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Biochemistry > Amino Acids > Flashcards

Amino Acids Flashcards

1
Q

Each amino acid has at least two pKas:

A
  • amino group attached to central alpha C
  • carboxylic acid group attached to central alpha C
  • R group/side chain
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2
Q

R groups are the only…

A

difference between the 20 amino acids

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3
Q

Amino acids are monomers of…

A

polypeptide/protein molecules

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4
Q

Protein shape and function are determined by…

A

sequence in which amino acids are linked together and the interactions with the side chains

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5
Q

Side chains and their position relative to the adjacent/nearby chain from another amino acid determine…

A

shape and function of protein

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6
Q

Sequence of amino acids are also known as…

A

primary structure of proteins

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7
Q

Longer side chains leads to the molecule becoming more…

A

hydrophobic

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8
Q

Examples of uncharged polar side chains:

A
  • Glutamine (Glu)
  • Tyrosine (Tyr)
  • Cysteine (Cys)
  • Serine (Ser)
  • Threonine (Thr)
  • Asparagine (Asn)
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9
Q

Examples of charged polar side chains:

A
  • Lysine (Lys)
  • Arginine (Arg)
  • Histidine (His)
  • Aspartic acid (Asp)
  • Glutamic acid (Glu)
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10
Q

Histidine is often used in…

A

acid/base enzyme reactions due to pKa close to neutrality

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11
Q

Lysine and Arginine side chains are always…

A

positive at physiological pH

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12
Q

Aspartic and Glutamic acid are the only amino acids w/…

A

negative charge at physiological pH

- often termed aspartate and glutamate due to negative charge

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13
Q

Carboxylic acid (COOH) and amine group (NH3+) remains protonated at…

A

pH at or below their own pKa

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14
Q

Zwitterionic molecules have…

A

net charge of 0

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15
Q

Isoelectric point (pl) is the point where…

A

net charge is equal to 0

pl = [pKa1 + pKa2]/2

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16
Q

If pH is above the pKa…

A

group is deprotonated

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17
Q

If pH is below/equal to the pKa…

A

group is protonated

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18
Q

Changes in charge on amino acids are important b/c…

A
  • can make amino acid inactive
  • disrupt protein structure/function
  • alter E levels of protein
  • keep reaction from occurring
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19
Q

Fully protonated amino acid would have a _____ pH

A

low

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20
Q

Fully deprotonated amino acid would have exist at pH…

A

above pKa of amino group on side chain

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21
Q

T/F: amino acids are optically active

A

T

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22
Q

Why are amino acids optically active?

A
  • rotate the plane of polarized light
  • asymmetric
  • result from chiral C
  • are enantiomers
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23
Q

Dextrorotatory (D form) amino acids are…

A

on the right side

24
Q

Levorotatory (L form) amino acids are…

A

on the left side

25
Q

T/F: all amino acids incorporated by organisms in proteins are of the D form

A

F, they’re of the L form

26
Q

Modified amino acids are…

A

amino acids that are modified after incorporation into a protein

27
Q

5-HTP (5-hydroxytryptophan):

A
  • derivative of amino acids
  • used to treat neurological problems associated w/ PKU and depression
  • ex: serotonin and melatonin
28
Q

Serotonin is a:

A

neurotransmitter that doesn’t cross blood brain barrier

29
Q

Serotonin is involved in regulation of:

A
  • mood
  • sleep
  • vomiting
  • sexuality
  • appetite
30
Q

Serotonin is associated w/…

A
  • depression
  • migraines
  • bipolar-disorder
  • anxiety
31
Q

Precursor of serotonin:

A

Trp and 5HTP

32
Q

Ecstasy is thought to cause…

A

a mass release of 5 HT

33
Q

Levels of serotonin are controlled by…

A
  • MAO inhibitor: stops breakdown of neurotransmitters

- reuptake inhibitors

34
Q

Melatonin regulates…

A

circadian cycle

35
Q

Melatonin can prevent…

A

hyperphosphorylation of tau

36
Q

DOPA (L-dihydroxyphenylalanine) is a drug that is used to treat…

A

Parkinson’s

37
Q

Examples of DOPA (L-dihydroxyphenylalanine) are…

A
  • epinephrine

- norepinephrine

38
Q

Epinephrine is involved in…

A

stress action

39
Q

Action of epinephrine:

A
  • binds to multiple receptors

- participates in adenylate cyclase pathway that breaks down glycogen

40
Q

Norepi is involved in…

A
  • ADD/ADHD
  • depression
  • replenishing catecholamine stores
41
Q

T/F: tyrosine and cysteine carry a positive charge

A

F, they don’t carry a charge

42
Q

What is the side chain of cysteine in its reduced form?

A

SH

43
Q

When cysteine participates in a disulfide bonds w/ another cysteine amino acid, the side chain turns into its…

A

oxidized form (S-S)

44
Q

Which amino acids are hydrophobic?

A
  • gly
  • ala
  • val
  • leu
  • ile
  • pro
  • phe
  • met
  • trp
45
Q

Which amino acids are hydrophilic?

A
  • lys
  • arg
  • his
  • asp
  • glu
  • ser
  • thr
  • tyr
  • gln
46
Q

Cysteine has a side chain that…

A

ionizes

47
Q

Amino acids that are ionizable:

A
  • arg
  • asp
  • cys
  • glu
  • his
  • lys
  • tyr
48
Q

Functional group on side chain of lysine:

A

NH3+

49
Q

Functional group on side chain of arginine:

A

guanidino

50
Q

Functional group on side chain of histidine:

A

imidazole ring

51
Q

Functional group on side chain of glutamate:

A

COOH

52
Q

Functional group on side chain of aspartate:

A

COOH

53
Q

How are disulfide bonds formed?

A

oxidation between pairs of cysteine side chains

54
Q

What reduces disulfide bonds?

A

dithiotheritol (DTT)

55
Q

What oxidizes disulfide bonds?

A

cysteine

Biochemistry (9 decks)

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