Last week’s quizzes and reports See me for your quizzes and lab reports before leaving, after cleaning up. Grading questions etc.? Office hours: Mon 11-1 Ramaley N-197

Microscopy  Properly use a microscope/camera.  Compare resolution & magnification.  Identify types/structures of cells.  Prepare for quiz next week

The Microscope  Correct use and care: transport and lenses  Parts of the bright field microscope  Magnification and resolution  Types of lenses  Estimation of size

The Microscope Each type of microscope has a specific function, which makes them suitable for different types of tasks. Fig. 1: dissecting, fluorescence, phase-contrast and electron microscopes.

Bright field microscopy Light is sent up from under stage Light goes through condenser and is focused on object. Light goes through object into objectives and object is magnified Light goes through oculars to eye and is magnified again

The Microscope Ocular Binocular tube Arm Revolving nosepiece Objectives Condenser Lamp Base Coarse focus adjust. Fine focus adjust. Mechanical stage adjustment (x,y)

The Microscope Magnification: number of times an object is magnified by the lenses Resolution: the ability of a microscope to show to separate dots as discrete units

The Microscope Lenses: “Low power" objectives: are very useful to get overview images of larger sections. “High power" objectives: are mostly for details and there are more delicate (dry and wet lenses). As the magnification increases in the lenses, the working distance decreases.

The Microscope Lenses: The Immersion lens (100X). Used with oil because its refractive index is close to that of glass, avoiding loss of light. Working distance very small Dealing with oil 1. Don’t get oil on other lenses 2. Don’t use cover slip with oil 3. Wipe off oil with lens tissue DO NOT GO BACK TO LOWER POWER OBJECTIVE

W hat we are going to do? Take digital pictures of plant cells Identify cellular components Mount and dye cheek cells, identify components Identify bacteria Take pictures

Example

Cell Theory  Cells are the basic units of life  All living organisms are composed by cells  Prokaryotic vs. Eukaryotic cell  Animal vs. Plant cell

B iodiversity Living organisms are organized into 3 domains

B iodiversity Today, we will see examples of 2 of them 2 domains

The Cell Plant cell Remove a thin leaf from the tip of a Elodea sp. plant Place the leaf on the microscope slide with a drop of water Add a cover slip and soak up extra water with a tissue Identify: cell wall, cell membrane, chloroplasts, central vacuole and nucleus.

The Cell Animal cell Take a toothpick and gently scrape the inside of your cheek and around your gums Place a small drop of water on a microscope slide and stir the content Evaporate the water Pass the slide over a Bunsen burner Mark the area on the other side Add two drops of methylene blue (60sec. and wash it off) Dab off remaining water

The Cell Prokaryotic cell: Bacteria Identify and obtain digital images of rod-shaped and coccus-shaped bacteria

Digital Cameras Be gentle, no jamming of cables Upload photos, choose the best for each (plant & cheek), to yourself, and me Remove one eyepiece to use camera Some cameras have damaged USB ports, and require card readers to upload

Bunsen burners Keep slides right-side up No oil on any lenses but 100x, wipe Dr. Basey’s demonstration Hints & Warnings