biochemistry Flashcards

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1
Q

amino acids have _ groups attached to a central carbon

A

four

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2
Q

_ groups include:
1. amino group
2. carboxylic acid group
3. hydrogen atom
4. R group

A

amino acid

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3
Q

determines chemistry and function of amino acid

A

what is the R group?

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4
Q

there are _ amino acids that appear in proteins of eukaryotic organisms

A

20

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5
Q

stereochemistry for central carbon in eukaryotes will always be

A

L

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6
Q

_ amino acids can exist in prokaryotes

A

D

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7
Q

all amino acids have S configuration except _

A

cysteine

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8
Q

_ is the only achiral amino acid

A

glycine

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9
Q

glycine has R group: _

A

H atom

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10
Q

what do these amino acids have in common?
- glycine
- alanine
- valine
- leucine
- isoleucine
- methionine
- proline

A

these amino acids are nonpolar and nonaromatic

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11
Q

what do these amino acids have in common?
- tryptophan
- phenylalanine
- tyrosine

A

these amino acids are aromatic

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12
Q

what do these amino acids have in common?
- serine
- threonine
- asparagine
- glutamine
- cysteine

A

these amino acids are polar

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13
Q

what do these amino acids have in common?
- aspartate
- glutamate

A

these amino acids are acidic and negatively charged

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14
Q

what do these amino acids have in common?
- lysine
- arginine
- histidine

A

these amino acids are basic and positively charged

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15
Q

amino acids with long alkyl chains are _ while amino acids with charges are _

A

hydrophobic; hydrophilic

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16
Q

amino acids can both accept and donate protons, which means they are _

A

amphoteric

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17
Q

pH at which half of the species is deprotonated

A

what is pKa?

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18
Q

amino acids exist in _ forms at different pH values

A

different

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19
Q

amino acids are fully protonated at _ pH

A

low/acidic

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20
Q

amino acids are fully deprotonated at _ pH

A

high/alkaline

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21
Q

when the pH is near the pI of an amino acid, it is called _

A

zwitterion

22
Q

isoelectric point (pI) can be calculated by averaging two pKa values for amino acids _ a charged side chain

A

without

23
Q

amino acids can be _ (method)

A

titrated

24
Q

titration curve is mostly _ at pKa value and _ at pI value (of amino acids)

A

flat; vertical

25
Q

isoelectric point (pI) can be calculated by averaging two pKa values (protonation and deprotonation) for amino acids _ a charged side chain

A

with

26
Q

pI of amino acids without charged side changes …

A

= 6

27
Q

pI of ACIDIC amino acids …

A

below 6

28
Q

pI of BASIC amino acids …

A

above 6

29
Q

dipeptides have _ AA residues; tripeptides have _ residues

A

2; 3

30
Q

amino acid subunits

A

what are residues?

31
Q

oligopeptides have _ residues while polypeptides have _ residues

A

few (less than 20); many (over 20)

32
Q

the release of one water molecule

A

what is dehydration (condensation)?

33
Q

_ reaction forms the peptide bond

A

condensation (dehydration)

34
Q

amide bonds are rigid due to _

A

resonance

35
Q

nucleophilic amino group attacks _ of another amino acid

A

electrophilic carbonyl group

36
Q

breaking a peptide bond is a _ reaction

A

hydrolysis

37
Q

linear sequence of amino acids a in peptide

A

what is primary structure?

38
Q

primary structure is stabilized by _

A

peptide bonds

39
Q

local structure of neighboring amino acids

A

what is secondary structure?

40
Q

secondary structure is stabilized by _ between amino groups and nonadjacent carboxyl groups

A

hydrogen bonding

41
Q

clockwise coils around central axis

A

what are alpha helices?

42
Q

rippled strands that can be parallel or antiparallel

A

what are beta pleated sheets?

43
Q

_ can interrupt secondary structure due to rigid cyclic structure

A

proline

44
Q

3D shape of single polypeptide chain

A

what is tertiary structure?

45
Q

_ structure is stabilized by _ hydrophobic and acid-base interactions, hydrogen bonding, and disulfide bonds

A

tertiary

46
Q

push hydrophobic R groups to interior of a protein

A

what are hydrophobic interactions?

47
Q

hydrophobic interactions _ entropy and creates _ Gibbs free energy

A

increases; negative

48
Q

forms when 2 cysteine molecules are oxidized and forms cystine (covalent bond)

A

what are disulfide bonds?

49
Q

interaction between peptides in protein that contain multiple subunits

A

what is quaternary structure?

50
Q

proteins with covalently attached molecules

A

what are conjugated proteins?

51
Q

attached molecules that can include metal ions, vitamin, lipid, carbohydrate, nucleic acid

A

what are prosthetic groups?

52
Q

loss of a 3D protein structure due to heat and increasing solute concentration

A

what is denaturation?