Macromolecules, Cell Throery, Microscopy (Lecture 2)

Question 1

What are the 4 macromolecules and what polymers are they made of?

Answer 1

1. Carbohydrates - polymers of sugars
2. Lipids - not polymers
3. Proteins - polymers made of amino acids
4. Nucleic acids - polymers made of nucleotides

Question 2

How do most bio-polymers arrange? What are examples?

Answer 2

The chains arrange into varied levels of higher-ordered structure

Ex. DNA double helix, protein folding

Question 3

What are 4 structures of protein polymers? What are their shape/characteristics?

Answer 3

(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)

Question 4

What determines a proteins structure?

Answer 4

The properties and order of the amino acids

Question 5

R = sidechain, what does sidechain mean?
H3N+—C—C=O
I
R

Answer 5

Sidechain properties define the chemistry of proteins

Question 6

Primary protein structure
1. How are amino acids linked?
2. What are proteins also known as?

Answer 6

1. By covalent bonds called peptide bonds
2. Polypeptides

Question 7

secondary protein structure

Answer 7

Hydrogen bonds between nearby amino acids cause polypeptides to twist (alpha helix) or form sheets (beta sheets)

Question 8

tertiary protein structure

Answer 8

Chemistry between sidechains causes higher-order folding

Question 9

Quaternary protein structure

Answer 9

Individual proteins interact to form complexes
Again, determined by their structure and chemistry

Question 10

What are polymer examples of carbohydrates? (Glucose in different forms)

Answer 10

• Amylose (a component of starch)
• Cellulose
• Chitin

Question 11

Cell theory: 3 components?

Answer 11

1. All organisms are composed of one or more cells
2. The cell is the basic structural and functional unit of all living organisms
3. Cells arise only from the division or pre-existing cells

Question 12

When was the Establishment of cell theory?

Answer 12

1800’s

Question 13

What did Theodore Schwann and Matthias Schleiden propose?

Answer 13

All living organisms are made of cells

Question 14

What did Robert Remak and Rudolph Virchow propose?

Answer 14

That all cells come from previous cells

Question 15

What did Louis Pasteur confirm?

Answer 15

Confirmed other hypothesis by demonstrating that the long-standing theory of spontaneous generation was bunk

Question 16

Cells in regard to surface area

Answer 16

• 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

Question 17

What does a cell do if the cell really requires a large surface area?

Answer 17

Develops convoluted / branchy surface morphologies

Question 18

What is resolution?

Answer 18

The ability of a microscope to distinguish two objects as being separate

Question 19

What does higher magnification do?

Answer 19

Higher magnification increases resolution

Question 20

What does higher contrast do?

Answer 20

Higher contrast gives more detail, but can’t increase resolution

Question 21

What are the Microscopy types?

Answer 21

A. Light Microscope
1. Reflected light
2. Transmitted light
3. Fluorescence

B. Electron Microscopy
1. Transmission
2. Scanning

Question 22

Reflected light?

Answer 22

• stereo microscope (a.k.a. Dissecting microscope)
• lighting from top
• can see bigger size cells

Question 23

Transmitted light

Answer 23

• stereoscopes (some can also use light from the bottom)
• compound microscopes

Question 24

What are the variations on transmitted light compound?

Answer 24

• brightfield (ones we use in our labs)
• darkfield
• phase-contrast
• differential interference contrast (DIC)

Question 25

What do darkfield, phase-contrast, and DIC, have in common?

Answer 25

• Contrasting-enhancing methods
• Exploit the light-scattering (refractive) properties of specimens
• Variations in specimens thickness and density influence how light passes through it

Question 26

Brightfield

Answer 26

Like the ones we use in labs

Question 27

Contrast enhancing methods - Darkfield

Answer 27

• 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

Question 28

Contrast enhancing methods - phase contrast

Answer 28

• This method creates slight phase shifts in the illuminating light, which manifest as higher detailed images

Question 29

Contrast enhancing methods - DIC

Answer 29

• Similar to phase-contrast
• Gives a pseudo-3D appearance

Question 30

Fluorescence

Answer 30

• 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)

Question 31

What are three common sources of fluorescence in Biology?

Answer 31

• Intrinsic fluorescence (autofluorescence) from specimen (pigments)
• Fluorescent dyes
• fluorescent proteins

Question 32

What are the advantages of fluorescence microscopy?

Answer 32

• Colour-specific illumination allows visualization of specific structures of interest

Question 33

What do Confocal fluorescence microscopes do?

Answer 33

• 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