digestion and hydrolysis
breaks down molecules to
two- and three-carbon compounds
degradation
is in the citric acid cycle and electron transport provide ATP energy (electrons are carried by NADH and FADH2)
oxidation
As long as the cells have oxygen, the hydrogen ions and electrons from the __ to synthesize ATP.
reduced coenzymes are transferred to electron transport
9 Cell structure
Plasma Membrane
Mitochondria
Rough Endoplasmic reticulum
Smooth Endoplasmic reticulum
ribosomes
lysosomes
golgi complex
nucleus
cytoplasm
Is the energy form stored in cells.
▪ Is obtained from the oxidation of food
Adenosine Triphosphate (ATP)
Structure of ATP:
Adenine (nitrogen base)
ribose sugar
three phosphate groups
Requirement of ATP to be oxidized:
7.3 kcal/mol (31 kJ/mol)
3 phosphate groups
AMP
ADP
ATP
The hydrolysis of ATP to ADP releases 7.3 kcal (31 kJ)/mole
ADP + Pi + 7.3 kcal/mol (31 kJ/mol
hydrolysis of ADP to AMP releases 7.3 kcal (31 kJ)/mole.
AMP + Pi + 7.3 kcal/mol (31 kJ/mol)
ATP links ___ with ___ in the cells
energy-producing reax ; energy requiring reax
What has low energy bond?
phosphate ester bond in first p group
What has high energy bond
phospho-anhydride bonds in ADP and ATP
ATP or ADP + Pi: used in anabolic reaction
ATP
ATP or ADP + Pi: energy-storage molecule
ATP
ATP or ADP + Pi: coupled withe nergy-requiring reactions
ATP
ATP or ADP + Pi: hydrolysis products
ADP
Several metabolic reactions that extract energy from our food what reactions?
REDOX
associated with the loss of H atoms
oxidation
associated with the gain of H atoms
reduction
required to carry the hydrogen ions and electrons from or to the reacting substrate.
coenzymes
oxidation
loss of e-
loss of H+
gain of oxygen
release of energy
reduction
gain of e-
gain of H+
loss of oxygen
input of energy
Three coenzymes
NAD+
FAD+
Acetyl CoA
Participates in reactions that produce a carbon-oxygen double bond (C=O)
▪ Is reduced when an oxidation provides 2H+ and 2e-
NAD+ (nicotinamide adenine dinucleotide)
Oxidation of NAD+
CH3—CH2—OH to CH3—C (=O) —H + 2H+ + 2e
Reduction of NAD+
NAD+ + 2H+ + 2e- NADH + H+
Structure of NAD+
Contains ADP, ribose, and nicotinamide.
Reduces to NADH when the
nicotinamide group accepts H+ and 2e-
.
Participates in reactions that produce a carbon-carbon double bond (C=C).
▪ Is reduced to FADH2
FAD (flavin adenine dinucleotide)
ox of FAD
—CH2—CH2— —CH=CH— + 2H+ + 2e
red of FAD
FAD + 2H+ + 2e- FADH2
structure of FAD
Contains ADP and riboflavin (vitamin B2).
= undergoes reduction when the 2 nitrogens in the flavin part react with two hydrogen atoms (2H+ + 2e-)
Consists of pantothenic acid (vitamin B5), phosphorylated ADP, and aminoethanethiol
= activates acyl groups such as the two-carbon acetyl group for transfer.
Coenzyme A
The reactive feature of coenzyme A ___ , which bonds to a two-carbon acetyl group to produce ___
thiol group (-SH); energy-rich thioester acetyl CoA
Structure of CoA
pantothenic acid (vitamin B5), phosphorylated ADP, and aminoethanethiol
MT: Coenzyme used in oxidation of carbon-oxygen
bonds.
NAD+
MT: Reduced form of flavin adenine dinucleotide
FADH2
MT: Used to transfer acetyl groups
CoA
MT: Contains riboflavin
FAD, FADH
MT: The coenzyme after C=O bond formation
NADH + H+
2 STAGES OF DIGESTION OF CARBS
Stage 1, the digestion of carbohydrates
Stage 2: Glycolysis
Stage 1:
Mouth where salivary amylase breaks down
Small intestine where pancreatic amylase hydrolyzes
hydrolyzes MAL, LAC, SUC to glucose which enters bloodstream to transport to the cells
enzymes produced in
the mucosal cells that
line the small intestine
maltase
lactase
sucrase
The bloodstream carries the monosaccharides to the liver, where __
fructose and galactose are converted to glucose
Glycolysis
uses glucose for metabolic pathway
degrades glucose to pyruvate
an anaerobic process
Energy is required to add phosphate groups to glucose.
Glucose is converted to two three-carbon molecules.
Reaction 1-5
Reaction 1-5 Products
Glucose
Glusose-6-phosphate
Fructose-6-Phosphate
Fructose-1,6-biphosphate
dihydroxyacetone phosphate
glyceraldehyde-3-phosphate
Reaction 1-5 Enzymes
hexokinase
phosphoglucoisomerase
phosphofructokinase
fructose-1,6-biphosphate aldolase
triosephosphate isomerase
Aldol reaction
fructose-1,6-biphosphate to DHAP and G3P; cofactors: Mn; Mg
Sugar phosphates are cleaved to triose phosphates.
▪ Four ATP molecules are produced
reax 6-10
Reaction 6-10 products
glyceraldehyde-3-phosphate
1,3-Biphosphoglycerate
3-phosphoglycerate
2-phosphoglycerate
phosphoenolpyruvate
pyruvate
Reaction 6-10 enzymes
glyceraldehyde-3-phosphate-dehydrogenase
phosphoglycerate kinase
phosphoglycerate mutase
enolase
pyruvate kinase
What happens in reax 6?
2 NAD+ was oxidized to 2NADH + 2H+
What happens in reax 7?
2 ATP was released
What happened in reax 9?
H2O was released
What happened in reax 10?
2 ATP was released
Processes reax 1-10
- phosphorylation: 1st ATP
- Isomerization
- Phosphorylation: 2nd ATP
- cleavage: 2 trioses formed
- isomerization of triose
- First energy production yields NADH
- Next energy production yields 2 ATP
- Formation of 2-phosphoglycerate
- Removal of water makes a high-energy enol
- Third energy production yields a second ATP (2)
In glycolysis, what happened to steps 1 and 3?
2 ATP add phosphate to glucose and fructose eme
In glycolysis, what happened to steps 7 and 10?
Four ATP are formed in energy-generation by direct transfers of phosphate groups to four ADP
Glycolysis net gain
ATP and 2 NADH
overall equation of glycolysis:
glucose + 2NAD+2ADP + 2Pi = 2 Py + 2NADH +2 ATP + 2ATP + 2H+ + 2H2O
Key regulatory steps
hexokinase, phosphofructokinase, and
pyruvate kinase (1,3,10)
Glycolysis is regulated by three enzymes, Reaction 1
Hexokinase is inhibited by high levels of
glucose-6-phosphate, which prevents the
phosphorylation of glucose.
Glycolysis is regulated by three enzymes, Reaction 3
Phosphofructokinase, an allosteric
enzyme, is inhibited by high levels of ATP and activated by high levels of ADP and AMP. If cells have plenty of ATP, glycolysis slows down
Glycolysis is regulated by three enzymes, Reaction 10
Pyruvate kinase, another allosteric
enzyme is inhibited by high levels of ATP or acetyl CoA
in glycolysis, what compounds provide phosphate groups for the production of ATP?
In reaction 7, phosphate groups from two 1,3-bisphosphoglycerate molecules are transferred to ADP to form two ATP.
In reaction 10, phosphate groups from two phosphoenolpyruvate molecules are used to form two more ATP
fructose
In the muscles, it is converted to fructose-6-phosphate, entering glycolysis at step 3. In the liver, it is converted to the trioses used in step 5.
Fructose uptake by the cells is not __: all fructose in the _
regulated by insulin; bloodstream is forced into catabolism.
The triose products created in the liver ___ that, if not required for energy by the cells, __
provide an excess of reactants that create excess pyruvate and acetyl CoA ; is converted to fat
Pyruvate: Under aerobic conditions (oxygen present),
▪ Three-carbon pyruvate is decarboxylated.
▪ Two-carbon acetyl CoA and CO2 are produced.
▪ Occurs in the mitochondria
Pyruvate is converted __ under aerobic conditions ___. The NADH is oxidized ___
to acetyl CoA and NADH; when oxygen is plentiful; back to NAD+ to allow glycolysis to continue.
Pyruvate under anaerobic conditions (without oxygen),
Pyruvate is reduced to lactate.
▪ NAD+ is produced and is used to oxidize more glyceraldehyde-3 phosphate in the glycolysis pathway, which produces a small but needed amount of ATP.
▪ Occurs in the cytosol
lactate in muscles: during strenous exercise:
Oxygen in the muscles is depleted.
▪ Anaerobic conditions are produced.
▪ Lactate accumulates.
▪ Muscles tire and become painful.
After exercise, a person breathes heavily to: ???????????
to repay the oxygen debt and reform pyruvate in the liver (lactate is transported to the liver).
Occurs in anaerobic microorganisms such as yeast.
▪ Regenerates NAD+ to continue glycolysis.
fermentation
what is decarboxylated in fermentation?
pyruvate to acetaldehyde, which is reduced to ethanol
The first step in conversion of pyruvate to ethanol
a decarboxylation reaction to produce acetaldehyde.
The second step in fermentation
involves acetaldehyde reduction to produce ethanol
Produced during anaerobic conditions
lactate
Reaction series that converts glucose to
pyruvate.
glycolysis
Metabolic reactions that break down large molecules to smaller molecules + energy.
catabolic reaction
Substances that remove or add H atoms in oxidation and reduction reactions.
coenzymes
Operates under aerobic conditions only.
▪ Oxidizes the two-carbon acetyl group in acetyl CoA to 2CO2
▪ Produces reduced coenzymes NADH and FADH2 and one ATP directly.
citric acid cycle
(3) What happens in citric acid cycle?
Acetyl (2C) bonds to oxaloacetate (4C) to
form citrate (6C).
▪ Oxidation and decarboxylation
reactions convert citrate to oxaloacetate.
▪ Oxaloacetate bonds with another acetyl to repeat the cycle.
KREBS: Processes
1: Formation of Citrate Condensation
2: Isomerization to Isocitrate
3: oxidative decarboxylation
4: oxidative decarboxylation
5: phosphorylation / hydrolysis
6: oxidation / dehydrogenation
7: hydration
8: oxidation / dehydrogenation
KREBS: PRODUCT
Acetyl CoA
Citrate
Isocitrate
a-keto
succinyl CoA
succinate
furamate
malate
oxaloacetate
KREBS: Enzymes
Citrate Synthase
Aconitase
Isocitrate Dehydrogenase
a-ketoglutarate Dehydrogenase
Succinyl COA Synthase
Succinic Dehydrogenase
Fumarase
Malate Dehydrogenase
SO AT DISCO, DEVIL SLIPPED DOWN FIVE DRINKS
Combines with the two-carbon acetyl group to form citrate.
oxaloacetate
Isomerizes to isocitrate.
▪ Has a tertiary —OH group converted to a secondary —OH in isocitrate that can be oxidized.
citrate
Undergoes decarboxylation (carbon removed as CO2).
▪ Oxidizes the —OH to a ketone releasing H+ and 2e−.
▪ Provides H to reduce coenzyme NAD+
to NADH.
isocitrate
▪ Undergoes decarboxylation to form succinyl CoA.
▪ Produces a 4-carbon compound that bonds to CoA.
▪ Provides H+ and 2e−
to reduce NAD+
to NADH.
a-ketoglutarate
Undergoes breaking of the thioester bond.
▪ Provides energy to add phosphate to GDP and form GTP, a high energy compound.
Succinyl CoA
Undergoes dehydrogenation.
▪ Loses two H and forms a double bond.
▪ Provides 2H to reduce FAD to FADH2
succinate
Undergoes hydration.
▪ Adds water to the double bond.
▪ Is converted to malate.
fumarate
Undergoes dehydrogenation.
▪ Forms oxaloacetate with a C=O double bond.
▪ Provides 2H that reduce NAD+
to NADH + H+
malate
KREBS PRODUCTS
3: Remove (2) CO2
3: produces 3 ATP
3-4: reduce NAD+ to NADH
4: produces 3 ATP
5: GDP +Pi to GTP; releasing 1 ATP
6: FAD to FADH; having 2 ATP
8: NAD+ to NADH + H+; having 3 ATP
Summary of CAC
- An acetyl group bonds with oxaloacetate to form citrate.
- Two decarboxylations remove two carbons as 2CO2
- Four oxidations provide hydrogen for three (3) NADH and one (1) FADH2
- A direct phosphorylation forms GTP (ATP).
OVERALL CHEM REAX
acetyl-CoA + 3NAD+ + FAD + GDP + Pi + 2H2O
to
2CO2 + 3NADH + 3H+ + FADH2 + HS-CoA + GTP
In 1 turn of CAC produces:
2 CO2
1 GTP (1ATP)
3 NADH
1 HS-CoA
1 FADH2
The reaction rate for
the citric acid cycle increases when ?
low levels of ATP or NAD+ activate isocitrate dehydrogenase.
The reaction rate for the citric acid cycle decreases when ?
high levels of ATP or NADH inhibit citrate synthetase (first step in cycle).
Regulation of CAC: Pyruvate dehydrogenase
activated by: ADP
inhibited by: NADH; ATP
Regulation of CAC: Isocitrate
activated by: ADP
inhibited by: NADH; ATP
Regulation of CAC: a-Ketoglutarate
activated by: ADP
inhibited by: Succinyl CoA; NADH
oxidized and reduced as hydrogen and/or electrons are transferred from one carrier to the next.
Electron Carriers
Electron Carriers (4)
FMN
Fe-S clusters
Coenzyme Q
cytochromes
▪ Accept hydrogen and electrons from the reduced coenzymes.
▪ Are oxidized and reduced to provide
energy for the synthesis of ATP.
Electron Carriers
Contains flavin, ribitol,and phosphate. Accepts 2H+ + 2e to form reduced
coenzyme FMNH2.
Flavin Mononucleotide
▪ Are groups of proteins containing iron ions and sulfide.
▪ Accept electrons to reduce Fe3+ to Fe2+, and lose electrons to re-oxidize Fe2+ to Fe3+
Iron-Sulfur (Fe-S) Clusters
A mobile electron carrier derived from quinone.
▪ Reduced when the keto groups accept 2H+ and 2e-
Coenzyme Q or CoQ
Proteins containing
heme groups with
iron ions. Fe3+ + 1e- Fe2+
Cytochromes
Cytochromes abbreviations
cyt a
cyt a3
cyt b
cyt c
cyt c1
Reduced form of coenzyme Q.
CoQH2 or QH2
Oxidized form of flavin mononucleotide
FMN
Reduced form of cytochrome c
Cyt c (Fe2+)
Inidications of exponent in REDOX of electron carriers:
increase: oxidized
decreased: reduced
Where does ATP synthase happen?
in mitochondrion matrix
Uses electron carriers.
▪ Transfers hydrogen ions and electrons from NADH and FADH2 until they combine with oxygen.
▪ Forms H2O.
▪ Produces ATP energy
Electron Transport
The electron carriers are attached to the inner membrane of the mitochondrion.
Electron transport system
4 protein complexes
Complex I NADH dehydrogenase
Complex II Succinate dehydrogenase
Complex III CoQ-Cytochrome c reductase
Complex IV Cytochrome c oxidase
Complex 1
NADH dehydrogenase
Complex II
Succinate dehydrogenase
Complex III
CoQ-Cytochrome c reductase
Complex IV
Cytochrome c oxidase
Where does electron transport chain happen?
inner mitochondrial membrane
ETC From High energy to Low Energy
NADH (to NAD+, releasing ATP)
FMN
Q (binded to FADH2, to FAD)
Cyt b (releasing ATP)
cyt c1
cyt c
cyt a (releasing ATP)
cyt a3
O2 + 4H+ = 2 H2O
Complex I
- Hydrogen and electrons are transferred from NADH to FMN.
- FMNH2 transfers hydrogen to Fe-S clusters and then to coenzyme Q reducing Q and regenerating FMN.
Overall reaction of Complex 1:
NADH + H+ + Q QH2 + NAD+
a mobile carrier, transfers hydrogen to
Complex III
QH2
At Complex II, with a lower energy level than Complex I,
- FADH2 transfers hydrogen and electrons to coenzyme Q.
- Q is reduced to QH2 and FAD is regenerated.
What happens at Complex III
- Electrons are transferred from QH2 to two Cyt b.
- Each Cyt b (Fe3+) is reduced to Cyt b (Fe2+).
- Q is regenerated.
- Electrons are transferred from Cyt b to Fe-S clusters, to Cyt c1, and to Cyt c, the second mobile carrier.
At Complex IV, electrons are transferred from:
Cyt c to Cyt a
Cyt a to Cyt a3
Cyt a3 to oxygen and H+ to form water
Accepts H and electrons from NADH + H+
FMN
A mobile carrier between Complex II and III
Cyt c
Carries electrons from Complex I and II to Complex III
Q
Accepts H and electrons from FADH2
Q
CO2 is product of
CAC
FADH2 is product of
CAC
NAD+ is product of
ETC
NADH is product of
CAC
H20 is product of
ETC
in chemiosmotic model, Complexes I, III, and IV pump protons into the
intermembrane space ___
creating a proton gradient
The flow of protons through ATP synthase provides ___?
the energy of ATP synthesis (oxidative phosphorylation)
ATP Synthesis (oxidative phosphorylation)
ADP + Pi + Energy –> ATP
ATP Synthase: Protons flow back to
the matrix through a channel in the
F0 complex (high potential)
ATP Synthase: Proton flow provides the energy that drives ATP synthesis by the
F1 complex (low potential)
Composition of F1 complex of ATP synthase:
- center subunit (y)
-surrounded by 3 protein subunits:
Loose (L)
Tight (T)
Open (O)
Process of ATP synthesis in F1:
- ADP and Pi enter the loose L site.
- The center subunit turns changing the L site to a tight T conformation.
- ATP is formed in the T site where it remains strongly bound.
- The center subunit turns changing the T site to an open O site, which releases the ATP.
Contains subunits for ATP synthesis
F1 Complex
Contains the channel for proton flow
F0 Complex
The subunit in F1 that binds ADP and Pi
L site
The subunit in F1 that releases ATP
O site
The subunit in F1 where ATP forms
T site
In electron transport, the energy level decrease for electrons from NADH (Complex I)
NADH + 3ADP + 3Pi NAD+ + 3ATP
In electron transport, the energy level decrease for electrons From FADH2
(Complex II)
FADH2 + 2ADP + 2Pi FAD + 2ATP
The electron transport system is regulated by (2):
- Low levels of ADP, Pi, oxygen, and NADH that decrease electron transport activity.
- High levels of ADP that activate electron transport.
The complete oxidation of glucose yields
6 CO2
6 H2O
32 ATP
ATP from Glycolysis
Activation of glucose -2 ATP
Oxidation of 2 NADH 5 ATP
Direct ADP phosphorylation (two triose) 4 ATP
Summary of ATP from Glycolysis
C6H12O6 2 pyruvate + 2H2O + 7 ATP
ATP from 2 Pyruvate
2 Pyruvate 2 Acetyl CoA + 5 ATP
From 2 Pyruvate, under aerobic conditions:
▪ 2 pyruvate are oxidized to 2 acetyl CoA and 2 NADH.
▪ 2 NADH enter electron transport to provide 5 ATP.
ATP from CAC:
3 NADH x 2.5 ATP = 7.5 ATP
1 FADH2 x 1.5 ATP = 1.5 ATP
1 GTP x 1 ATP = 1 ATP
total: 10 ATP
Summary of CAC
Acetyl CoA 2 CO2 + 10 ATP
For two acetyl CoA from one glucose, two turns of the citric acid cycle produce:
2 Acetyl CoA 4 CO2 + 20 ATP
ATP FORM CAC FINAL
Ox of 2 isocitrate (2NADH) 5 ATP
Ox of 2 a-ketoglutarate (2NADH) 5 ATP
(2GTP) 2 ATP
Ox of 2 succinate (2FADH2) 3 ATP
Ox of 2 malate (2NADH) 5 ATP
Full summary of CAC mahibi na q di lansang
2Acetyl CoA —> 4CO2 + 2H2O + 20 ATP
ATP overall final.jpeg
From glycolysis 7 ATP
From 2 pyruvate 5 ATP
From 2 acetyl CoA 20 ATP
OVERALL ATP ORODUCTION FOR ONE GLUCOSE
C6H12O6 + 6O2 + 36ADP + 36Pi
TO
6CO2 + 6H2O + 32 ATP
Indicate the ATP yield for: complete oxidation of glucose
32 ATP
Indicate the ATP yield for: FADH2
1.5 ATP
Indicate the ATP yield for: Acetyl CoA in CAC
10 ATP
Indicate the ATP yield for: NADH
2.5 ATP
Indicate the ATP yield for: pyruvate decarboxylation
2.5 ATP
break fat globules into smaller particles called micelles in the small intestine
bile salts
hydrolyze ester bonds to form monoacylglycerols and fatty acids, which recombine in the intestinal lining.
pancreatic lipases
Fatty acids bind with proteins forming __ to transport triacylglycerols to the cells of the heart, muscle, and adipose tissues
lipoproteins
transport the triacylglycerols to the cells
of the heart, muscle, and adipose tissues.
chylomicrons
When energy is needed in the cells, enzymes hydrolyze the triacylglycerols to:
yield glycerol and fatty acids
Digestion of triacylglycerol in small intestine:
triacylglycerol —> (pancreatic lipase) monoacylglycerol + 2 fatty acids
digestion in intestinal wall:
monoacylglycerol + 2 fatty acids —> triacylglycerols –> lipoproteins
digestion in the cell:
glycerol + fatty acids
chylomicrons then proceed to:
lymphatic system
blood stream
cells
Breaks down triacylglycerols in adipose
tissue.
▪ Forms fatty acids and glycerol.
▪ Hydrolyzes fatty acid
initially from C1 or C3 of
the fat.
fat mobilization
reaction in fat mobilization
triacylglycerols + 3 H2O —>
glycerol + 3 fatty acids
Adds a phosphate from ATP to form glycerol-3-phosphate.
Undergoes oxidation of the –OH group to
dihydroxyacetone phosphate.
glycerol
metabolism of glycerol reaction
Glycerol + ATP + NAD+ —->
dihydroxyacetone phosphate + ADP + NADH + H+
Oxidation of glycerol
glycerol (glycerol kinase) –> glycerol-3-phosphate (glycerol phosphate dehydrogenase) –> dihydroxyacetone phosphate
glycolysis
What is the function of bile salts in fat digestion?
Bile salts break down fat globules allowing pancreatic lipases to hydrolyze the triacylglycerol.
Why are the triacylglycerols in the intestinal lining coated with proteins to form chylomicrons?
The proteins coat the triacylglycerols to make water soluble chylomicrons that move into the lymph and bloodstream.
How is glycerol utilized?
Glycerol adds a phosphate and is oxidized to an intermediate of the glycolysis pathway.
Allows the fatty acids in the cytosol to enter the mitochondria for oxidation.
▪ Combines a fatty acid with CoA to yield fatty acyl-CoA that combines with carnitine.
Fatty acid activation
Fatty Acid Activation in Cytosol:
Fatty acid + CoA + ATP –> CoA + AMP + 2 Pi
Fatty Acid Activation in IS:
fatty acyl – CoA + Carnitine –> Fatty acyl – carnitine
Beta-Oxidation of Fatty Acids
1: dehydrogenation
2: hydration
3: Oxidation
4: cleavage
dehydrogenation
removes one hydrogen from the alpha and beta carbons, and a double bond is formed. These hydrogens are transferred to FAD to form FADH2
hydration
water is added to the
a and β carbon double bond as
–H and –OH, respectively.
oxidation
The alcohol formed on the β carbon
is oxidized to a ketone. As we have seen before in the citric acid cycle, the hydrogen from the alcohol reduces NAD+
to NADH.
Cleavage
In the fourth reaction of the cycle, the
bond between the and β carbon is broken and a second CoA is added, forming an acetyl CoA and a fatty acyl CoA shortened by two carbons. The fatty acyl CoA can be run through the cycle again.
Match the reactions of beta-oxidation when water is added
hydration
Match the reactions of beta-oxidation with FADH2 forms
oxidation 1
Match the reactions of beta-oxidation when a 2-carbon unit is removed
acetyl CoA cleaved
Match the reactions of beta-oxidation a hydroxyl group is oxidized
oxidation 2
Match the reactions of beta-oxidation: NADH forms
oxidation 2
ATP PRODUCTION FROM B OX FOR MYRISTIC ACID (C14)
Activation - 2 ATP
b oxidation - 6 NADH x 2.5 = 70
6 FADH x 1.5 ATP = 9 ATP
total: 92 ATP
ATP for Lauric Acid C12
ATP production for lauric acid (12 carbons):
Activation of lauric acid -2 ATP
6 acetyl CoA x 10 ATP/acetyl CoA 60 ATP
5 Oxidation cycles
5 NADH x 2.5 ATP/NADH 12.5 ATP
5 FADH2 x 1.5 ATP/FADH2 7.5 ATP
Total 78 ATP
The total ATP produced from the -oxidation of stearic acid (C18) is
120 ATP
Activation -2 ATP
9 Acetyl CoA x 10 ATP 90 ATP
8 NADH x 2.5 ATP 20 ATP
8 FADH2 x 1.5 ATP 12 ATP
120 ATP
2 Ketone Bodies:
- acetoacetyl CoA
- Acetone
If carbohydrates are not available
Body fat breaks down to meet energy needs.
Ketone Bodies
produced mostly in the liver and transported to cells in the heart, brain,
and skeletal muscle, where small
amounts of energy can be obtained by
converting acetoacetate or hydroxybutyrate back to acetyl CoA
Ketone bodies
▪ Large amounts of acetyl CoA accumulate.
▪ Two acetyl CoA molecules combine to form acetoacetyl CoA.
▪ Acetoacetyl CoA hydrolyzes to acetoacetate, a ketone body.
▪ Acetoacetate reduces to hydroxybutyrate or loses CO2 to form acetone, both ketone bodies
ketogenesis
In diabetes, diets high in fat, and starvation.
▪ As ketone bodies accumulate.
▪ When acidic ketone bodies lowers blood pH below 7.4 (acidosis).
Ketosis
▪ Insulin does not function properly.
▪ Glucose levels are insufficient for energy needs.
▪ Fats are broken down to acetyl CoA.
▪ Ketogenesis produces ketone bodies.
Ketone bodies and in diabetes
In all types of diabetes, insufficient amounts of glucose are available in the muscle, liver, and adipose tissue. OH TAPOS????????
As a result, liver cells synthesize
glucose from noncarbohydrate sources
(gluconeogenesis) and break down fat, elevating the acetyl CoA level. Excess acetyl CoA undergoes ketogenesis, and ketone bodies accumulate in the blood. As the level of acetone increases, its odor can be detected on the breath of a person with uncontrolled diabetes who is in ketosis.
KETOGENESIS: Acetoacetate produce acetone
decarboxylation
KETOGENESIS: Acetoacetate produce b-hydroxybutyrate
reduction
Process of digestion of proteins (3):
- Begins in the stomach where HCl in stomach acid activates pepsin to hydrolyze peptide bonds.
- Continues in the small intestine where trypsin and chymotrypsin hydrolyze peptides to amino acids.
- Is complete as amino acids enter the bloodstream for transport to cells
Digestion of Proteins: What happens in stomach?
Pepsinogen to pepsin
proteins to denaturation to polypeptides
Digestion of Proteins: What happens in the small intestine?
polypeptides to trypsin, chymotrypsin to AA
Amino acids then proceed to:
intestinal wall and bloodstream
Proteins provide (3):
- Amino acids for protein synthesis.
- Nitrogen atoms for nitrogen-containing compounds.
- Energy when carbohydrate and lipid resources are not available.
Amino acids are degraded in the liver.
▪ An amino group is transferred from an amino acid
to an -keto acid, usually -ketoglutarate.
transamination
enzymes in transamination
transaminase or aminotransferase
transamination reaction:
alanine + a-ketogyltarate –> pyruvate + glutamate
Removes the amino group as an ammonium ion from
glutamate.
▪ Provides -ketoglutarate for transamination.
oxidative deamination
oxidative deamination reactioin
glutamate _ NAD+ + H2O by glutamate dehydrogenase –> a-ketoglutarate
Write the products from the transamination of a-ketoglutarate by aspartate.
oxaloacetate, glutamate sa baba
Detoxifies ammonium ion from amino acid degradation.
▪ Converts ammonium ion to urea in the liver.
urea cycle
formed when in the mitochondria, when ammonium ion reacts with CO2
from the citric acid cycle, 2 ATP, and water.
carbamoyl phosphate
reaction in forming carbamoyl phosphate
NH4+ + CO2 + 2ATP + H2O to carbamoyl phosphate
4 reactions of urea cycle
1 Transfer of Carbamoyl Group
2 Condensation with Aspartate
3 Cleavage of Fumarate
4 Hydrolysis Forms Urea
The carbamoyl group is transferred to ornithine to form citrulline.
Citrulline moves across the mitochondrial membrane into the cytosol.
urea cycle 1
takes place in the
cytosol, citrulline
combines with
aspartate.
▪ Hydrolysis of ATP to
AMP provides energy.
▪ The N in aspartate is
part of urea.
urea cycle 2
Is cleaved from argininosuccinate.
▪ Enters the citric acid cycle.
urea cycle 3
Arginine is hydrolyzed
▪ Urea forms.
▪ Ornithine returns to the
mitochondrion to pick
up another carbamoyl
group to repeat the
urea cycle
urea cycle 4
Urea cycle conversion:
Ammonium ion to urea
▪ Aspartate to Fumarate
▪ 3ATP to 2ADP, AMP, 4Pi
site of Formation of urea
cytosol
site of Formation of carbamoyl phosphate
mitochondrion
site of Aspartate combines with citrulline
cytosol
site where Fumarate is cleaved
cytosol
citrulline forms
mitochondrion
When needed, carbon skeletons of amino acids are used
to
produce energy by forming intermediates of the citric
acid cycle.
Three-carbon skeletons: pyruvate
alanine
serine
cysteine
4C skeleton oxaloacetate
aspartate
aspargine
5C skeletons glutamate
glutamine
glutamate
proline
arginine
histidine
Amino acids are classified as _ if they generate pyruvate or oxaloacete, which can be used to synthesize glucose
Glucogenic
Amino acids are classified as _ if they generate acetoacetyl CoA or acetyl CoA, which can form ketone bodies or fatty
acids
ketogenic
acetyl coa
isoleucine
leucine
threonine
tryptophan
acetoacetyl CoA
leucine
lysine
phenylalanine
tyrosine
AA pathways to CAC Ketone bodies process:
pyruvate to acetyl CoA to acetoacetyl CoA then ketogenesis
PYRUVATE AA PATHWAYS:
Alanine
glycine
cysteine
serine
threonine
tryptophan
Overview of Metabolism: (6)
- Catabolic pathways degrade large molecules.
- Anabolic pathway synthesize molecules.
- Branch points determine which compounds are degraded to acetyl CoA to meet energy needs or converted to glycogen for storage.
- Excess glucose is converted to body fat.
- Fatty acids and amino acids are used for energy when carbohydrates are not available.
- Some amino acids are produced by transamination.
