Polymers, Amino Acids & DNA Flashcards
What is a polymer
A long chain molecule formed from thousands of small molecules called monomers
What are the 2 types of polymer
Addition
Condensation
What happens during addition polymerisation
Unsaturated molecules (alkenes) add together
How are condensation polymers formed
By a condensation reaction where a small molecule like water is released
What are 2 examples of condensation polymers
Polyamides
Polyesters
What are 2 ways condensation polymers are formed
2 moments with functional groups at both ends of the molecule
One monomer such as amino acid with 2 functional groups on the molecule
How are polyesters formed from 2 monomers and 1 monomer
Do carboxylic acid and a diol
One monomer with both the carboxylic acid and the alcohol group
Where is the H and OH lost from when drawing repeating units of polyesters
OH from the carboxylic acid
H from the alcohol group
What is the ester link
C double bond O and O
How many molecules of water are lost when polyesters are made
(2n-1)
What 2 monomers are reacted to form polyamides
What monomer is used to form polyamides
Dicarbixylic acid and a diamine
Or react amino acids which have both groups
What is the H and OH lost from when drawing polyamide repeat units
OH from carboxylic acid
H from amine
Draw an amide link
Photo
What 2 monomers make terylene
Benzene 1,4 dioic acid
Ethane 1,2 diol
How many water molecules are lost when polyamides are formed
(N-1)
How is Kevlar made
Benzene 1,4 dioic acid
Benzene 1,4 diamine
What is a property and use of Kevlar
Incredibly tough
Bulletproof jackets
What 2 monomers are used to make nylon6,6
Hexanedioic acid
Hexane 1,6 diamine
What are polyesters used to make
Fibres and plastic bottles for fizzy drinks
Why is pet the main plastic for making fizzy drink bottles (3)
It’s light, strong and resistant to corrosion
What is hydrogen bonding in polyamides
The lone pair on oxygen in the C double bond O forms a hydrogen bond with the delta positive bridges in the NH of another chain
Where do permanent dipole dipole forces exist in polymers
In polyesters and addition polymers that have electronegative atoms as functional groups
In acid hydrolysis of polyesters what is formed
What type of reaction is it
The carboxylic acid and the diol
Reversible
In base hydrolysis of polyesters what is formed
The salt of the carboxylic acid and the diol
How do you get the carboxylic acid back in de hydrolysis of polyesters
By neutralising the salt
What is formed in the acid hydrolysis of polyamides
What type of reaction is it
The carboxylic acid
The di ammonium ion (pronated diamine)
Reversible reaction
What is formed in the base hydrolysis of polyamides
The salt of the carboxylic acid and the diamine
Why is base hydrolysis the preferred method
It’s not a reversible reaction so 100% yield can be achieved
Whereas acid hydrolysis is reversible so it has a lower yield
What are 3 ways of disposing of polymers
Landfill
Recycling
Burning / incineration
What is 2 advantages of recycling
It reduces the amount of plastic disposed in landfill sites
It conserves crude oil which is the source of most monomers used
What is a disadvantage of recycling
The plastics must be collected, sorted and processed which is expensive
Why are addition polymers chemically unreactive
They are saturated compounds and don’t have polar bonds
What is an advantage of addition polymers being non polar
What is a disadvantage
They are useful as they aren’t attacked by acids, bases or oxidising agents
It makes them non biodegradable
Why are polyalaknes not bio degradable (3)
They are inert
They have polar bonds
Not easily attacked by nucleophiles
Why are condensation polymers biodegradable (2)
They gave polar bonds
Can be hydrolysed by Nucleophiles
Draw the general structure of amino acids
Photo
Why do amino acids exhibit both basic and acidic properties
They have both a carboxylic acid and an amine group
How is the NH2 group in amino acids basic
It can gain a H+ ion to form NH3+
Why is the COOh group acidic
It cha lose a H+ to form COO- ion
How do amino acids act as acids and as bases
They donate protons to bases
As bases they accept protons from acids
What is the structure of glycine
Photo
What are amino acids like in their pure state (3)
White crystalline solids with a relatively high melting point for their mr
Generally soluble in water to produce a solution that conducts electricity
Most insoluble in non polar solvents
Why do amino acids have high melting points
They have ionic bonding in their solid form as they exist as zwitteriojs in their pure state
What is a zwitterion
A diplomat in with both a positive and negative change on different parts of the molecule
What is the isoelectric point
The ph at which the overall charge on an amino acid is 0
What happens when the ph is decreased in amino acids in their pure state (zwitterions)
The COO- group gains a proton
What happens when the ph is increased in amino acids in their pure state
The NH3+ group loses a proton
What is the most important reaction of amino acids and how does it occurs
Polymerisation
Occurs by condensation reactions
How are peptides and proteins formed
The enzymes catalyse the polymerisation of amino acids in living organism
How is a tripeptide formed
From 3 amino acids
How are polypeptides formed (2)
From joining many amino acids
Or linking 2 peptide chains together
What are the conditions for hydrolysing proteins
Boiling the protein with 6mol dm-3
HCL for 24 hours
Why do amino acids have different RF values
They have different r groups so they have different solubilities in the mobile phase
What chemical makes amino acids visible in tlc
Ninhydrin
What is the primary structure in proteins
The order or sequence of amino acids in the protein chain
What is the secondary structure id proteins
The hydrogen bond interaction between amino acids within the same chain causing the chain to have areas of 3D sections
What do the secondary structures of amino acids consist of (2)
Alpha helix
And beta pleated sheets
What is the tertiary structure of proteins and why does this occur
The way in which the protein helix is bent, twisted or folded
The interactions between R groups in the amino acids that make up the protein
What are the possible interactions between R groups in amino acids
Hydrogen bonding
Ionic bonding
Dipole dipole interactions
S-S bonds
When do hydrophobic interactions occur
Between non polar side chains in tertiary structures
When do disulfide bonds occur
Between 2 amino cysteine amino acids in tertiary structures
What type of reaction is a disulfide bond formation
Oxidation (loss of hydrogen )
What are all enzymes
Proteins
What part of the enzymes is involved in catalysis
What is the rest if the amino acids for
The active site
Maintaining the precise shape of the enzyme and active site
What is stereospecific
The active sites of enzymes only bind / react with one particular stereoisomer (ez or optical)
What do active sites of enzymes do
They bind the substrate molecules of a biochemical reaction
Why is it important to maintain the specific physical and chemical requirements of enzymes
Changes in physical (temp) or chemical (ph) factors can break the secondary and tertiary structures which changes the active site and affects catalytic activity
What are enzymes inhibitors
Molecules that have similar shapes to the active site and compete with the reactant molecules (substrates) to bond to the active site
What happens when enzyme inhibitors block active sites
They prevent catalysis from happening as the reactant molecules can’t fit into the active sites anymore
What does the amount of inhibition depend on (3)
The relative concentrations of reactant (substrate) and inhibitors
The more inhibits the more active sites blocked
Also depends how strongly the inhibitor bonds to the active site
How can enzyme inhibition be useful
It is used in some antibiotics to block the active sites of an enzyme in bacteria which makes cell walls
This causes the cell walls to weaken and over time the bacteria bursts
How are enzyme inhibitors developed
Computers are used to model the shape of the enzyme active site and predict how well potential drugs will bind with the active site
What are nucleotides
Nitrogen containing organic substances that form the basis of the nucleic acids dna and rna
What 3 groups do all nucleotides contain
Phosphate group (circle )
Nitrogen containing base (hexagon)
Penrose sugar (pentagon )
What is the sugar in dna
2 depxyribose
What forms the basis of the nucleic acid DNA
Polynucleotides which are formed by nucleotides polymerising
How are 2 DNA nucleotides joined
What type of reaction is it
When the OH group on C3 joins to the phosphate group on C5 to form a phosphodiester bond
Condensation
What are the complimentary pairs in DNA
How are they linked
AT and CG
Hydrogen bonds
How many hydrogen bonds are C and G linked by
3
How many hydrogen bonds are A and T linked by
2
How does cis platin work
It prevents dna replication by preventing the DNA double helix molecule from unwinding
It does this by forming co ordinate bonds with the nitrogen in the dna base guanine
What are 3 risk of using cis platin
Prevents normal cells form replicating too (hair loss)
Patients experience side effects like nausea and kidney damage
Patients can become resistant to cis platin
What are 2 reasons cis platin is still used despite the side effects
The benefits outweigh the side effects
Doctors use small amounts to reduce the side effects
