Amino Acids

Question 1

Proteins

Answer 1

Are large macromolecules made up of a chain of amino acids joined together by peptide bonds.

Made by transcription of DNA and RNA and then translation of RNA and Protein.

Question 2

amino acids

Answer 2

building blocks of proteins/ monomers of proteins

Tetrahedral structures

amino acids can be L or D config.

Question 3

L amino acids

Answer 3

ALL NATURAL AA IN PROTEINS ARE L CONFIG.

manufactured in cells and incorporated into proteins

Question 4

D amino acids

Answer 4

generally found in cell wall of bacteria

Question 5

Amino Acid - Classification Types

Answer 5

1. on the basis of R group
   hydrophobic, hydrophilic, acidic and basic
2. on the basis of nutrition
   essential, conditionally non essential and non essential
3. on the basis of catabolism
   glucogenic, ketogenic or both glucogenic and ketogenic

Question 6

on the basis of the R group – Hydrophobic

Answer 6

As a result of being hydrophobic most are buried within the core of a protein structure.

Question 7

on the basis of the R group – Hydrophilic

Answer 7

As a result of being hydrophilic most are on the outside of a protein structure.

Question 8

amino acid classification – extra info!!

Answer 8

the properties and residues can shift depending on the environment

Question 9

AA classifications

Answer 9

Non polar (9AA)
Polar (6AA)
Acidic (2AA)
Basic(3AA)

Question 10

Additional Descriptions within groups:

Answer 10

Aliphatic
Aromatic
Amide
Thiol (Sulfur-Containing)
Hydrophobic
Hydrophilic
Charge (positive, negative or neutral)
Special characteristics of individual AA

Question 11

Non Polar Amino Acids

Answer 11

Non Polar covalent bonds: 2 atoms share a pair of electrons with each other

All Hydrophobic

Question 12

Polar -Neutral Amino Acids

Answer 12

Polar covalent bonds: 2 atoms share a pair of electrons unequally

Side chains are uncharged at neutral pH

All hydrophilic (except tyrosine, although its more hydrophilic than Phe)

Question 13

Acidic Amino Acids

Answer 13

Contain carboxyl groups

Negatively charged at physiological pH, present as conjugate bases

Hydrophilic

Carboxyl groups function as nucleophiles in some enzymatic reactions

Question 14

carboxyl groups

Answer 14

weaker acids than a-carboxyl group

Question 15

nucleophiles

Answer 15

can donate an electron pair to form a chemical bond

Question 16

Basic Amino Acids

Answer 16

Hydrophilic nitrogenous bases

Positively charged at physiological pH

Question 17

Zwitterion

Answer 17

also called a dipolar ion

No net charge

Question 18

Ionisation

Answer 18

Is the process where a molecule becomes positively or negatively charged by gaining/losing electrons

Question 19

Acids and Bases

Answer 19

Acids are proton (H+) donor

Bases are proton (H+) acceptors

Question 20

pH

Answer 20

Provides a simple index for expressing the (H+) level.

pH is indicated in terms of the following expression, where the smaller the number, the stronger the acidity (higher proton concentration)

NOTE= One important point regarding pH is that a change of only 1 in the pH value is equivalent to a 10-fold change in proton concentration.

Question 21

strong acids

Answer 21

completely dissociate in water

Question 22

weak acids

Answer 22

partially dissociate

Question 23

what happens when an acid dissociates??

Answer 23

It releases a proton to make the solution acidic, but weak acids have both a dissociated state (A-) and an undissociated state (AH) that coexist according to the following dissociation equilibrium equation.

Question 24

pKa and pH relationship

Answer 24

pKa and pH are equal when exactly half of the acid has dissociated.

Question 25

Weak Acid pKa

Answer 25

for a weak acid, the Pka is the pH where there is an equal amount of ionised and non-ionised molecules.

Question 26

pl (isoelectric point)

Answer 26

The pH at which the number of positive and negative charges on a population of molecules is equal (i.e. no net charge)