2.1.3 Nucleotides and Nucleic Acids

Question 1

what are the similarities and differences between dna replication and transcription?

Answer 1

similarities —

• both involve unwinding of DNA
• strands act as template strands

differences —

• both involve complimentary base pairing
• in replication both strands act as templates but only one in transcription
• in dna replication, new dna strands stay in nucleus
• transcription uses RNA polymerase but dna replication uses DNA polymerase

Question 2

how is hydrogen bonding important in DNA?

Answer 2

• holds two polynucleotides together by complimentary base pairing
• stabilises DNA

Question 3

what does RNA polymerase do?

Answer 3

• initiates transcription
• joins RNA nucleotides together

Question 4

why is it important new DNA is identical to old DNA?

Answer 4

• new one should be genetically identical
• minimises risk of mutations

Question 5

why is it important for codons to be universal?

Answer 5

genetic information can be transferable between species

Question 6

what is the practical for purifying DNA with a precipitation reaction?

Answer 6

1. break up cells using a blender
2. make up a solution of detergent, salt and distilled water
3. add broken cells into a beaker containing detergent solution and incubate in water bath at 60 degrees for 15 mins
4. put beaker in ice bath to cool the mixture. filter and transfer into clean boiling tube
5. add protease enzymes to break down proteins
6. dribble cold ethanol down side of tube, DNA will form a white precipitate