BSI Lecture 2 Protein Structure

Question 1

What are proteins made of ?

Answer 1

Amino acids

Question 2

Primary protein structure

Answer 2

Amino acid sequence

Question 3

Secondary protein structure

Answer 3

Formation of alpha helix and beta sheets

Question 4

Tertiary protein structure

Answer 4

Overall 3-dimensional shape of protein

Question 5

Quaternary protein structure

Answer 5

More than one polypeptide (dimers, oligomers)

Question 6

How many amino acids are there?

Answer 6

20 (8 essential and 12 nonessential)

Question 7

What is the basic structure of an amino acid?

Answer 7

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

Question 8

Asp

Answer 8

Aspartic acid, negative (acidic side chain)

Question 9

Glu

Answer 9

Glutamic acid, negative (acidic side chain)

Question 10

Arg

Answer 10

Arginine, positive (basic side chain)

Question 11

Lys

Answer 11

Lysine, positive (basic side chain)

Question 12

His

Answer 12

Histidine, positive (basic side chain)

Question 13

Asn

Answer 13

Asparagine, uncharged polar

Question 14

Gln

Answer 14

Glutamine, uncharged polar

Question 15

Ser

Answer 15

Serine, uncharged polar

Question 16

Thr

Answer 16

Threonine, uncharged polar

Question 17

Tyr

Answer 17

Tyrosine, uncharged polar

Question 18

Ala

Answer 18

Alanine, nonpolar

Question 19

Gly

Answer 19

Glycine, nonpolar

Question 20

Val

Answer 20

Valine, nonpolar

Question 21

Leu

Answer 21

Leucine, nonpolar

Question 22

Ile

Answer 22

Isoleucine, nonpolar

Question 23

Pro

Answer 23

Proline, nonpolar

Question 24

Phe

Answer 24

Phenylalanine, nonpolar

Question 25

Met

Answer 25

Methionine, nonpolar

Question 26

Trp

Answer 26

Tryptophan, nonpolar

Question 27

Cys

Answer 27

Cysteine, nonpolar

Question 28

Which amino acids can be phosphorylated? Why?

Answer 28

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

Question 29

Which amino acid can form disulfide bonds? Why?

Answer 29

Cysteine because it contains SH functional group

Question 30

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

Answer 30

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

Question 31

3 Facts about Primary Structures

Answer 31

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

Question 32

What is the end of the protein?

Answer 32

Carboxyl Group

Question 33

What is the beginning of the protein?

Answer 33

Amino Group

Question 34

4 Facts about Secondary Structures

Answer 34

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

Question 35

4 Facts about Tertiary Structures

Answer 35

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

Question 36

Facts about Quaternary structures

Answer 36

More than one polypeptide chain (dimers and oligomers)

Question 37

Hydrogen bond

Answer 37

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

Question 38

Hydrophobic interaction

Answer 38

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

Question 39

Ionic bond

Answer 39

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

Question 40

Van der Waals attraction

Answer 40

The attraction of intermolecular forces between molecules.

Question 41

Disulfide bridge

Answer 41

A covalent bond derived from two thiol groups.

Question 42

Homodimer

Answer 42

Formed by two identical molecules (a process called homodimerisation)

Question 43

Heterodimer

Answer 43

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

Question 44

Oligomer

Answer 44

a molecular complex that consists of a few monomer units.