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Biochemistry > Chapter 1-Amino Acids Peptides And Proteins > Flashcards

Chapter 1-Amino Acids Peptides And Proteins Flashcards

1
Q

What are the four parts of an amino acid?

A
  1. Amino group
  2. Carboxylic acid
  3. Hydrogen
  4. R group
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2
Q

What is the stereo chemistry of the alpha carbon for all chiral amino acids in eukaryotes?

A

L

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3
Q

Which amino acid is the only achiral amino acid?

A

Glycine

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4
Q

All chiral amino acids have what configuration?

A

S

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5
Q

Which chiral amino acid has an R configuration?

A

Cysteine

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6
Q

Amino acids are amphoteric. What is the meaning of amphoteric?

A

The ability to except or donate protons.

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7
Q

How is a peptide bond formed?

A

Combination of amino acid subunits or residues via a dehydration or condensation reaction.

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8
Q

What is a dipeptide?

A

Two amino acid residues

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9
Q

What is a tripeptide?

A

Three amino acid residues

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10
Q

What is an oligopeptide?

A

A few amino acid residues less than 20.

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11
Q

What is a polypeptide?

A

More than 20 amino acid residues.

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12
Q

What makes amide bonds rigid?

A

Resonance

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13
Q

What type of reaction is the breaking of a peptide bond?

A

Hydrolysis.

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14
Q

What types of bonds are associated with primary protein structure?

A

Peptide bonds.

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15
Q

What types of bonds are associated with secondary protein structure?

A

Hydrogen bonding

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16
Q

What types of bonds are associated with tertiary structure?

A

Hydrophobic, hydrogen, disulfide.

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17
Q

What is the primary structure of proteins?

A

Primary structure of the interaction of individual amino acids. Involves peptide bonding.

18
Q

What is secondary structure of proteins?

A

Involves alpha helix and beta pleated sheets. Hydrogen bonding holds the structures together.

19
Q

What is tertiary structure of proteins?

A

The 3-D shape of one polypeptide chain.

20
Q

What is the quaternary structure of proteins?

A

The interaction of peptides with multiple subunits.

21
Q

Which amino acid can cause kinks in an alpha helix and beta pleated sheets?

A

Proline because of its rigid cyclic structure

22
Q

What can lead to denaturation?

A

Extreme heat and increasing solute concentration.

23
Q

What is denaturation?

A

Loss of 3-D structure of a protein

24
Q

PKa

A

Ph where 1/2 the species is deprotonated

25
Q

pI

A

pH where molecule is electrically neutral

26
Q

At low pH are amino acids protonated or deprotonated?

A

Protonated (positively charged)

COOH
NH4+

27
Q

At high ph are amino acids protonated/deprotonated?

A

Deprotonated (negatively charged)

COO-
NH2

28
Q

Estimation for the pI of an acidic vs basic amino acid

A

Acidic way less than 6

Basic way more than 6

29
Q

Formula to calculate for the pI of an acidic amino acid

A

Average of pKa of the R group and COOH

30
Q

Formula to calculate for pI of a basic amino acid

A

Average of the pKa of the R group and NH3

31
Q

What is a peptide?

A

Formed from amino acid subunits/ residues

32
Q

What bond joins together the residues in a peptide?

A

Peptide bond

The electrophilic carbonyl carbon of one amino acid is attacked by the nucleophilic amino group in a second amino acid

33
Q

Peptides drawn and read in what direction?

A

N to C

34
Q

What things can cause denaturation?

A

Heat, increasing solute concentration

35
Q

What is denaturation?

A

Loss of 3D structure

36
Q

Conjugated proteins

A

Proteins with covalently attached molecules called prosthetic groups

37
Q

What is the effect of placing a hydrophobic side chain in aqueous solution

A

Hydrogen bonds not able to form with side chain. Water molecules forced to group and bond together. This decreases entropy/disorder (S) of the surrounding water molecules and makes the overall process nonspontaneous (positive delta G)

38
Q

What is the affect of place if a hydrophilic side chain in an aqueous solution?

A

Hydrogen bonds are able to form with the side chain. Giving water molecules more latitude in their position. This increases entropy/disorder (S) of the surrounding water molecules and makes the overall process spontaneous (negative delta G)

39
Q

Which amino acids are likely found in beta turns of beta pleated sheets?

A

Histidine and Proline

40
Q

Higher ratio of basic amino acids to acidic amino acids will have a higher/lower pI?

A

Higher pI

Biochemistry (10 decks)

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