Lab 4 - Microscopy
The field of view is the
Amount of the slide you are able to see through the eyepiece
Microscopes are often used to study
Bacteria, cells, and it uses
Stage adjustment knobs
Brings stage into center of view and focus -top brings forward and backward -bottom brings side to side
What is the most prominent organelle that you see in the Elodea images?
Chloroplasts
Which structure normally found in plant cells ( such as Elodea cells) is missing from the onion cells?
Chloroplasts -because it grows underground ( the onion bulb not photosynthetic) -the leaves are above ground and are green - has chorloplast so are is photosynthetic part of plant
What is the general shape of the cheek cell?
Circular and round shape ( fried egg)
iris diaphragm
Controls amount of light going to specimen
Glass that covers top of the pond water
Cover slide
The goal of microscopy is to
Create a magnified image of objects too small to be seen with the eye alone
Some chloroplasts appear to be moving ( crimculating). WHat is this activity called AND why are they moving?
Cytoplasmic Streaming -cytoplasm stream where organelles, this case chloroplasts, are transported via the cytoplasm stream to distribute nutrients and therefore food
As magnification of the image decreases the light intensity
Decreases and will have to be adjusted
How is the general shape of the cheek cell different from the plant cells you observed?
Different because plant cells are rectangular, while cheek cells ( animal) are round
3 factors that determine the quality of a microscopic image:
Magnification, resolution, and contrast
Objective lenses
Magnify the image from light at higher magnification up to 100x
Glass piece that forms base in wet mount is
Microscope slide
The sliding bar on the condenser lens is the aperture. -as you move the aperture to decrease the light to the slide, the contrast increases
Move the aperture to increase the light to the slide, the contrast decreases.
To calculate total magnification,
Multiply the magnification of ocular lens ( 10x) with the magnification of the objective lens
In what ways are plant and animal cells similar in structure?
Nucleus, arranged in tissues, mutipule organelles, and has endomemebrane system
Brightfield microscopes use a combination
Of glass lenses and light to view the specimen
The condenser lens focuses
The light on the slide
When focusing on a slide, start on the scanning or low power, objective lens
The lower the power objective, the greater the field of view.
Total magnification is
The overall enlargement of the image of a specimen
Light source
Use light to see the image
Oculars
eyepiece lenses of a microscope ( magnify the image at low magnification 10x)
In what ways are the cells and Elodea similar?
nucleus, cell walls, thin cells, rectangular like, and tightly arranged
what objective lens do you always start with then viewing a slide?
scanning objective, 4x
Cytocology
study of cells
Histology
study of tissues
how do the coarse and fine focus knobs work on a brightfield microscope?
the focus knob moves the stage up or down
most animal cells are colorless and appear transparent under the light microscope so it is helpful to stain them to impact color for viewing -true or false
true
To move the slide, you move the stage/ -the stage knob
-top moves the stage forward and back -bottom moves the stage side to side
Differences of cheek cells and the Euglena?
-Euglena has chloroplasts - photosynthetic -photoreceptor ( Euglena)
If you were given another unknown organism, how you would determine if the cells were prokaryotic or eukaryotic?
-Nucleus ( eukaryotic) or nucleotoid ( prokaryote) Prokaryotes do NOT have a nucleus that holds DNA. No endomembrane system -size: prokaryotes are very small. At 1000x magnification still cannot see the prokaryotes in detail. Also are single called
If you were given a slide of cells from an unknown organism, how you would determine if the cells were from a plant or an aminal?
-arrangement of cells in tissue ( tight - plant; loose-animal) -cell structures ( cell wall, chloroplasts , central vacuole - plants only) -cell shape/size ( rectangular -plants ; circular - animal)
Advantages of wet mount
-fast preparation -requires no special equipment other than a transfer puppeteer, slide, and cover slip -organisms may be viewed in their living state -movement of motile microorganisms can be observed
Similarities between plant cells ( onion and elodea) and the euglena?
-has chloroplast, photosynthetic -eukaryotic
Differences between the plant cell ( onion and Elodea) and the euglena?
-not same structure -not ridged like plants -able to move ( locomotive by flagella-unlike plants_ -does change shape ( unlike plant cells) -no cell wall ( unlike plant cells)
When adjusting focus always start with ____ ___ ____ then _____ _____ ____
-start with course focus knob, then fine focus
Only _____ lens are used with oil
100x
Total magnification = __________X__________
10x ( ocular) X 4x,10x, 40xor 100x, ( objective )
What is the total magnification of the observed objects in a microscope that is using the 40x objective lens?
400x ( 10x times 40x)
what is one objective view you do not use coarse focus knob as it would scratch glass
40x
The microscope you are using has 4 objective lenses to magnify the image:
4x, 10x, 40x, and 100x
Why are stain used when observed cells like onion?
Enhance contrast And details that we may not see as well without stain
Similarities of cheek cells and Euglena( protist)?
Eukaryotic In shape Capable of moving and surrounded by plasma membrane no Cell wall
Course focus
Finds focus
How does changing light intensity affect the contrast to an image in a microscope?
High light can blind the view where only you see is light. Dimming light allows you to see the contrast/increases contrast -increased light decreases contrast -decreased light increases contrast
Rotating nosepiece
Holds and rotates the objective lenses -changes magnification Ex/4x-100x
Mechanical stage
Holds and slightly moves the slide
When using the 100x objective lens, a drop of _____ is needed on the specimen slide.
Immersion oil
Resolution
Is the ability to distinguish fine detail
Magnification
Is the apparent increase in image size
Condenser
Lenses that collect light and directs it to specimen ( focuses it to specimen )
What is the stigma for the Euglena?
Photoreceptors which attracts/detects light to move by its flagella -is a eukaryotic , but not plant nor animal, but is a protist
What is the general shape of one Elodea cell?
Rectangular
Contrast
Refers to the ability to distinguish objects, such as cells, from the background
What is the difference between resolution and contrast?
Resolution is finding fine details while contrast is finding small details from the background
Course focus
Sharpens/enhances further focus (from course focus)
How do you bring a specimen into focus quickly?
Starting with larger field of view, ex/4x
Pathology
Study of disease
the Euglena were green in color because they contain
chloroplasts
what part of microscope is located below the stage and is used to focus the beam of light on the specimen ?
condenser
what is affected by the light source?
contrast