BSI Lecture 2 Protein Structure Flashcards Preview

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Flashcards in BSI Lecture 2 Protein Structure Deck (44):
1

What are proteins made of ?

Amino acids

2

Primary protein structure

Amino acid sequence

3

Secondary protein structure

Formation of alpha helix and beta sheets

4

Tertiary protein structure

Overall 3-dimensional shape of protein

5

Quaternary protein structure

More than one polypeptide (dimers, oligomers)

6

How many amino acids are there?

20 (8 essential and 12 nonessential)

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What is the basic structure of an amino acid?

Central carbon (alpha carbon) with a single hydrogen atom, amino group, a carboxyl group, and a side chain (R group).

8

Asp

Aspartic acid, negative (acidic side chain)

9

Glu

Glutamic acid, negative (acidic side chain)

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Arg

Arginine, positive (basic side chain)

11

Lys

Lysine, positive (basic side chain)

12

His

Histidine, positive (basic side chain)

13

Asn

Asparagine, uncharged polar

14

Gln

Glutamine, uncharged polar

15

Ser

Serine, uncharged polar

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Thr

Threonine, uncharged polar

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Tyr

Tyrosine, uncharged polar

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Ala

Alanine, nonpolar

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Gly

Glycine, nonpolar

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Val

Valine, nonpolar

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Leu

Leucine, nonpolar

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Ile

Isoleucine, nonpolar

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Pro

Proline, nonpolar

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Phe

Phenylalanine, nonpolar

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Met

Methionine, nonpolar

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Trp

Tryptophan, nonpolar

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Cys

Cysteine, nonpolar

28

Which amino acids can be phosphorylated? Why?

Serine, Threonine, and Tyrosine because they have a hydroxyl group (OH).

29

Which amino acid can form disulfide bonds? Why?

Cysteine because it contains SH functional group

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What are the 8 essential amino acids that can't be produced by the body?

Threonine, Methionine, Lysine, Valine, Leucine, Isoleucine, Phenylalanine, Tryptophan

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3 Facts about Primary Structures

1. Stabilized by peptide bond
2. Peptide bond is covalent
3. Bond forms between amino group and and carboxyl group, resulting in the loss of a water molecule

32

What is the end of the protein?

Carboxyl Group

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What is the beginning of the protein?

Amino Group

34

4 Facts about Secondary Structures

1. Alpha helix and beta sheets are most common
2. Hydrogen bonds stabilize
3. Hydrogen bonds are non-covalent
4. Hydrogen bond between back
5. Very stable and rigid structures
6. These structures do not involve unique side chains, therefore they do not require a unique amino acid sequence to form

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4 Facts about Tertiary Structures

1. Folded polypeptide strand into three dimensional shape (no two proteins will have the same tertiary structure)
2. Determined by unique amino acid sequence
3. Domains
4. Types of bonds that will stabilize tertiary structures are Hydrogen bonds, Ionic bonds, hydrophobic interactions, Van der Waals attractions, and Disulfide bonds

36

Facts about Quaternary structures

More than one polypeptide chain (dimers and oligomers)

37

Hydrogen bond

weak interactions that form between a hydrogen with a partial positive charge and a more electronegative atom

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Hydrophobic interaction

The tendency of nonpolar molecules in a polar solvent (usually water) to interact with one another.

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Ionic bond

The complete transfer of valence electron(s) between atoms that form a cation and anion.

40

Van der Waals attraction

The attraction of intermolecular forces between molecules.

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Disulfide bridge

A covalent bond derived from two thiol groups.

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Homodimer

Formed by two identical molecules (a process called homodimerisation)

43

Heterodimer

A heterodimer is formed by two different macromolecules (called heterodimerisation).

44

Oligomer

a molecular complex that consists of a few monomer units.

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