This lesson describes how the expression of a gene mutation impairs the functioning of the organ systems in people with cystic fibrosis. The detailed PowerPoint and accompanying worksheets have primarily been designed to cover point 2.16 in AS unit 1 of the Edexcel International A-level Biology specification but also challenge the students on their knowledge of previously-covered topics such as inheritance, protein synthesis and the genetic code as well as making links to the upcoming topics of loci and post-transcriptional changes.
The main focus of the lesson is the CFTR gene and the functions of the ion channel that is synthesised when this gene is expressed. As well as explaining that this channel allows chloride ions to flow across the apical membrane of the epithelial cells, time is taken to emphasise the importance of its inhibition on the ENaC, which prevents the flow of sodium ions back into the cells. A step by step guide is then used to describe the sequence of events that result in mucus which is motile and can be moved by the wafting action of the cilia in healthy individuals. This leads into the section of the lesson which considers the inheritance of cystic fibrosis in an autosomal recessive manner and then focuses on the change in the primary structure of the channel which results from one of over 1500 different gene mutations. Again, the students are guided through the events that lead to the depletion of the apical surface liquid and the cilia being unable to move the viscous mucus. Although the majority of the lesson is described with reference to the gaseous exchange system, the impaired functioning of the digestive system in terms of the blockage of the pancreas and liver secretions is considered and discussed and the students are challenged on their understanding through a range of exam-style questions.
All of the questions included in the lesson have mark schemes which are embedded into the PowerPoint and this allows the students to assess their progress.
Due to the detailed content of this lesson, it is estimated that it will take in excess of 3 hours of allocated A-level teaching time to cover
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DNA, RNA, Genetics and Inheritance (Edexcel Int. A-level Biology)
This lesson bundle contains 16 lessons which have been designed to cover the Edexcel International A-level Biology specification points which focus on the structure of DNA and RNA, their roles in replication and protein synthesis, and genetics and inheritance. The lesson PowerPoints are highly detailed, and along with their accompanying worksheets, they have been planned at length to contain a wide range of engaging tasks which cover the following A-level Biology content found in topics 2, 3 and 6 of the course: 2.9 (i): Know the basic structure of mononucleotides (deoxyribose or ribose linked to a phosphate and a base, including thymine, uracil, adenine, cytosine or guanine) and the structures of DNA and RNA (polynucleotides composed of mononucleotides linked by condensation reactions to form phosphodiester bonds) 2.9 (ii): Know how complementary base pairing and the hydrogen bonding between two complementary strands are involved in the formation of the DNA double helix 2.10 (i): Understand the process of DNA replication, including the role of DNA polymerase 2.11: Understand the nature of the genetic code 2.12: Know that a gene is a sequence of bases on a DNA molecule that codes for a sequence of amino acids in a polypeptide chain 2.13 (i): understand the process of protein synthesis (transcription and translation), including the role of RNA polymerase, translation, messenger RNA, transfer RNA, ribosomes and the role of start and stop codons 2.13 (ii): Understand the roles of the DNA template (antisense) strand in transcription, codons on messenger RNA and anticodons on transfer RNA 2.14 (i): Understand how errors in DNA replication can give rise to mutations (substitution, insertion and deletion of bases) 2.14 (ii): Know that some mutations will give rise to cancer or genetic disorders, but that many mutations will have no observable effect 2.15 (i): Know the meaning of the terms: gene, allele, genotype, phenotype, recessive, dominant, codominance, homozygote and heterozygote 2.15 (ii): Understand patterns of inheritance, including the interpretation of genetic pedigree diagrams, in the context of monohybrid inheritance 2.15 (iii): Understand sex linkage on the X chromosome, including red-green colour blindness in humans 2.16: Understand how the expression of a gene mutation in people with cystic fibrosis impairs the functioning of the gaseous exchange, digestive and reproductive systems 2.17 (i): Understand the uses of genetic screening, including the identification of carriers, pre-implantation genetic diagnosis (PGD) and prenatal testing, including amniocentesis and chorionic villus sampling 2.17 (ii): Understand the implications of prenatal genetic screening 3.9 (i): Know that a locus is the location of genes on a chromosome 3.9 (ii): Understand the linkage of genes on a chromosome 3.18: Understand how cells become specialised through differential gene expression, producing active mRNA, leading to the synthesis of proteins which, in turn, control cell processes or determine cell structure in animals and plants 3.19: Understand how one gene can give rise to more than one protein through posttranscriptional changes to messenger RNA (mRNA). 3.20 (i): Phenotype is an interaction between genotype and the environment 3.21: Understand how some phenotypes are affected by multiple alleles for the same gene at many loci (polygenic inheritance) as well as the environment and how this can give rise to phenotypes that show continuous variation 6.17: Know how DNA can be amplified using the polymerase chain reaction (PCR)
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Edexcel Int. A-level Biology Topic 2: Membranes, Proteins, DNA and Gene expression
Hours and hours of planning have gone into each and every lesson that's included in this bundle to ensure that the students are engaged and motivated whilst the detailed content of topic 2 of the Edexcel International A-level Biology specification is covered. Membranes, proteins, DNA and gene expression represent some of the most important structures, molecules and processes involved in this subject and a deep understanding of their role in living organisms is important for a student's success. The 20 lesson PowerPoints and accompanying resources contain a wide range of activities which cover the following topic 2 specification points: * Know the properties of gas exchange surfaces in living organisms * Understand how the rate of diffusion can be calculated using Fick's Law of Diffusion * Understand how the structure of the mammalian lung is adapted for rapid gas exchange * The structure and properties of cell membranes * The movement of free water molecules by osmosis * The movement across membranes by passive and active transport * The role of channel and carrier proteins in membrane transport * The basic structure of an amino acid * The formation of polypeptides and proteins * The structure of proteins * The mechanism of action and specificity of enzymes * Enzymes are biological catalysts * Intracellular and extracellular enzymes * The basic structure of mononucleotides * The structure of DNA and RNA * The process of DNA replication * The nature of the genetic code * A gene as a sequence of bases on DNA that codes for a sequence of amino acids * The process of transcription and translation * Errors in DNA replication give rise to mutations * Mutations give rise to disorders but many mutations have no observable effect * The meaning of key genetic terms * Understanding the pattern of monohybrid inheritance * Sex linkage on the X chromosome * Understand how the expression of a gene mutation in people with cystic fibrosis impairs the functioning of the gaseous exchange, digestive and reproductive systems * The uses and implications of genetic screening and prenatal testing Due to the detail included in all of these lessons, it is estimated that it will take in excess of 2 months of allocated A-level teaching time to complete the teaching of the bundle If you would like to sample the quality of these lessons, then download the rapid gas exchange, osmosis, DNA & RNA, genetic code, genetic terms and cystic fibrosis lessons as these have been uploaded for free.
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