Molecular Biology

Question 1

Parietal Cells

Answer 1

Found in stomach. Produce HCL and Intrinsic Factor

Question 2

HCL

Answer 2

Degrades protein, activates pepsinogen

Question 3

Chief Cells

Answer 3

Found in stomach. Produce pepsin

Question 4

Endopeptidase

Answer 4

Degrades protein to peptide

Question 5

G Cell

Answer 5

Found in stomach. Produces gastrin (blood stream)

Question 6

Mucus Cell

Answer 6

Found in stomach. Secretes Mucus and HCO3 to protect the stomach lining

Question 7

Enteropeptidase/Enterokinase (brush border)

Answer 7

Found in duodenum. Activates trypsinogen -> trypsin, which in turn activate proteases to hydrolyze protein.

Question 8

Hyperchlorhydria

Answer 8

Zollinger Ellison syndrome. Gastrin secreting tumor

Question 9

HYPOchlorhydria

Answer 9

Pernicious Anemia. Autoimmune destruction of parietal cells. B12 deficiency

Question 10

Cystic Fibrosis

Answer 10

Decrease pancreatic enzymes. Mutation in CFTR

Question 11

Hartnup disease

Answer 11

Defect absorbing neutral AA. Decrease in Tryptophan and Niacin (Pellagra like manifestations) Photosensitivity.

Question 12

Cystinuria

Answer 12

Defect in dibasic AA absorption (Cysteine). Cysteine stones - Kidney stones

Question 13

H2 Blocker

Answer 13

Treats HYPOchlorydria

Question 14

Glucogenic AA Degradation

Answer 14

Alanine -> Pyruvate -> Glucose

TCA Intermediates

Question 15

Ketogenic Degradation of AAs

Answer 15

Lysine -> Acetyl CoA -> Ketone Bodies

Question 16

Purely Ketogenic Amino Acids

Answer 16

Leucine & Lysine

Question 17

Glucogenic & Ketogenic Amino Acids

Answer 17

Isoleucine, Phenylalanine, Threonine, Tryptophan & Tyrosine

Question 18

Transamination

Answer 18

Catalyzed by aminotransferases/transaminases. Pyridoxal Phosphate (B6) - cofactor. Transfers alpha amino group from one carbon skeleton (amino acid) to another (α-keto acid, which becomes an amino acid). Can not be done to lysine or threonine.

Question 19

Trans-deamination

Answer 19

Transaminate L-amino acids to generate glutamate, which can then be oxidatively de-animated to to form α-ketoglutarate and ammonia.

Question 20

Excretion from Intestines

Answer 20

NH3 -> directly to Portal system (Liver) (Periportal)

Question 21

Excretion from Liver

Answer 21

Urea / Protein (synthesis) to transport nitrogen

Question 22

Excretion from Muscle

Answer 22

Breaks down branched chain amino acids (BCAAs)
Form Alanine -> transport NH3 to liver
Form Glutamine -> transport NH3 to kidneys

Question 23

Urea Cycle Rate Limiting Step

Answer 23

Carbamoyl Phosphate Synthase 1

Question 24

Source of Nitrogen in Urea

Answer 24

N1 -> Free NH3
N2 -> Aspartate

In essence, both come (indirectly) from glutamate, which gathers nitrogen from other amino acids to repeat the process.

Question 25

Non Oxidative deamination

Answer 25

Serine and threonine can be directly de animated to NH4+. Catalyzed by serine dehydratase or threonine dehydratase.

Question 26

Oxidative deamination

Answer 26

Occurs in liver and kidneys. Catalyzed by glutamate dehydrogenase (GLDH). Located in mitochondria.

Question 27

Urea Cycle step 1 (Rate Limiting)

Answer 27

Ammonia + Bicarbonate + ATP -> Carbamoyl Phosphate via CPS-1

Question 28

Urea cycle step 2

Answer 28

Carbamoyl Phosphate -> citrulline via Ornithine transcarbomylase

Question 29

Urea cycle step 3

Answer 29

Citrulline is taken out of mitochondria, converted to arginosuccinate via arginosuccinate synthase

Question 30

Urea cycle step 4

Answer 30

Arginosuccinate -> Arginine via arginosuccinate lyase

Question 31

Urea cycle step 5

Answer 31

Arginine -> Urea via arginase. (Conversely, arginine could be converted back to ornithine and then citrulline to redo the cycle)

Question 32

Pyridoxine (B6) - Pyridoxal Phosphate

Answer 32

Co-factor required for transamination

Question 33

Folate

Answer 33

Co-factor required for one carbon transfer

Question 34

Tetrahydrobiopterin

Answer 34

Co-factor required for hydroxylation

Question 35

Serine Hydroxy-methyltransferase

Answer 35

Converts serine to glycine and vice versa

Question 36

Cystathionine β synthase

Answer 36

Creates cystathionine from serine and methionine, which can be converted to cysteine.

Question 37

AAs derived from glycolysis intermediates

Answer 37

Serine and glycine from 3-phosphoglycerate, Cysteine from methionine and serine, alanine from Pyruvate (via transamination with B6)

Question 38

AAs derived from TCA cycle (α-ketoglutarate)

Answer 38

Glutamate (directly), Glutamine (from glutamate), Proline (from glutamate semialdehyde) and Arginine (from ornithine)

Question 39

AAs derived from TCA cycle (Oxaloacetate)

Answer 39

Aspartate (Transamination of oxaloacetate) and Asparagine (from Aspartate via asparagine synthetase)

Question 40

Tyrosine synthesis/catecholamine synthesis step 1

Answer 40

From Phenylalanine via phenylalanine hydroxylase. Requires THB as a co-factor.

Question 41

Catecholamine synthesis step 2

Answer 41

Tyrosine -> Dopa via tyrosine hydroxylase. Rate Limiting Step. Requires THB as a co-factor.

Question 42

Catecholamine synthesis step 3

Answer 42

DOPA -> Dopamine via DOPA decarboxylase. B6 as a co-factor

Question 43

Catecholamine synthesis step 4

Answer 43

Dopamine -> Nor-epinephrine. Uses Ascorbate as a co-factor

Question 44

Catecholamine synthesis step 5

Answer 44

Nor-epinephrine -> Epinephrine. Requires SAM as a co-factor. Uses cortisol.

Question 45

Schizophrenia cause

Answer 45

Overproduction of dopamine

Question 46

Parkinson’s disease cause

Answer 46

Underproduction of dopamine

Question 47

Pheochromocytoma

Answer 47

Benign tumor that produces excessive catecholamine secretion. Can cause life-threatening hypertension or cardiac arrhythmias.

Question 48

MAO

Answer 48

Mono amino oxidase. Enzyme that breaks down catecholamines.

Question 49

COMT

Answer 49

Catecholamine O-methyl transferase. Enzyme that breaks down catecholamines

Question 50

Formation of melanin

Answer 50

DOPA -> Dopaquinone via tyrosinase, copper as a cofactor. Melanin is then produced.

Question 51

Thyroglobulin

Answer 51

Used by thyroid to produce T3 and T4 hormones. Made up primarily of tyrosine residues.

Question 52

Melatonin

Answer 52

Hormone derived from Serotonin (5-hydroxytryptamine) which is synethesized from tryptophan

Question 53

5-Hydroxy indole acetic acid

Answer 53

Product of serotonin breakdown by MAO

Question 54

MAO-A

Answer 54

Can catabolize Epinephrine, Norepinephrine, serotonin, melatonin, Dopamine, Tyramine, and tryptamine

Question 55

MAO-B

Answer 55

Can catabolize dopamine, tyramine, and tryptamine