Transcription and Gene expression Topics 2.7 and 7.2
Understandings
2.7.U4 Transcription is the synthesis of mRNA copied from the DNA base sequences by RNA polymerase.
2.7.U6 The amino acid sequence of polypeptides is determined by mRNA according to the genetic code.
2.7.U7 Codons of three bases on mRNA correspond to one amino acid in a polypeptide.
7.2.U1 Transcription occurs in a 5’ to 3’ direction.
[RNA polymerase adds the 5´ end of the free RNA nucleotide to the 3´ end of the growing mRNA molecule.]
7.2.U2 Nucleosomes help to regulate transcription in eukaryotes.
7.2.U3 Eukaryotic cells modify mRNA after transcription.
7.2.U4 Splicing of mRNA increases the number of different proteins an organism can produce.
7.2.U5 Gene expression is regulated by proteins that bind to specific base sequences in DNA.
7.2.U6 The environment of a cell and of an organism has an impact on gene expression.
Applications & Skills
7.2.A1 The promoter as an example of non-coding DNA with a function.
2.7.S4 Deducing the DNA base sequence for the mRNA strand.
7.2.S1 Analysis of changes in the DNA methylation patterns.
Nature of Science
NOS 7.2 Looking for patterns, trends and discrepancies—there is mounting evidence that the environment can trigger heritable changes in epigenetic factors.
[Text in square brackets indicates guidance notes]
2.7.U4 Transcription is the synthesis of mRNA copied from the DNA base sequences by RNA polymerase.
2.7.U6 The amino acid sequence of polypeptides is determined by mRNA according to the genetic code.
2.7.U7 Codons of three bases on mRNA correspond to one amino acid in a polypeptide.
7.2.U1 Transcription occurs in a 5’ to 3’ direction.
[RNA polymerase adds the 5´ end of the free RNA nucleotide to the 3´ end of the growing mRNA molecule.]
7.2.U2 Nucleosomes help to regulate transcription in eukaryotes.
7.2.U3 Eukaryotic cells modify mRNA after transcription.
7.2.U4 Splicing of mRNA increases the number of different proteins an organism can produce.
7.2.U5 Gene expression is regulated by proteins that bind to specific base sequences in DNA.
7.2.U6 The environment of a cell and of an organism has an impact on gene expression.
Applications & Skills
7.2.A1 The promoter as an example of non-coding DNA with a function.
2.7.S4 Deducing the DNA base sequence for the mRNA strand.
7.2.S1 Analysis of changes in the DNA methylation patterns.
Nature of Science
NOS 7.2 Looking for patterns, trends and discrepancies—there is mounting evidence that the environment can trigger heritable changes in epigenetic factors.
[Text in square brackets indicates guidance notes]
translation SL and HL Topics 2.7 & 7.3
Understandings
2.7.U5 Translation is the synthesis of polypeptides on ribosomes.
2.7.U6 The amino acid sequence of polypeptides is determined by mRNA according to the genetic code.
2.7.U7 Codons of three bases on mRNA correspond to one amino acid in a polypeptide.
2.7.U8 Translation depends on complementary base pairing between codons on mRNA and anticodons on tRNA.
7.3.U1 Initiation of translation involves assembly of the components that carry out the process.
[Examples of start codons are not required. Names of the tRNA binding sites are expected as well as their roles.]
7.3.U2 Synthesis of the polypeptide involves a repeated cycle of events.
7.3.U4 Free ribosomes synthesize proteins for use primarily within the cell.
7.3.U5 Bound ribosomes synthesize proteins primarily for secretion or for use in lysosomes.
7.3.U6 Translation can occur immediately after transcription in prokaryotes due to the absence of a nuclear membrane.
7.3.U7 The sequence and number of amino acids in the polypeptide is the primary structure.
7.3.U8 The secondary structure is the formation of alpha helices and beta pleated sheets stabilized by hydrogen bonding.
7.3.U9 The tertiary structure is the further folding of the polypeptide stabilized by interactions between R groups.
[Polar and non-polar amino acids are relevant to the bonds formed between R groups.]
7.3.U10 The quaternary structure exists in proteins with more than one polypeptide chain.
[ Quaternary structure may involve the binding of a prosthetic group to form a conjugated protein.]
Applications and Skills
7.3.A1 tRNA-activating enzymes illustrate enzyme–substrate specificity and the role of phosphorylation.
2.7.S1 Use a table of the genetic code to deduce which codon(s) corresponds to which amino acid.
2.7.S3 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.
7.3.S1 Identification of polysomes in electron micrographs of prokaryotes and eukaryotes.
7.3.S2 The use of molecular visualization software to analyse the structure of eukaryotic ribosomes and a tRNA molecule.
2.7.U5 Translation is the synthesis of polypeptides on ribosomes.
2.7.U6 The amino acid sequence of polypeptides is determined by mRNA according to the genetic code.
2.7.U7 Codons of three bases on mRNA correspond to one amino acid in a polypeptide.
2.7.U8 Translation depends on complementary base pairing between codons on mRNA and anticodons on tRNA.
7.3.U1 Initiation of translation involves assembly of the components that carry out the process.
[Examples of start codons are not required. Names of the tRNA binding sites are expected as well as their roles.]
7.3.U2 Synthesis of the polypeptide involves a repeated cycle of events.
7.3.U4 Free ribosomes synthesize proteins for use primarily within the cell.
7.3.U5 Bound ribosomes synthesize proteins primarily for secretion or for use in lysosomes.
7.3.U6 Translation can occur immediately after transcription in prokaryotes due to the absence of a nuclear membrane.
7.3.U7 The sequence and number of amino acids in the polypeptide is the primary structure.
7.3.U8 The secondary structure is the formation of alpha helices and beta pleated sheets stabilized by hydrogen bonding.
7.3.U9 The tertiary structure is the further folding of the polypeptide stabilized by interactions between R groups.
[Polar and non-polar amino acids are relevant to the bonds formed between R groups.]
7.3.U10 The quaternary structure exists in proteins with more than one polypeptide chain.
[ Quaternary structure may involve the binding of a prosthetic group to form a conjugated protein.]
Applications and Skills
7.3.A1 tRNA-activating enzymes illustrate enzyme–substrate specificity and the role of phosphorylation.
2.7.S1 Use a table of the genetic code to deduce which codon(s) corresponds to which amino acid.
2.7.S3 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.
7.3.S1 Identification of polysomes in electron micrographs of prokaryotes and eukaryotes.
7.3.S2 The use of molecular visualization software to analyse the structure of eukaryotic ribosomes and a tRNA molecule.
Helpful Animations and Tutorials
Harvard Animation
DNA Learning Center's 3D & Real Time Translation
McGraw Hill's Animation
Sumanas, Inc. Polyribosome Animation
Jmol for 3D structures of ribosomes and tRNA.
Harvard Animation
DNA Learning Center's 3D & Real Time Translation
McGraw Hill's Animation
Sumanas, Inc. Polyribosome Animation
Jmol for 3D structures of ribosomes and tRNA.
2.7 Vocabulary Quizlet
7.2 Vocabulary Quizlet
7.3 Quizlet