Microscopes, Cell Theory and Cell Structure

Microscope and Cell Theory Robert Hooke (1665) Looked at a thin slice of cork and saw many honeycomb-shaped structures. Called them cells.

Leeuwenhoek Used a handmade microscope to look at living blood cells, bacteria and organisms in a drop of water. Looked at plant cells and described the nucleus. Brown

Beginning of Cell Theory: Schwann & Schleiden: Said that all plants and animals were made of cells. Beginning of Cell Theory: 1) All living things are made of one or more cells. 2) The cell is the functional unit of life. 3) All cells come from pre-existing cells (don’t just appear!).

Types of Microscopes Compound Light Microscope Phase-Contrast Microscope Electron Microscope Scanning Electron Microscope

Light Microscopes Increased magnification by adding a second lens Images are magnified by multiplying 2 lens powers together. Maximum magnification of 2000 x

Transmission Electron Microscopes First one created an image 400x bigger; now they are capable of 2 000 000 x magnification Uses electron beams instead of light beams. Problems: you can only use thin layers and specimen can’t be kept alive. Must view on computer screen. $$$

Scanning Electron Microscope Produces a 3-D image. Uses electron beams. magnification is less than transmission electron (about 200,000x magnification).

Animal Cell

Plant Cell

Protects and controls things coming in & out of cell. Outside layer of every cell. Large circle near middle of cell. “brain” of the cell. Control centre and stores genetic material Inside of cell not counting organelles. where the work is done.

Carry genetic information.(blue- Thin strands found in nucleus print of the cell) Thin strands found in nucleus Digestion Sacs in cytoplasm Look like sausages Respriation:turning sugar into energy. Transportation of materials throughout cell. Tubes running through cytoplasm

Flattened sacs Storage of proteins Small granules stuck to E.R. Make proteins. Support and protection. Only gases pass through. Thick outer coating in plant cell only

Green sacs inside plant cells. Filled with chlorophyll Photosynthesis occurs. Where sugar is made Large sac in plant; smaller ones in animal cells. Fill with H2O. Control water in cell. Small, round membrane-covered sacs Transport and/ or store materials inside cell.

Animal Cell

What is the difference between plant and animal cells?

1. Shape. (generalization only) Plant cells are stacked like boxes; animal cell are oval. 2. Cell Wall Plant cells have them; animals don’t. 3. Chloroplasts Plant cells have them; animals don’t. 4. Vacuoles Plant cells have only one big one; animal cells have many small ones.

5. Centrioles Animal cells have them, plants don’t 6. Cell Plate Plant cells have them; animals don’t. 7. Cleavage furrow Animal cells have them; plants don’t. 8. Mitochindria Not a difference. Both have them.

Cheek cell: human

Cross section of an artery

Red blood cells: human

Ceopod Daphnia: microscopic water organism

Paramecium: single celled organism

Nerve cells: human

Algae nematod stentor planaria

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