LEVEL TWO BIOLOGY: GENE EXPRESSION Protein synthesis DNA structure and replication Polypeptide chains and amino acids Mutations Metabolic pathways Protein Synthesis: I can define a protein in terms of gene expression. I can explain the relationship between proteins, polypeptide chains and amino acids. I can define DNA in terms of the information it encodes. I can define RNA by using the terms single-stranded, copy and gene. I can explain why RNA is necessary for protein synthesis by comparing the size and importance of RNA and DNA. I can show that I understand the processes of transcription and translation by stating the result of each process and why each process is necessary for protein synthesis. I can differentiate between transcription and translation by explaining which occurs first and why and where each process occurs in a cell. I can show that I know the difference between mrna, trna and rrna by explaining the role of each type of RNA and where they are found in a cell.
I can state where ribosomes are found in a cell and can describe their important role in translation. I can explain the similarities and differences between a triplet, a codon and an anticodon. I can show that I understand the importance of complementary base pairing by explaining how the presence of triplets, codons and anticodons results in the synthesis of the protein coded for by the original DNA molecule. I can discuss the importance of protein folding by relating structure to function. I can use all of the above understanding to describe the steps of protein synthesis: DNA in the nucleus gene codes for a protein Transcription of a gene to form mrna Removal of introns mrna travelling to a ribosome trna bringing in the correct amino acids to the ribosome The formation of a polypeptide chain Protein folding to form the resultant protein DNA Structure and Replication: I can describe the structure of DNA molecules by explaining the components of its nucleotide monomers: sugar, phosphate and nitrogenous base. I can state the names of all the nucleotides: A, T, C, G and U. I can state which bases pair-up in complementary base pairing. I can state which four bases are present in DNA and which four bases are present in RNA.
I can discuss the steps of DNA replication by including in my discussion: Unwinding the DNA Complementary base pairing Semi-conservative replication Parent and daughter strands Leading and lagging strands The direction of replication: 5 to 3 Okazaki fragments I can show that I understand how DNA replicates by explaining how the replication of DNA from 5 to 3 results in the leading strand and the lagging strand. I can explain what an Okazaki fragment is, why they form and how they are resolved. I can explain why DNA replication is necessary for mitosis by discussing the steps that follow DNA replication. I can discuss the advantages of DNA copying itself by semi-conservative replication. I can discuss the effect of enzymes, catalysts and other external factors on DNA replication. Polypeptide Chains and Amino Acids: I can state where START codons and STOP codons are found and explain their importance. Given a sequence of bases and a given amino acid table, I can determine the order of amino acids to form the corresponding polypeptide chain. I can explain the term redundancy due to degeneracy within the code.
I can show that I understand the significance of redundancy due to degeneracy within the code by discussing why it is important in relation to protein synthesis. I can discuss why redundancy is only significant in some situations by referencing a given table of amino acids and their corresponding codons. Mutations: I can show that I understand what a mutation is by giving a concise definition in terms of the order of bases in a DNA molecule. I can define the terms nonsense mutation and missense mutation. I can describe the difference between a point mutation and a chromosomal mutation. I can show that I understand the following types of mutations by defining each and writing out an example of each (in a sequence of bases): Substitution Deletion Insertion Duplication Inverse Frameshift I can explain the impact that the above types of mutations have on the genetic code and can discuss which ones are worse for the organism and why. I can explain the differences between silent, advantageous and disadvantageous mutations and can discuss the impact of these on an organism.
I can describe the different ways in which mutations arise (e.g. random mutations due to errors in DNA replication, or mutations caused by mutagens). I can define the term mutagen and can name some examples. I can explain the difference between phenotype and genotype. I can show that I understand the difference between a mutagen and an environmental factor by comparing: The effects of mutagens and mutations on genotypes and phenotypes. The effects of environmental factors on phenotypes only. I can show that I understand how a single mutation affects a phenotype by discussing amino acids, polypeptide chains and proteins. Metabolic Pathways: I can give a concise definition of the term metabolic pathway. I can explain the role of enzymes and biochemical reactions in metabolic pathways. I can show that I understand how a metabolic pathway works by explaining how the products of one reaction take part in the next reaction until the final product (the phenotype) is eventually made. I can show that I understand how protein synthesis relates to enzymes by explaining that enzymes are types of proteins. I can link protein synthesis, enzymes, mutations and metabolic pathways by discussing why a mutation in the genetic code could potentially affect an entire metabolic pathway.