FINAL amino acid degradation

Question 1

Excess amino acids cannot be stored or excreted, and are instead processed to be used as metabolic fuels True or false ?

Answer 1

True

Question 2

Where does the primary source for amino acid precursors that synthesize new cellular proteins ?

Answer 2

Dietary proteins

Question 3

What are the primary fates of amino acids that are obtained from digestion of proteins?

Answer 3

Primary: synthesis of amino acids
Secondary : processed as metabolic fuels because the they are not excreted or stored

Question 4

Protein injected in the diet are digested into what ?

Answer 4

Small peptides or free amino acids later on injected by intestine

Question 5

Where does protein digestion begin?

Answer 5

Stomach

Question 6

What about the environmental conditions of our stomach favor protein degradation?

Answer 6

Highly acidic which causes denaturation of diet proteins

Question 7

What is the major digestive protease?

Answer 7

Pepsin

Question 8

oligopeptides are results of?

Answer 8

The pancreatic proteases hydrolyzing the proteins into small fragments

Question 9

digestion is completed by enzymes called?

Answer 9

peptidases that are attached to the external surfaces of the intestinal cells

Question 10

What is the role of peptidases
When in relationship with obligo peptides?

Answer 10

These enzymes cleave the oligopeptides into amino acids and di- and tripeptides

Question 11

What goes into the blood stream are single amino acids true or false?

Answer 11

True- after peptidases cleave the AA they are transported, the absorbed AA are released into the body by antiporters

Question 12

The first step of entrance into the metabolic mainstream is

Answer 12

Remove amino group

Question 13

Why must we remove the amino group?

Answer 13

Allow remainder of molecule to be converted into glucose , TCA intermediates or acetyl CoA

Question 14

For mammals the major site of amino acid metabolism is ?

Answer 14

Liver

Question 15

he polypeptide products of pepsin digestion stimulate the release of the hormone

Answer 15

CCK

Question 16

effects of CCK hormone release?

Answer 16

The pancreas responds to CCK by releasing a host of digestive enzymes into the intestine, where the digestion of proteins continues.

Question 17

Aminotransferase Enzymes Play an Important Role in the Catabolism of Amino Acid. One product of this reaction, regardless of the identity of the amino donor, is always the amino acid

Answer 17

glutamate

Question 18

what catalyzes the transfer of an α-amino group from an α-amino acid to an α-ketoacid.

Answer 18

aminotransferase

Question 19

Once glutamate has been synthesized from a transamination of α-ketoglutarate

Answer 19

the nitrogen atom is converted to an ammonium ion

Question 20

oxidative deamination reaction of glutamate is catalyzed by

Answer 20

glutamate dehydrogenase

Question 21

When glutamate is processed by glutamate dehydrogenase the resulting product is ?

Answer 21

Free ammonium ion and regeneration of a-ketoglutarate

Question 22

Ammonium ion is a weak base and is cytotoxic at high concentrations. true or false?

Answer 22

false it is a strong base

Question 23

Amino acids are processed?

Answer 23

liver

Question 24

Is the liver the only location that is capable of amino acid degredation?

Answer 24

skeletal muscle- under special circumstances
peripheral tissue

Question 25

For peripheral tissue and muscles why can the not process glutamate into urea ?

Answer 25

they lack the enzymes of urea cycle

Question 26

Can the glucose alanine cycle happen in peripheral tissue?

Answer 26

no- it is used as a way to transfer ammonium from muscles into the liver

Question 27

Where does glutamine synthesis take place ?

Answer 27

In peripheral tissue

Question 28

During prolonged exercise and fasting, muscle uses branched-chain amino acids (Val, Ile, Leu) as fuel. The nitrogen removed is transferred (through glutamate). The resulting glutamate can then be used to transaminate what very common product of glycolysis?

Answer 28

pyruvate

Question 29

Why is it significant that pyruvate was formed?

Answer 29

From pyruvate we are able to form alanine that can be transferred into the liver where it is transformed back into glutamate then secret ammonium as urea

Question 30

Inside the liver, pyruvate can participate in gluconeogenesis to form glucose, which is released back into the bloodstream. The net reaction is the exchange of glucose for ammonium (in the form of alanine). how is this similar to the cori cycle?

Answer 30

This glucose-alanine cycle is conceptually similar to the Cori cycle, where lactate is exchanged for glucose.

Question 31

peripheral tissues also contain the enzyme glutamine synthetase. This enzyme catalyzes the ATP- dependent synthesis of glutamine from free ammonium ion and glutamate. the results :

Answer 31

glutamine products can be secreted into the bloodstream- urea cycle

Question 32

purpose of the urea cycle ?

Answer 32

package waste nitrogen in a water soluble form that can be readily excreted

Question 33

where does the urea cycle take place ?

Answer 33

liver

Question 34

What does the urea cycle start with ?

Answer 34

the formation of Carbamoyl phosphate

Question 35

How is Carbamoyl phosphate formed?

Answer 35

cycle couples free ammonia (NH3) to bicarbonate (HCO3-) and synthesized by carbamoyl phosphate synthetase

Question 36

carnbamoyl phosphate is simple and require little to non energy. true or false ?

Answer 36

False - it is energetically costly having 2 ATP's consumed

Question 37

carbamoyl phosphate contains an anhydride bond, and therefore has a high carbamoyl group transfer potential allowing it to couple with what ?

Answer 37

ornithine

Question 38

The second reaction of the urea cycle is catalyzed by ..........., and results in the formation of ........ as follows:

Answer 38

1. ornithine transcarbamoylase 2. citrulline

Question 39

The first and second reaction of the urea cycle happen specifically in ?

Answer 39

The mitochondrial matrix

Question 40

Once formed, citrulline is transported into the ......, where it reacts with ....... in a reaction catalyzed by ........

Answer 40

1. cytoplasm 2. aspartate 3. argininosuccinate synthetase

Question 41

The second reaction of the urea cycle requires ATP true or false?

Answer 41

true

Question 42

The fourth reaction takes the product ...... of the third reaction and uses ........... to cleave into ..........

Answer 42

1. Argininosuccinate 2. Argininosuccinase 3. Arginine and fumerate

Question 43

What is the final step of Urea cycle catalyzed by

Answer 43

arginase.

Question 44

The final yielded product of the urea cycle is ?

Answer 44

Urea and ornithine

Question 45

What are the 7 end products resulting from the degradation of 20 major amino acids?

Answer 45

acetyl-CoA acetoacetyl-CoA pyruvate α-ketoglutarate succinyl-CoA fumarate oxaloacetate

Question 46

What is the connection of the side product fumarate what was generated in the fourth reaction of the urea cycle?

Answer 46

fumarate can be hydrated to malate and serve as an intermediate of the TCA Cycle

Question 47

Why does the urea cycle require so much energy?

Answer 47

It is costly because of the toxicity of ammonium ion

Question 48

What would happen if you had a urea cycle that did not function correctly?

Answer 48

Any patient with a defect in the urea cycle will present clinically with elevated blood levels of ammonium ion.

Question 49

If there is an overload of glutamate dehydrogenase reaction what could this mean?

Answer 49

Ammonia is the depletion of the TCA intermediate and causes a deficiency in ATP

Question 50

Ketogenic definition

Answer 50

can give rise to ketone or fatty acids

Question 51

gluconeogenic

Answer 51

can participate in gluconeogenesis

Question 52

How do breakdown of amino acids and breakdown of fatty acids intersect

Answer 52

In a way they use the same enzymes but are modified just a bit

Question 53

FAD-linked dehydrogenase and an ATP-dependent carboxylation to yield β-methylglutaconyl-CoA, this can be seen similarly in?

Answer 53

just like in fatty acid oxidation and acetyl-CoA carboxylase

Question 54

Describe what inborn errors of metabolism are ?

Answer 54

Inborn errors of metabolism is when there is a hereditary defect in any of the enzymes. Thus compromising a particular pathway

Question 55

Is it possible for inborn errors of metabolism to disrupt amino acid degradation?

Answer 55

yes- it is a one route typically

Question 56

The diseases that deal with inborn error are autosomal recessive or dominant

Answer 56

dominant

Question 57

Example of inborn errors of metabolism is maple syrup urine disease, what causes it?

Answer 57

deficiency in the branched-chain α-ketoacid dehydrogenase complex α-ketoacids begins to accumulate

Question 58

phenylketonuria is an example of what?

Answer 58

Inborn error of metabolism-absence - deficiency in phenylalanine hydroxylase causing a rise in the phenylalanine in the blood