Amino Acids and Peptides

Question 1

Gama Amino Acid Outline

Answer 1

3 Cs between amine and carboxyl group

Question 2

Beta Amino Acid Outline

Answer 2

2 Cs between amine and carboxyl group

Question 3

Alpha Amino Acid Outline

Answer 3

Amine and carboxyl group are attached to the same C

Question 4

Where are all proteins made

Answer 4

The ribosome

Question 5

Where peptides can be made

Answer 5

Both in and out of ribosome. Amino acids synthesized mainly in prokaryotes by an enzyme

Question 6

How many different amino acids are there and how are they differntiated

Answer 6

20. Each has a different side chain (20 different side chains)

Question 7

Alpha C Outline

Answer 7

C with amine (NH3+), carboxyl (CO(double)O-(single)), H and side chain attached

Question 8

Amino Acid charge

Answer 8

Zwitterion. Contains both positive and negative charge. Undergoes internal acid and base reactions (internal salts). Indicates it’s properties

Question 9

Characteristics of amino acid zwitterions

Answer 9

High boiling point, water soluble and crystalline

Question 10

Alpha C simple structure

Answer 10

C-CO^-(single)O(double)-R-

Question 11

Non-polar aliphatic (straight chain) group (Hydrophobic)

Answer 11

Valine, Alanine, Glycine, Isoleucine, Leucine and Methionine

Question 12

Non-polar aromatic (aromatic) group (realtively hydrophobic)

Answer 12

Phenylalanine, tyrosine and tryptophan

Question 13

Polar uncharged group (hydrophilic)

Answer 13

cysteine, serine, asparagine, proline (both hydrophilic and hydrophobic), threonine and glutamine

Question 14

Polar negatively charged group (hydrophilic)

Answer 14

Aspartic acid and Glutamic acid

Question 15

Polar positively charged group (hydrophilic)

Answer 15

Lysine, arginine and histidine

Question 16

Why histidine is sometimes shown with no charge on side chain

Answer 16

histidine has 2 forms. pKa = 7, side chain is easily protonated

Question 17

Acid charge at physiological pH

Answer 17

negative

Question 18

Base charge at physiological pH

Answer 18

positive

Question 19

2 sulfur containing side chains

Answer 19

cysteine and methionine

Question 20

How many amino acids are chiral

Answer 20

19/20. Glycine is chiral

Question 21

How many amino acids are S oriented

Answer 21

18 out of 19 chiral aas. CO2^- (carboxyl) is higher priority then side chain

Question 22

How many amino acids are R oriented

Answer 22

1 out of 19 chiral aas. For cystine side chain (due to presence of S) is higher priority then carboxyl

Question 23

What direction do alpha amino acids in proteins deflect light

Answer 23

Anticklockwise (left). Levo isomers

Question 24

Macromolecules formed from alpha amino acid polymerisation

Answer 24

Polyamide (linear alpha amino acid backbone, peptide (C to N bonds) and side chains (branch off polyamide, type and distance dictates function).

Question 25

Peptide Order Def

Answer 25

Defined order of peptide bonds. If order is rearranged function of protein is altered

Question 26

Covalent bonds in peptide and proteins

Answer 26

Disulfide bond between 2 cysteine side groups

Question 27

Protein Functions

Answer 27

Give elasticity to skin, muscle/tendon composition, antibody, haemoglobin and enzymes

Question 28

2 Protein Classifications

Answer 28

Fibrous (insoluble, no defined shape) and globular (soluble, spherical)

Question 29

Fibrous Protein Examples

Answer 29

Keratins (protective tissue), collagens (connective tissue) and silks (spiders webs)

Question 30

Globular Protein Examples

Answer 30

Enzymes (biological catalysts), Hormones (chemical messangers) and Transport proteins (haemoglobin, myoglobin)

Question 31

Primary Structure Outline

Answer 31

Sequence of amino acids (exact sequence dictates progression of protein's shape).

Question 32

H bonds Outline

Answer 32

Formed between 2 amine bonds. Slightly positive H and slightly negative O

Question 33

Quaternaty Structures Outline

Answer 33

2+ polypeptides assemble together to form protein structure. Held together by H bonds, hydrophobic and electrostatic interactions

Question 34

Tertiary Structure Outline

Answer 34

Bending/folding/twisting of secondary structures. Involves interactions with side chains between non-adjacent molecules. Stabilised by non-covalent bonds (H bonds, salt bridges and hydrophobic interactions)

Question 35

Secondary Structure Outline

Answer 35

3 dimensional repeating pattern. Alpha helix and beta pleated sheets. Covalent (amide) bonds hold sequence together, hydrophobic forces twist structure and H bonds stabilise structure

Question 36

Alpha Helix Outline

Answer 36

Polypeptide backbone coiled as a screw with side chains sticking out. Side chain interactions between proteins dictate behaviour. H bonds extend from H on NH to O 4 substituents away

Question 37

Beta Pleated Sheets Outline

Answer 37

Several protein chains stacked together side by side while running in opposite direction (anti-parallel). NH bonds to carbonyl group on opposite chain