Amino Acids and DNA A2

Question 1

What’s the functional group of amino acids

Answer 1

Carboxylic acid and primary amine

Question 2

What are zwitterions

Answer 2

Ions that have a permanent positive and negative charge, but is overall neutral

Question 3

What occurs when amino acids are placed with something highly acidic

Answer 3

The lone pair at the amine accepts a H+ ion, forming a positive ions

Question 4

What occurs when amino acids are placed with something highly alkaline

Answer 4

The -OH loses a proton to form a negative ion

Question 5

What occurs when two amino acids react

Answer 5

Forms an amide linkage -CONH-. This is a peptide

Question 6

What are proteins

Answer 6

Molecules containing more than 50 amino acids, forming a polypeptide

Question 7

What is the primary structure of a protein

Answer 7

A fixed sequence of amino acids for each particular protein

Question 8

What occurs when polypeptides are boiled with HCl calatyst

Answer 8

All the original amino acids are reformed as the bonds are hydrolysed

Question 9

What is the secondary structure of a protein

Answer 9

Forms either a helix or a pleated sheet structure, held together by hydrogen bonds or sulfur-sulfur bonds

Question 10

Where do sulfur-sulfur bonds come from

Answer 10

Amino acids like cysteine has sulfur side chain which can bond the sulfurs together

Question 11

What is the tertiary structure of a protein

Answer 11

The alpha-helix or beta-pleating sheet can itself be folded into 3 dimensions, containing hydrogen bonds, sulfur-sulfur bonds and ionic interactions

Question 12

How can the structure of a protein be identified

Answer 12

Reflux with 6 moldm-3 HCl to hydrolyse the protein into amino acids, forming a mixture. This is then used on thin-layer chromatography

Question 13

Describe thin-layer chromatography

Answer 13

Mixture of amino acids are placed on a starting line and a solvent is placed 0.5cm below the starting line. After some time, the solvent will go up pulling each amino acids at different rates, depending on the affinity for their stationary phase

Question 14

What is done to the amino acids at the end of thin-layer chromatography

Answer 14

Developing agents are sprayed on the plate such as ninhydrin (or UV) to form a purple compound. The amino acids will be separated

Question 15

How to calculate Rf

Answer 15

Distance moved by spot / Distance moved by solvent

Question 16

What are enzymes

Answer 16

Protein-based catalysts, optimised for just one reaction

Question 17

Describe the shape of an enzyme

Answer 17

They have a crevice called the active site, where the catalysis takes place

Question 18

What does stereospecificity mean

Answer 18

The active site of an enzyme is so specific that it can catalyst only one of a pair of enantiomers

Question 19

How to stop an enzyme’s power to catalyse

Answer 19

Enzyme inhibition where a molecule similar to the shape of the substrate is produced, taking its spot. Penicillin does this

Question 20

How are drugs produced to cause enzyme inhibition

Answer 20

Using computers to analyse long protein chains

Question 21

What are nucleotides

Answer 21

Monomers which make up the DNA

Question 22

What makes up a nucleotide

Answer 22

Phosphate group, bonded with the sugar 2-deoxyribose and one of the four organic bases

Question 23

Describe the full structure of DNA

Answer 23

DNA exists as two complementary strands arranged in the form of a double helix, via hydrogen bonds

Question 24

What is the example of an anti-cancer drug

Answer 24

Cisplatin, with the formula Pt(Cl)2(NH3)2

Question 25

How does cisplatin work

Answer 25

They bond to strands of DNA, distorts their shape and stop replication of cells. A dative bond is formed between platinum and a nitrogen atom on guanine

Question 26

What are the issues with cisplatin

Answer 26

They can stop the replication of healthy cells like hair cells