Macromolecules, Cell Throery, Microscopy (Lecture 2) Flashcards
What are the 4 macromolecules and what polymers are they made of?
- Carbohydrates - polymers of sugars
- Lipids - not polymers
- Proteins - polymers made of amino acids
- Nucleic acids - polymers made of nucleotides
How do most bio-polymers arrange? What are examples?
The chains arrange into varied levels of higher-ordered structure
Ex. DNA double helix, protein folding
What are 4 structures of protein polymers? What are their shape/characteristics?
(Primary protein structure) 1 structure - amino acid chain
(Secondary protein structure) 2 structure - ex) a-helix, B-sheet (coiling)
(Tertiary protein structure) 3 structure - folding (coils folding)
(Quaternary protein structure) 4 structure - assembling with other proteins into a complex (folded coils assembling with other folded coiled proteins)
What determines a proteins structure?
The properties and order of the amino acids
R = sidechain, what does sidechain mean?
H3N+—C—C=O
I
R
Sidechain properties define the chemistry of proteins
Primary protein structure
1. How are amino acids linked?
2. What are proteins also known as?
- By covalent bonds called peptide bonds
- Polypeptides
secondary protein structure
Hydrogen bonds between nearby amino acids cause polypeptides to twist (alpha helix) or form sheets (beta sheets)
tertiary protein structure
Chemistry between sidechains causes higher-order folding
Quaternary protein structure
Individual proteins interact to form complexes
Again, determined by their structure and chemistry
What are polymer examples of carbohydrates? (Glucose in different forms)
- Amylose (a component of starch)
- Cellulose
- Chitin
Cell theory: 3 components?
- All organisms are composed of one or more cells
- The cell is the basic structural and functional unit of all living organisms
- Cells arise only from the division or pre-existing cells
When was the Establishment of cell theory?
1800’s
What did Theodore Schwann and Matthias Schleiden propose?
All living organisms are made of cells
What did Robert Remak and Rudolph Virchow propose?
That all cells come from previous cells
What did Louis Pasteur confirm?
Confirmed other hypothesis by demonstrating that the long-standing theory of spontaneous generation was bunk
Cells in regard to surface area
- surface area must be sufficient to allow exchange of stuff between the cell and its surroundings
- larger volumes require more surface area
- larger volumes require more structural support
What does a cell do if the cell really requires a large surface area?
Develops convoluted / branchy surface morphologies
What is resolution?
The ability of a microscope to distinguish two objects as being separate
What does higher magnification do?
Higher magnification increases resolution
What does higher contrast do?
Higher contrast gives more detail, but can’t increase resolution
What are the Microscopy types?
A. Light Microscope
1. Reflected light
2. Transmitted light
3. Fluorescence
B. Electron Microscopy
1. Transmission
2. Scanning
Reflected light?
- stereo microscope (a.k.a. Dissecting microscope)
- lighting from top
- can see bigger size cells
Transmitted light
- stereoscopes (some can also use light from the bottom)
- compound microscopes
What are the variations on transmitted light compound?
- brightfield (ones we use in our labs)
- darkfield
- phase-contrast
- differential interference contrast (DIC)
What do darkfield, phase-contrast, and DIC, have in common?
- Contrasting-enhancing methods
- Exploit the light-scattering (refractive) properties of specimens
- Variations in specimens thickness and density influence how light passes through it
Brightfield
Like the ones we use in labs
Contrast enhancing methods - Darkfield
- Illuminates sample at an angle so light does not hit the objective lens directly
- Only light that is scattered upwards by the sample reaches the objective lens
Contrast enhancing methods - phase contrast
- This method creates slight phase shifts in the illuminating light, which manifest as higher detailed images
Contrast enhancing methods - DIC
- Similar to phase-contrast
- Gives a pseudo-3D appearance
Fluorescence
- Electron absorbs a photon and gets excited to a higher energy state (valance)
- Excited electron returns to its ground state, releasing a photon of longer wavelength (lower energy)
What are three common sources of fluorescence in Biology?
- Intrinsic fluorescence (autofluorescence) from specimen (pigments)
- Fluorescent dyes
- fluorescent proteins
What are the advantages of fluorescence microscopy?
- Colour-specific illumination allows visualization of specific structures of interest
What do Confocal fluorescence microscopes do?
- Increases contrast by capturing very thin slices of a specimen
- Does this by passing the emitted light through a tiny pinhole which removes out of focus light
