Nucleotides and Nucleic Acids

What Nucleotides and Nucleic Acids covers

Nucleotides and nucleic acids is the third section of Module 2. It covers what a nucleotide is made of, how nucleotides join into DNA and RNA, the structure of the double helix, how DNA copies itself semi-conservatively, and how a gene is read out into a polypeptide.

The 5 subtopics

Each one has its own page.

• Nucleotide structure and the basesThe pentose sugar, phosphate group and nitrogenous base of a nucleotide, the sugars that separate DNA from RNA, and which bases are purines and which are pyrimidines.Open →
• Polynucleotides, ADP and ATPPhosphodiester bonds and the condensation and hydrolysis reactions that make and break a polynucleotide, together with the composition of ADP and ATP.Open →
• The structure of DNAComplementary base pairing and the hydrogen bonds between strands, the antiparallel arrangement that produces the double helix, and how DNA is extracted.Open →
• Semi-conservative DNA replicationWhat semi-conservative means, the bonds helicase breaks, how DNA polymerase builds the new strand, why accuracy matters, and what a mutation is.Open →
• The genetic code, transcription and translationThe triplet code and what non-overlapping, degenerate and universal mean, RNA polymerase and the making of mRNA, and the roles of mRNA, tRNA and rRNA.Open →

What you need to know

Answer each one before you reveal it.

Take Nucleotides and Nucleic Acids further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Purine vs Pyrimidine

  Purine: a nitrogenous base with a double ring structure, adenine or guanine. Pyrimidine: a nitrogenous base with a single ring structure, thymine, cytosine or uracil.

• Phosphodiester bond vs Hydrogen bond

  Phosphodiester bond: the covalent link joining the sugar of one nucleotide to the phosphate of the next. Hydrogen bond: the weak attraction holding complementary bases together across the helix.

• Transcription vs Translation

  Transcription: copying a gene's base sequence into messenger RNA in the nucleus. Translation: building a polypeptide from that sequence at the ribosome.

Questions from this topic

Each one with the model answer underneath.

1. 1

   What is a nucleotide?

   Model answer

   A nucleotide is the monomer from which nucleic acids are made, consisting of three components: a pentose sugar, a nitrogenous base, and a phosphate group.

2. 2

   Name the sugar component found in a nucleotide.

   Model answer

   A pentose sugar.

3. 3

   What nitrogen-containing component is present in every nucleotide?

   Model answer

   A nitrogenous base.

4. 4

   Which acidic group is attached to the pentose sugar in a nucleotide?

   Model answer

   A phosphate group.

5. 5

   Which pentose sugar is found in DNA nucleotides?

   Model answer

   Deoxyribose.

6. 6

   Which pentose sugar is present in RNA nucleotides?

   Model answer

   Ribose.

What is inside Levo

Six ways to work the same material.

Nucleotides and Nucleic Acids revision questions

What does Nucleotides and Nucleic Acids cover in OCR A-Level Biology?

5 subtopics: nucleotide structure and the bases, polynucleotides, adp and atp, the structure of dna, semi-conservative dna replication and the genetic code, transcription and translation. Each one has its own page with questions and model answers.

How is Nucleotides and Nucleic Acids organised?

By the OCR H420 specification, subtopic by subtopic, so it matches the order you are taught it in.