DNA Technology, Bacteria, Virus and Meiosis Test REVIEW

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1 Be prepared to turn in a completed test review before your test. In addition to the questions below you should be able to make and analyze a plasmid map. Prokaryotic Gene Regulation 1. What is meant by a 'universal genetic code?' The same four nucleotides, A, T, C & G are found in all organisms but in a different sequence. They also all have the same amino acids. Therefore, a gene from one organism can be expressed by another organism. 2. Describe when and how the lac Operon functions. The lac Operon is usually off, but can be induced in the presence of lactose. Bacteria prefer glucose, but will breakdown lactose for energy when necessary. When lactose concentrations are high the operon turns on to break down lactose. a. What substrate will induce the lac operon to function? lactose b. What is the product of the lac operon? lactase 3. Describe when and how the trp Operon functions. The trp Operon is normally on, making the amino acid tryptophan. When enough tryptophan is present, it will bind to the repressor and turn the operon off. a. What product will repress the trp operon? Tryptophan 4. Which of the operons are inducible and which are repressible? a. lac operon - inducible b. trp operon - repressible Eukaryotic Gene Regulation 5. How do histone proteins aide the packing of DNA? DNA is wrapped around histone proteins which enables it t fit in the nucleus. 6. How are DNA methylation and acetylation related to each other? In eukaryotes, methylation turns off transcription by adding methyl groups to DNA which causes it to wrap more tightly around histone proteins. Acetylation turns it on by adding acetyl groups which loosens DNA. 7. What is a gene? A section of DNA that codes for a particular protein 8. What is apoptosis and what role does it have in the development of embryos? Apoptosis is cell programmed death. In the development of an embryo, its role is to eliminate cells that are not predetermined for other roles in body development.

2 9. Information flow in cells can be regulated by various mechanisms. (a) Describe the role of the following in the regulation of protein synthesis: - RNA capping : RNA is protected in the cytoplasm from digestive hydrolytic enzymes due to 5' GTP cap and 3' poly A tail. - Ubiquitin and Proteosome Ubiquitin tags protein for destruction / digestion. Proteosome break down the tagged protein. DNA Technology 10. What is the function of the following enzymes / proteins? a. Restriction enzyme Cuts DNA into short segments at a specific sequence b. Ligase Seals DNA pieces back together 11. What is the relationship between DNA, a gene and a chromosome? A short segment of DNA that codes for a protein is called a gene. When DNA is wrapped tightly around histone proteins it forms chromosomes 12. What is the central dogma? DNA -> RNA -> protein -> traits 13. How do plasmids replicate? They are self replicating 14. What role does a DNA palindrome have in terms of a restriction enzyme? This is usually where restriction enzymes cut DNA 15. In the transformation lab which plates were supposed to have bacterial growth? WHY? +pglo LB/amp & +pglo LB/amp/ara were both supposed to have growth because we inserted the gene for ampicillin resistance, which should have caused the bacteria to grow in the presence of ampicillin. The pglo in LB should also have grown as this was the control. The pglo in LB/amp should NOT have grown because it did not receive the plasmid and should have not been resistant to the antibiotic. 16. In transformation, what does it mean when the bacteria is competent? The cell was able to take in the plasmid (we achieved this using CaCl 2 and heat shock)

3 Use the information to answer the question that follows: A scientist is using an ampicillin-sensitive strain of bacteria that cannot use lactose because it has a nonfunctional gene in the lac operon. She has two plasmids. One contains a functional copy of the affected gene of the lac operon, and the other contains the gene for ampicillin resistance. Using restriction enzymes and DNA ligase, she forms a recombinant plasmid containing both genes. She then adds a high concentration of the plasmid to a tube of the bacteria in a medium for bacterial growth that contains glucose as the only energy source. This tube (+) and a control tube (-) with similar bacteria but no plasmid are both incubated under the appropriate conditions for growth and plasmid uptake. The scientist then spreads a sample of each bacterial culture (+ and -) on each of the three types of plates indicated below. 17. What results would you expect to see on the plates shown? Growth on plates 1, 2, 3 & Think about the transformation lab and describe how: Bacteria 19. Describe the domain Archae - Unicellular prokaryotes, cell wall with no peptidoglycan, DNA contains histone proteins, but in a single circular chromosome, extremophiles

4 20. Name and describe the process for bacterial reproduction? Binary fission (no mitosis/meiosis). Once bacteria are big enough, they copy their DNA and then the cytoplasm divides into two cells. 21. By which processes can bacteria ensure genetic variation? (name 5) Transduction, transformation, conjugation, mutation, transposons 22. Which process listed from #19 most commonly introduces the most genetic variation in bacteria? Mutation 23. How are prokaryotic ribosomes different than eukaryotic ribosomes? Prokaryotic ribosomes are smaller than eukaryotic ribosomes. However, prokaryotic ribosomes are similar to mitochondrial and chloroplast ribosomes. 24. Why are bacteria needed for? a. decomposition: They help break down dead organisms and recycle nutrients back to the soil b. nitrogen fixation: They change nitrogen in the air, that is unusable to plants and animals, into a usable form. This nitrogen is used to make proteins and nucleic acids 25. Define the following modes of nutrition in bacteria a. Photoautotroph Photosynthetic; Uses light to make energy i. What is a photoautotrophs source of carbon? Carbon Dioxide b. Chemoheterotroph- Live on plant and animal matter, decomposers and pathogens (make you sick) c. Chemoautotroph Oxidizes inorganic compounds like nitrogen and sulfur to make energy 26. What does it mean if a bacterium is described as a thermoacidophile? It loves environments with high temperatures and high acidity (low ph) 27. What are similarities and differences between ribosomes in prokaryotes, eukaryotes and organelles? Prokaryotic ribosomes are smaller than eukaryotic ribosomes. However, prokaryotic ribosomes are similar to mitochondrial and chloroplast ribosomes. 28. What must happen to a eukaryote gene before a bacteria can make a protein from it? All introns must be removed (bacterial chromosomes are exons only) c. When or where during transcription and translation in a eukaryote, would this gene be found? The gene that could be read by bacteria would have to come from the mature mrna found in the cytoplasm (the primary transcript in the nucleus has not undergone splicing) 29. If Archaebacteria is described to be more closely related to Eukaryotes than Eubacteria because of its DNA, what else may be true when comparing the two kingdoms? Archaebacteria have larger ribosomes, like eukaryotes, compared to Eubacteria. (Their DNA has histone proteins, like eukaryotes)

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