3.3.12-13 Polymers, DNA, proteins and amino acids Flashcards
How do you produce a polyester?
- Dicarboxylic acid + diol (ester bond)
- Hydroxycarboxylic acids
What monomers is Terylene made from?
Ethane-1,2-diol
Benzene-1,4-dicarboxylic acid
How do you produce polyamides?
Diamine + dicarboxylic acids
What monomers is Nylon-6,6 made from?
1,6-diaminohexane
1,6-hexanedioic acid
What monomers is Kevlar made from?
1,4-benzenediamine
1,4-benzenedicarboxylic acid
Why does Kevlar have a high melting point ?
- Chains are straighter, lie closer together
- Hydrogen bonds form between the N-H polar bonds and lone pair on the C=O in the amide bonds
What is the use of polyesters like Terylene?
- Thermoplastic that can form fine fibres
- Use in artificial fabrics
- Moulded into plastic bottles and containers
What is the use of the artificial polyamide Nylon-6,6?
- Cheap substitute for silk
- Use in ropes, velcro, clothing and carpets
What is the use of the aromatic polyamide Kevlar?
- Tough and lightweight
- Bulletproof vests
Why are polyesters and polyamides preferred over polyalkenes?
- Polyesters/amides are more easily broken down in landfill sites using hydrolysis reactions
- Hydrolyse the ester/amide bond
- Polyalkenes are inert due to the C-C bond between the monomers
What three ways can polymers be disposed of?
Landfill
Incineration
Recycling
What are the advantages and disadvantages of landfill?
+ve = biodegradable polymers slowly degrade
-ve = limited land available, leaching of toxic compounds, gas emissions (methane)
What are the advantages and disadvantages of incineration?
+ve = energy released for generating electricity, less space than landfill
-ve = CO2 gas emissions, toxic gas emissions
What are the advantages and disadvantages of recycling?
+ve = reuse and conservation of hydrocarbon resources, less waste to landfills
-ve = time consuming, expensive, requires energy for collection/sorting/seperating/remoulding
What bond forms between amino acids and how?
Amide bond
Condensation reaction
What happens to amino acids in acidic/alkaline conditions?
Acidic = Gain proton at -NH2
Alkaline = Lose proton at -OH
What are amino acids said to be because of their basic/acidic properties?
Amphoteric
What is a zwitterion?
Where does it occur?
- Amino acid with both a positive NH3+ and a negative COO-
- A solution of amino acid in water will exist as zwitterons (acting as a buffer)
What is it called when the zwitterion is neutral (neither negative/positive is dominating)?
Isoelectric point of the amino acid
What bonds are found in the tertiary structure of a protein?
What do they occur between?
Occur between the R groups of amino acids:
- Hydrogen bonds
- Ionic bonds
- Disulfide bridges
- Hydrophobic interactions
How do you hydrolyse an amide bond?
- Concentrated HCl and heat
- Enzymes
Why can only certain stereoisomers of a drug be useful in treating a disease?
Receptor sites for drug are stereoselective, active site of enzyme only has complimentary shape to the correct isomer.
What are the two ends of a DNA molecule that are recognised by an enzyme?
3’ (OH- on bottom deoxyribose sugar)
5’ (carbon on top phosphate)
How many hydrogen bonds form between each of the base pairs in DNA?
C≡G
A=T
