Cells Introduction

First – Review of Microscopes! And a quiz right after!

Microscopes Simple light microscope One lens Living or dead specimen From: http://www.darwincountry.org/explore/001168.html

Microscopes Compound light microscope more than one lens resolution is a problem Must be transparent (very thin) Living or dead specimen This is what we use

Microscopes Electron microscopes – use a beam of electrons (on a dead specimen) 2/17/2019

Microscopes Electron microscopes types– Transmission (TEM)- electrons pass through - very thin specimen Scanning (SEM)- electrons bounce off and get an image from the outside 2/17/2019

Microscopes Other types– Scanning tunneling Uses a microprobe Can be used on living or dead organisms 2/17/2019

Microscope Parts

Miscroscope Parts Remember, the compound microscope has more than one system of lenses The first lens system is the ocular or eyepiece located at the top of the microscope.

Miscroscope Parts Objectives Depending on your microscope, the lowest (and shortest) lens is often called the scanning lens as it is used to “scan” the specimen to find your “target” for viewing. Usually these lenses magnify specimens 4x.

Miscroscope Parts Objectives The next two lenses are considered “high” and “low” power objectives because of the power of magnification they have. These may vary from 10x-43x

Base-area on which the microscope rests and used to help carry the microscope Arm-vertical piece that supports the body; also used to help carry the microscope Body Tube-the portion of the microscope that contains the objective lenses Revolving Nosepiece-the assembly that contains the objective lenses

Stage-the platform upon which objects to be examined are placed; Some can be moved up and down Stage Clips-hold the object to be viewed in place Condenser-lens that concentrates light on objects to be viewed

Diaphragm-series of holes that control the amount of light that reaches the object to be viewed. Sometimes aperture (opening) numbers are found on holes Illuminator-light source; usually an electric light or a mirror

Course Adjustment Knob-used to bring the object into view Course Adjustment Knob-used to bring the object into view. Always look to the side when using this and NEVER use it with the high power objective. Fine Adjustment Knob-used to clear up the view of the object. Can be used with any objective lens.

Ocular lens (Eyepiece) Body Tube Nosepiece Arm Objectives Scanning-shortest Low-mid-size High-longest Stage Stage Clips Coarse Adjustment Diaphragm Fine Adjustment Light Base Condenser

Microscope Parts Eyepiece (ocular lens) Tube (body) From: http://www.microscopy.info/microscopy/light/glossary.aspx Eyepiece (ocular lens) Tube (body) Revolving Nosepiece Objectives Scanning Low High Focus knobs Coarse fine Base Stage clips Diaphragm/iris/condenser Light 2/17/2019

2/17/2019

Characteristics of Microscopes Magnification Image appears larger than it is Eyepiece 10x Objectives 4x, 10x, 40x* Resolution Clarity of the image Gets poorer with increased magnification 2/17/2019

Magnifications: Simple light: 5-25x Compound light: up to 2000x Electron microscopes SEM 200,000x TEM 2,000,000x Scanning tunneling: 1,000,000,000x 2/17/2019

Care and Use 1. Always carry the microscope with 2 hands by the arm and the base 2. Cleaning-be sure that all lenses are clean using lens paper provided by your teacher and wiping off lenses in circular motions. Plain water may leave images blurry.

Care and Use 3. Turn on the microscope and then rotate the nosepiece to click the scanning objective into place. 4. Place a slide on the stage and secure it using the stage clips.

5. Focusing a. While looking from the side, Turn the course adjustment know until the lens is as close to the specimen as possible without touching it.  b. Look into the ocular and use the coarse adjustment knob (large knob) to bring the image into view. Look through the eyepiece lens and focus until the image is clear **NEVER USE THIS KNOB ON HIGH POWER! It may crash into the slides which could break both the slides and the lenses!

Focusing c. Use the fine adjustment knob* (small knob) to make is sharper or to finish the focus. *This knob may be used freely with any power.

Once you have an image in view using the scanning objective, rotate the nosepiece to view it under different powers. 1. When you want to change the view of the object between low and high powers you will only need to use the fine adjustment knob. 2. Again, you should NOT focus with the course adjustment knob while using high power, as it leads to broken slides and damaged lenses!.

Adjustment of Light- - The diaphram controls the quality of light that reaches the slide. - To control the light adjust only the diaphragm. Be careful-too much light can wash an image out and make it harder to see!

***Special Note: As we increase the power of the objectives we use, the smaller our field becomes and we often require less light. In other words-we see less of the object but sometimes better detail.

When you are done viewing objects, return your microscope to its storage place with the light source off and the scanning objective in place. Put away all your slides!

What's Your Power? To calculate the power of magnification, multiply the power of the ocular lens by the power of the objective. 10 x 40= 400x

Which of these images are viewed at a higher power of magnification? Comparing Powers of Magnification We can see better details with higher the powers of magnification, but we cannot see as much of the image. Which of these images are viewed at a higher power of magnification?

Microscope Images Mitochondrion Parasitic insect emerging from host 2/17/2019

Microscope Images Mouse lung DNA 2/17/2019

Examples from light microscopes Pseudostratified ciliated columnar epithleium Simple columnar epithelium 2/17/2019

Summarize your Notes Quiz time! More on Cells to come!

The Scientists

Robert Hooke (English, 1665) Looked at cork and named cells - after rooms in a monastery thought only plants had cells “...I could exceedingly plainly perceive it to be all perforated and porous, much like a Honeycomb...these pores or cells , were not very deep, but consisted of a great many little boxes...” --Hooke describing his observations on a thin slice of cork. 2/17/2019

2/17/2019 From: http://askabiologist.asu.edu/research/buildingblocks/rhooke.html

Anton van Leeuwenhoek (Dutch, 1674) First to use microscope to observe living cells Father of microbiology looked at pond water - animacules (little animals) 2/17/2019

Cell Theory Matthias Schleiden (1838) All plants are made of cells Theodore Schwann (1839) All animals are made of cells Rudolf Virchow (1858) All cells come from preexisting cells 2/17/2019

Cell Theory All living things are composed of one or more cells. Cells are the basic units of structure and function in living things. All cells come from preexisting cells. 2/17/2019

Cells Introduction

Cell Size and Function

Structure and Function From:http://casweb.cas.ou.edu/pbell/Histology/ Captions/Cellmethods/54.blood.Wright%27s3.html From: http://casweb.cas.ou.edu/pbell/Histology/Captions/Cellmethods/108.cilia.100x.html

Structure and Function From: http://www.howstuffworks.com/brain2.htm Structure and Function Nerve tissue From: http://www.cord.edu/faculty/todt/336/lab/nervous/neuron2.html Examples of skin and nervous tissue 2/17/2019

Structure and Function Skin Tissue From: http://cytochemistry.net/Cell-biology/Medical/practice_lab_exam_Epithelium.htm Examples of skin and nervous tissue 2/17/2019

Structures and Functions From: http://www.technion.ac.il/~mdcourse/274203/slides/Connective%20%20Tissue/4-Adipose%20Tissue-White.jpg Fat Example of fat cells 2/17/2019

Cell Size Most organisms have many small cells rather than fewer large ones Why? Surface area-to-volume ratio 6:1 good 3:1 very large for cells Any lower than this is very dangerous

Cell Size Most organisms have many small cells rather than fewer large ones Why? Allows transfer of materials in and out of cell easily Cell size = small, Surface Area:Vol = high Cell size = large, Surface Area:Vol = low

2/17/2019

All cells have… Cell membrane – around outside Cytoplasm – fluid of cell Cytoskeleton – structure of cell Ribosomes – make protein DNA – used as instructions to make protein Some lose these after time due to specialization 2/17/2019

Prokaryotes Bacteria Single celled organism Lacks nucleus and membrane bound organelles* DNA in a circular loop Cell wall *An organelle is a structure within a cell that performs a specific function 2/17/2019

Eukaryote Organism that has cells with nuclei and internal compartments (membrane bound organelles) ex. animals, fungi, plants, protists 2/17/2019

2/17/2019 From: http://www.windows.ucar.edu/tour/l ink=/earth/Life/cell_organelles.html&edu=elem http://darkwing.uoregon.edu/~bsl/astronomy/Images/prokaryote.jpg 2/17/2019

2/17/2019

Summarize your Notes Quiz next time! More on Cells to come!