Nucleotides, DNA structure and replicationEdexcel A-Level Biology A: Flashcards

What these 14 flashcards ask

What are the three parts of a mononucleotide?
Which sugar and base differ between DNA and RNA?
Name the four bases in DNA.
What type of reaction joins nucleotides?
Between which parts does a phosphodiester bond form?
What holds the two DNA strands together?
How many hydrogen bonds join A–T and C–G?
If a DNA sample is 30% adenine, what are the percentages of the other bases?
What does DNA helicase do?
What does DNA polymerase do in replication?
Why is replication semi-conservative?
Why did bacteria grow for many generations in ¹⁵N in the Meselson and Stahl experiment?
What did generation 1 show in the Meselson and Stahl experiment?
What did generation 2 show?

Exam questions on Nucleotides, DNA structure and replication

A student extracts DNA and RNA from the same cells and analyses the nucleotides that each is made of.
Describe how two DNA nucleotides are joined together in a polynucleotide.2 marks
Two samples of double-stranded DNA of the same length, sample X and sample Y, are heated slowly until the two strands of each separate. In sample X, 20% of the bases are adenine. In sample Y, 35% of the bases are adenine.
Explain why the strands of sample X separate at a higher temperature than those of sample Y.2 marks
A section of one strand of a DNA molecule has the base sequence ATGCCGTA. This strand acts as a template during DNA replication in a dividing cell.
Describe how a new strand is formed on this template during DNA replication.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).