Van Leeuwenhoek
Optics- discovered early microscopes
Discovered single-cell organisms
Hooke
coined term ‘cell’ (monk’s room)
Brown
Found ‘kernel’ of cell - nucleus
Schleiden & Schwann
developed Cell Theory
- all organisms consist of one or more cells
- the cell is the basic structure of all organisms
Cell Theory
- all organisms consist of one or more cells
- the cell is the basic structure of all organisms
Prokaryotes and eukaryotes evolved from..
Primordial cell 4x10^9 yrs ago
Prokaryotes
Single celled organisms
archaea & eubacteria
Eukaryotes
- have compartmentation - different functional areas inside cell
- have a cytoskeleton (cell skeleton) - defined internal structure
Prokaryotes
Single celled organisms
(archaea & eubacteria)
Cell wall, plasma membrane, DNA, ribosomes in cytosol, flagellum
Eukaryotes
- have compartmentation - different functional areas inside cell
- have a cytoskeleton (cell skeleton) - defined internal structure
Eukaryote vs prokaryote DNA
Eukaryote - DNA in nucleus ( enclosed intracellular compartment with a distinct membrane)
Prokaryote - no distinct nuclear compartment
Prokaryotes (shapes & sizes)
Spherical cells (Streptococcus), Rod-shaped cells (E. coli, Vibrio cholerae), Spiral cells (Treponema pallidum), Smallest cells (Mycoplasma, Spiroplasma),
Prokaryotes (specialisation of function)
- live in enormous variety of ecological niches
- varied in biochemical capabilities
Prokaryotes (basic cell structure)
Single celled organisms
(archaea & eubacteria)
Cell wall, plasma membrane, DNA, ribosomes in cytosol, flagellum
Eukaryotes (basic cell structure)
- have compartmentation - different functional areas inside cell
- compartments: plasma membrane, nucleus & membrane, organelles (mitochondria, lysosomes, peroxisome)
- have a cytoskeleton (cell skeleton) - defined internal structure
Eukaryotes (Multicellularity evoked: …)
- Specialisation: tissues & organs appeared as organisms became more complex
- Command/Control/Communication
- long/ short range signals
- quick/ long lasting
- specific (eg nervous)/ general (eg endocrine)
Tools
- Microscopes
- Dyes & antibodies(selective molecules-only bind target areas)
- Microprobes(instruments that apply a beam of charged particles to a sample to determine the elemental composition)
- Fractionation
- Autoradiography
Light Microscope- Compound Microscope (Optical tricks to see different components of cell without touching it)
- Bright-field: light passing through cells in culture forms image directly
- Phase-contrast: phase of light changed- more light through different wavelengths
- Differential interference: polarises light
- Dark-field: light rays directed at an angle - appears as bright object against a dark background.
Dyes
Histology-stained cells & tissues
-Fluorescence:
-UV stimulation evokes tissue fluorescence (autofluorescence)
-Specific dyes fluoresce at different wavelengths (colours) when UV is shined on them.
- Antibodies & dyes
-Indicator Dyes
eg dye binds to Ca and fluoresces at different colours depending on conc of Ca
Electron microscopes
TEM (transmission) shows structures inside cells in greater detail.
Measure electrical activity in:
- Single channels: patch electrodes
- Membranes: microelectrodes & fluorescent dye
- Whole tissues: extracellular electrodes
