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Biochemistry > Chapter 3: Amino Acids > Flashcards

Chapter 3: Amino Acids Flashcards

1
Q

Proteins are __________ of amino acids residue joined to its neighbor

A

Polymers (residue meaning lost water when one animo acid joined to another)

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2
Q

All 20 common acids share common ________ features

A

Structural

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3
Q

All 20 common amino acids are ____ amino acids where they have a carboxyl group & an animo group bonded to the same carbon atom (the alpha carbon)

A

Alpha amino

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4
Q

The difference in amino acids is based on their ________

A

Side chains (R groups)

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5
Q

The alpha carbon is a __________ center

A

Chiral center

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6
Q

Amino acids have sterisomers called _____________

A

enantiomers

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7
Q

The absolute configuration of the 4 substituents of carbon atoms is the _________ system

A

D,L system

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8
Q

The amino acid residues in proteins are ______ steroisomers

A

L

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9
Q

Amino acids can be classified by their ___ group

A

R group

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10
Q

Amino acids are group into groups based on their _____ which is the tendency to interact with water at pH= 7.0

A

Polarity

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11
Q

What are the 5 R groups of animo acids?

A
  1. Nonpolar aliphatic R groups
  2. Aromatic R groups
  3. Polar uncharged R groups
  4. Positively charged (Basic) R groups
  5. Negatively charged (Acidic) R groups
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12
Q

What are the 6 uncommon amino acids?

A
  1. 4-hydroxyproline
  2. 5-hydroxylysine
  3. 6-N-methyllysine
  4. Y-carboxyglutamate
  5. Desmosine
  6. Selenocysteine & pyrrolysine
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13
Q

Amino acids can act as ______ & ______

A

Acids & Bases

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14
Q

The amino & carboxyl group of amino acids & the ionizable R group of some amino functions as weak _____ & ____

A

Acids & bases

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15
Q

When an amino acid lacking an ionizable R group is dissolved in water a pH = 7 it exist in solution as the __________ which can act as either acid or base

A

dipolar ion (zwitterion)

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16
Q

Substances having the dual (acid-base) nature are _______ & called _____

A

Amphoteric, ampholytes

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17
Q

Titration curves can predict the __________ of amino acids

A

Electric charge

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18
Q

Isoelectric pH (isoelectric point)(pI)

A

The concentration pH at which the net electric charge is zero

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19
Q

Amino acids with an ionizable R group have a titration curve with ______ stages (or flat spots) & have 3 pKa values

A

3

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20
Q

_________ are chains of amino acids

A

Peptides

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21
Q

Two amino acid molecules can be covalently joined through a substituted amide linkage called _________ to make a dipeptide

A

Peptide bond

22
Q

To form a dipeptide the elements of water is removed from the ________& _________ group

A

alpha carboxyl group & alpha amino group

23
Q

Peptide bond formation is a ___________

A

condensation reaction

24
Q

3 amino acids can form a _________< 4 can form a tetrapeptide, 5 can form a pentapeptide, etc

A

Tripeptide

25
Q

When only a few amino acids are linked together (like 2 or 3) then its called an __________

A

Oligopeptide

26
Q

When many animo acids are joined (Like 5 or 6) then its called a _______________

A

Polypeptide

27
Q

In a peptide, the amino acid residue at the end with a free alpha-amino group is called _____________ residue

A

Amino-terminal (or N-terminal) residue

28
Q

In a peptide the free carboxyl group is called the _________ residue

A

Carboxyl terminal (r C-terminal) residue

29
Q

When an amino acids sequence of a peptide, polypeptide or protein is shown the amino-terminal end is placed on the _______ & the carboxyl-terminal end is on the _______

A

Left, right

30
Q

Peptides are named beginning with the _________ residue

A

Amino-terminal residue

31
Q

Acid-base behavior of a peptide can be predicted from its free ____________________ & its ionizable R group

A

alpha amino & alpha carboxy group

32
Q

Multisubunit proteins

A

Have two or more polypeptide associated noncovalently

33
Q

The individual polypeptide chains in a multisubunit protein may be __________ or ________

A

Identical or different

34
Q

If at least two polypeptides chains in multisubunit proteins are identical then they are called ________ & the different units are called ________

A

Oligomeric, protomers

35
Q

The average molecular weight of the 20 common amino acids is about _____

A

138

36
Q

The average molecular weight if protein amino acid is near ____

A

128

37
Q

Simple proteins

A

Contain only amino acids residues & no other chemical constituents

38
Q

Conjugated proteins

A

Proteins that have permanently associated chemical components & amino acids residues

39
Q

The non-amino acid part of a conjugated protein is usually called its _______

A

Prosthetic group

40
Q

Conjugated proteins can be classified on the basis of the chemical nature of their ___________

A

Prosthetic group (ex. lipoproteins contain lipids)

41
Q

Proteins can be _________ & _________

A

Separated & purified

42
Q

The 1st step in an y protein purification procedure is to break open the microbial cells ( the source of a protein) & releasing their proteins into a solution called a ______________

A

Crude extract

43
Q

Once the extract preparation is ready then the extract is subjected to _____________

A

Fractionation

44
Q

Fractionation

A

Separating the proteins into different fractions on a property such as size or charge

45
Q

After a protein is fractionize then the solution or protein is _________ by adding salts to selectively precipitate some proteins (unwanted proteins) (ex. ammonium sulfate is an effective salt to salt out unwanted protons)

A

“Salt out”

46
Q

After a solution contains only the wanted proteins then its ________

A

Dialysis

47
Q

Dialysis

A

Procedure that separates proteins from small solutes (keeps large proteins & can get rid of the salt added)

48
Q

___________________ is a method used for fractionating proteins

A

Column chromategraphy

49
Q

Column chromatography is a method used for ______________ proteins

A

Fractioning

50
Q

Ion-exchange chromatography

A

Exploits difference in the sign & magnitude of the net electric charge of proteins at a given pH

Biochemistry (26 decks)

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