Lecture #69

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Gluconeogenisis
- use metabolic preurosor fo new synthesis of glucose
- reverse of glycolysisi
why is glucose homeostatis imp
- for RBc because they have no mitochondria
- brain does not have gltcogen storage
- biosynthesis of ribose for nucleic acids
- glucose can be used to modify other proteins
- important of homeosotatesof other molecules
where does glucose product happen the most?
- the liver 90%
- kidney makes the rest but are selfish and only makes it for itself
where does gluconeogenisis take place

both cytosol and mtichon
what are the precursors of gluconeogenisis
- lactatepyruvate
- glycerol
- a-ketoacid
what are the 4 enzymes that can reverse the 3 irreversible steps in the glycolysis
- Pyruvate Carboxylase
- PEPCK phosphopenol pyruvate carboxykinase)
- Fructise 1,6 bisphosphatase
- G-6-P
Which enzyme reverses step 10 in glycolysis for gluconeogensis ?
- Pyruvate carboxylase
- PEPCK ( in this order)
Which enzyme reverses step 3 in glycolysis for gluconeogensis ?

Fructose 16 bisphophatase
Which enzyme reverses step 1 in glycolysis for gluconeogensis ?

G-6-p
what are the similarities of gluconeogenisis and glycolsysis

They share 7 reversible reactions
Step1 gluconeogensis
- change pyruvate to Oxaloacetate (OAA) via pyruvate carboxylase
- this step isirreversible and allosterically activated ny acetyl coA
- carboxyl group is added
where foes steo 1 happen og vluconeo

mitochondria
what does pyruvate carboxylase require to function

biotin and ATP
Step 2 of GNG
- oAA changes to PEP vis PEPCK
- irreversible
- require GTP
- carboxyl group is removed
where does Step 2 of GNG take place

1/2 in the mitochondria and 1/2/ cytosol
Step 3 of GNG
- f16bisphosphate changes to F-6-P via F16bisphosphatase
- irreversible
what inhibts step 3 of GNG

F26BP and AMP
what does the F26BP inhibit and activate
- PFK1 is activated
- inhibti F1-6 bisphosphatatse
step 4 of GNG
- turn G6P to Glucose via glucose 6 phosphattase
- irreversible
where does step 4 of GNG take place

ER membrance
what are the only organs that release glucoes?

liver and kidney
the enzyme G6Ptas only exists in which organs?

liver and kidney
how much ATp does GNG comsume ?

6 ATP and 2 NADh which leads to a total 12 ATP
what are the precursors of GNG?
- Lactate
- Alanina
- Glycerol
how is lactate produces
- from anerobic glycolysis
- primarily from RBC or excercising muscle cells
how is alanine produced?
- pyruvate transaimated in muscle
- alanine exported from liver
- alanine can transanimate back to pyruvate
- Glucose alanine cycle
how to pyruvate created from lactate to enter the GNG

lactate dehydrogenase
what is the glucose alanine cycle?

cycle btw the muscle and the liver where alanine is convereted to pyruvate pro
what is a glucogenic amino acid

aa that it can be utilized for GNG
what is a ketogenic amino acid
- aa that can only be utilized to make acetyl coa ad thus keton bodies
- ACETYL COA CANNOT BE USED TO MAKE GLUCOSE!
how is glycerol produced for GNG
- when tricglycerides are hydrolyzes
- fat cells
how is Glycerol encorporated into GNG
- used the enzymes glycroal kinas and glycerol 3 phosphate dehydrogenase to produce dihydroxyacetone phosphate (DHP)
- which is used ot create glucose in GNG
when is GNG upregulated ?
- Acetyl-coA
- Fasting
- prolong excercise
- high protein, low carb
- stress and injury
- plenty substrate available
- Glucagon
- activated (dephosphorylated ) FB-2
when is GNG downregulated ? & why
- alchol impariment
- F26bisphosphate
- AMP
- Insulin
- well fed
- eating
where does energy for GNG come from during afsting ?

Beta oxidation
purpose of PPP
- generate 5C sugar for nucleic acid synthesis
- NADH used for variety of pathways
wwhat is the starting product for PP P

glucose
the PPP can be broken down into

oxidative and non oxidative
oxidative PPP produces?

NADPH and ribose 5 phosphate
non-oxidative PPP produces?

fructose 6 phosphate to fluel the glycolysis pathway
what are the uses of NADPH ?
- reduction of glutathione
- reduction of 02 toform ROS
- reductive biosynthesis
- create Ribose 5 phosphate
- to make nucleic acids
what are the oxidative stesp of PP

G6P >6phosphoglucono -δ-lactone> 6 phosphogluconate> ribose 5 phosphate
what is the produce of the oxidative of PP

2X NaDPH
in regards to reversibility is how do the nonaxidative and oxidative portions of PPP differ?

non-oxidative is reversible while ox is not.
hows does transketolase work and what does it need to function ?
- move a ketone group around.
- creates 3c and 5c molecules within this transfer
it need TPP thiamine pyrophosphate to funtion.
hows does transaldolase work and what does it need to function ?

transfer 3 carbon unit
what cause hemolytic anemia and G5PD deficiency ?
- RBc generate alot oft ROs reactive oxygen species and this this can damge HB
- usually the NADPH in the PPP reduce GSH ( glutathione and reduce the ROS thus repairing and preventing BY damage. When the PPP is down this causes an increase in the ROS and the RBC start to get lysed by the ROS
- Heinz bodies form in RBC and RBC membrance becomes very fragile
whatis glutathione

an antioxidant produces by the PPP
what is significant about glucose 6 phosphate dehydrogenase ?

It is the first enzyme in both PPP and glycolysis
what population does the G6PD deficieny affect?
10% African american man
- there is a G6PD mutation that correlated around the malarial belt
- people with sickle cell anemia
- Thalassemia

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Iana

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Lecture #69

Description

Gluconeogenesis and Pentose Phosphate Pathway

Updated

2020-09-20T17:12:43Z

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