Carb Metabolism (Exam 1) Flashcards
Glucose is the sole energy source for the following (dependent on glucose to function properly):
1) RBCs
2) adrenal medulla
3) CNS
4) gamates
T/F: only the liver has glycogen metabolism AND carb metabolism and controls blood glucose
TRUE
Where does glycogenesis occur?
in the cytoplasm of liver and muscle
Where does glycogenolysis occur?
in cytoplasm of liver and muscles
Where does glucogenesis occur?
in mitochondria AND cytoplasm of LIVER
Where does glycolysis occur?
in the cytoplasm of ALL tissues
Glycolysis has 3 stages. What steps are a part of the energy investment stage/preparatory stage/stage 1?
step 1, 2, 3
Glycolysis has 3 stages. What steps are a part of the splitting stage/stage 2 (no energy is involved here)?
step 4 and 5
Glycolysis has 3 stages. What steps are a part of the energy payoff stage/ stage 3?
step 6-10
step 6 is the only step that creates NADH
step 7 and 10 create ATP through substrate level phosphorylation
Which metabolic pathway converts glucose to pyruvate?
glycolysis
How many steps are there in glycolysis?
10 steps
What are the net products of glycolysis?
1 glucose molecule= 2 NADH and 2 ATP
What are the 2 rate limiting steps in stage 1 of glycolysis?
step 1 and 3
What are the 3 rate limiting steps in glycolysis?
step 1, 3, and 10
What type of reaction is step 1 of glycolysis?
phosphorylation reaction
What energy is invested during stage 1 of glycolysis?
2 ATP
1 ATP during step 1 and another during step 3 of glycolysis
What enzyme converts glucose to G6P in step 1 of glycolysis?
HK or GK
What type of reaction is step 2 of glycolysis?
isomerization reaction
What enzyme converts G6P to F6P during step 2 of glycolysis?
phosphogluco-isomerase (PGI)
What type of reaction is step 3 of glycolysis?
phosphorylation reaction
Which enzyme converts F6P to fructose 1,6 biphosphate?
phospho-fructokinase 1 (PFK1)
note: PFK2 also exists and would move the phosphate to C2, but this is not in glycolysis…. to be continued
Stage 2 of glycolysis is where “glucose” gets split into 2 molecules. This is step 4 and 5 of glycolysis. What happens here?
-fructose 1,6 BP gets split into 2 trioses
-the 2 trioses are glyceraldehyde 3 phosphate (GAP) and dihydroxyacetone 3 phosphate (DHAP)
-this step is catalyzed by an aldolase
-DHAP and GAP are isomers and can easily be interchanged with triose phosphate isomerase
-only GAP enters into stage 3 of glycolysis, so DHAP will have to convert to GAP, and 2 GAPs will enter the next stage
What enzyme converts GAP to 1, 3 biphosphoglycerate (1, 3 BPG)?
GAP dehydrogenase
note: NADH is made in this step!!!
What type of reaction is step 6 of glycolysis?
oxidation reaction
the aldehyde (GAP) is oxidized to carboxylate and a phosphate (1, 3 BPG)
note: 1,3 BPG is a high energy molecule because it has an O-P bond
Which enzyme converts 1,3 BPG to 3 phosphoglycerate in step 7 of glycolysis?
phosphoglycerate kinase
note: 1,3 BPG is a high energy phosphate molecule and is used to make the first ATP in glycolysis with substrate level phosphorylation
What steps of glycolysis undergo substrate level phosphorylation?
step 7 and 10
What enzymes in glycolysis can do substrate level phosphorylation?
phosphoglycerate kinase in step 7
pyruvate kinase in step 10
Which enzyme converts 3 phosphoglycerate to 2 phosphoglycerate in step 8 of glycolysis?
phosphoglycerate mutase
Which enzyme converts 2 phosphoglycerate to phosphoenolpyruvate (PEP) in step 9 of glycolysis?
enolase
What type of a reaction is step 4 of glycolysis?
lyase reaction
What type of reaction is step 9 of glycolysis?
dehydration reaction (remove water)
note: PEP (end product of step 9) is a high energy phosphate molecule
What enzyme converts PEP to pyruvate in step 10 of glycolysis?
pyruvate kinase
The 2NADH created in glycolysis will go to the ETC which is in the….
inner mitochondrial membrane
What happens to NADH if theres no oxygen present?
it will be converted to NAD+ by donating H to pyruvate, and pyruvate will become lactate
What has more energy- pyruvate or lactate?
lactate because it has more H bonds
What is the net product of anaerobic glycolysis?
1 glucose molecule= 2 ATP, 0 NADH
Accumulation of lactic acid ________________ pH
decreases
What is the Cori cycle?
-in times of anaerobic glycolysis, later lactate will need to be broken down
-lactate produced by the muscle enters the liver
-in the liver, lactate will be converted back to glucose
-anything that helps blood flow like light cool down post workout, stretching, massage gun, etc will help Cori cycle and reduce soreness
-soreness happens when muscles cannot process lactate and Cori cycle is delayed (like when you workout and just stop without cool down)
Which enzyme converts pyruvate to lactate, or lactate to pyruvate?
lactate dehydrogenase (LDH)
What are 4 reasons anaerobic glycolysis occurs?
1) fast contracting muscles during exercise
2) acute or chronic medical conditions that affect oxygen like anemia, any lung condition, or any cardiovascular disease
3) hepatic diseases because the liver is the only location for ALL of the glycogen and carb metabolism
4) RBCs do not have mitochondria so there is no ETC
T/F: 2, 3 BPG and 1,3 BPG are isomers
true
_____________ makes 1,3 BPG, whereas __________ make 2,3 BPG
Glycolysis, RBCs
in RBCs, glucose gets converted to GAP. GAP will convert to 1,3 biphosphoglycerate with what enzyme?
GAP DH
In RBCs, glucose gets converted to GAP. GAP will convert to 1,3 biphosphoglycerate with GAP DH. At this point it can go 1 of 2 ways. 1,3 biphosphoglycerate can be converted to 3 phosphoglycerate and then pyruvate. What enzyme does this and what reaction is this?
phosphoglycerate kinase converts 1,3 BPG to 3 phosphoglycerate and makes ATP through substrate level phosphorylation
In RBCs, glucose gets converted to GAP. GAP will convert to 1,3 biphosphoglycerate with GAP DH. At this point it can go 1 of 2 ways. 1,3 BPG can be converted to 2,3 BPG when there is low oxygen in RBCs. What enzyme does this?
biphosphoglycerate mutase
In RBCs, glucose gets converted to GAP. GAP will convert to 1,3 biphosphoglycerate with GAP DH. At this point it can go 1 of 2 ways. 1,3 BPG can be converted to 2,3 BPG when there is low oxygen in RBCs with biphosphoglycerate mutase. Then once the body no longer needs 2,3 BPG, it will be converted to 3 phosphoglycerate and then pyruvate. Which enzyme converts 2,3 BPG to 3 phosphoglycerate?
2,3 biphosphoglycerate phosphatase
Where does ATP come from in RBCs?
substrate level phosphorylation
When would we see a right shift in the hemoglobin oxygen binding curve?
-Hb-oxygen binding affinity decreases
-tissues will have more oxygen
-high levels of 2,3 BPG causes a R shift
-2,3 BPG is created in RBCs
-acidic/low pH with lactic acid present (Bohr’s effect)
-lactic acid is created in muscles
-2,3 BPG binds to hemoglobin
T/F: the inner membrane of the mitochondria is very selective and only VIP molecules can make it inside without a shuttle
true
In the malate shuttle process, where does NADH come from?
NADH generating step of glycolysis (step 6)
In the malate shuttle process, NADH donates a H to who?
OAA which will become malate
What are the 2 VIP molecules related to the malate shuttle that dont need a shuttle to get into the inner membrane of the mitochondria?
malate and aspartate
Once malate gets into the inner membrane of the mitochondria through the malate shuttle, what does it get converted to?
Malate donates H back to NAD+ and NAD+ will become NADH which will go to the ETC and generate 3 ATP
the malate in this process will be converted back to OAA
After the malate shuttle transported malate inside and was converted to OAA, what was the next conversion?
OAA was converted to aspartate
aspartate is a VIP molecule and can easily go in and out
an amino group was removed from OAA to make aspartate
After the malate shuttle, once the aspartate makes it back to the cytoplasm what does it become?
OAA when an amino group is added
Which mitochondrial shuttle produces more ATP- malate shuttle or glycerol 3 phosphate shuttle?
malate shuttle
How do you know which shuttle will be used in the mitochondria?
it depends on what is available- enzymes and AAs
T/F: NADH needs a shuttle to get into the mitochondria
true!!!! theres 2 different shuttles that can do this
T/F: there is only one ETC in each mitochondria
false- theres multiple in each mitochondria
How many ATP are generated from the malate shuttle?
1 NADH= 3 ATP
During glycolysis, DHAP is generated and will undergo reaction with NADH to be converted to glycerol 3 phosphate. What enzyme converts glycerol 3 phosphate to allow the molecule through the shuttle and produce FADH2 as a result?
glycerol 3 phosphate DH
How many ATP are generate with the glycerol 3 phosphate shuttle?
1 NADH= 2 ATP
2 NADH= 4 ATP
How many ATP are generated per glucose in aerobic glycolysis?
6-8 ATP, 0 NADH (2 were used to make ATP), 0 CO2 (not generated here)
6 ATP come from ETC, 2 ATP come from substrate level phosphorylation (so the max is 8)
if she tries to trick you——
-if theres 2 ATP, then there is still 2 NADH available to make MORE ATP (hasn’t gone through ETC yet)
How many ATP are generated per glucose in anaerobic glycolysis?
2 ATP (they came from substrate level phosphorylation)
The rate limiting steps in glycolysis are step 1, 3, and 10, so these steps need to be _______________
regulated
HK and GK are the rate limiting enzymes of step 1 of glycolysis. What is the allosteric inhibitor for each one?
HK allosteric inhibitor= G6P
GK allosteric inhibitor= F6P
PFK1 is the rate limiting enzyme in step 3 of glycolysis. It has 4 different allosteric regulators. Who are the activators?
high ADP or AMP
or
fructose 2,6 biphosphate
(Increased levels of ADP and AMP infer reduced levels of ATP suggesting a need for glucose catabolism to generate more ATP)
(F 2,6 BP is a regulatory molecule responsive to the blood sugar hormones, glucagon, and insulin)
PFK1 is the rate limiting enzyme in step 3 of glycolysis. It has 4 different allosteric regulators. Who are the inhibitors?
high ATP
or
high citrate
(high ATP levels indicate sufficient energy levels and a reduced demand for glucose catabolism)
(citrate is generated in the TCA cycle. Excess citrate infers a sufficient supply of TCA cycle intermediates and no demand for additional glucose catabolism)
What hormones regulate PFK2?
insulin and glucagon
Are PFK2 and PFK1 activated at the same time?
yes
Which enzyme of glycolysis pathway is sensitive to raising insulin levels?
PFK2
T/F: the product of PFK2 regulates PFK1
true- the product is F 2, 6 BP
Which allosteric activator will turn on PFK1?
F 2, 6 BP
this is the strongest activator of PFK1!!!!! Even if ATP was inhibiting PFK1, F2,6BP can overpower it when needed
Pyruvate kinase is the RLE in step 10 of glycolysis. Pyruvate kinase is inhibited by….
ATP and acetyl coA
high acetyl coA= inhibit PDH AND pyruvate kinase
In the process of glycolysis, one mole of glucose is oxidized to form 2 moles of pyruvate, and?
2 moles of NADH and 2 moles of ATP
In RBCs, the NADH from glycolysis donates electrons to _______________ which produces __________ additional ATP
pyruvate, 0
(only substrate level phosphorylation or ETC can make ATP)
In a yeast cell under aerobic conditions, pyruvate is oxidized to acetyl CoA, which enters the ________________. NADH donates electrons to a protein of the ETC. The total ATP/glucose produced from these processes and glycolysis is _______
citric acid cycle, ~36
