Catabolic Metabolism - Carbohydrate and Glycolysis

Question 1

Relate the structures of mannose, fructose and galactose to their entry into glycolysis.

Answer 1

Mannose (Hexokinase) -> Mannose-6-Phosphate (isomerization) -> Fructose-6-phosphate

Fructose (Hexokinase) -> Fructose-6-phosphate
OR
Fructose (Fructokinase) -> Fructose-1-P (Aldolase b) -> Glyceraldhyde

Galactose (Galactokinase) -> Galactose-1-P (Uridyltransferasekinase) -> Glucose-1-P (Phosphoglucomutase) -> Glucose 6-phosphate

Question 2

Recognize the two configurations of monosaccharides and how their structure is seen in disaccharide and polysaccharide bonding

Answer 2

Alpha-d-glucose - Oxygen is in axial position
Beta-d-glucose - Oxygen is in equatorial position

Cellubiose (has B 1-4 bond) - humans cannot digest this bond because we do not produce cellulase

Question 3

Recognize the different modifications to monosaccharide structure seen in biological systems

Answer 3

1. Carbon 1 and 6 can be oxidized into aldehydes and carboxylic acids
2. addition of amine group (+ charge at 7.4 pH)
3. addition of sulfate group

Question 4

Compare the structures of different disaccharides and polysaccharides and what monosaccharides are generated from their hydrolysis.

Answer 4

Maltose: Glucose(alpha 1-4 bond)Glucose; digested by Maltase
Lactose: Galactose(Beta 1-4 bond)Glucose; digested by lactase
Sucrose: Glucose(A1-B2 bond)Fructose; digested sucrase
Cellulose: Glucose(beta 1-4 bond)Glucose; digested by cellulase
Polysaccharide Amylose: Glucose(A 1-4 bond)Glucose(A1-4 bond)…; digested by salivary and pancreatic amylase
Polysaccharide Amylopectin: Branched amylose
(with a1-6 bonds)

Question 5

Diagram the balance of NAD+/NADH+H+ and ATP/ADP + Pi within anaerobic glycolysis.

Answer 5

Anaerobic - NAD+ is regenerated from the formation of lactate

Alcoholic Fermentation - NAD+ is regenerated from the formation of alcohol

Question 6

Identify how the anaerobic metabolism of glycolysis only generates a net of 2 ATP

Answer 6

2 ATP are used in the beginning to phosphorylate glucose and F-6-P; 2 ATP are produced at the very end (PEP-pyruvate)

net gain of 2 ATP is due to (G-3-P to 3-PG)