1
Q
A cell is…
A
- The vehicle for hereditary information
- Includes the machinery to gather its own raw materials
- Has the ability to replicate and pass on its genetic material
2
Q
Z.Janssen and H.Janssen (1590)
A
1st compound microscope
3
Q
Robert Hooke (1665)
A
- Described chambers in cork
- Coined the term cell
- Wrote Micrographia
4
Q
Antoine Van Leeuwenhoek (1673)
A
Made his own microscopes (300x)
First to observe and describe living cells
5
Q
Schwann and Schleiden’s Cell Doctrine
A
- All life forms are made from one or more cells
2. Cell is the basic unit of structure for all organisms
6
Q
Virchow’s addition to the cell doctrine
A
- All cells arise ONLY from pre-existing cells
7
Q
Spontaneous generation
A
The theory that living material can spontaneously arise from non-living material
8
Q
Francesco Redi (1625-1697)
A
- Performed experiments that proved that maggots do not spontaneously arise from meat
- 1 jar w/ just meat, 1 jar covered in gauze, 1 jar covered in paper
9
Q
John Needham (1713-1781)
A
- Boiled mutton to remove microbes, put it in a flask, let the flask cool, and stoppered it.
- There was bacterial growth in the flask
- Problem: Microbes entered before the flask was stoppered
10
Q
Lazzaro Spallanzani (1729-1781)
A
- Same experiment as Needham, but he stoppered the flasks before boiling.
- There was no growth **
11
Q
Louis Pasteur (1822-1885)
A
- Elongated the neck of the flask of one, but not of the other. The elongated flask had no growth, but the other one did.
- Rabies vaccine, Pasteurization
12
Q
Acellular
A
Exceptions to the typical cell definition
13
Q
Acellular: Eg. Viruses
A
- Can’t harvest their own nutrients
- Can’t reproduce on their own
14
Q
Acellular: Eg. Liposomes
A
- Don’t divide
- Created artificially
15
Q
1/10 cell features
A
All cells store their hereditary information in the same linear chemical code (DNA)
16
Q
2/10 cell features
A
All cells replicate their hereditary information by templated polymerization (semi-conservative replication)
17
Q
3/10 cell features
A
All cells transcribe portions of their hereditary information into the same intermediary information (RNA)
18
Q
4/10 cell features
A
All cells use proteins as catalysts
19
Q
5/10 cell features
A
All cells translate RNA into proteins in the same way
20
Q
6/10 cell features
A
The fragments of genetic information corresponding to one proteins is one gene
21
Q
7/10 cell features
A
Life requires free energy
22
Q
8/10 cell features
A
All cells function as biochemical factories dealing with the same basic molecular building blocks
23
Q
9/10 cell features
A
All cells are enclosed in a plasma membrane across which nutrients and waste materials must pass
24
Q
10/10 cell features
A
A living cell CAN exist with fewer than 500 genes
25
Limit of resolution for a light microscope
200nm
26
Resolution =
0.61(wavelength) / NA (nsinø)
27
EMR wavelength =
0.004nm
28
Why do we use light with shorter wavelength?
Because we are more likely to see every detail
| -Skipping rope example
29
Brightfield
See almost nothing b/c light passes through the sample
30
Brightfield (stained)
Increase contrast by staining
31
Fluorescence
Shows specific molecules. Fluorescent substances absorb UV radiation and emit light.
32
Phase contrast
Increase contrast by amplifying variations in refractive index
33
Differential interference contrast
Uses optical mods to amplify variations in refractive index
34
Confocal
Uses lasers and optics to focus a beam of light on one part of a specimen
35
Fluorescent microscopy
- Absorbs light at a low wavelength
- Emits light at a high wavelength
- Dichromic mirror: Below certain wavelength, mirror reflects light
36
Green Fluorescent Protein (GFP)
Can be inserted into a reporter gene or made into a fusion protein
37
Gene regulation
Determine which cells make what proteins
38
3 domains of life
Archaea
Bacteria
Eukaryotes
39
Why are cells so small?
To increase their Surface Area : Volume ratio
40
Unicellular
"One celled" organisms
41
Multicellular
Have different types of cells for different functions
42
Eukaryotic cells
- Compartmentalized for organization and transport
| - These compartments are called organelles
43
Mass culture
Large population of cells
44
Clonal culture
Genetically identical- Have a known genetic lineage
45
Axemic culture
Only one species grown
46
Cells are grown in 3 ways:
- Suspended in a liquid
- Suspended in a semi-solid (Ex: <0.5% agar)
- Plated on a semi-solid (Ex: 1-2% agar)
47
Anchorage dependent
Normal cells
| -Requires attachment to extracellular matrix material
48
Growth factor dependent
Normal cells
| -Signals telling it when to grow or die etc.
49
Contact inhibited
Normal cells
- Stop dividing because of growth factor
- Form monolayer at confluence
50
Have a finite lifespan
Normal cells
| -Divide to their Hayflick limit
51
Anchorage independent
Transformed cells
52
Growth factor independent
Transformed cells
53
Not contact inhibited
Transformed cells
54
Can grow indefinitely
Transformed cells (Ex: Cancer cells)
55
Eagle's Basal Medium
Widely used synthetic basal medium for growing cells
56
Amino acids and Vitamins in the medium
Cofactors for enzymes
57
Salts
Maintain osmolarity
58
Glucose
Food source
59
Penecillin and Streptoman
Kill bacteria
60
Phenol red
pH mediator
61
Step 1 of culture
- Use whole organism or obtain tissue
| - Requires dissection, vivisection, or euthanasia
62
Step 2 of culture
Disaggregate the sample into single cells
- Mechanical disruption: blender or homogenizer
- Enzymatic disruption: proteases like trypsin
63
Step 3 of culture
Place cells in a suitable environment
- Eagle's Basal medium or equivalent
- Key factors: Water, Temp, Aeration, Nutrients
64
First Human Cell Culture
- George Gey
- Small biopsy of cervical tumour
- Culture grew and grew and grew
- Called them HeLa cells (after Henrietta Lacks)
- HeLa cells are immortal, can grow easily, and do not always behave expectedly
65
Cryobiology
Studies the effects of low temperatures on organisms or the use of cryopreservation
66
Advantages of cryopreservation
- Biological backups: Cells of interest always available
- Repetitions of the same experiment
- "Suspended animation"- Stops biological time
67
Disadvantages of cryopreservation
- Some loss of viability in thawing
- Cryoprotectants required b/c of slow rate of freezing
- Some cryoprotectants are dangerous to handle
- Always side effects on the cells
68
Polge, Smith, and Parkes (1949)
- Initial discovery of cryopreservation
| - Used chicken spermatozoa with glycerol as the protectant
69
Covalent bonds
- Shared electron pairs- Strongest bonds
| - Ex: Backbones of polymers, DNA, RNA
70
Electrostatic bonds
- Charge to Charge interactions
| - Strength depends on nature of charges, distance between them, and dielectric constant (what's between them)
71
Hydrogen bonds
- Strong bonds that are essential for life
| - Ex: Water, Base pair bonding in DNA
72
Van der Waal's interactions
- Close together, then things repel
- Far away, then things attract
- At the Van der Waal's contact distance, experience these interactions
73
Water
- Hydrogen bonding
- Electrostatic interactions with ionic solutes
- Polar molecule
- Interacts favourably with other polar molecules (Hydrophilic)
74
Proteins (general)
- Most versatile macromolecules (many functions)
| - Catalyze reactions, Motility, Transport, Signalling, Hormonal, Defense
75
Conformation
Spatial arrangement of atoms in a protein
76
Native state
Lowest energy state of a protein
77
Dalton (unit of mass)
g/mol
78
R-groups
Amino acid side chain
79
Amino acids
- Properties are determined by the R-group
| - L-isomer is only form found in proteins by ribosomes
80
Absolute configuration
L or D (left and right) isomers
- H interchanges with an NH3 group
- Aldehyde group interchanges with Carboxyl
- BUT R group NEVER changes
81
Non-polar amino acids
```
Glycine
Alanine
Valine
Leucine
Isoleucine
Methionine
Phenylalanine
Tryptophan
Proline
```
82
Polar uncharged amino acids
```
Serine
Threonine
Cysteine
Tyrosine
Asparagine
Glutamine
```
83
Polar charged amino acids
```
Aspartate
Glutamate
Lysine
Arginine
Hystidine
```
84
Peptide bonds (general)
Amino acids covalently linked with peptide bonds
| -Amino acid terminus (N-term) and Carboxyl (C-term)
85
Primary structure (1°)
- Includes all covalent bonds and is defined by the amino acid sequence
- The linear sequence of amino acids in a protein
86
Secondary structure (2°)
- Regular repeating structure adopted by a polypeptide
- Arranged in motifs (supersecondary structure)
- Ex: Helices
87
Tertiary structure (3°)
- How everything is arranged in a single protein
| - Weaker bonds
88
Quaternary structure (4°)
-How everything is arranged in a multiple protein
89
Ribonuclease experiment
-Showed that amino acid sequence contains all info needed to fold chain into the correct 3D structure
90
Nucleic acids
- Information storage
- DNA (hereditary information)
- Carriers of chemical energy (NADH, ATP, NADPH)
91
Central dogma of micro
DNA --> RNA --> Protein
92
Nucleic acid composition
- Nitrogenous base
- A pentose sugar
- 1 or more phosphate groups
93
Why are nucleosides not nucleotides?
Nucleosides lack the phosphate group
94
Polynucleotides
- Many nucleotides linked by phosphodiester bonds
| - Can be single (ssDNA) or double (dsDNA) stranded
95
Purines- Nucleic acids
Adenine
| Guanine
96
Pyrimidines- Nucleic acids
Thymine
Cytosine
Uracil
97
B-DNA structure (normal DNA structure)
- Double, right-handed helix
- 2 anti-parallel strands
- Bases inside
- Phosphodiester bonds outside
- Hydrogen bonded
98
B-DNA characteristics
- Negative charge b/c of phosphate groups
- Not completely stable
- Proteins can interact w/ bases in grooves
99
Chargaff
Discovered that amount of A=T, and C=G
100
Watson-Crick base pairing
- H-bonds form between G-C and A-T (or U)
| - Also called canonical base pairing
Biology 225
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