A-Level OCR Chemistry Salters B - Polymers and life

What are the conditions for esterification using a carboxylic acid?

60°C

Conc sulfuric acid

What are the conditions for esterification using an acyl chloride or acid anhydride?

60°C

Anhydrous conditions

What is condensation?

A reaction where 2 small molecules react together to form a larger molecule with the elimination of a small molecule (e.g. H₂O)

What is a primary amine?

A carbon that's bonded to a nitrogen that's bonded to 2 hydrogens

What is a secondary amine?

A carbon bonded to a nitrogen that's bonded to another carbon and a hydrogen

Give 3 properties of an amine

-They act as a base (lone pair is a H⁺ acceptor)

-They act as a nucleophile

-They're responsible for solubility

How do you go from ammonia to a primary amine to a secondary etc

Add halogenated alkanes

How do you name nylons?

Nylon then the number of carbons on the amine followed by the number of carbons on the carboxylic acid or acyl chloride etc

What happens when an amide is split using hydrolysis under acidic conditions?

The acid or acyl chloride etc is formed then the amine converts to NH₃⁺ due to it acting as a base

What happens when an amide is split using hydrolysis under alkaline conditions?

An amine is formed then a carboxylate ion is formed from the acid

What is a zwitterion?

They act as a buffer by keeping pH constant due to them having a positive and negative charge

What is the bond between amino acids called?

Peptide bond

What is optical isomerism?

When the mirror images of a molecule are non super imposable.

It happens when there are 4 different groups around the alpha carbon

What is an enantiomer?

Optically active molecule

What is a racemic mixture?

A 50/50 split of the 2 enantiomers (mirror images of a molecule)

What is a chiral center?

A carbon surrounded by 4 different groups

Why isn't the amino acid Glycine optically active?

It doesn't have 4 different groups around the chiral carbon

How do you know if a ring structure shows optical isomerism?

Look for asymmetry

What is the primary structure of a protein?

The order of amino acids

What is the secondary structure of a protein?

The formation of alpha helices and beta sheets

What is there tertiary structure of a protein?

The folding of secondary structure to make a three dimensional structure

What makes up a nucleotide?

Phosphate, sugar and nitrogenous base

What is DNA?

The genetic blueprint of life

How are the phosphate and deoxyribose bonded by?

Condensation polymerisation

How are the nitrogenous bases bonded together?

Hydrogen bonds

How many hydrogen bonds hold A and T together?

2

How many hydrogen bonds hold G and C together?

3

What is the difference between DNA and RNA

RNA's sugar is ribose rather than deoxyribose

Has Uracil rather than Thymine

What is transcription?

Copying of DNA to mRNA

What do tRNA have?

An amino acid binding site at one end

What is a first order reaction in terms of enzymes?

As you double the concentration of the substrate, the rate of reaction doubles

What is a zero order reaction in terms of enzymes?

As you double the concentration of the substrate, the rate of reaction stays the same

How does pH affect enzyme activity?

A change in pH above optimum reduces activity because it breaks the ionic bonds holding the tertiary structure together which alters the shape of the active site so the substrate can't bind

Why does enzyme activity exponentially increase when temp increases until it reaches optimum?

More particles have kinetic energy greater than or equal to the activation enthalpy

Why does the enzyme activity decrease above optimum temperature?

The hydrogen bonds holding the tertiary structure together vibrate more and break changing the structure of the active site

What is an enzyme inhibitor?

They block the active site

What is a competitor inhibitor?

They form weak bonds with the enzyme then leave so they compete with the substrate

How can you change the competitiveness of a competitive inhibitor?

Change their concentration

What is a non-competitive inhibitor?

They form strong covalent bonds with the enzyme so they block the substrate form binding

What is a pharmacophore?

The part of the molecule that causes the pharmacological effect

Why may more than one pharmacophore need to be created?

To reduce side effects

How do pharmacophores work?

They form intermolecular bonds with the receptor sites and have the correct size and shape to fit

What do the peaks on ¹³C NMR show?

The number of carbon environments

What is TMS used for in NMR?

It's a blank and is used as a reference

What is low resolution proton NMR

It just looks at hydrogen environments

What does high resolution proton NMR show?

The relative number of hydrogens in each environment

What is the n+1 rule?

It shows the number of hydrogens attached to the neighbouring carbon(s)

How is peak splitting caused in NMR?

By spin-spin coupling of electrons because of interference between adjacent non-equivalent nuclei

What is the 3 bonds apart rule?

Splitting can only be caused by protons in an environment no more than 3 bonds apart