GENETICS & GENETIC ENGINEERING 23 APRIL 2014

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1 GENETICS & GENETIC ENGINEERING 23 APRIL 2014 In this lesson we: Lesson Description State what is meant by genetic engineering State what is meant by biotechnology Describe how each of the following examples of genetic engineering represent the use of biotechnology to satisfy human needs: Stem cell research (what are stem cells; sources of stem cells; uses of stem cells) Genetic modification (example in plants and animals; benefits of genetic modification) Cloning (an example; description of process) State views for and against genetic engineering Describe the role of each of the following in paternity testing: Blood grouping DNA profiles Describe how mutations in mitochondrial DNA may be used in tracing female ancestry Dihybrid crosses: State Mendel s principle of independent assortment Solve dihybrid genetics problems Determine proportion/ratio of genotypes and phenotypes Challenge Question 1. If AaBb is crossed with aabb, what proportion of the offspring would be expected to be aabb? 2. If the offspring of a dihybridcross show a 9/16 to 3/16 to 3/16 to 1/16 ratio (9:3:3:1), what are the genotypes the parents? 3. Assume that you mated two individuals heterozygous for each of two traits and obtained 80 offspring. How many of them would be expected to look like their parents?

2 Paternity Testing Summary GENETIC ENGINEERING Stem cell research GMO'S Cloning Blood groups DNA profile Mitochodrial DNA Dihybrid crosses

3 Test Yourself Select the most correct answer from the options given. Write down only the correct letter Question 1 The deliberate modifications of an organism's genetic information by directly changing its nucleic acid content is a subject matter of A B C D genetic engineering population studies microbiology protein engineering Question 2 An organism of genotype AaBb can make gametes of all the following kinds except: A B C D ab Bb ab AB Question 3 Genes that assort independently are A B C D located on different chromosomes located on the same chromosome alleles of each other co-dominant Question 4 If W = purple flower and w = white, and D = tall plants and d = short plants, a wwdd plant would be A B C D purple and tall purple and short white and tall white and short

4 Question 5 Indicate whether each of the statements in COLUMN I applies to A only, B only, both A and B or none of the items in COLUMN II. Write A only,b only, both A and B ornone next to the question number ( ) in the ANSWER BOOK. COLUMN I 1 Using DNA to manufacture human insulin COLUMN II A: Stem cell therapy B: Protein synthesis 2 Tracing maternal lineage A: Mitochondrial DNA B: Nuclear DNA 3 An arrangement of black bars representing nucleic acid fragments that can be used to determine whether people are related A: Blood grouping B: DNA fingerprinting 4 A cross involving seed colour and pod shape 5 Used in the manufacture of human insulin A: Dihybrid B: Monohybrid A: Plasmid B: Bacteria

5 Question 6 An investigation to determine the effect of increasing radiation on lethal (deadly) mutations on X chromosomes in fruit flies was undertaken by scientists. The results are shown in the graph below. 6.1 Formulate a possible hypothesis for this investigation. 6.2 Name ONE factor that was varied by the scientists in this investigation. 6.3 How many different values of the factor named in QUESTION 6.2 above were used? 6.4 Name TWO factors that would have to be kept constant during this investigation. 6.5 What conclusion can be drawn from the results presented in the graph? 6.6 If you were carrying out this investigation, describe ONE way in which you would ensure that the results obtained are reliable. Question 1 Improve your Skills 1.1 About 70% of Americans get a bitter taste from the substance called phenylthiocarbamide (PTC). It is tasteless to the rest. The "taster" allele is dominant to non-taster. Also, normal skin pigmentation is dominant to albino. A normally pigmented woman who is taste-blind for PTC has an albino-taster father. She marries an albino man who is a taster, though the man's mother is a non-taster. Show the expected offspring of this couple.

6 Question Distinguish between genetic engineering and biotechnology. (2) 2.2 Read the passage below and answer the questions that follow. GENETICALLY MODIFIED PIG BRED WITH 'GOOD FAT' Scientists in the United States of America have produced genetically modified pigs with fat containing omega-3 fatty acids. These fatty acids, which are usually found in salmon, mackerel and fresh tuna, are thought to be responsible for a number of benefits, from combating heart disease to improving intelligence. Researchers from the University of Pittsburgh School of Medicine created piglets capable of converting less useful omega-6 fatty acids into omega-3 fatty acids. They implanted embryos into 14 female pigs. Ten live offspring, which were able to make high levels of omega-3 fatty acids, were born. [Adapted from: Cape Argus,27 March 2006] Name TWO health benefits of omega-3 fatty acids. What percentage success did the scientists have with the implanted embryos in forming a clone of pigs capable of producing omega-3 fatty acids? Show ALL working. To produce genetically modified pigs, the gene that produces omega-3 fatty acids is inserted into the pig embryos. Describe the steps in forming and introducing many copies of the desirable gene (using bacteria) into the pig embryos. Give TWO reasons why: (2) (3) (4) (a) (b) Some people may supportthe use of genetically modified pigs to produce omega-3 fatty acids Some people may be against the use of genetically modified pigs to produce omega-3 fatty acids (2) (2)

7 Question 3 Study the pedigree diagram of a family with a particular disorder and answer the questions. 3.1 Is the disorder caused by a dominant or recessive? (1) 3.2 Explain your choice in 3.1. (2) 3.3 Assume that the letters used to solve this disorder are T and t. Use a genetic diagram to show the cross between the parents in the parent generation. Question 4 The diagram below shows the steps of an experiment in which a largenumber of genetically identical frogs were developed from unfertilised frogeggs. The nucleus of each unfertilised egg was destroyed and replaced by anucleus obtained from a body cell from frog X. 4.1 The diploid number of chromosomes in the above frogs is 26. How many chromosomes are present in the nucleus of the following cells? a.) Cell A b.) Cell B 4.2 Why can an egg containing a nucleus from the body cell of a frog develop into a tadpole? (1) 4.3 Explain why all the frogs produced from the treated eggs are genetically identical. (2) 4.4 Name the method of producing genetically identical offspring as shown in the diagram. (1) 4.5 State ONE reason why some people might: (a) Favour the process shown in the diagram (1) (b) Be against the process shown in the diagram (1)

8 Links Stem cell research: Making human insulin: