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 oil1. Don’t get oil on other lenses2. Don’t use cover slip with oil3. Wipe off oil with lens tissueDO NOT GO BACK TO LOWER POWER OBJECTIVE

What 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

Biodiversity

Living organisms are organized into

3 domains

Biodiversity

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), e-mail 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