Metabolism -- Normal and Abnormal Carb Metabolism

Question 1

∆G(ATP hyd)

Answer 1

-7.3 Kcal/mol

Question 2

Define catabolism

Answer 2

Conversion of energy-yielding nutrients into energy-poor end products (larger to smaller molecules, basically)

Question 3

Define anabolism

Answer 3

Conversion of precursor molecules into complex molecules (smaller to larger, basically)

Question 4

Components of lactose

Answer 4

Galactase - glucose

Question 5

Components of maltose

Answer 5

Glucose - glucose

Question 6

Components of sucrose

Answer 6

Glucose - fructose

Question 7

Where do disaccharides get digested into monosaccharides?

Answer 7

In gut

Question 8

Where do monosaccharides become transformed and phosphorylated for further metabolism?

Answer 8

In liver

Question 9

Phosphorylated product of glucose

Answer 9

Glucose-6-P

Question 10

Phosphorylated product of fructose

Answer 10

Fructose-1-P

Question 11

Phosphorylated product of galactose

Answer 11

Glucose-1-P

Question 12

Metabolic fates of glucose-6-P

Answer 12

Can either:

1. Enter glycolysis
2. Convert into glucose-1-P for conversion into glycogen

Question 13

Metabolic fate of fructose-1-P

Answer 13

Glycolysis

Question 14

Metabolic fate of glucose-1-P

Answer 14

Glycogen

Question 15

Define lactose intolerance

Answer 15

Deficiency in gene expression for lactase (as we age), causing gut flora to use the lactose instead, creating acid and CO2 in gut –> bloating, cramping and diarrhea

Question 16

Disaccharide intolerance of Inuits

Answer 16

Sucrose intolerance (10%)

Question 17

Define type I diabetes mellitus

Answer 17

Autoimmune destruction of insulin-producing beta cells of the pancreas

Question 18

Define type II diabetes mellitus

Answer 18

Insulin is not sensed is later under produced (“insulin resistance” and deficiency – strongly linked with obesity

Question 19

Consequence of diabetes mellitus

Answer 19

Glucose and fat homeostasis are deregulated –> hyperglycemia and a very large number of serious health risks

Question 20

Location of GLUT-2

Answer 20

Liver, pancreas, kidney

Question 21

Location of GLUT-4

Answer 21

Muscle and adipose tissue

Question 22

What controls GLUT-4 availability?

Answer 22

Insulin

Question 23

Input for glycolysis

Answer 23

• 2 ATP
• 1 glucose

Question 24

Output of glycolysis

Answer 24

• 4 ATP
• 2 NADH
• 2 pyruvate

Question 25

Net profit from glycolysis

Answer 25

* 2 ATP * 2 NADH * 2 pyruvate

Question 26

What is required to make ATP out of NADH

Answer 26

Oxygen

Question 27

Location of hexokinase

Answer 27

In tissues other than the liver and pancreas

Question 28

Hexokinase's maximal speed and what this means

Answer 28

Moderate = tissues don't take more glucose than they can use

Question 29

Location of glucokinase

Answer 29

Liver and pancreas

Question 30

Glucokinase use in liver

Answer 30

Soak up all the sugar from a meal (high maximal speed)

Question 31

Glucokinase use in pancreas

Answer 31

Sense glucose levels and control insulin release

Question 32

What regulated GK transcription in the liver?

Answer 32

+ = insulin - = glucagon

Question 33

3 glycolysis enzymes whose transcriptions are regulated by insulin and glucagon

Answer 33

* Glucokinase * PFK-1 * PK

Question 34

Drug target for type II diabetes and why

Answer 34

Glucokinase --\> up-regulate activity (soak up more sugar and release more insulin)

Question 35

Condition associated with a single gene mutation in glucokinase

Answer 35

Maturity-Onset Diabetes of the Young (MODY)

Question 36

Consequence of mutating both genes of glucokinase

Answer 36

Permanent Neonatal Diabetes Mellitus (PNDM)

Question 37

3 consequences of aldolase B deficiency

Answer 37

* Hypoglycemia * Secretion of all phosphate --\> unable to synthesize ATP * Fructose bypasses regulation by glucokinase --\> Hereditary fructose intolerance

Question 38

Define the Warburg effect?

Answer 38

* Cancer cells use glucose faster --\> lactate instead of acetyl CoA * Overexpression of hexokinase * Expression of special variant of pyruvate kinase

Question 39

Why can lactic acidosis occur?

Answer 39

Lack of oxygen, as seen in: * Myocardial infarction * Pulmonary embolism * Uncontrolled hemorrhage * Tumor microenvironment * Muscle overuse/exertion

Question 40

Enzyme to convert pyruvate to acetyl CoA

Answer 40

Pyruvate dehydrogenase

Question 41

2 ways that pyruvate dehydrogenase is regulated

Answer 41

* Phosphorylation/dephosphorylation cycle * Product inhibition

Question 42

Vitamin required as a cofactor in PDH

Answer 42

Thiamine

Question 43

Consequence of thiamine deficiency

Answer 43

Lactic acidosis

Question 44

Consequence of PDH deficiency

Answer 44

Chronic lactic acidosis --\> severe neurological defects --\> usually lethal

Question 45

ETC complex that is NOT a proton pump

Answer 45

Complex II

Question 46

ETC complex that FADH2 enters

Answer 46

Complex II

Question 47

Effect of cyanide poisoning

Answer 47

Stops ETC by CN- binding Fe3+ in complex IV --\> rapid cell death and DNS damage

Question 48

Effect of CO poisoning

Answer 48

Stop ETC by CO binding Fe2+ in complex IV

Question 49

Special property of brown fat

Answer 49

Contains proteins in mitochondria that form a channel to allow H+ back into the mitochondria without going through ATP synthase

Question 50

Enzyme to link glucose molecules together to form glycogen

Answer 50

Glycogen synthase UDP-glucose + (glucose)_n --\> (glucose)_n+1 + UDP

Question 51

Activator fro glycogen synthase

Answer 51

Insulin

Question 52

Inhibitor of glycogen synthase

Answer 52

Glucagon

Question 53

Purpose of liver in gllucose storage

Answer 53

For later supply of glucose to other tissues in times of fasting

Question 54

Purpose of muscle in glucose storage

Answer 54

Use as energy source during exercise

Question 55

Enzyme to remove one glucose link from glycogen

Answer 55

Glycogen phosphorylase Glycogen chain + Pi --\> Glucose 1-P

Question 56

Enzyme to convert glucose 6-P to Glucose

Answer 56

Glucose 6-phosphatase

Question 57

Fate of gllucose-6-P in muscle

Answer 57

Glycolysis directly

Question 58

Fate of glucose-6-phosphate in liver

Answer 58

Conversion into glucose by glucose-6-phosphatase for distribution to other tissues

Question 59

2 pathologies of glycogenolysis

Answer 59

McArdle Disease Von Gierke Disease

Question 60

Enzyme affected bby McArdle disease

Answer 60

Glycogen phosphatase

Question 61

Enzyme affected by Von Gierke Disease

Answer 61

Glucose-6-Phosphatase

Question 62

3 irreversible reactions in glycolysis

Answer 62

* Glucose --\> Glucose-6-P * Fructose-6-P --\> Fructose 1-6-bisP * PEP --\> pyruvate

Question 63

4 enzymes to get around glycolysis' irreversible steps in gluconeogenesis

Answer 63

* Glucose-6-phosphatase * Fructose-1,6-bisphosphatase * Pyruvate carboxylase * PEPC

Question 64

AEnzyme most tightly regulated to differentiate between the bodies needs for gluconeogenesis vs. glycolysis

Answer 64

Fructose-1,6-bisphosphatase

Question 65

Activator of fructose-1,6-bisphosphatase

Answer 65

Glucagon

Question 66

INhibitor of fructose-1,6-bisphosphatase

Answer 66

Insulin

Question 67

Activator of pyruvate carboxylate

Answer 67

Acetyl-CoA