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Amino acids > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

Biochemistry

-Definition

A

It is the science of the chemical basis of life. It describes in molecular terms: structures, mechanisms, chemical processes shared by all organisms.

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2
Q

Prokaryotes

A
  • Lack defined nucleus or internal membrane structures.
  • Unicellular.
  • Variety of shapes, sizes and living conditions.
  • DNA is a single circular strand in nucleoid region.
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3
Q

Eukaryotes

A
  • The nucleus consists of nuclear material enclosed within a double membrane.
  • Single cell organisms or multicellular.
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4
Q

Covalent bond

A

It is a chemical bond that involves the sharing of electron pairs between atoms.

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5
Q
  • Non- polar covalent bond
  • Polar covalent bond
  • Ionic bond
A
  • Bonding electrons share equally between atoms. No charge.
  • Bonding electrons share unequally between atoms. Partial charge.
  • Complete transfer of one or more valence electrons. Full charge.
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6
Q

Functional roles of proteins

A
  • Enzymes.
  • Signalling.
  • Gene regulation.
  • Structural.
  • Transport.
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7
Q

General structure of an amino acid

A
  • Alpha carbon.
  • Carboxyl group.
  • Amino group.
  • Side chain.
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8
Q

Non-polar amino acids

Polar amino acids

A
  • Glycine, leucine, isoleucine, valine, tryptophan, methionine, proline, alanine, phenylalanine.
  • Serine, threonine, tyrosine, cysteine, asparagine, glutamine.
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9
Q

Positively charged (basic).

Negatively charged (acidic).

A
  • Histidine, lysine, argigine.

- Glutamic acid, aspartic acid

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10
Q

Chiral / Chiriality

A

An object that cannot be superimposed on its mirror image

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11
Q
  • When can enatiomers occur?

- Which amino acid CANNOT occur in two isomeric forms?

A
  • Only when there is 4 different attachments on the alpha carbon
  • Glycine.
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12
Q

Which type of amino acids are manufactured in cells? D or L form?

A

L form.

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13
Q

What are essential amino acids? Give three examples.

A

They are essential in a diet and are not synthesized in the human body.

Ex: valine, leucine, lysine, histidine, isoleucine.

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14
Q

Amino acids are weak

A

Polyprotic acids

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15
Q

At neutral pH, amino acids are present as..

A

Zwitter ions

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16
Q

The strong prositive charge on the amino group induces…

A

a tendency for the carboxylic acid group to lose a proton.

17
Q

Isoelectric point

A

pH value at which the net charge of a compound is zero.

18
Q

Non- polar side chain

  • Characteristics
  • Name all of them (9)
A

-Hydrophobic, do not gain or loose protons, do not participate in hydrogen or ionic bonds.

GAVE YOU LIP PTM
Glycine, Alanine, Valine, Leucine, Isoleucine, Proline, Phenylalanine, Tryptophan, Methionine

19
Q

Hydrophobic interactions

  • Important for…
  • In a hydrophobic environment, nonpolar side chain are located….
A
  • Stabilizing the protein.

- Outside

20
Q

Proline differs from other amino acids because…

A
  • It has a five- membered ring.
  • It contains a secondary amino group.
  • Referred to as imino acid.
21
Q

The polar hydroxyl group of serine, threonine, tyrosine and the carbonyl and amide group of asparagine and glutamine contribute to the formation of…

A

Hydrogen bonds

22
Q

Disulfide bonds form when..

A

The -SH group of two cysteine undergo oxidation and form a S-S

23
Q

Amino acids with uncharged polar side chains (6)

A

GIULIA AMA COMER TAPIOCA SEM TOFU

Glutamine, cysteine, threonine, tyrosine, serine, asparagine

24
Q

Amino acids with acidic side chains (2)

  • Name
  • Characteristics.
A

-Aspartic and glutamic acid.

  • Negatively charged at physiological pH.
  • Proton donors
25
Q

Amino acids with basic side chains (3)

  • Names
  • Characteristics
A

LOVE HIS ART
Lysine, histidine, arginine.

  • Accept protons.
  • Positively charged at physiological pH.
  • Histidine is the only one that can ionize at physiological pH.
26
Q

What does a

  • Large Ka represent
  • Small Ka represent
A
  • Stronger acid

- Weaker acid

27
Q

Maximum buffering capacity is when..

A

pH = pKa

28
Q

Buffers

  • Definition
  • It can be created by…
A

A solution that resists a change in pH after the addition of a acid or base.

-A mixture of a weak acid + conjugate base, or vice-versa.

29
Q

Titration of an amino acid

  1. At a low pH
  2. As the pH increases
  3. Next group to dissociate
A
  1. Both groups are protonated (amino and carboxyl). Net charge is +1
  2. -COOH dissociates, donates a proton. Net charge is 0.
  3. Amino group dissociates. Net charge is -1.
30
Q

Titration of an amino acid

  1. pk1
  2. pk2
  3. pk1 = pH
  4. pk2 = pH
A
  1. -COOH
  2. NH3
  3. amount of form I (net charge +1) equals amount of form II (net charge 0).
  4. amount of form II (net charge 0) equals amount of form III (net charge -1).
31
Q

Amphoteric substance

A

Substances that can act either as an acid or a base.

32
Q

Which type of amino acids serve as buffers

A

Free and charged amino acids

Amino acids (6 decks)

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