Lab Assignment 1

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University of Manitoba *

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1010

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Biology

Date

Dec 6, 2023

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pdf

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4

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Lab assignment 1: Microbiology and microorganisms Answer the questions directly in the space provided. Do not attach additional pages. This is an individual assignment. By entering your name below, you certify that you have completed the lab yourself, and the answers given are your own. Copying assignments of other students, or other forms of plagiarism will result in a grade of zero, and will be reported to the Faculty of Science. Name: ____________________________________ Student number: _____________________ When your assignment is complete, submit it to the assignment 1 drop box on UM Learn. This assignment is due at the end of Lab 1. Exercise 1: Getting to know your microscope 1) When should you use the coarse focus knob on the microscope? When should you use the fine focus knob? (2 marks) 2) How should you position the condenser on the Nikon E100 brightfield microscope? What does the condenser do? (1 mark) 3) How should you position the iris diaphragm when viewing a colored specimen, like stained bacteria? Explain why. (1 marks) Exercise 2: How can you tell the difference between prokaryotes and eukaryotes 4) Examine the picture showing the mixed bacteria (3 types) slide in the online Lab 1. What three cell shapes are shown on this slide? (1 mark)
5) Explain why we almost always use the 100x oil immersion objective when viewing bacteria with the microscope in the lab (rather than using lower powered objectives, like the 40x). (1 mark) 6) Examine the picture of the Halobacterium salinarum slide. What shape are the cells of Halobacterium salinarum ? (0.5 marks) 7) How does the cell size of Archaea compare to that of the cells in the mixed bacteria (3 types) slide? (Look carefully at all of the bacterial cells, including the largest on the slide.) Can you tell the difference between Archaea and Bacteria by size? (1 mark) 8) Is Anabaena a prokaryote or a eukaryote? (0.5 marks) 9) Examine the picture of Anabaena . Are any special structures shown? If so, which one(s)? (1 mark) 10) Examine the short video of Euglena . In the cells in the video there is a red spot clearly visible. What is this red spot? (0.5 marks) 11) Examine the picture of Saccharomyces cerevisiae . How was the condenser positioned to take this picture? Explain why. (1 mark) 12) How do the cells of S. cerevisiae compare to the cells of prokaryotes that you observed on previous slides? (2 marks)
13) Examine the picture of Penicillium. What are the structures shown at the end of the branched hyphae? (0.5 marks) Exercise 3: Where can I find a good bacterium when I need one? 14) Describe the characteristics of any one bacterial colony and any one fungal colony using the terms on pages 18‐19 of the lab manual. Be sure to clearly identify which sample the colony came from) (ie. Which plate did you find the colony on?) (3 marks) Colony type: Bacterium Origin of sample: Colony characteristics Form: Margin: Color: Surface qualities: What features make you think it’s a bacterium? Colony type: Fungus Origin of sample: Colony characteristics Form: Margin: Color: Surface qualities: What features make you think it’s a fungus? 15) Give two tips to avoid contamination of your plates in future lab periods. (1 mark) Tip 1: Tip 2:
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16) Examine the “Air” plate on the online Lab 1 results page. At what temperature was this plate incubated, and for how long? (1 mark) 17) How do you think it’s appearance of the ‘Air’ plate would have changed if it was incubated at 37 ° C for 24 hours? Consider what you know about the growth of both bacteria and fungi, and describe how the colonies of each would differ if the incubation conditions were changed. (2 marks) 18) Examine the two plates that were inoculated with swab samples. Swab of window sill. Are the colonies on this plate predominantly fungi or bacteria, or is it a mix of both? Explain how you know. (1 mark) Swab of shoe. Are the colonies on this plate predominantly fungi or bacteria, or is it a mix of both? Explain how you know. (1 mark) Total = /22