Cell Biology - Histology exam 2

Cell Biology summary (Cell Biology - Histology exam 2)

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Cells & organelles (Chapter 1) 3 Intracellular transport (Chapter 11 p.375-380 + Chapter 15) 4 Extracellular matrix (Chapter 20 p.691-708) 9 Cell cycle (Chapter 18) 11 Cytoskeleton (Chapter 17) 14 Cell communication (Chapter 16) 17 Signal transduction 19

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Cells & organelles (Chapter 1)

-Characteristics of the cell:

-Is essential building block of all life on earth -Has limiting membrane (inside/outside compartments) -Contains biomolecules (e.g. protein/RNA/DNA) -Is autonomous unit in performing a function -Can respond+adapt to stimuli -Can (often) reproduce itself

-Cell types:

-Bacteria — no nucleus/other organelles -Archaea — no nucleus, often extremophiles (= can survive under extreme circumstances where other cells cannot) -Eukaryotes — nucleus + other organelles, sometimes multicellular life forms (human/ yeast/maize)

-Microscopy:

-Light microscopes — use visible light to illuminate specimens; up to 200 nm > Properties of light (specifically its wavelength) limit fineness of detail > Investigation of plant+animal tissues with light microscope led to cell theory: all living cells are formed by growth+division of existing cells > Sample often has to be fixed -> embedded -> sliced -> stained > Possibility of living cells as samples -Fluorescence microscopes — type of LM that use sophisticated methods of illumination and electronic image processing to see fluorescently labeled cell components in much finer detail; up to 20 nm > Fluorescent dyes used for staining

> Illuminating light is passed through 2 filters:

• Filters light before reaching specimen, passing only wavelengths that

excite particular fluorescent dye

• Blocks out this light and passes only those wavelengths emitted when

dye fluoresces -Electron microscopes — use beams of electrons as source of illumination; up to 0,2 nm > Electrons have much shorter wavelength -> finer details > Similar preparation of cells as LM, but much thinner slices, no possibility of living cells (vacuum), stained with electron-dense heavy metals, and time- consuming method

• Transmission EM — used to look at thin sections of tissue; similar to LM, but

transmits beam of electrons through the sample instead of light

• Scanning EM — used to look at surface detail of cells and other structures;

scatters electrons off the sample surface

> Compartments:

• Condenser — controls beam of electrons / spotsize
• Objective — focuses image
• Wobbler — moves specimen in focal plane
• Apertures — filter out scattered electrons
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