Essential Idea
Genetic information in DNA can be accurately copied and can be translated to make the proteins needed by the cell.
Understandings
The replication of DNA is semi-conservative and depends on complementary base pairing.
Helicase unwinds the double helix and separates the two strands by breaking hydrogen bonds.
DNA polymerase links nucleotides together to form a new strand, using the pre-existing strand as a template.
Transcription is the synthesis of mRNA copied from the DNA base sequences by RNA polymerase.
Translation is the synthesis of polypeptides on ribosomes.
The amino acid sequence of polypeptides is determined by mRNA according to the genetic code.
Codons of three bases on mRNA correspond to one amino acid in a polypeptide.
Translation depends on complementary base pairing between codons on mRNA and anticodons on tRNA.
Applications
Use of Taq DNA polymerase to produce multiple copies of DNA rapidly by the polymerase chain reaction (PCR).
Production of human insulin in bacteria as an example of the universality of the genetic code allowing gene transfer between species.
Skills
Use a table of the genetic code to deduce which codon(s) corresponds to which amino acid (VIDEO).
Analysis of Meselson and Stahl’s results to obtain support for the theory of semi-conservative replication of DNA.
Use a table of mRNA codons and their corresponding amino acids to deduce the sequence of amino acids coded by a short mRNA strand of known base sequence (VIDEO).
Deducing the DNA base sequence for the mRNA strand (VIDEO).
Guidance
The different types of DNA polymerase do not need to be distinguished.
Key Vocabulary
Semi-conservative model
Complimentary base pairs
Helicase
DNA polymerase
Transcription
RNA polymerase
mRNA
Translation
Codon
tRNA
Anticodon
Textbook Reading and/or Activities
Click HERE for a pdf of chapter 2.
Notes
2.7 DNA Replication, Transcription and Translation
A detailed set of notes, prepared by Bob Smullen, examining all of the IB learning expectations.
i-Biology Notes (Not available)
A detailed set of notes, prepared by Stephen Taylor, examining U1 - U8 and A1 - A4.
A series of questions, prepared by Stephen Taylor, to help check your understanding of DNA replication. This is VERY GOOD practice.
A series of questions, prepared by Stephen Taylor, to help check your understanding of transcription and translation. This is VERY GOOD practice.
A detailed set of notes, created by Chris Paine, examining all of the IB learning expectations.
A series of questions, created by Chris Paine, to help check your understanding of the IB learning expectations. This is VERY GOOD practice.
A detailed set of notes, prepared by Jacob Cedarbaum, examining U1 - U3 and A1 (slides 1-17), of the IB learning expectations.
A detailed set of notes, prepared by Jacob Cedarbaum, examining U4 U8 and A1 - A2, of the IB learning expectations.
2.7 Study Questions (NEW Syllabus)
A series of questions, prepared by Jacob Cedarbaum, to help check your understanding of the IB learning expectations. This is VERY GOOD practice but the OLD also includes some HL material so please mind the SL Understandings and Applications at left. Answers (OLD).
Learning Activities
WS - From DNA to Proteins and Back
This worksheet will help you improve your understanding of how DNA code is transcribed into an RNA code, which then becomes a polypeptide chain.
Cell Function Animation and Notes
This simple animation, produced by John Kyrk, outlines the processes involved from the production of an mRNA strand during transcription to the production of a polypeptide during translation.
DNA Replication Animation and Notes
This detailed animation, produced by John Kyrk, outlines the processes involved in copying DNA (including relevant enzymes).
Transcription Animation and Notes
This detailed animation, produced by John Kyrk, outlines the processes involved in transcribing an mRNA copy from a DNA sequence.
Translation Animation and Notes
This detailed animation, produced by John Kyrk, outlines the processes involved in translating an mRNA code into an amino acid sequence (a polypeptide).
Engage in this short online activity to better understand the PCR process which is used in the lab to multiply DNA. This process is used extensively in forensics and genetic research and its invention won Kary Mullis a Nobel Prize in Chemistry (1993).
Must Watch Videos
"What is DNA?" by Stated Clearly (5:23)
This video outlines the basics of DNA and how it is used within a cell to produce proteins.
"DNA Transcription" by DNA Learning Center (1:52)
This video outlines the process of DNA transcription which involves the formation of an RNA molecule carrying a genetic code that has been copied from a DNA molecule.
"mRNA Translation" by DNA Learning Center (3:03)
This video provides a more detailed look at the process involved in converting the genetic code stored in DNA into the functional proteins that drive the metabolism of most types of living organisms.
"Polymerase Chain Reaction (PCR)" by DNA Learning Center (1:27)
This video outlines the PCR, which is a process used within the lab to replicate a target sequence of DNA.
Should Watch Videos