Exam 3 - Glycolysis

Question 1

General Metabolic Pathways and Glucose:

1. Glucose –> Glycogen =
2. Glycogen –> Glucose =
3. Glucose –> Lactate/Pyruvate =
4. Pyruvate/Lactate —> Glucose =

Answer 1

1. Glycogenesis
2. Glycogenolysis
3. Glycolysis
4. GLyconeogenesis

Question 2

What is the generic molecular formula for carbohydrates?

Answer 2

(CH₂O)_n

Question 3

What does the D or L designation on enantiomers depend on?

Answer 3

Their resemblence to Glyceraldehyde

Question 4

Diastereomers, also called [], are different with respect to OH at only [] stereogenic position…

Answer 4

1. epimers
2. one

Question 5

1. Isomers that differ only in the order in which the atoms are connected are called - ??
2. What are common sugar examples of this?

Answer 5

1. Constitutional Isomers
2. Aldose vs Ketose

Question 6

Enatiomers are….

Answer 6

optical isomers that are non-superimposable mirror images

Question 7

How are diastereomers and epimers different?

Answer 7

• Epimers are a type of diastereomer but their configuration is different at only ONE stereogenic center

Question 8

What is a special type of epimer used to describe cyclic saccharides?

What are their designations?

Answer 8

• Anomer
• Alpha and Beta

Question 9

What conformation do physiological sugars come in? D or L?

Answer 9

D

Question 10

What are the main examples for Aldose sugars…

Also - how many carbons does each have?

Answer 10

1. Glyceraldehyde - 3 Carbons
2. Erythrose - 4 Cs
3. Ribose - 5 C
4. Glucose and Galactose - 6 Cs

Question 11

What are the main examples of Ketose sugars…

Also - how many carbons does each have?

Answer 11

1. Ribulose and Xylulose - 5 Cs
2. Fructose - 6 Cs

Question 12

When a ring structure is formed, the carbonyl carbon becomes []?

This carbon is called the [] carbon

Answer 12

1. asymmetrical
2. Anomeric

Question 13

How do you classify the anomeric carbon as alpha or beta on a cyclic sugar?

Answer 13

• Look at the hydoxyl on the 6th carbon.
• If it is CIS from the OH attached to the anomeric carbon —- then it is a BETA anomer
• If it is TRANS from teh OH attached to the anomeric carbon —- then it is an ALPHA anomer

Question 14

The Pyran structure refers to a [] carbon ring

The furan structure refers to a [] carbon ring

Answer 14

• 6 carbon
• 5 carbon

Question 15

What monosaccharides make up sucrose?

Answer 15

Fructose and glucose

Question 16

What monosaccharides make up Lactose?

Answer 16

Glucose and Galactose

Question 17

What monosaccharides make up Maltose?

Answer 17

Glucose and glucose

Question 18

What are the 3 main disaccharides?

Answer 18

Sucrose

Lactose

Maltose

Question 19

What is another name for the Glycolytic pathway?

Answer 19

Embden-Meyehof

Question 20

Is glycolysis an oxidative pathway?

Answer 20

Yes

Question 21

What Glut transport does brain tissue use?

What is the metabolic fate of glucose in brain tissue?

Answer 21

• Glut III
• Glucose –> Pyruvate –> TCA

Question 22

What Glut transporter do RBCs use?

What is the metabolic fate of glucose in RBCs?

Answer 22

• Glut I
• Glucose –> Pyruvate –> Lactate –> which is then exported with H+

Question 23

What type of Glut transporter do muscle cells use?

What is the metabolic fate of glucose in muscle cells?

Answer 23

• Glut IV
• Glucose
  
  • Can be stored as glycogen
  • Can be used to make pyruvate and sent through TCA cycle
• Pyruvate can be used to make lactate if no Oxygen…
  
  • lactate would then be exported

Question 24

What is the Glut transporter in Adipose Cells?

What is the metabolic fate of glucose in adipose tissue?

Answer 24

• Glut IV
• Glucose
  
  • Could be used to make glycogen
  • Used to make pyruvate
• Pyruvate then is used to make Acetyl CoA –> fats.

Question 25

What Glut transporter do Liver Cells use? Lactate is [] to make pyruvate in the liver cells...

Answer 25

* Glut II * imported

Question 26

1. What enzyme start glycolysis by converting glucose --\> glucose 6-phosphate? 2. Are any other substrates needed?

Answer 26

1. Hexokinase 2. **ATP** is used and ADP is byproduct

Question 27

1. What enzyme converts glucose 6-phosphate --\> Fuctose 6-phosphate? 2. Are any other substrates needed?

Answer 27

1. Phosphoglucose Isomerase 2. No

Question 28

1. What enzyme converts Fructose 6-phosphate to Fructose 1,6-bisphosphate? 2. Are any other substrates needed?

Answer 28

1. 6-phosphofructo-1-kinase 2. Phosphate is cleaved from **ATP**

Question 29

1. What enzyme converts Fructose 1,6-bisphosphate to Glyceraldehyde 3-phosphate and DHAP? 2. Are any other substrates needed?

Answer 29

1. Fructose bisphosphate aldolase 2. No

Question 30

1. What enzyme converts DHAP to GAP? 2. Are any other substrates required?

Answer 30

1. Triose phosphate isomerase 2. No

Question 31

1. What enzyme converts GAP to 1,3 Bisphosphoglycerate 2. Are any other substrates needed?

Answer 31

1. Glyceraldehyde 3-phosphate dehydrogenase 2. Reduces NAD+ to NADH 1. Adds a phosphate to the molecule

Question 32

What is the most important bioenergetic step of Glycolysis? Why?

Answer 32

* GAP --\> 1,3 bisphosphoglycerate * It uses the coupled rxn of.... * Aldehyde --\> Carboxylic Acid * NAD+ --\> NADH * Adds a high energy phosphate, creating a mixed anhydride, to the molecule for later use.

Question 33

1. What enzyme converts 1,3 Bisphosphoglycerate to 3-Phosphoglycerate? 2. Are any other substrates involved?

Answer 33

1. Phosphoglycerate Kinase 2. ATP is produced from ADP

Question 34

1. What enzyme converts 3-phosphoglycerate to 2-phosphoglycerate? 2. Any other substrates involved?

Answer 34

1. Phosphoglycerate mutase 2. No

Question 35

1. What enzyme converts 2-phosphoglycerate to Phosphoenolpyruvate? 2. Any other substrates involved?

Answer 35

1. Enolase 2. Condensation reaction --\> H2O is released

Question 36

1. What enzyme converts phosphoenolpyruvate to pyruvate? 2. Any other substrates involved?

Answer 36

1. Pyruvate kinase 2. ATP is created from ADP

Question 37

What are the 3 irreversible steps of the glycolytic pathway? What enzyme is involved in each step?

Answer 37

1. Glucose --\> Glucose 6-phosphate 1. Hexokinase 2. Fructose 6-phosphate --\> Fructose 1,6-bisphosphate 1. 6-phosphofructo-1-kinase 3. Phosphoenolpyruvate --\> Pyruvate 1. Pyruvate Kinase

Question 38

What is the 2nd most important bioenergetic step in Glycolysis? Why?

Answer 38

1. 2-phosphoglycerate --\> Phosphoenolpyruvate 2. Enolase destabilizes the phosphoester of 2-phosphoglycerate creating an enol phosphate 1. The phosphoester is worth -3 kcal/mol while the enol phosphate is worth -15 kcal/mol 2. This sets up the final step of glycolysis to be very energetically favorably and "almost" impossible to reverse.

Question 39

What molecule is needed in all cells to phosphorylate phosphoglycerate mutase - making it active and enabling it to convert 3-phosphoglycerate to 2-phosphoglycerate? Where is this molecule made?

Answer 39

* 2,3-bisphosphoglycerate * Red Blood cells

Question 40

1,3-Bisphosphoglycerate can also be used to make [] by the enzyme []? This molecule functions in controlling the binding of [] to hemoglobin...

Answer 40

1. 2,3-Bisphosphoglycerate by 2,3-BPG Mutase 2. Oxygen (O₂)

Question 41

What are the roles of the bifunctional enzyme 2,3-BPG mutase/phosphatase

Answer 41

1. Making 2,3-BPG from 1,3-BPG 2. Removing the Phosphate from 2,3-BPG creating 3-phosphoglycerate 1. In RBCs, this allows O₂ to bind to hemoglobin

Question 42

What enzyme oxidizes NADH in the malate-aspartate shuttle system - yielding NAD+ for Glycolysis?

Answer 42

Malate Dehydrogenase OAA \<---\> Mal

Question 43

What enzyme catalyzes OAA \<---\> Asp for the malate -aspartate shuttle system?

Answer 43

* Aspartate Amino-transferase or * Glutamate Oxaloacetate Transaminase

Question 44

What are two shuttles systems that provide Glyceraldehyde 3-Phosphate Dehydrogenase with adequate NAD+ to continue wiht Glycolysis?

Answer 44

* Glycerol Phosphate Shuttle * Malate-Aspartate shuttle