Biochemistry I

Front 1

What are the major roles played by Amino acids in the body?

Back 1

1. Building blocks from which proteins and peptides are made.
2. Neurotransmitter and precursors for other neurotransmitters.
3. Precursors for the synthesis of Glucose in Gluconeogenesis, hormone synthesis and other important molecules such as: porphyrins, purines, pyrimidines and urea in nitrogen metabolism.

Front 2

Describe the structure of amino acids found in mammalian proteins.

Back 2

They are alpha amino acids containing an amino group and a carboxyl group attached to the same carbon atom.

Front 3

What is the name of the optical isomer found in mammalian systems?

Back 3

L isomer

Front 4

What are the groups containing the L-alpha amino acids?

Back 4

1. Aliphatic amino acids
2. Amino acids with hydroxyl or sulfur containing sidechains
3. Aromatic amino acids
4. Basic amino acids
5. Acidic amino acids and their amides.

Front 5

What are the names of the Aliphatic aminoacids?

Back 5

Glycine (gly), alanine (ala), valine (val), leucine (leu), proline (pro), isoleucine (ile)

Front 6

From the Aliphatic amino acids, (a) which is not hydrophobic?
(b) Which is the most hydrophobic?

Back 6

a) Glycine.
b) Isoleucine.

Front 7

From the aliphatic amino acids, which one is likely to be found at the interior of proteins away from the solvent? Why?

Back 7

Isoleucine. Because of his hydrophobic character.

Front 8

Why is the amino acid, glycine, important?

Back 8

Glycine is important as a precursor for the synthesis of both hemes and purines.

Front 9

What is the importance of the amino acid alanine?

Back 9

Alanine is important as a precursor for the synthesis of glucose in gluconeogenesis.

Front 10

From the Aliphatic AA group, mention those that have branched sidechains.

Back 10

valine, leucine, proline, and isoleucine.

Front 11

Defect in the BCAA's metabolism may give rise to what disease? What this disease can cause to the body if left untreated?

Back 11

Maple syrup urine disease.
This disease can cause mental retardation and early death.

Front 12

Describe what the cyclic structure found in proline does?

Back 12

This structure is hydrophobic, and because of eits rigidity, puts contraints upon the shape that polypeptide chains containing it may take.

Front 13

Mention the names of the amino acids in the group of amino acids with hydroxyl or sulfur containing sidechains.

Back 13

serine (ser), threonine (thr), cysteine (cys), methionine (met)

Front 14

In the AA with hydroxyl and sulfur containing sidechains group, which have hydroxyl groups and which have sulfur groups?

Back 14

Hydroxyl groups:
serine and threonine
Sulfur groups:
cysteine and methionine

Front 15

What is the importance of serine?

Back 15

Serine is important as a precursor for the synthesis of purines, pyrimidines and sphingosine (used for sphingolipid synthesis)

Front 16

Are AA with hydroxyl or sulfur containing sidechains more or less hydrophilic than Aliphatic AA?

Back 16

More hydrophilic. Because they are weakly polar by their sidechain ionization.

Front 17

What does the AA methionine have in its side chain and what role does that structure play in biosynthetic pathways?

Back 17

The AA methionine has a methyl thioether on its sidechain.
This structure is a major source of methyl groups in biosynthetic pathways.

Front 18

When AA with hydroxyl and sulfur sidechains are in proteins, what kinds of reactions do these AA occasionally undergo?

Back 18

AA with hydroxyl groups (serine and threonine) are frequently found modified by phosphorylation in many proteins.
AA with sulfur sidechains (cysteine and methionine) can undergo a reaction in which their sulfhydryl groups get oxidized to form a disulfide linkage between different parts of a polypeptide.

Front 19

Which of the AA are aromatic?

Back 19

phenylalanine (phe), tyrosine (tyr), tryptophan (trp).
Mnemonics: PTT

Front 20

What is a solubility characteristic found in phenylalanine?

Back 20

Phenylalanine is one of the most hydrophobic AA, and thus it is frequently located inside of proteins away from the solvent.

Front 21

What is a condition caused by defects in the metabolism of phenylalanine?

Back 21

Phenylketonuria (PKU). This disease like Maple Syrup Urine Disease, if left untreated, can cause mental retardation and early death. All newborn babies are tested for PKU in the U.S.

Front 22

Phenylalanine is one of the AA which is a component of_____________. (used in food industry)

Back 22

Artificial sweetener aspartame (Nutrasweet)

Front 23

Are tyrosine and triptophan more or less soluble than phenylalanine? Why?

Back 23

More soluble (less hydrophobic). Because they have polar groups on their sidechains.

Front 24

Why is the AA tyrosine so important to the body?

Back 24

Tyrosine is a precursor for the synthesis of thyroid hormone, the catecholamines, the compound known as dopa, and melanin.

Front 25

What are some of the conditions caused by defects in the metabolism of the AA tyrosine?

Back 25

Tyrosinosis, albinism, and alcaptonuria ("dark urine disease" not clinically a severe condition).

Front 26

Tryptophan is one of the precursors for the synthesis of_______________.

Back 26

nicotinamide nucleotides. Thus NAD+ can be synthesized from either tryptophan or nicotinic acids.

Front 27

What could be a consequence of a lack of tryptophan in the diet?

Back 27

Pellagra.

Front 28

What is the neurotransmitter for which its synthesis tryptophan is a precursor?

Back 28

Serotonin.

Front 29

In some parts of the brain this neurotransmitter is __________ while in other parts it is ______________.

Back 29

inhibitory, stimulatory.

Front 30

How drugs such as Prozac (fluoxetine) function?

Back 30

by preventing sertotonin reuptake by presynaptic neurons in the parts of the brain where serotonin is stimulatory, increasing its circulatory levels resulting in relief of depression.

Front 31

What are the name of the basic AA?

Back 31

histidine (his), lysine (lys), arginine (arg)
Mnemonics: LAH

Front 32

What are the solubility characteristics found in Basic AA?

Back 32

They carry a basic group on their sidechains. They are strongly polar, positively charged at neutral pH.

Front 33

Where are basic AA most likely to be found in proteins?

Back 33

On the surface of proteins where they have access to the solvent.

Front 34

What are the characteristics exhibited by the basic AA histidine?

Back 34

Histidine is the least basic of this series. This AA is frequently involved in enzymatic reactions as a site where proton exchange with the solvent or proton transfer reactions can take place. Histidine is also a precursor for the synthesis of histamine, a biogenic amine which plays major roles in immunounflammatory responses and also appears to be a neurotransmitter.

Front 35

Lysine metabolism defects can cause what diseases?

Back 35

Hyperlysinemias. In accute cases, lysine can accumulate to the point of competing with arginase causing hyperammonemia.

Front 36

What are some of the major roles of the AA arginine in the body?

Back 36

It plays a role in proteins and with the urea cycle in nitrogen metabolism. It is also a precursor for the synthesis of an important unique gaseous second messenger and neurotransmitter, nitric oxide (NO).

Front 37

What are the names of the Acidic AA and their Amides?

Back 37

Aspartic (asp), glutamic (glu), asparagine (asn), glutamine (gln).

Front 38

Are AA from the group of Acidic AA and their Amides hydrophilic or hydrophobic?

Back 38

Hydrophilic

Front 39

What are some of the functions of AA aspartate

Back 39

It is a constituent of the artificial sweetener Aspartame. It is also a precursor for the synthesis of several other AA (asparagine, lysine, methionine, threonine, and isoleucine). It is also used in urea, pyrimidine, and purine nucleotide synthesis.

Front 40

What are the major roles played by the AA glutamate in the body?

Back 40

Glutamate is the major excitatory neurotransmitter. It also serves as the precursor for the synthesis of the major inhibitory neurotransmitter, gamma aminobutyric acid (GABA). It serves as a precursor for the synthesis of AA glutamine, arginine, proline and hydroxyproline. It is also involved in the synthesis of creatine phosphate.

Front 41

What is the function of Creatine Phosphate in the body?

Back 41

It is used as a storage form for high energy phosphate in muscle.

Front 42

What is the function of the amide AA asparagine?

Back 42

It is the site of attachment of small carbohydrate chains in many glycoproteins.

Front 43

What is the function of the amide AA glutamine?

Back 43

It serves as a precursor for the synthesis of histidine and tryptophan. Its amide nitrogen is used in the synthesis of purine and pyrimidine nucleotides, amino sugars, and glycoproteins. It also plays a role in nitrogen metabolism as a way to transport ammonia nitrogen to the liver.

Front 44

What is the species predominantly found at physiological pH (7.4) in AA?

Back 44

A zwitterion ion (doubly charged ion).

Front 45

What reactions act almost like a switch to turn on and off activity of enzymes in particular?

Back 45

phosphorylation and dephosphorylation.

Front 46

What are Essential AA?
Name all nine of them.

Back 46

Essential AA are those that cannot be synthesized by humans and need to be obtained in the diet.
The nine essential AA are:
Phenylalanine, Valine, Threonine, Tryptophan, Methionine, Histidine, Isoleucine, Leucine, and Lysine (and in children Arginine).
Mnemonics: Pvt.TimHall

Front 47

Name at least 4 types of compounds for which AA are the precursors.

Back 47

1. Synthesis of Glucose in Gluconeogenesis.
2. Precursor for neurotransmitters: serotonin.
3. Precursor for hormone synthesis: thyroid hormone.
4. Precursor for important molecules: purines, pyrimidines, urea, etc.