DNA Flashcards
What is the backbone of DNA made up of?
Deoxyribose and phosphate
What part of a DNS molecule contains nitrogen?
Bases
T A G C
What are the bonds that hold bases together?
Hydrogen bonds
How does a changed in DNA sequence result in a non-functional enzyme
Change in base sequence of AA
Change in bonds e.g. Tertiary structure
Enzyme different shape
substate can no longer bind to active site
What is the purpose of deoxyribose sugar?
Give structure and stability
What is the purpose of the phosphate group?
Protect data from chemical and physical forces from outside
What are the bond between deoxyribose and phosphate
Phosphodiester bonds
What are the purpose of hydrogen bonds in DNA
Week hydrogen bonds separate easily during DNA replication
What is pyridimine?
One ring
C & T
What is purine
Double Ring
G & A
What are the properties of faces that make them join together
They are complementary and specific
What single units is DNA made up of?
Mononucleotides
Make up polynucleotides
How can a sequence of DNA be changed
Mutation:-
Substitution – exchanging one base for another
Insertion – adding extra base has e.g. codon
Deletion – sections of DNA are lost
Frameshift – and thousands of solutions that disrupt codons
What happens when DNA mutates?
Causes no change Alter the single amino acid Codes for different amino acid Animo acid cannot be produced Changes to stop codon
Protein therefore may not be produced
How many amino acids can DNA code for?
20
What are start/stop codons?
Show where a gene begins and ends
What is a dispersive model?
New DNA strands with a mixture of original strands a new bases
Mixture
What is the Conservative model?
Old DNA strand remains new strands of form alongside it
What is the semiconservative model?
Original Strand on the new bases are attracted exposed to the original bases
What was that Melselon and Stahl experiment?
The DNA bases contained nitrogen of different isotopes N15=heavyN14=light
They took heavy DNA and let it replicate the solution of N14 bases
1. All DNA contains one heavy and one light polynucleotide strand
2. Half of the DNA contained light nitrogen. the other half was a mixture of light and heavy
