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B2 Topic 1 Revision Slides 2-12 GM - these activities are designed to take a whole lesson. Make sure you stick to the timings given in the notes that go with each slide. Slides 13- 19 Graphs, data and enzymes - these activities should take 30mins. Slides 20-29 Mitosis & Meiosis, protein synthesis and DNA replication - this content recap and exam questions should take 30-40mins Slide 30 - Revision Quiz, covers lots of bits and pieces, 15 questions, will probably take 20-25mins Science-y bit - step by step guide to GM (worth 4 marks) Unpicking the Question At least 6 statements about science in your answer 1. This question is about genetic modification Explain how bacteria can be genetically modified to produce human insulin. Suggest benefits of using human insulin rather than insulin extracted from animals. (6 marks) 2 reasons why it is used (think science proteins and their shape) (The quality of written communication will be assessed in your answer to this question) Logical order, uses key words, good spelling, good punctuation The Science - Genetic Engineering 1. Isolate the desired gene using enzymes 4. Transfer vector containing gene into bacteria 2. Replicate the gene 3. Put gene into vector (eg a plasmid) 5. Bacteria will now produce the protein from the desired gene Decide: which two of the following are relevant to the question being asked? Suggest benefits of using human insulin rather than insulin extracted from animals. Using human insulin is better because vegetarians will be able to use it too Human insulin will be an exact match for the insulin needed by the diabetic person, animal insulin is a slightly different shaped protein It isn’t right to kill pigs to collect insulin from them The immune system might reject or attack the pig insulin as the protein is a different shape to human insulin Explain how bacteria can be modified to produce human insulin. Suggest benefits of using human insulin rather than insulin extracted from animals (6 marks QWC). Vocab Diagrams 2 mins 3 mins Bullet points 4 mins Paragraph 5 mins Swap books and mark someone else’s answer. Give them a WWW and EBI. How many marks did they get for the Science (max 6)? Now mark the quality of their writing using the criteria on the left. Did they use the key words? Is it logical? Are all the spellings correct? Good use of punctuation? Give them a WWW and EBI for the quality of their answer Now improve your answer! 3 minutes Mark your own work this time. How did you do compared to your first attempt? Now take what you know and apply it! Organisms can be genetically engineered to make them more useful to humans. Suggest how wheat could be genetically engineered to allow it to grow in wet, marshy land (6 marks QWC) Mark scheme - mark your own this time Identify a gene that allows a plant to grow in wet/marshy areas. Isolate/extract/cut out the gene with a restriction (endonuclease)/enzyme Replicate the gene Insert desired gene into a vector (eg plasmid/virus) Transfer vector/plasmid containing desired gene into wheat/crop Crop plant will now produce/synthesis protein that allows it to grow in wet/marshy conditions Give yourself a WWW and EBI The Science - Genetic Engineering 1. Isolate the desired gene using enzymes 4. Transfer vector containing gene into bacteria 2. Replicate the gene 3. Put gene into vector (eg a plasmid) 5. Bacteria will now produce the protein from the desired gene 2 - Daunting Data and Grim Graphs Why is the volume at it’s highest here? Tell me what you see, using numbers from the graph (ii) Describe the effect of temperature on the volume of juice produced between 10°C and 40°C (2) (iv) Use the lock and key hypothesis to help you explain the activity of pectinase in juice production between 10°C and 70°C (6) What is happening to the enzymes here? What is happening Use Science to tell me why to the enzymes you see this pattern here? Student Model Answers Student A a) As the temperature increases, the volume of juice produced increases. b) Between 10oC and 40oC the enzymes are gaining kinetic energy meaning they are moving around faster and will form more enzyme-substrate complexes. At 70oC the enzymes have been denatured and don’t work anymore. Student B a) The volume of juice produced increases as the temperature increases. At 10oC 0.6cm3 is produced and at 40oC 2.7cm3 of juice is produced. b) The enzyme has a specific active site and the substrates will only fit into the active site if it hasn’t been denatured by getting too hot. On the graph it denatures when it goes down. Before that, the enzyme works faster as it gets hotter. Student C a) The graph goes up and then goes down again. It goes up between 10oC and 40oC from 0.6 to 2.7. b) The enzyme works faster as the temperature gets hotter. From 10oC to 40oC the enzymes gain kinetic energy so collide with each other more often, forming more enzyme-substrate complexes. The substrate fits into the active site, but when it gets too hot the enzyme denatures and the active site changes shape meaning that no more enzymes-substrate complexes will be formed. The graphs dips down after 50oC when the enzyme denatures. Mark the student answers and give each a WWW and EBI Use what you have learnt! Now write your own response to the questions (ii) Describe the effect of temperature on the volume of juice produced between 10°C and 40°C (2) (iv) Use the lock and key hypothesis to help you explain the activity of pectinase in juice production between 10°C and 70°C (6) Now mark your own answers 3 - Genes, Protein Synthesis, DNA Replication, Mitosis and Meiosis, Cloning Protein Synthesis Ribosome Transcription Translation DNA Replication Before mitosis and meiosis Semi-conservative 1. Enzyme unzips DNA 2. Free complementary bases line up with exposed bases on DNA 3. A different enzyme zips them together 4. Two identical strands of DNA formed Mitosis or Meiosis? Daughter cells are genetically identical to parent cells Produces cells with only half the number of chromosomes Produces gametes The cell goes through one division Produces 4 daughter cells that are genetically different Produces diploid cells Is a process within the cell cycle Occurs in the ovaries and testes The cell goes through two divisions Is used in Asexual reproduction Describe and explain the differences in chromosome number between the daughter cells produced by Mitosis and Meiosis (6 marks) Mitosis 1 division/2 daughter cells Chromosome number maintained Daughter cells contain 2n/23 pairs/46 chromosomes For growth and repair/ asexual reproduction Meiosis 2 divisions/ 4 daughter cells Chromosome number halved Daughter cells contain n/23 individual chromosomes For making gametes/egg cells/sperm cells Chromosome number restored at fertilisation Cloning - put these statements into the correct order A Enucleate the egg cell B The diploid nucleus inside the egg cell starts dividing by mitosis C Insert the diploid donor nucleus into the enucleated egg cell D Implant the growing embryo into womb of surrogate E Collect an egg cell from the egg cell donor F Diploid nucleus is removed from body cell of organism you want to clone G Stimulate the diploid nucleus using an electric shock or chemicals A clone is born! Answer: F, E, A, C, G, B, D Q1. (a) The diagram shows the mass of DNA (m), before, during and after cell division in one cell. (i) Name the type of cell division taking place in this cell. (1) (ii) Complete the sentence: A gene is a section of DNA that codes for ……………………(1) (b) Mutations can cause genetic disorders in humans. Phenylketonuria (PKU) is a genetic disorder caused by a gene mutation. People with PKU produce an inactive enzyme. The normal base sequence and the mutated base sequence which can cause PKU are shown below. normal base sequence ....... C T C G G C C C T ....... mutated base sequence ....... C T T G G C C C T ....... (i) Describe how the changes that have occurred in the mutated base sequence produce an inactive enzyme (2) (ii) Explain how the mutated base sequence will result in an inactive enzyme being produced during protein synthesis. (6) (c) Explain how the shape of an enzyme can make it inactive. (2) Mark scheme a) i) Meiosis ii) C b) i) A description including any two from the following points • change in a base from C to T (1) • (causes) change in one {codon/triplet} of bases (1) • results in a different amino acid (1) b) ii) next page c) An explanation linking the following points • active site {different / blocked / changed} (1) • substrate cannot bind /eq (1) An explanation linking some of the following points • enzymes are proteins • mutation in DNA will result in different mRNA strand • during transcription • mRNA leaves the nucleus through the nuclear pore • the attachment of mRNA at the ribosomes • involvement of tRNA and amino acids • at the ribosome • which is translation • amino acid chain/peptide sequence altered • different protein formed/protein not folded correctly (6) QWC 5 - 6 marks the response is likely to indicate the type of mutation and link this to a change of codon/protein the response will show good evidence of understanding that an incorrect mRNA molecule is formed and translation by tRNA will result in an incorrect amino acid being incorporated into the protein chain the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately spelling, punctuation and grammar are used with few errors 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. Revision Quiz Name two of the scientists involved in the discovery of DNA How many cells are produced as a result of meiosis By how much can an electron microscope magnify a specimen? What bonds hold the two complementary strands of DNA together? What does the word ‘diploid’ mean? In cloning, what is used to stimulate the egg cell to start dividing? Give one feature of a bacterial cell that isn’t present in animal or plant cells. What is the function of the mitochondria? By how much can a light microscopes magnify a specimen? What do the letters A, T, C and G stand for in DNA? A specimen appears 15mm under a light microscope at a magnification of 1000, what is its real length? What is a gene? Name two organisms that have been genetically engineered to benefit humans Where do the majority of stem cells come from that are used in stem cell research? What happens when an enzyme becomes denatured? 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. Watson, Crick, Rosalind, Franklin Four 2 000 000x Hydrogen bonds Two of each chromosome/chromosomes in pairs Body cell nuclus donor Plasmid/chromosomal DNA, cell wall not made of cellulose, mesosome, Pilli (not flagella; sperm cells have flagella so be careful with this one) Release energy OR produce/make ATP (NOT make energy!) 1500x Adenine, thymine, cytosine, guanine 0.015mm (remember the units!) Section of DNA that codes fro a protein Bacteria to produce insulin, golden rice, herbicide resistant crop plants Embryos left over from IVF The active site changes SHAPE