Robert Hooke – built the first microscope (30x magnification); viewed slices of cork called cellula (little rooms). Antoni Van Leeuwenhoek - worked with glass huge improvement in quality of lenses nearly 300x magnification became possible first to observe:
* single-celled organisms “animalcules”
* protists from pond water
* bacteria from his mouth – “father of microbiology” * blood cells
* banded pattern in muscle cells
* sperm from ...
1830s – Compound microscope - improved magnification and resolution and allowed visualization of objects less than 1 μm. 1000-1500x magnification Beginning of Cell Theory
Robert Brown (botanist) - noticed that every plant cell contained a round structure called it ‘kernel’-nucleus Matthias Schleiden (another botanist) - all plant tissues are composed of cells; embryonic plant always arose from a single cell Theodor Schwann (zoologist) - similar observations in animal cells; recognition of structural similarities btw plants and animals! * Cell Theory formulated by Schwann
1. all organisms consist of one or more cells
2. the cell is the basic unit of structure for all organisms 3. added 20 years later: all cells arise only from pre-existing cells fact (scientific) - an attempt to state our best current understanding, based on observations and experiments(valid only until revised or replaced) Steps in Scientific Method
1. make observations
2. use inductive reasoning to develop tentative explanation (hypothesis) 3. make predictions based on your hypothesis
4. make further observations or design and carry out controlled experiments to test your hypothesis 5. interpret your results to see if they support your hypothesis Theory - a hypothesis that has been tested critically under many different conditions andby many different investigators .using a variety of different approaches. By the time an explanation is regarded as a theory it is widely accepted by most scientists in the cell * the “solid ground” of science: evolution, germ theory, cell theory *If a theory is thoroughly tested and confirmed over many years by such large numbers of investigators that there is no doubt of its validity … it may eventually be regarded as a law. Gravity, laws of thermodynamics, laws that govern behaviour of gases ‘Strands’ of Cell Biology
looks at cork
looks at lots
synthesis of urea in lab
fermentation done by cells!
every cell comes from a cell
Schleiden & Schwann formulate cell theory
stains & dyes
Mendel, pea plants
DNA double helix
Dolly the sheep!
Bright field – light passes through specimen, contrast is slow and specimen is hard to see Phase contrast – contrast is changed by changing light in microscope DIC – uses optical modifications to change contrast between cell and background – due to density differential Staining – stain used to visualize cell and components, only some stains can be used on living cells 14
tissue – small intestine
Fluorescent Microscopy – fluorescent dyes bind to protein or DNA to see where they are in cells – tracks movement Electron Microscopy(Scanning & Transmission):
SEM – scan surface of specimen to form image by detecting electrons from outer surface. Good surface images TEM – forms image from electrons passing through specimen therefore fine details of internal organelles 16
Basic Properties of Cells:
* are highly complex and organized
* atoms molecules macromolecules (organelles ) enclosed in plasma membrane * use the same ‘genetic program’ Central Dogma...