This lesson describes the nature of the genetic code as near universal, non-overlapping and degenerate and relates this to the triplet code. The engaging lesson PowerPoint has been designed to cover point 2.11 of the Edexcel International A-level Biology specification and clear links are made to protein synthesis and gene mutations which students will meet in the next lot of lessons.
At the start of the lesson, the students are challenged to use their knowledge of the bases in DNA and RNA to complete a definition which describes the genetic code as being near universal, non-overlapping and degenerate. Time is taken to explain how three bases on DNA (a triplet) and three bases on mRNA (a codon) encode for a single amino acid or a stop codon and this is the triplet code. A quick quiz competition is used to generate the number 20 so that the students can learn that there are 20 proteinogenic amino acids in the genetic code. This leads into a challenge, where they have to use their prior knowledge of DNA to calculate the number of different DNA triplets (64) and the mismatch in number is then discussed and related back to the lesson topic. Moving forwards, base substitutions and base deletions are briefly introduced so that they can see how although one substitution can change the primary structure, another will change the codon but not the encoded amino acid. The lesson concludes with a brief look at the non-overlapping nature of the code so that the impact of a base deletion (or insertion) can be understood when covered in greater detail in the lesson covering point 2.14
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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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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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Excellent as are the other resources that you have produced. Thank you
Excellent - great info, presented well, great interactive activities too. Thank you!
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