Bookmark and Share

Front Back
What is cellulose?
Glucose/Glucose, with a B 1/4 linkage!
What are the three main carbohydrates in are diet?
1. Glucose (aldo-hexose) righit, left, right, right

2. Galactose (aldo-hexose), right, left, left, right (an epimer of glucose).  

3.  Fructose (keto-hexose),  (Glut 5 transporter)
What glucose transporter can take up galactose?

Can Glut 5 take up Glucose?
1. SGLT1, Glut 2, Glut 4! Yep, b/c there an epimer

2. No! hahahaha
How does the glucose ring structure form? What is the prevelant form in the blood?
1. the ring structure, b/c the O on the 6 carbon performs a nucleophilic attack!

inter-converts, non-enzymatically!
What is the 0H on the ring version of glucose?

What form does glucose have to be in for oxidation?
1. alpha  (2 down, 3 up, 4 down, 5 CH2OH up)


2. beta is more stable, so you'll get 60 beta but the enzyme
What is the enzyme that ensures we have all alpha and no beta for oxidation?
phospho gluco-mutase:  it converts B to Alpha so that we can use all the Alpha!

(the isomerase rxn that converts to fructose needs alpha - not the hexokinase)
Is a double bond saturated or unsaturated?
What is the last carbon in every FA?
How do you get acetyl CoA?
By oxidizing the B carbon so you get the Carboxylic acid and the alpha carbon!
Why are trans fats bad?
B/c FA stay in a linear forma nd are packed tightly together!

Boom! They pack together tight!

Does the body make trans fats?

Why do we have trans in our diets?

Trans fats increase shelf life of food.

Tactile taste sensation - trans fat receptors lget excited!

What about hydrogenation?
1. unsaturated go rancide in quickly. so we hydrogenate the double bonds to preserve.
What is the primary carrier for FA in the blood?
What is th ebest way to transport fats?
Glycerides, which are synthesized from the glyceride backbone!
What is the primary substrate for Triglyceride synthesis in an enterocyte?
1. 2 mono-glyceride!

(most prominent reaction at brush border!)

How does the liver pacakge triglycerides?
Phosphatidic acid pathway!

1. Gonna start out with glycerol 3-phophate!

2.  Add FA to 1 and 2

3. Remove phophate and add to 3rd carbon!

LIVER - b/c glycerol 3 phosphate comes from the glycolitic pathway!
What does NAD+ stand for?
1.  Nicotinamide adenine dinucleotide

NAD+ gets reduced and grabs how many electrons?
2e!  so, NAD is reduced

Electrons carry voltage potential!

How do NAD and FAD differ?
1. Pull hydrogen from C-H or C-C to convert alcohol to ketone!

And moving 2e in one shot (dehydrogenase!)

NAD is soluble in cyto and mito

NAD makes 3 ATP

2. FAD takes 2e but takes them 1 at a time! Primarily used when forming a double bond!
takes one hydrogen from the carbon on each side of to-be bond!

Typically bound to a protein!

FAD makes 2 ATP!  
What are the two phases of Glycolysis and what products kick them off?
1.  Preparatory phase, which consumes 2ATP and produces Fructose 1,6 bis-P

2. ATP-Generating phase, Fructose 1-6-bis-P to 2 triose phosphates, gives you 2NADH, and 4ATP, and leaves you with 2 Pyruvate!
What is the first step in Glycolytic Pathway?
Glucose to Glucose 6-Phosphate converted by hexokinase (but glucokinase in the liver)

Consumes an ATP, with

Delta G of -8.0, so its not easily reversible!

What is the second step?
Conversion of Glucose 6-Phosphate to Fructose 6-Phosphate, which makes a ketone of 2nd carbon

Catalyzed by Phosphoglucose isomerase

Reversible step!
What is the third step?
1.  Fructose 6-phosphate to Fructose, 1-6 bis Phosphate....

catalyzed by phosphofructokinase 1!

This step requires ATP and is not reversible!
What is unique about the 4th step?
We have intermediaries!  Very cool.

The Fructose 1-6 bis phosphate is cleaved into 2 3 carbon molecules by an aldolase.

Two intermediaries:

1. Dyhydroxyacetone which converts to Glyceraldehyde 3 phosphate  via Triose Phosphate Isomerase

What happens in the 5th step?
1.  Glyceraldahyde 3-phosphate is converted to 1-3 bis phosphoglycerate by Glyceraldehyde 3-P dehydrogenase and

converts an NAD+ to NADH,

What is the 6th step?
1,3 bis-phosphoglycerate PRODUCES an ATP and results in 3 phosphoglycerate  
What is the 7th step?
3-phosphoglycerate is converted to 2-phosphoglycerate by

What is the 8th step?
2- Phosphoglycerate is converted to Phosphoenolate pyruvate by an enolase!

What is the 9th and final step?
The conversion of phosphoenolate pyruvate to pyruvate by pyruvate kinase and PRODUCING an ATP!

What is important about the product of the first step, Glucose 6- Phosphate?
It is the branch point for glucose metabolism

Either glycogen synthesis, pentose phosphate branch point or glycolysis
What is the deal with the 1,3 bis-phosphoglycerate and RBCs?
It is an isomer of 2,3 DPG, which makes the deoxygenated version of heme more popular in red blood cells, thereby causing the unloading of oxygen!

What is it metabolized to?
What is the Glycerol 3-phosphate shuttle (major in most tissue)?
It is a way to recycle NAD+ from NADH!

Involves the dihydroxyacetone phosphate produced from the cleaving of Fructose 1,6-P into 2 3Carbons
What is the core forward and reverse reactions of the Glycerol 3-Phosphate shuttle?
Forward:  dihydoxyacetone and NAHD are converted by glycerol 3 phosphate dehydrogenase (GPD) to NAD and Glycerol 3 Phosphate!

Recycle:  Glycerol 3-Phosphate is converted back to dihyroxyacetone phosphate by glycerophosphate dehydrogenase, this time reducing one molecule of enzyme-bound  (FAD) to FADH2. FADH2 then reduces coenzyme Q (ubiquinone to ubiquinol) which enters into oxidative phosphorylation This reaction is irreversible
How do we get NAD back when theres anearobic respiration?
lactate dehydrogenase reduces 2 pyruvate to 2 lactate and in the process oxidizes NADH to NAD_
What is surprising about the presentation of lactate dehydrogenasae deficiency?
1.  It presents with very little anemia!

2. it is autosomal recessive, presents with exercise intolerance and myoglobinuria

Where does hexokinase work?

Where does glucokinase work?
1.  adipocytes, muscle (GLUT 1, 3, 4) 2. liver, B-cells (GLUT 2)  
What is the key function for hexokinase?
It traps glucose in the cell?

How are Glucokinase and Hexokinase regulated?
1.  Hexokinase is inhibited by product formation (G6P)

2. Glucokinase is not inhibited by product - it is inhibited hormonally by insulin and glucagon only in the liver! (increased with insulin)
HbA1c - what is it?
HbA is adult hemoglobin

When too much glucose - you have a non-enzymatic glycosilation...simply due to mass action. When glucose is out of the ring structure and the aldehyde is exposed an amine group from HbA attacks it!
Why do you want to regulate hexokinase?
so you can get glucose out of RBCs when glycolysis is overfed and your HbA doesn't get glycosylated

Describe regulation by PFK1 (in skeletal muscles)
PFK1 is the entry point for glycolysis - it is the gatekeeper?  the reaction's DG is -5.3, so its irreversible.

Measures the amount of AMP, b/c

2ADP = ATP and AMP (catalyzed by adenylate kinase)  
What is the Fructose 2,6 biphosphate do?
It positively regulates the activity of PFK1, getting you to Fructose 1,6 bis Phosphate
What is the malate aspartate shuttle?
Its going on in the liver, NADH gets recycled by changing NADH to NAD and converting malate, which goes into the mitochondria and is the returned to oxaloacetate and converts NAD to NADH, which gives electrons to the electron transport chain
Where is Pyruvate Kinase control most prominent?
1. In the liver

2.  It is increased by Fructose 1,6 bisphosphate (feed forward - telling downstream glycolysis to get ready!)

3.  It is decreased by ATP (in the muscles),  but it is also decreased by products produced in the liver from gluconeogenesis.
What two steps require ATP in glycoysis?
1. First step, to G6P

2.  Thrid step, F6P to Fructose 1,6 bisphosphate, which is the commited step for glycolysis, impacted by Phosphofructokinase1
Which steps produce ATP?
1.  1,3 bisphosphoglycerate to 3 phosphoglycerate (makes sense b/c you're losing a PO4)

2.  Phosphoenol pyruvate to pyruvate by Pyruvate Kinase
What step reduces NAD+?
 Glyceraldehyde 3-P to 1,3 bis phosphoglycerate, catalyzed by Glyceraldehyde 3-P dehyrdogenase!

How does Fructose 2,6 bisphosphate do this?
1. extra Fructose 6-Phosphate is converted to Fructose 2,6 bisphosphate by PFK2

2.  When its down, the phosphatase activity covnertes Fructose 2,6 bisphosphate to Fructose 6 phosphate.
Is a rxn reversible that releases CO2
x of y cards Next > >> >|