Week 2

Question 1

What are conformers (conformational isomers)?

Answer 1

They are an isomer that differs from another isomer by the rotation of a single bond in the molecule

Question 2

What is more stable: a staggered conformation or an eclipsed conformation? Why?

Answer 2

Staggered conformation is more stable as all the atoms are as far apart from each other as possible.

Question 3

Define isomer?

Answer 3

Molecules with the same molecular formula but different structural formula

Question 4

What are stereoisomers?

Answer 4

isomers with the same order of attachment of atoms, but a different orientation of their atoms in space

Question 5

What is an enantiomer?

Answer 5

Stereoisomers that are non superimposable mirror images of each other

Question 6

What are diastereomers?

Answer 6

Stereoisomers that are not mirror images

Question 7

What are the shapes the molecules make when they are cis- and trans-?

Answer 7

cis- forms a ‘U’ shape. The carbon chain on the same side.

trans- forms a staircase shape. with the carbon chains on opposite sides on the molecule

Question 8

What is chirality?

Answer 8

It is a single bonded carbon bearing four different groups. They are dennoted by an asterisk (*)

Question 9

What is the difference between the R configuration and S?

Answer 9

R configuration is when the groups (that are prioritised 1-3) are arranged in a clockwise direction

S configuration is where the groups are in a counterclockwise direction

Question 10

What is chiral recognition?

Answer 10

This is where a molecule will only fit in a binding site if the molecule is arranged in the correct order. The sites can distinguish between different enantiomers

Question 11

What are the two functional groups that make up an amino acid?

Answer 11

A carboxyl group and an amino group

Question 12

What configuration are natural amino acids found in (L or D)?

Answer 12

They are found in the L-configuration

Question 13

What is the difference between the D and L configuration?

Answer 13

D-configuration is when the amino group is on the right

L-configuration is when the amino group is on the left

Question 14

What are peptides made of?

Answer 14

They are amino acids linked by amide (pepetide) bonds

Question 15

What are dipeptides and polypeptides?

Answer 15

Dipeptide is a molecule containing 2 amino acids linked together

Polypeptides are molecules containing 3 or more amino acids linked together

Question 16

In what direction are polypeptides named?

Answer 16

Written from left to right starting with the N-terminal and moving towards the C-terminal

Question 17

Is peptide synthesis a condensation or hydolysis reaction?

Answer 17

Condensation as it results in the loss of water

Question 18

Explain the difference between primary, secondary, tertiary and quaternary structures of a protein.

Answer 18

Primary is the order in which the amino acids are arranged.

Secondary is how the molecules interact and what bonds are formed. They can form ß sheets or an alpha helix

Tertiary is the folding pattern of the protien and the creation of a sub-unit

Quatenary is how the subunits interact with other subunits

Question 19

Aldohexoses are a group of carbohydrates. Are natural aldohexoses found in the L or D configuration?

Answer 19

They are found in the D-configuration