Biochemistry - Amino Acids

Question 1

Alpha Amino Acids

Answer 1

These are AA with primary amino grup(NH2)

Question 2

What does pK value measure?

Answer 2

Availability of protons, the lower the less tightly they are held.

Question 3

What are features of Amino Acids?

Answer 3

R Group
Dipolar due to Amino and Carboxylic functional groups readily ionising.

Question 4

Conjugate

Answer 4

This is a substance formed when an acid loses a hydrogen ion

Question 5

Zwitterions

Answer 5

Neutral molecules that intramolecularly have both a positve and negative charge

Question 6

Why is all AA being zwitterions important?

Answer 6

More soluble in polar solvents than nonpolar

Question 7

Where are peptide bonds found?

Answer 7

Between CO and NH by condensation reactions

Question 8

Condensation Reactions

Answer 8

These are reactions between two reactangs yielding one large product and a smaller product such as water.

Question 9

What is the primary structure of protein?

Answer 9

Linear peptide with NTD and CTD with variable electrostatic charges

Question 10

What are the three categories of electrostatic charge of amino side chains?

Answer 10

Polar, Charged or Non Polar

Question 11

Non Polar AA

Answer 11

Nine, like glycine with H and Ala, Val, Leu being aliphatic

Question 12

Aliphatic

Answer 12

These are organic compounds where the carbon atoms form open chains.

Question 13

What is the side chain of methionine?

Answer 13

Thioether side chain

Question 14

Uncharged Polar Side Chains

Answer 14

These have either Hydroxyl, Amide or Thiol groups

Question 15

Serine

Answer 15

This has a thiol group with capacity of disulphide bond formation

Question 16

Amide

Answer 16

This is a functional group containg a carbonyl group and a nitrogen atom

Question 17

Thiol(Sulfhydryl)

Answer 17

These consist of a S with two lone pairs bound to a H

Question 18

Charged Polar Side Chaines

Answer 18

These are either anionic or cationinc, being 5

Question 19

How is histidine unique?

Answer 19

Carrying an imidazole group ionizing readily at physiological pH so can be both neutral or cationic

Question 20

What do polypeptide chains depend on?

Answer 20

Hydration tendency of polar and ionic side chains and non-polar side chains with each other.

Question 21

Hydrophobic Effect

Answer 21

THis is the tendency of non-polar molecules and molecular segments in an aqueous solution to avoid contact with water molecules

Question 22

Which amino acids are optically active?

Answer 22

All except glycine

Question 23

Optically Active

Answer 23

This is the ability of a substance to rotate the plane of polarization of a bean that passes through it.

Question 24

Why are AA optically active?

Answer 24

Chiral Centre

Question 25

Chiral Centre

Answer 25

This is an atom in a molecule bounded to four different chemical species.

Question 26

Enantiomer

Answer 26

Two isomers that cannot be superimposed on one another.

Question 27

Why is chirality important?

Answer 27

It derives enantiomer forms.

Question 28

Superimposition

Answer 28

This is where you may lay two things over one another where you cant tell them apart

Question 29

What are the two Enantiomers of amino acids?

Answer 29

Can exist in L and D forms being mirror images.

Question 30

Plane-polarized light

Answer 30

This is the light form in which the electric field oscillates in a single plane.

Question 31

How does Plane-Polarised Light relate to AA?

Answer 31

Light passing through chiral molecules results in CW or CCW optical rotation

Question 32

Why does AA rotate under plane-polarised light?

Answer 32

Asymmetric arrangement of atoms, where EM radiation interact with electrons, inducing oscillations creating polarized EM field rotation in direction of light propogation

Question 33

What is an example of different biological functions in AA enantiomers?

Answer 33

Thalidomide L forms for sedation whilst D forms birth defects

Question 34

Fischer Projection

Answer 34

This is a 2D representation of a 3D organic molecule

Question 35

Racemic Mixture

Answer 35

This means equal amounts of each enantiomer

Question 36

How is equilibrium favoured in one direction in racemic mixtures?

Answer 36

Chiral processes like enzyme.