Amino Acids

Question 1

Amino Acid Groups

Answer 1

NH2 and COOH
alpha aa has NH2 and COOH bonded to same carbon

Question 2

Amino Acid Structure

Answer 2

Question 3

Amino Acid if R group is H

Answer 3

Glycine

Not Optically Active

Question 4

Amino Acid if R group is CH3

Answer 4

Alanine

Optically Active - most aa are

Question 5

Two Groups in Equilibrium w/ H+ Ions

Answer 5

Question 6

Equilibria in Acidic Solution

Answer 6

A is pushed RHS
B is pushed LHS

Question 7

Amino Acid In Low pH

Answer 7

Question 8

Equilibria in Alkaline Solution

Answer 8

A is pushed LHS
B is pushed RHS

Question 9

Amino Acid in high pH

Answer 9

Question 10

Zwitterion

Answer 10

have a permanent positive and negative charge, but are neutral overall

Question 11

Isoelectric Point

Answer 11

Certain pH amino acid exists as a dipolar zwitterion

Question 12

Structure and IUPAC
Glycine

Answer 12

Aminoethanoic Acid

Question 13

Structure and IUPAC
Alanine

Answer 13

2-aminopropanoic acid

Question 14

Structure and IUPAC
Lysine

Answer 14

2,6-diaminohexanoic acid

Question 15

Structure and IUPAC
Glutamic Acid

Answer 15

2-aminopentanedioic acid

Question 16

Physical Properties Amino Acids

Answer 16

•high mp
-exist as dipolar ions - attraction between is strong

•soluble in water
-dipolar ions can interact with polar water molecules

Question 17

Amino Acid w/ Sodium Carbonate

Answer 17

Reactions occur at COOH

Obsv: bubbles of colourless gas(CO2)

Question 18

Amino Acids w/ Nitrous Acid

Answer 18

HNO2 formed in situ from sodium nitrite and HCl

NH2 replaced by OH

Obsv: bubbles colourless gas (N2)

Question 19

Glycine w/ Copper(II) Sulfate

Answer 19

Complex formed with coord number 4

Glycine acts as bidentate ligand

Obs: blue solutions formed on mixing

Question 20

Formation of Peptides

Answer 20

Amino acids react together in condensation reaction to form peptides

Question 21

Acid Hydrolysis of a Peptide

Answer 21

Amino acids formed are protonated - all NH2 become NH3+

Positive amino acid ions

COOH stay as COOH

Question 22

Alkaline Hydrolysis of Peptide

Answer 22

Amino acids are deprotonated - all COOH become COO-

Negative amino acid ions

NH2 stay as NH2

Question 23

How may Amino Acids prod in Hydrolysis be seperated and identified

Answer 23

Thin-Layer Chromatography

Colourless so Ninhydrin stain used to locate position of spot

Rf used to identify amino acids

Question 24

Primary Protein

Answer 24

Sequence of amino acids joined by peptide links in a chain

Question 25

Secondary Protein

Answer 25

twisted/coiled ß-pleated sheet/a-helix which is formed and held together by intramolecular hydrogen bonding

Question 26

Tertiary Protein

Answer 26

bending/folding of the secondary structure to give a precise 3D shape which is held together by H bonding/disulfide bridges/ionic interactions/van der Waals forces

Question 27

Enzyme

Answer 27

Protein that is a biological catalyst

Question 28

Active Site

Answer 28

Site on surface of the enzyme into which its substrate fits

Question 29

Induced Fit Model

Answer 29

involves the substrate inducing a change in the shape of the active site of the enzyme

Question 30

Enzymes Stereospecific

Answer 30

Only one optical isomer of a substrate will fit into active site

Question 31

Enzyme Function Temp Dependant

Answer 31

Optimum temp in which function is at maximum Higher temp = denatured - coiling and folding break down Peptide bonds do not break above opt temp

Question 32

Enzymes Optimum pH

Answer 32

Enzyme denatures when pH altered due to equilibrium of NH2 and COOH group alters - changing bonding Peptide bonds not broken

Question 33

Enzymes in Biological Washing Powders/Liquids

Answer 33

Added to break down biological molecules in stains - trad detergents without enzymes may not be able to remove stains of blood and fatty food stains **Protease** added to breakdown protein stains **Amylase** break down carb **Lipase** break down fats, hudrolysis Allows washing powders to function at lower temp - more cost effective