Week 13

Question 1

_______________ are an inactive form of enzymes also known as proenzymes and are how organisms protect themselves from their own digestive enzymes.

Answer 1

Zymogens

Question 2

_____________ are proteases that cleave peptide (amide) linkages between amino acids.

Answer 2

Pancreatic enzymes.

Question 3

________________ are enzymes that cleave peptides into smaller individual amino acids or small peptides (di- or tripeptides).

Answer 3

Peptidases

Question 4

The enzyme pepsin is an ______________ protease.

Answer 4

Aspartyl.

Question 5

The enzymes trypsin and chymotrypsin are _______________ proteases.

Answer 5

Serine.

Question 6

Why would the active sites of trypsin and pepsin not function well in each other’s normal environment?

Answer 6

Trypsin is a serine protease- requires a neutral to basic environment to deprotonate serine.

Pepsin is an aspartyl protease- requires an acidic environment to readily protonate/deprotonate aspartate.

Question 7

________________ is the process in which ammonia can be removed from an amino acid.

Answer 7

Transamination.

Question 8

In transamination the _________________ is transferred to an α-keto acid (often pyruvate or α-ketoglutarate).

Answer 8

Amine.

Question 9

__________________ is the enzyme that transaminates pyruvate to the amino acid alanine.

Answer 9

Alanine Transaminase

Question 10

Alanine then travels from the muscle to the liver, where it can be transaminated to ________________ from __________________.

Answer 10

Glutamate, α-ketoglutarate.

Question 11

__________________ is the process in which an amine is released as ammonia. Yields an α-keto acid and NADH/H+ is generated.

Answer 11

Oxidative Deamination

Question 12

_________________ is commonly used and interconverted to α-ketoglutarate.

Answer 12

Glutamate

Question 13

Free ______________ may be converted to waste products (in many organisms including mammals, urea).

Answer 13

Ammonia.

Question 14

_________________ is the enzyme used to oxidatively deaminate glutamate and regenerate α-ketoglutarate.

Answer 14

Glutamate Dehydrogenase.

Question 15

________________ is the metabolic process through which nitrogenous wastes generated in muscle are transferred to pyruvate, generating alanine; the alanine in turn is transported to the liver, where it is deaminated and the pyruvate presumably used in gluconeogenesis.

Answer 15

Glucose–Alanine Shuttle

Question 16

________________ ATP-dependent enzyme responsible for the synthesis of glutamine from glutamate and ammonium ion in the liver.

Answer 16

Glutamine Synthetase

Question 17

_________________ is the main enzyme that deaminates glutamine and yields glutamate and free ammonia.

Answer 17

Glutaminase

Question 18

Amines are added to pyruvate in the ______ and removed from the resulting alanine in the ______.
A. liver; kidney
B. muscle; kidney
C. kidney; liver
D. muscle; liver

Answer 18

D. muscle; liver

Question 19

In the urea cycle, Ornithine and Carbomyl phosphate undergo a condensation to give rise to _________________ and the enzyme responsible for this is _________________.

Answer 19

Citrulline. Ornthine transcarbamoylase.

Question 20

In the urea cycle, cirtrulline is converted to ______________ by the enzyme _________________.

Answer 20

Argininosuccinate. Argininosuccinate synthase

Question 21

In the urea cycle, _______________________is split off from argininosuccinate to yield _________________. The enzyme responsible for this step is __________________.

Answer 21

Fumarate, Arginine. Argininosuccinate lyase.

Question 22

In the urea cycle, _______________ is cleaved off from arginine to generate _________________ by the enzyme________________.

Answer 22

Urea, Ornithine. Arginase.

Question 23

The function of the urea cycle is to detoxify and dispose of _______________.

Answer 23

Ammonia.

Question 24

________________ is the compound created from ammonia in order to reduce ammonia levels in the blood and lower the risk for toxicity.

Answer 24

Carbamoyl Phosphate

Question 25

________________ is the enzyme involved in the production of carbamoyl phosphate for the urea cycle.

Answer 25

Carbamoyl phosphate synthetase I (CPS-1).

Question 26

_______________ is the enzyme responsible for the production of building blocks for pyrimidine biosynthesis.

Answer 26

Carbamoyl phosphate synthetase II (CPS-2).

Question 27

_________________ are organisms that typically eliminate wastes as ammonia secreted through the skin.

Answer 27

Ammonotelic

Question 28

______________ are organisms that synthesize uric acid and eliminate it in their waste, which is technically not urine.

Answer 28

Uricotelic

Question 29

Which amino acid is directly generated in the urea cycle?

Answer 29

Arginine

Question 30

Amino acids can be broken down into two categories:

Answer 30

glucogenic and ketogenic.

Question 31

_____________ are the amino acids that are broken down into products that undergo gluconeogenesis.

Answer 31

Glucogenic

Question 32

______________ are the amino acids that metabolizes products into ketone bodies. Made from over abundance of Acetyl-CoA.

Answer 32

Ketogenic.

Question 33

3 carbon skeleton amino acids are broken down into _______________.

Answer 33

Pyruvate.

Question 34

Which amino acids are used in ketogenesis but not glucogenesis?

Answer 34

Leucine and lysine

Question 35

________________ are molecules the body recognizes as foreign. Not molecules found in human metabolism and need to be eliminated. May be cleaved into smaller fragments.

Answer 35

Xenobiotics.

Question 36

__________________ is the process by which the body detoxifies and eliminates foreign molecules.

Answer 36

Xenobiotic metabolism.

Question 37

In _____________ of xenobiotic metabolism, Oxidation or cleavage occurs, xenobiotics become more hydrophilic and products are metabolically active.

Answer 37

Phase I

Question 38

In _____________ of xenobiotic metabolism, conjugation to larger molecules such as glutathione or glucuronic acid.

Answer 38

Phase II

Question 39

___________________ are broad family of enzymes that employ NADPH and molecular oxygen (O2) to oxidatively modify substrate molecules. Membrane-associated enzymes commonly found in either the inner mitochondrial membrane or the endoplasmic reticulum.

Answer 39

Cytochrome P450

Question 40

_______________ are enzymes that deactivate neurotransmitters. Covalently fix FAD+ to catalyze the conversion of a primary amine to an aldehyde.

Answer 40

Monoamine Oxidases.

Question 41

_______________ oxidized form of glucose in which C-6 is oxidized to a carboxylic acid.

Answer 41

Glucuronic acid.

Question 42

_________________ tripeptide of glycine, cysteine, and glutamate. Conjugated to xenobiotic via glutathione-S-transferase.

Answer 42

Glutathione (GSH).

Question 43

___________________ is a network of highly porous capillaries that act as filters. Large objects are retained in the capillaries, and small molecules are filtered out.

Answer 43

Glomerulus

Question 44

_________________ is a peptide hormone that acts via a seven-transmembrane helix spanning receptor to elevate cytosolic levels of cAMP.

Answer 44

Antidiuretic Hormone.

Question 45

Pyrimidine is synthesized from amino acids ______________ and ________________.

Answer 45

Glutamate and Aspartate.

Question 46

Presence of carbamoyl phosphate synthetase in the mitochondria means we go through __________________ and presence in the cytoplasm means we go through ____________________.

Answer 46

Urea cycle. Pyrimidine bio-synthesis.