F334 The Thread of Life

HideShow resource information
DNA is made of how many strands?
It's a double-stranded helix
1 of 33
What are the strands made from?
sugar groups (deoxribose), phosphate groups and bases adenine, thymine, cytosine and guanine
2 of 33
What is the 'backbone' and how is it made?
A sugar phosphate backbone made from a condensation reaction between the sugar and phosphate groups
3 of 33
How many bases are joined to each sugar residue and how?
One and a condensation reaction
4 of 33
How are the strands of DNA held together?
Hydrogen bonds between pairs of bases
5 of 33
What are the pairs of bases? (Complementary base pairing)
Adenine with thymine and cytosine with guanine
6 of 33
What does base pairing allow for?
A DNA molecule to copy itself before cell division - a process called replication
7 of 33
In 1953, Francis Crick and James Watson published what?
A proposition for the double-helix structure of DNA
8 of 33
What is a nucleotide?
A substance that acts as a monomer to form the condensation polymers that DNA is made from. It contains one sugar, one phosphate and one base joined together
9 of 33
Describe protein synthesis
DNA unzipped. Code transcibed into mRNA. mRNA passes from cell nucleus to cyptoplasm. Ribosomes translate the code. Each 3base codon on mRNA strand = 1 amino acid. Amino acids brought to ribosome by specific tRNA molecules and joined to make protein
10 of 33
How does DNA fingerprinting work?
Sample is cut into fragments using a restriction enzyme. Fragments separated by size using electrophoresis. Each fragment marked with probe and exposed on X-ray film. Pattern of black bars produced - DNA fingerprint
11 of 33
What are the units of rate of reaction?
mol dm-3 s-1
12 of 33
How do you work out the rate of reaction?
change in concentration of reactant or product / time taken
13 of 33
What is the rate-determining step?
The slowest step in a multi-step reaction
14 of 33
What is a chiral centre?
An atom that has 4 different atoms/groups attached to it.
15 of 33
Optical isomerism is possible when what is present?
Chiral centre with non-superimposable mirror images
16 of 33
In what 2 ways do optical isomers behave differently from each other?
Rotate the plane of plane-polarised light in different directions (l-isomer rotates it anticlockwise and d rotates it clockwise). Behave differently in presence of other chiral molecules.
17 of 33
What is a racemic mixture?
A 50:50 mixture of d-(dextrorotatory) and l- (laevorotatory)optical isomers
18 of 33
What is an amino acid called if both the amino and carboxyl functional groups are attached to the same carbon atom?
a (alpha) - amino acid
19 of 33
All proteins are made from the same set of how many a-amino acids?
20
20 of 33
What is a zwitterion?
An ion with both a positive charge and a negative charge
21 of 33
What is a dipeptide?
2 amino acids joined together forming a secondary amide/peptide link
22 of 33
What's a polypeptide
Several amino acids joined together
23 of 33
What is the primary structure of a protein?
The order in which amino acids join together
24 of 33
What is the secondary structure of a protein?
When the primary structure folds and forms intermolecular bonds between chains to form an alpha helix or beta pleated sheets
25 of 33
What is the tertiary structure of a protein?
Further folding of the polypeptide chains to give it a unique shape
26 of 33
What are the four type of bonds responsible for maintaining tertiary structure?
Id-id between non-polar side chains. Hydrogen bonds between polar side chains (N, O, F). Ionic bonds between ionisable side chains. Covalent bonds (e.g.'sulfur bridges')
27 of 33
How do you hydrolyse a protein?
Heat under reflux with moderately concentrated acid or alkali. The C-N bond is broken.
28 of 33
What are enzymes?
Metabolic catalysts that are proteins with a high specificity for a given substrate.
29 of 33
What causes the enzyme to be denatured/lose its shape?
Disruption of hydrogen bonds on heating, disruption of ionic interactions through changes in pH
30 of 33
What is it called when a molecule of a similar shape to the substrate occupies the active site?
Competitive inhibition
31 of 33
Why do enzyme-catalysed reactions change from first order to second order as the substrate concentration increases?
At low concentrations, there are plenty of active sites for the substrate to bind to. At high concentrations, all active sites on the enzymes have been saturated
32 of 33
Why are enzymes useful?
They are specific in a mixture of reactants. Work well at low temps. Work well in aqueous enviornments (reduces need for organic solvents which can be flammable/damaging. Can often convert reactant to product in 1 step (increases % atom economy).
33 of 33

Other cards in this set

Card 2

Front

What are the strands made from?

Back

sugar groups (deoxribose), phosphate groups and bases adenine, thymine, cytosine and guanine

Card 3

Front

What is the 'backbone' and how is it made?

Back

Preview of the front of card 3

Card 4

Front

How many bases are joined to each sugar residue and how?

Back

Preview of the front of card 4

Card 5

Front

How are the strands of DNA held together?

Back

Preview of the front of card 5
View more cards

Comments

lydiamiller

dope

Similar Chemistry resources:

See all Chemistry resources »See all Everything resources »