Genetics
Biology 3.3
Describe the role of DNA in relation to gene expression (4 credits)
Achievement

Describe the role of DNA
in relation to gene
expression.
Achievement with Merit

Achievement with Excellence
Explain the role of DNA
in relation to gene
expression.

Discuss the role of DNA
in relation to gene
expression.
Learning Outcomes
On completion of this unit you should be able to1. To understand the role of DNA in gene expression:

Describe the structure of DNA including the antiparallel strands, 3´–5´ linkages and hydrogen bonding
between purines and pyrimidines.
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Describe a gene as a sequence of bases on a DNA molecule.
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Understand features of the genetic code, including universality and degeneracy.
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Describe DNA replication
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Distinguish between the structure and function of the types of RNA,ie. mRNA, tRNA, rRNA.
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Distinguish between terms: triplet, codon and anticodon
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Describe protein structure and function
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Describe mitosis and DNA replication.
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Describe the process of protein synthesis, specifically transcription and translation.
2. To understand the control of gene expression :
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Describe how genes can control a metabolic pathway
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Describe the metabolism of phenyalanine and explain how PKU occurs.
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Interpret a metabolic pathway diagram.
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Explain how gene expression can be controlled by feedback in prokaryotes and enhancers and
transcription factors in eukaryotes.
3. To understand mutations in gene expression :
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Describe mutation as a change in genetic code.
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Describe mutagens in terms of environmental factors, (eg radiation, chemical, viruses) that cause
mutations.
Describe gene mutations (base and block mutations)
Analyse data (bases sequences) to identify mutations and determine consequences in terms of amino acid
sequence.
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Describe sickle cell anaemia as an example of a base mutation (and pleiotropy).
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Describe chromosome mutations (aneuploidy)

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Analyse data (karyotypes) to identify mutations and determine consequences in terms of amino acid
sequence.
Describe and explain examples, eg Klinefelters, Turners, Down’s Syndrome.
3. To understand Gene-gene interactions in gene expression: will be selected from: Describe meiosis and
Mendel’s laws. (revision)
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Predict monohybrid and dihybrid ratios and recognise that 3:1 and 9:3:3:1 are theoretical ratios. (revision)
Interpret pedigrees. (revision)
Describe and determine ratios for multiple allele inheritance
Understand human blood group (ABO) system as an example of multiple allele inheritance.
Describe and predict inheritance ratios in examples for gene-gene interactions:
o
collaboration,
o
complementary genes,
o
supplementary genes,
o
polygenes
Describe and predict inheritance ratios for sex linkage
Understand haemophilia as an example of sex linkage.
Describe and predict inheritance ratios for linkage to identify recombinant and parental types from dihybrid
cross data.
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Calculate cross-over frequency
Draw gene maps from recombinant frequency.
Describe pleiotropy
Understand sickle cell anaemia as an example of pleiotropy.