Cell Study

Microscope History Robert Hooke First described cells in 1665. He viewed thin slices of cork and compared the boxy partitions he observed to the cells (small rooms) in a monastery. (1635–1702)

Microscope History Anton van Leeuwenhoek In 1676 the Dutch scientist observed single- cell organisms ("little animalcules“). He was likely the first person to observe a red blood cell and a sperm cell. (1632–1723)

Microscope History Robert Brown In 1831, Scottish scientist Robert Brown gave the nucleus of a cell its name. (1773–1858)

Methods of Cell Study Advances in instruments has led to a better understanding of the structure and function of cells. Compound Light Microscope A. Two lenses (ocular and objective) B. Specimen must be transparent

The Compound Light Microscope

Function of the Compound Light Microscope Ocular – (eye piece) look through, magnifies the image Body Tube - holds lenses Nosepiece - rotates the objectives (lenses)

Function of the Compound Light Microscope Stage – platform for slide Stage Clips - holds slide in place Diaphragm - controls the amount of light passing through the specimen

Function of the Compound Light Microscope Mirror or Light Source (illuminator) - lights the specimen so it is easier to observe Arm – used to carry the microscope Base - supports the microscope

Function of the Compound Light Microscope Coarse Adjustment Knob - used for preliminary focusing, NEVER used on high power.

Function of the Compound Light Microscope Fine Adjustment Knob – used to focus on high power, and to fine tune low power.

Function of the Compound Light Microscope High Power Objective: This objective has a magnification of 100x (maximum magnification)

Function of the Compound Light Microscope Low Power Objective: This objective has a magnification of 10x (minimum magnification) Scanning objective – has a magnification of 4x

Magnification & Resolution C. Magnification power is equal to the product of the ocular lens times the objective lens. Ocular Objective Total Magnification 10x 100x 40x 400x 15x 600x Resolution - ability to distinguish between (separate) two objects very close together. The properties of light limit the resolving power of the light microscope. If you can’t read this, it is because you can’t distinguish between the letters

Resolution

Electron Microscope Uses a beam of electrons instead of light to get greater resolution and magnification (up to 250,000X).

Electron Microscope

Dissecting Microscope Used for viewing opaque (not see- through) specimens. Provides a 3-D view. Does not reverse or invert the image

Phase Contrast Microscope Provides contrast without stains (stain kills specimens)

Phase Contrast Microscope

Ultracentrifuge Separates cell parts (organelles) by spinning them in a test tube at high speed (denser parts sink to the bottom of the test tube).

8.Measurements with the microscope Millimeter = mm Micrometer = µm 1000 µm = l mm 1 µm = 1/l000 mm

Measuring with a Microscope Measuring the Field of View (FOV) Place a ruler on the stage, and line up one measurement line at the edge of the FOV Measure/estimate the size of FOV

Measuring with a Microscope Estimate the size of the object: Size of object = FOV # object that fit across the FOV How big is this cell?

Cells

Structure of Living Organisms The cell is the basic unit of life.

I. The Cell Theory All organisms are made up of one or more cells. These cells working individually, or together in tissues or organs, perform all life functions. All cells come from pre-existing cells.

II. Exceptions to the Cell Theory The first cell could not have come from a pre-existing cell. Viruses - which are not cells have hereditary material and can reproduce. Organelles such as mitochondria and chloroplasts have genetic material (DNA) and can reproduce.

Two types of Cells Prokaryotic Eukaryotic

Prokaryote Do not have structures surrounded by membranes Few internal structures One-celled organisms (ex: bacteria)

Eukaryote Contain organelles surrounded by membranes Most living organisms

Examples of Cells Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell

Cell Organelles Organelles are small specialized structures that carry out life functions within cells.

Animal Cell

Plant Cell

1. Plasma (Cell) Membrane Regulates the movement of materials into or out of cells. Semi-permeable Selectively-permeable Composed of a lipid bilayer with embedded proteins. It is “fluid” – meaning it is flexible and the parts can move around within the membrane.

2. Cytoplasm Jelly like environment of the cell (mostly H2O) Cyclosis: Movement of the cytoplasm (transports materials within the cell)

Nucleus and Nucleolus Nucleus – controls cell activities surrounded by nuclear membrane. - Contains genetic material (DNA and RNA) - Involved in Reproduction Nucleolus – dense region in the nucleus. involved in the synthesis of ribosomes.

5. Mitochondrion Site of cellular respiration Produces ATP (energy) for metabolism

6. Golgi Complex Synthesizes, packages and secretes (releases) cellular products.

7. Ribosomes Site of protein synthesis (ex: enzymes are proteins)

8. Endoplasmic Reticulum (ER) Forms passages throughout the cell for intracellular (within the cell) transport. Connects the nuclear membrane to the plasma membrane

8. Endoplasmic Reticulum (ER) Two Types of Endoplasmic Reticulum Rough Endoplasmic Reticulum- covered in ribosomes Smooth Endoplasmic Reticulum (no ribosomes)

9. Lysosome Contains digestive enzymes (breaks down damaged organelles or pathogens)

10. Vacuole Space in a cell surrounded by a membrane. Food vacuole - stores food to be digested. Contractile vacuole – helps to maintain water balance within a cell

Organelles in Animal Cells Only Centrioles – Play a role in cell division

Organelles in Plant Cells Only Chloroplast – Perform photosynthesis (produce nutrients)

Organelles in Plant Cells Only Cell Wall– non-living structure that surrounds, supports and protects the cell. Made of cellulose (a polysaccharide)