Metabolic fuels and precursors EC

Question 1

Why are intracellular carbohydrates phosphorylated?

Answer 1

To keep them from diffusing out of the cell

Question 2

Which isomer are most human sugars?

Answer 2

D isomer

Question 3

What are reducing sugars?

Answer 3

Open chain forms that allow carbonyl group to react with reducing agents

Question 4

Glucuronic acid

Answer 4

Reacts with unconjugated bilirubin to form conjugated

Component of GAGs (glycosaminoglycans)

Question 5

Sorbital derived damage in diabetes

Answer 5

Lens (cataracts)
Schwann cells (peripheral neuropathy)
Pericytes (retinopathy)

Question 6

Maltose

Answer 6

Glucose + Glucose

Question 7

Lactose

Answer 7

Glucose + Galactose

Question 8

Sucrose

Answer 8

Glucose + Fructose

Question 9

Monosacharides

Answer 9

Glucose, Fructose, Ribose

“GFR”

Question 10

Disaccharides

Answer 10

Maltose, Lactose, Sucrose

“MLS”

Question 11

Essential fatty acids

Answer 11

Linoleic acid (18C)
Linolenic acid (18C)

Question 12

Carnitine shuttle

Answer 12

Moves long chain fatty acids from cytosol to mitochondria

deficiency results in nonketotic hypoglycemia

Question 13

Corticosteroids effect on phospholipids

Answer 13

Inhibit phospholipase A2, inhibit arachadonic acid release

Question 14

Gly (glycine)

Answer 14

Smallest amino acid
Inhibitory neurotransmitter in spinal cord
Synthesis of heme
Abundant in collagen

Question 15

Ala (alanine)

Answer 15

Alanine cycle during fasting: major substrate for gluconeogenesis

Question 16

Val (valine)

Answer 16

Branched
Not degraded by liver
Used in muscle
Increased in maple syrup urine disease

Question 17

Leu (leucine)

Answer 17

Branched 
Not degraded in liver
Ketogenic
Used in muscle
Increased in maple syrup urine disease

Question 18

Ile (isoleucine)

Answer 18

Branched
Not degraded by liver
Used in muscle
Increased in maple syrup urine disease

Question 19

Met (methionine)

Answer 19

Polypeptide chain initiation
Methyl donor (as S-adenosylmethionine)

Question 20

Pro (proline)

Answer 20

Helix breaker
Only a.a. with side chain cyclized to alpha amino group
Hydroxylation in collagen via ascorib acid
Binding site for collagen cross-bridges

Question 21

Phe (phenylalanine)

Answer 21

Increased in PKU
Aromatic side chain (increased in hepatic coma)
Tyr>Dopa(malanin)>Dopamine>NE>Epi

Question 22

Trp (tryptophan)

Answer 22

Precurser to serotonin, niacin, and melotonin

Aromatic side chains (increased in hepatic coma)

Question 23

Cys (cysteine)

Answer 23

Forms disulphide bonds
Sensitive to oxidation
Component of glutathione (RBC antioxidation)
Deficient in G6PD deficiency

Question 24

Ser (serine)

Answer 24

Single carbon donor

Phosphorylated by kinases

Question 25

Thr (threonine)

Answer 25

Phosphorylated by kinases

Question 26

Tyr (tyrosine)

Answer 26

Precursor to melatonin, catacholamines, and thyroid hormones Phosphorylated by kinases Aromatic side chain (increased in hepatic coma) Must be supplied in PKU Signal transduction (tyrosine kinase)

Question 27

Asn (asparagine)

Answer 27

Insufficiently synthesized by neoplastic cells | Used to treat leukemia

Question 28

Gln (glutamine)

Answer 28

Most abundant Nitrogen carrier NO donor in purine/pyrimidine synthesis NH3 detox. in brain and liver Fasting state: carries amino group from muscle to other tissue Fasting state: fuel for kidneys, intestine, and immune system

Question 29

Lys (lysine)

Answer 29

Basic Ketogenic Abundant in histones Hydroxylation in collagen aided by ascorbic acid Binding site for cross-bridges in protocollagen

Question 30

Arg (arginine)

Answer 30

Basic Essential for growth in children Abundant in histones Precursor to creatine, urea, & NO

Question 31

His (histidine)

Answer 31

``` Basic: ZERO charge at pH=7.4 Physiologic buffer Histamine precursor Residue in Hg coordinated with heme Essential for growth in children ```

Question 32

Asp (aspartate)

Answer 32

Acidic Forms oxaloacetate by transamination Important for albumin binding properties

Question 33

Glu (glutamate)

Answer 33

Acidic Forms alpha-ketoglutarate by transamination Important for binding properties of albumin GABA and Glutathione precursor