Metabolism Flashcards
direct energy vs indirect energy
ATP= direct
NADH and FADH2 = indirect (go to ETC to make ATP)
gluconeogenesis
anabolic
makes glucose from precursor molecules
mitocondria and cytosol
glycogenesis
anabolic
make glycogen to store glucose
cytosol
fatty acid synthesis
anabolic
makes fatty acids from acetyl CoA
cytosol
lipogenesis
anabolic
adds fatty acids to a glycerol backbone to make triglyceride lipids
cytosol
ketogenesis
anabolic
makes ketone bodies from acetyl CoA
mitochondria
pentose phosphate shunt
anabolic
shunts glucose into the creation of various 5-carbon sugars and NADPH
cytosol
glycogenolysis
catabolic
breakdown of glycogen to release glucose, glucose can then enter glycolysis to produce energy
cytosol
glycolysis
catabolic
breakdown of glucose to pyruvate to produce energy (NADH, ATP). after glycolysis, pyruvate can be converted to acetyl CoA to enter the CAC to produce more energy
cytosol
lipolysis
catabolic
breakdown of lipids (triglycerides) to release fatty acids from the glycerol backbone. the fatty acids can then enter beta oxidation to produce more energy
beta oxidation
catabolic
breakdown of fatty acyl to acetyl CoA to produce energy (NADH, FADH2). acetyl CoA can enter the CAC to produce more energy
mitochondria
ketolysis
catabolic
breakdown of ketone bodies to acetyl CoA. acetyl CoA can enter the CAC to produce more energy
mitochondria
citric acid cycle
catabolic
breakdown of citrate (made from acetyl CoA and oxaloacetate) to produce energy (NADH, FADH2, ATP)
mitochondria
glycolysis
breakdown of glucose for energy
-glucose –> 2 pyruvate (and ATP and NADH)
anaerobic: convert pyruvate into lactate to regenerate NAD+, can enter mitochondria
gluconeogenesis
-make glucose with substrates: lactate, glycerol, amino acids
-in liver; send to other tissues when blood glucose low
glycogenolysis
breakdown glycogen
-in liver: release glucose to raise low blood sugar
-in muscles: use for energy in strenuous activity
glycogenesis
store excess glucose as glycogen
-anabolic, use ATP and UTP
pentose phosphate shunt
use glucose to make:
1. NADPH- used for fatty acid synthesis, antioxidation
2. 5-C sugars- such as ribose-5-P for nucleotide synthesis
-can feed sugars back into glycolysis “shunt” if needed
beta oxidation
-breakdown of fatty acids for energy
-make indirect energy (NADH and FADH2)
-fats broken down to acetyl CoA and if want more energy enter CAC into mitochondria
fatty acid synthesis
excess glucose to acetyl CoA to fatty acids
-store as triglycerides
lipogenesis
fatty acids + glycerol to make triglycerides (storage)
lipolysis
release fatty acids from triglycerides
-fatty acids–> fatty acyl CoA –> acetyl CoA to make energy
triglycerides for energy:
-take up less space than glycogen, more carbon atoms and easier reduction
ketogenesis
liver makes ketone bodies from acetyl CoA
-these ketone bodies can be used by other tissues (i.e. cardia muscle, smooth muscle, brain) when energy is needed
ketolysis
breakdown of ketone bodies to release acetyl CoA
-acetyl CoA goes into CAC to make energy
-liver only makes ketone bodies, cant use them
which 3 catabolic pathways feed into the citric acid cycle?
3 catabolic pathways that feed into CAC to make more energy
- glycolysis… –>pyruvate
- lipolysis … –>fatty acyl CoA
- ketolysis … –>ketones
all into acetyl CoA
what are the 3 irreverislbe steps in glycolysis?
- glucose –> glucose 6-phosphate (via hexokinase)
- fructose 6-phosphate –> fructose 1,6-bisphosphate (via phosphofructokinase 1) *main switch - rate limiting/commiting step
- phosphoenolypyruvate –> pyruvate (via pyruvate kinase)
what is the one kinase in glycolysis that is reversible?
phoshoglycerate kinase
1,3-bisphosphohlyverate –> 3-phoshoglycerate
what is the cofactor for ATP?
Mg2+ to bind and chelate for shape
what are the products of glycolysis?
2 pyruvate, net 2 ATP, 2NADH
anaerobic vs aerobic glycolysis for use of NADH
anaerobic: lactate dehydrogenase converts NADH back into NAD
aerobic: NADH to mitochondria, oxidized to acetyl CoA, then into CAC
-regenerate NAD
enzyme for the last step in anaerobic glycolysis
pyruvate –> lactate via lactate dehydrogenase
all molecules of glycolysis
G
G6P
F6P
F 1,6 bP
G3P
DHAP
GA3P
1,3 bPg
3Pg
2Pg
PPP
P
all steps of glycolysis
Glucose –> (hexokinase)
glucose 6 phosphate –> (phosphohexose isomerase)
fructose 6 phosphate–> (phosphofructokinase 1)
fructose 1,6 bisphosphate –> (aldolase)
[glyceraldehyde 3 phosphate + dihydroxyacetone phosphate]–> (trios phosphate isomerase)
glyceraldehyde 3 phosphate –> (glyceraldehyde 3 phosphate dehydrogenase)
1,3 bisphosphoglycerate–> (phosphoglycerate kinase)
3 phosphoglycerate–> (phosphoglycerate mutase)
2 phosphoglycerate–> (enolase)
phosphoenolpyruvate–> (pyruvate kinase)
pyruvate
gluconeogenesis purpose and location
make glucose from non-carb precursors
in liver and kidneys
provide glucose to other tissues
fasting
is gluconeogenesis the reversal of glycolysis? and why or why not?
no bc irreversible steps with kinases
1.pyruvate –> oxaloacetate
2. fructose 1,6 bisphosphate –> fructose 6 phosphate
3. glucose 6 phosphate –> glucose
3 substrates for gluconeogenesis and where they enter
- lactate (at pyruvate)
- glycerol (1st convert into glycerol 3-phosphate via glycerol kinase to trap it, then convert and join gluconeogenesis at dihydroxyacetone phosphate)
- glucogenic amino acids –> alanine (at pyruvate)
gluconeogenesis molecules
P
O
PPP
2-PG
3-PG
1,3- bPG
G3P
G3P + DHAP
F 1,6 bP
F 6-P
G 6-P
G
steps of gluconeogenesis
pyruvate–> (pyruvate carboxylase)
oxaloacetate–>(phosphoenolpyruvate carboxykinase)
phosphoenolpyruvate–> (enolase)
2- phosphoglycerate–> (phosphoglycerate mutase)
3- phosphoglycerate –> (phosphoglycerate kinase)
1,3 bisphosphoglcerate–> (glyceraldehyde 3-phosphate dehydrogenase)
glyceraldehyde 3-phosphate –> (triose phosphate isomerase)
[glyceraldehyde 3-phosphate + dihydroxyacetone phosphate]–> (aldolase)
fructose 1,6-bisphosphate –> (fructose 1,6-bisphosphatase)
fructose 6-phosphate –> (phoshoglucose isomerase)
glucose 6-phosphate –> (glucose 6-phosphatase)
glucose
lactate and the cori cycle and enters gluconeogenesis
-product of anaerobic glycolysis
-lactate goes from tissues to liver via blood
-once in the liver made into pyruvate for gluconeogenesis
-cori cycle: 4 lactate from anaerobic glycolysis in muscles is transported to liver and converted to glucose … return to muscles (cycle)
glycerol entering gluconeogenesis
-where is it from? where does it enter
-from lipolysis of triglycerides
-enters gluconeogenesis by being converted into dihydroxyacetone phosphate
glucogenic amino acids
-what are they, how do they enter gluconeogenesis, what needs to occur, what coenzyme used
**alanine and glutamine
-all amino acids expect leucine and lysine
-made into pyruvate or CAC intermediate (into oxaloacetate)
-alanine –> pyruvate using alanine transaminase enzyme and coenzyme derived from B6; PLP (pyridoxal phosphate)
–> use transamination
transamination
transfer amino group from amino acid to an alpha keto acid
alanine (AA) + alpha ketoglutarate (AKA) –> pyruvate (KA) + glutamate (AA)
shuttle systems
-gluconeogenesis beings in the mitochondria
-alanine –> pyruvate in mitochondria
-lactate –> pyruvate in cytosol and shuttled into mitochondria
-once in mitochondria pyruvate –> oxaloacetate (via pyruvate carboxylase enzyme)
–> oxaloacetate cant cross inner mitochondria matrix to get back into the cytosol to feed gluconeogenesis so need shuttle
malate aspartate shuttle- what is the starting substrate and steps
-starting substrate: alanine (or other glucogenic amino acids)
1. oxaloacetate converted into malate
2. malate crosses inner mitochondria membrane (with anti porter)
3. once in cytosol malate converted back to oxaloacetate
4. oxacloacetate –> phosphoenolpyruvate… continue gluconeogenesis
lactate shuttle
lactate –> pyruvate in cytosol
-pyruvate into mitochondria and converted into oxaloacetate
- oxaloacetate –> phosphoenolpyruvate and shuttle out to continue gluconeogenesis
3 ways that nitrogen can be incorporated into amino acids
- transamination (indirect)
- transamidation (indirect)
- direct incorporation
proline: special
cant rotate around alpha carbon –> non protein structure that require rotation (i.e. alpha helix)
cysteine and methionine: special
-cysteine: SH (thiole group) can form disulfide bonds
-in many important proteins and peptides: keratin, insulin, glutathione (Gly-Cys-Glu)
methane and cysteine: contain sulfer, help bind metals
serine and threonine: special
OH –> carbohydrate attachment or site for phosphorylation
asparagine: special
NH2 for carbohydrate attachment
transamination
-which 3 amino acids and alpha ketoacids
transfer of amino group from an amino acid to an alpha keto acid
-require B6 coenzyme (PLP)
all
people
are
over
getting
AK-47ed
AMINO ACID –> ALPHA KETOACID
alanine–>pyruvate
aspartate –> oxaloacetate
glutamate –> alpha ketoglutarate
transamidation
N comes from an amiDo group
-NH2 =O
direct incorporation- amino acid anabolism
which enzyme
add nitrogen from ammonia with B3 enzyme (niacin)
what are the 6 amino acid families with a common precursor
- glutamate family
- aspartate family
- serine family
- pyruvate family
- aromatic family
- histidine (family)
glutamate family
aspartate family
serine family
pyruvate family
aromatic family
histidine (family)
catabolism of amino acids
what is the mechanism and what is produced
deamination to produce carbon skeleton and ammonium ion (not opposite of anabolism)
2 main deamination pathways (to breakdown amino acids)
- glutamine synthetase reaction (direct incorporation)
-general- extrahepatic tissues to liver
-glutamine carries nitrogen to liver to make urea
2.glucose-alanine cycle (transamination)
-specific- muscle to liver
-alanine carries nitrogen to liver to make urea
urea cycle
-location
-reactants and products
-in liver
-start: ornithine + carbamoyl phosphate = citrulline
-products: ornithine (can start cycle over) and urea
-urea has 2 nitrogens:
-1 from aspartate
-1 from carbamoyl phosphate (get N from glutamine or glucose-alanine cycle)
how do the urea cycle and citric acid cycle connect?
CAC: oxaloacetate go intro urea cycle by transamination into L-asparate
in urea cycle: L-aspartate –> arginosuccinate –> L-fumarate –> fumarate –> oxaloacetate and continue citric acid cycle
how can amino acids be glucogenic and ketogenic
glucogenic i.e. asparagine –> aspartic acid –> oxaloacetate –> gluconeogenesis
ketogenic i.e. threonine –> acetyl-CoA –> ketogenesis
