Nucleic Acids (IB Topic A1.2)

Essential Idea(s): The structure of DNA allows efficient storage of genetic information.

Unit Length: 3 Lessons (+2 AHL)

  Guiding Questions

◊ How does the structure of nucleic acids allow hereditary information to be stored?

◊ How does the structure of DNA facilitate accurate replication?

Materials:

Self-Teaching Slides (SL) / Self-Teaching Slides (AHL)   Quizlet Vocab Set (SL) / Quizlet Vocab Set (AHL)
Teaching Slides (SL) / Teaching Slides (AHL)   Notes Template (SL) / Notes Template (AHL)

 

IB Statement(s) and Objective(s)

A1.2.1:  DNA as the genetic material of all living organisms

  • State the two types of nucleic acids
  • Explain how viruses use nucleic acids as genetic material 

 

A1.2.2:  Components of a nucleotide

  • Outline the parts of a nucleotide
  • Draw the basic structure of a single nucleotide
  • Identify and label carbons by number on a nucleotide drawing 

 

A1.2.3:  Sugar–phosphate bonding and the sugar–phosphate “backbone” of DNA and RNA

  • Explain how nucleotides can connect to form a nucleic acid polymer

 

A1.2.4:  Bases in each nucleic acid that form the basis of a code

  • State the names of the nitrogenous bases found in DNA and RNA
  • State the complementary base-pairing rules 

 

A1.2.5:  RNA as a polymer formed by condensation of nucleotide monomers

  • Draw the basic structure of a single RNA polymer
  • Explain a condensation reaction connecting two nucleotides in the formation of a nucleic acid

 

A1.2.6—DNA as a double helix made of two antiparallel strands of nucleotides with two strands linked by hydrogen bonding between complementary base pairs

  • Identify and label the 5’ and 3’ ends on a DNA or RNA diagram 
  • Define “antiparallel” in relation to DNA structure
  • Outline the formation of a DNA double helix by hydrogen bonding between nitrogenous bases

 

A1.2.7:  Differences between DNA and RNA

  • Compare the structure of DNA and RNA
  • Explain the difference between ribose and deoxyribose

 

A1.2.8—Role of complementary base pairing in allowing genetic information to be replicated and expressed

  • State the bond type that results in complementarity in DNA 
  • Outline the function of base pairing

 

A1.2.9—Diversity of possible DNA base sequences and the limitless capacity of DNA for storing information

  • Explain how base sequencing yields enormous capacity of DNA for storing data

 

A1.2.10—Conservation of the genetic code across all life forms as evidence of universal common ancestry

  • Explain the idea of a last universal common ancestor (LUCA)

Additional Higher Level Topics

A1.2.11:  Directionality of RNA and DNA

  • Explain the significance of 5′ to 3′ linkages for replication, transcription and translation

 

A1.2.12:  Purine-to-pyrimidine bonding as a component of DNA helix stability

  • Identify the four bases of DNA based on the number of rings as purine or pyrimidine 
  • Outline how purine-pyrimidine bonding affects the stability of the helical structure of DNA  

 

A1.2.13:  Structure of a nucleosome

  • Explain why chromosomes must condense
  • Draw and label the structure of a nucleosome
  • Identify nucleosome structures using molecular visualization software

 

A1.2.14:  Evidence from the Hershey–Chase experiment for DNA as the genetic material

  • State the experimental question being tested in the Hershey and Chase experiment
  • Explain the procedure of the Hershey and Chase experiment
  • Explain how the results of the Hershey and Chase experiment supported the notion of nucleic acids as the genetic material
  • NOS Concept: Technology Begets Discovery
  • Outline the use of radioactive isotopes in biological experiments 

 

A1.2.15:  Chargaff’s data on the relative amounts of pyrimidine and purine bases across diverse life forms

  • Explain how Chargaff’s data falsified the tetranucleotide hypothesis
  • NOS Concept: Explain how the “problem of induction” is addressed by the “certainty of falsification”
Activities: ⓟ = podcast / ⍰ = inquiry 5 / ⓦ = Write it /  Ӕ = The academy  / Ⓡ = Read it

Ⓛ (recommended): Extracting DNA from peas (💁/ 👭max 2)

Extracting DNA from a living organism (in this case, peas) is actually easier than it seems. Follow the directions on this lab and see how much you can get. The end result will be simple, but stasifying – you’ll have a spool of thin DNA stuck to a glass rod. 

Ӕ: Virtual Tour Guide: DNA (💁)

Take us on a virtual tour of a DNA molecule. Screencast yourself exploring a 3D model of DNA on this website. Explain the structure of DNA as you do so – making sure to cover the basic structure of nucleotides, the ribose-phosphate backbone, 5′ ends and 3′ ends, and general rules for base pairing (A-T / C-G).

 

ⓟ/ⓦ: “Inquiry 5″: Q&A on DNA and RNA (💁/ 👭max 2)

Create a list of 5 inquiry questions about this unit on DNA and RNA. Remember that good inquiry questions are conceptual / open-ended…such as: “How does DNA make each individual unique?; NOT: “What does DNA stand for?” If working solo, write out answers to your own questions; if working in pairs, record yourselves asking each other your 5 questions.

 

Lab! ⓟ/Ӕ: Make a 3D Model of DNA 👫 (max 2)

Pair up with a peer (or go it alone) and create a 3D model of a piece of DNA. Aim to include all the features described on the sheet – then record a brief overview of your DNA molecule.

 

(AHL) ⓟ/ⓦ: Video Review: The Story of Hershey and Chase (💁[writeup] / 👭 [podcast – max 2])

Watch this video that tells the story of the breakthrough experiment carried out by Hershey and Chase. Their method was one of the first to successfully use molecular “tags” – marking different parts of a virus with radioactive labels. It was simple, but groundbreaking – and changed the course of science. After watching, write/record a response, including; 1) The actual method Hershey and Chase used for the experiment; 2) What it revealed about genes and genetic information in living systems, and 3) How the results changed the course of history in biology.