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BMSC 200 > Chapter 3: Amino Acids > Flashcards

Chapter 3: Amino Acids Flashcards

1
Q

Which amino acid is the smallest? What is its side chain?

A

Glycine. A hydrogen atom.

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2
Q

Is glycine chiral or achiral? Why?

A

Achiral, as there are not 4 different groups coming off the α-carbon. Therefore, no L/D-isomers.

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3
Q

Which amino acid has a ring structure involving the amino group?

A

Proline.

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4
Q

Which amino acids have a sulfur atom?

A

Cysteine and methionine.

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5
Q

Which amino acid is the largest?

A

Tryptophan.

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6
Q

Which amino acids are aromatic?

A

Tryptophan, phenylalanine, and tyrosine.

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7
Q

Which amino acids are non polar and non aromatic?

A

Glycine, alanine, valine, leucine, isoleucine and methionine.

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8
Q

Which amino acids have polar side chains?

A

Serine, threonine, asparagine, glutamine, and cysteine.

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9
Q

What is the difference between asparagine and glutamine?

A

There is an added carbon group in the glutamine side chain.

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10
Q

What amino acids must be taken from diet (essential)?

A

Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

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11
Q

Which amino acids have positively charged (basic) side chains?

A

Arginine, lysine and histidine.

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12
Q

Which amino acids have negatively charged (acidic) side chains?

A

Aspartic acid, and glutamic acid. Their anions are aspartate and glutamate respectively.

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13
Q

What is the TLA of alanine? What is the OLA?

A

Ala, A

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14
Q

What is the TLA and OLA of arginine?

A

Arg, R

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15
Q

What is the TLA and OLA of asparagine?

A

Asn, N

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16
Q

What is the TLA and OLA of aspartic acid?

A

Asp, D

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17
Q

What is the TLA of cysteine? What is the OLA?

A

Cys, C

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18
Q

What is the TLA and OLA of glutamic acid?

A

Glu, E

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19
Q

What is the TLA and OLA of glutamine?

A

Gln, Q

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20
Q

What is the TLA and OLA of glycine?

A

Gly, G

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21
Q

What is the TLA and OLA of histidine?

A

His, H

22
Q

What is the TLA and OLA of isoleucine?

A

Ile, I

23
Q

What is the TLA and OLA of leucine?

A

Leu, L

24
Q

What is the TLA and OLA of lysine?

A

Lys, K

25
Q

What is the TLA and OLA of methionine?

A

Met, M

26
Q

What is the TLA and OLA of phenylalanine?

A

Phe, F

27
Q

What is the TLA and OLA of proline?

A

Pro, P

28
Q

What is the TLA and OLA of serine?

A

Ser, S

29
Q

What is the TLA and OLA of tyrosine?

A

Tyr, Y

30
Q

What is the TLA and OLA of threonine?

A

Thr, T

31
Q

What is the TLA and OLA of valine?

A

Val, V

32
Q

What part of tryptophan gives it a polar spot? What is the result of this spot?

A

The N-H bond in the 5C ring. This spot makes the molecule less hydrophobic.

33
Q

What type of side chain does alanine have?

A

An aliphatic side chain. (CH3).

34
Q

What is the correlation between pKa and the pH of the acid?

A

The smaller the pKa the stronger the acid.

35
Q

Which of the three forms is most neutral: protonated, Zwitterionic, or deprotonated?

A

Zwitterionic.

36
Q

What is the PI and where can it be found?

A

The PI is called the isoelectric point, which is a pH value where the molecule reaches neutrality in charge. When there is only two pKa values, it is the average in-between the two.

37
Q

What is an α-amino acid composed of?

A

An α-amino acid is composed of a central carbon atom called the α-carbon, which is linked to an amino group, a carboxylic acid, a hydrogen atom, and a distinctive side chain, called the R group. There are 20 different types of R’s.

38
Q

When do the hydrogen bond donor/acceptor change? When is the amino group no longer the acceptor?

A

Hydrogen bond donor/acceptor change with ionization state. Amino group is no longer acceptor once it has 4 valence bonds.

39
Q

What is chirality and what does it mean? What isomer is found in proteins?

A

When four different groups are bonded to the α-carbon, the amino acid is chiral, which means that they exist as two mirror-image forms called the L-isomer and the D-isomer. Only L-isomers are found in proteins.

40
Q

How many charged groups are in all amino acids? How do free amino acids exist in solution at neutral pH?

A

At least two. The amino group (NH3+) and the carboxyl group (COO−) are charged. (Note: amine group: NH2 is not the same as amino group NH3+). Free amino acids in solution at neutral pH exist as dipolar ions.

41
Q

What kind of side chains do hydrophobic amino acids have?

A

Mainly hydrocarbon side chains (consist mainly of carbon and hydrogen).

42
Q

Where do the hydrophobic amino acids tend to cluster on the protein structure?

A

The hydrophobic amino acids, particularly the larger aliphatic and aromatic ones, tend to cluster together inside the protein away from the aqueous environment of the cell.

43
Q

What is critical to entropy?

A

Movement.

44
Q

How many chiral centres does isoleucine have?

A
  1. The second is on the central carbon up from the α-carbon.
45
Q

Why are polar acids neutral yet polar?

A

Polar amino acids are neutral overall, yet they are polar because the R group contains an electronegative atom that hoards electrons.

46
Q

What charges do a positively charged amino acid swing back and forth from?

A

A positively charged amino acid swings from a charge of +1 to 0.

47
Q

Is the amine side chain or the amino group the stronger acid in lysine?

A

The amine side chain in lysine is a stronger acid than the amino at the top.

48
Q

Where is histidine often found? What distinct side chain does it have and what is the charge of the side chain at neutral pH?

A

Histidine is found at the active sites of many enzymes that require a proton donor or proton acceptor. Histidine has an imidazole side chain that can be uncharged or positively charged at neutral pH.

49
Q

How many of the amino acids have readily ionizable side chains? Which are they? What roles do they often play?

A

Seven of the 20 amino acids—tyrosine, cysteine, arginine, lysine, histidine, and aspartic and glutamic acids—have readily ionizable side chains. These seven amino acids are able to form ionic bonds as well as to donate or accept protons (called acid–base catalysis) to facilitate reactions.

50
Q

Why are tyrosine and cysteine not characterized as charged amino acids?

A

They are not categorized as charged amino acids because their side chain is predominantly neutral at neutral pH.

51
Q

Define essential and non essential amino acids?

A

Amino acids that cannot be generated in the body must be supplied by the diet and are termed essential amino acids. The others are called nonessential amino acids.

52
Q

What is Kwashiorkor?

A

Kwashiorkor is a form of malnutrition resulting from inadequate consumption of amino acids usually ingested as proteins.

BMSC 200 (5 decks)

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