BIOL225 > Topic 1a > Flashcards

Topic 1a Flashcards

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1
Q

Cell

A
  1. carries hereditary information that defines the species
  2. capable of self replication
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2
Q

Discovery of Cells

A
  1. Z & H Janssen
    first microscope
  2. Robert Hooke
    coined term “cell” after describing chambers in cork
  3. Anton van Leenwenhoek
    made his own refined microscopes (300x); first to observe living cells (animacules) in pond water and tooth scrapings
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3
Q

Birth of Modern Cell Biology

A
  1. Schleden and Schwann introduced first 2 rules of the Cell Theory
    - all life is made from 1+ cells
    - cell is basic unit of structure for all organisms
  2. Virchow added the final rules
    - all cells arise from pre-existing cells
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4
Q

Schleden and Schwann

A

Introduced first 2 rules of the Cell Theory
- all life is made from 1+ cells
- cell is basic unit of structure for all organisms

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5
Q

Virchow

A

Modified Schleden and Shwann’s Cell Theory
- all cells arise from pre-existing cells

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6
Q

Craig Venter

A

participated in human genome project
created first artificially created cell

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7
Q

Development of Cell Biology

A
  1. Cytology: emerged with Van Leewenhoek’s improvements upon the microscope.
  2. Biochemistry: facilitated by advancements in bioogical tecniques
  3. Genetics
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8
Q

Micrometer (um)

A

One-millionth of a meter, 1/25000 of an inch.
- unit of choice for describing cells and organelles

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9
Q

Nanometer

A

Unit of choice for molecules and subcellular structures; 1/billionth of a meter.

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10
Q

Microtome

A

Instrument developed for the rapid and efficient preparation of thin tissue slices.

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11
Q

Limit of Resolution & Resolving Power

A

LR: A quality refering to how far apart adjacent objects must be to appear as seperate entities.
RP: A microscope quality refering to the ability to see fine details of structure

  • the smaller the LR, the greater (&better!) the RP
  • using a light microscope under violet light, the theoretical LR is around 200nm
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12
Q

Brightfield Microscopy

A

White light is passed directly through a stained or unstained specimen while the field (background) is illuminated.
-limitation: specimen must be unalive and specifcally prepared to highlight transparent features

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13
Q

Types of Microscopy

A
  1. Phase contrast: enhances contrast in unstained cells by amplifying variations in refractive index within specimen; especially useful for examining living, unpigmented cells.
  2. Differential Interference Contrast: also uses optical modifications to exaggerate differences in refractive index
  3. Fluorescence: Shows locations of specific molecules within cell. Fluorescent substances absorb ultraviolet radiation and emit visible
    light. The fluorescing molecules may occur naturally but more often are made by tagging the molecules of interest with fluorescent dyes or antibodies.
  4. Confocal: Uses lasers and special optics to focus illuminating beam on a single plane within the specimen. Only those regions within a narrow depth of focus are imaged. Regions above and below the selected plane of view appear black rather than blurry.
  5. Brightfield: passes light directly through specimen; image has little contrast unless specimen is stained
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14
Q

Phase Contrast Microscopy

A

Enhances contrast in unstained cells by amplifying variations in refractive index within specimen; especially useful for examining living, unpigmented cells
- breaks waves which are in phase as a sample of light hits a specimen, then brings them back together at the eyepiece

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15
Q

Fluorescence Microscopy

A

Shows locations of specific molecules within cell. Fluorescent substances absorb ultraviolet radiation (short wavelength) and emit visible light (long wavelength)
- utilizes DICHROMAIC MIRROR; reflects short wavelength and transmits longer wavelengths
- fluorescing molecules may occur naturally but more often are made by tagging the molecules of interest with fluorescent dyes or antibodies.
- ideal wavelength for filter must be inbetween absorbance and reflective cutoffs (ie. abs. at 470, ref. at 550; dichoric mirror ideal at 470)
- resolution is not increased, you can just see more because it is illuminated

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16
Q

Differential Interference Contrast/ Nomarsky Microscopy

A

uses optical modifications to exaggerate differences in refractive index; good for living cells

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17
Q

Confocal Microscopy and Z-stacks

A

Specimen image is scanned on multiple focal plates and images are stacked upon eachother (z-stacks)to create a 3D image

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18
Q

Antibody

A

Protien molecule produced by the immune system which binds to one target molecule/antigen
- allows microscopers to visualize and identify soecific molecules within cells

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19
Q

Angstrom (Å)

A

0.1 nm, size of a hydrogen atom

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20
Q

Sizes of Cells & their Components

A

Typical eukaryotic cell: 10-100um
Typical prokaryotic cell: 1-10um
Light microscope limit of res: 0.2nm
Electron microscope limit of res: 0.2 nm/ 2 Å

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21
Q

Resolution Equation

A

resolution = 0.61 λ /NA

λ = wavelength (nm)
NA = numerical aperture = nsinθ

  • the smaller the better!
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22
Q

Importance of Wavelength

A

We are limited by the range of violet light (390nm), which is too large to hit small objects under a microscope; electromagnetic waves (0.004nm), allows for greater visibility.

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23
Q

Digital Video Microscopy

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A

attatches light-sensitive video camera to a light microscope to collect digital images for storage.

-allows cells to be observed for extended period of time

24
Q

Immunofluorescence

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A

A fluorescent molecule is attached to an antibody, which in turn recognizes and binds to one specific complementary target molecule/ antigen
- for fluorescence or confocal microscope

25
Primary/ Direct Immunofluorescence
Antibody molecules are labelled with a flurophore (fluorescent dye) -less common than secondary
26
Green Fluorescent Protien (GFP)
Fluorescent protien present in jellyfish which can be manipulated and inserted into other genes to make them fluorescent and visible without stain.
27
Electron Microscope
Uses a beam of electrons which is deflected and focused by an electromagnetic field, which allows for a significantly better limit of resolution (100x) when compared to visible light because the wavelength of electrons is so much shorter. usually have one of two basic designs: - transmission electron microscope - scanning electron microscope
28
Transmission Electron Microscope (TEM)
Forms an image from electrons that are transmitted through the specimen.
29
Scanning Electron Microscope (SEM)
Scans the surface of the specimen and forms an image by detecting electrons that are deflected by its outer surface. - allows for images with a sense of depth
30
Friedrich Wohler
Demonstrated that urea could be synthesized in the laboratory from inorganic starting materials. - proved that biochemical processes were not exempt from the laws of chemistry and physics - key in development of biochemistry as a dicipline
31
Louis Pasteur and the Buchner brothers
Louis: showed that yeast cells were responsible for the fermentation of sugar and alcohol. Buchners: found that fermentation could take place in isolated extracts from yeast cells, seperate of the living organism - showed that yeast contained specific biological molecules which served as catalysts for the chemical reaction (enzymes)
32
Fritz Lipmann
Showed that the high-energy compound adenosine triphosphate (ATP) is the principal energy storage compound in most cells.
33
Melvin Calvin
Pioneered the use of radioisotopes to trace the metabolic fate of certain atoms and molecules in his study with colleagues at Berkeley where carbon dioxide was traced in photosynthesizing algal cells; led to elucidation of the calvin cycle.
34
Centrifugation
Means of subcellular fractionation (seperating and isolating subcellular structures and macromolecules based on their size shape and density).
35
Ultracentrifuge
- can subject samples to forces over 500 000 times the force of gravity - useful for resolving small organelles and macromolecules
36
Chromatography
Techniques used to seperate a mixture of molecules in solution into individual components based on size, charge, or affinity for specific molecules or functional groups.
37
Electrophoresis
Techniques that use an electric field to seperate macromolecules based on their movement through a semisolid gel; molecules move different distances based on their size and charge.
38
Biochemistry Methods
1. Subcellular fractionation (via centrifugation or ultracentrifuge) 2. Chromatrography (speration of a molecules in solution) 3. Electrophoresis (use of electrical field to seperate macromolecules based on mobility in gel)
39
Gregor Mendel
Discovere genes via pea plant expiriment.
40
Walther Flemming
- identified chromosomes in dividing cells - called process of cell division mitosis
41
Roux and Weissman
suggested (seperately) that chromosomes are the bearers of genetic information
42
Chromosome Theory of Heredity
Hereditary factors responsible for mendelian inheritance are located on chromosomes within the nucleus - early 1900s
43
Miescher
Discovered DNA in 1869 - isolated it from SALMON SPERM and HUMAN PUS; called it nuclein
44
Watson/Crick & Franklin
Proposed double helix model of DNA structure and, in turn, theory od DNA replication. Crick later proposed the central dogma of DNA, or the replication/transcription/translation chain
45
Recombinant DNA Technology
Technology which allows scientists to cleave DNA molecules at specific sequences, generating DNA sequences from two different sources, via the use of restriction enzymes. - led to develpment of DNA cloning and DNA transformation (process of introducting DNA into cells)
46
DNA Sequencing
Technology used to rapidly determine the base sequences of DNA molecules.
47
Bioinformatics
A study which merges computer science data and biology as a means of making sense of sequence data. Genomics: study of all genes in an organism Proteomics: study of all the protiens (structure and function) in a cell
48
Viruses
Acellular, parasitic particles which are incapable of preforming functions required for independant existence and therefore invade and infect host cells and redirect their machinery toward the production of more virus particles, after which they erupt from the host cell and destroy it. - consist of a protien capsid, which gives them a characteristic shape, and one or more molecules of either DNA OR RNA - smaller than most cells, 25 (size of a ribosome) - 300 (quarter of a bacterial cell) nm
49
Bacteriophages/ phages
Viruses that infect bacterial cells
50
Envelloped Viruses
Viruses surrounded by a membrane derived from the plasma membrane of the host cell in which the particles were synthesized. -ie. HIV
51
Fundamental Properties of Living Things
1. Metabolism: cellular reactions organized into coherent pathways 2. Irritability: perception of, and response to, environmental stimuli 3. Ability to Reproduce
52
Viroids
Small, circular RNA molecules that infect only eukaryotic cells. - do not code for any protien - responsible for diseases in several crop plants; theory that they may interfere with transcription of host cell (gene-silencing) - transmitted from adjeacent cells when their surfaces are damaged, allowing RNA molecules to pass - ie. cadang-cadang disease of the coconut palm
53
Prions
Abnormally folded versions of normal cellular protiens; may affect receptors that detect nerve signals. - chronic wasting disease (USA), kuru (New Guinea), scrapie (sheep & goats)
54
unaided human eye limit of res
100-200 um
55
typical cell size
-10-100 um -1-10 um
56
microscope limit of res
light: 200 nm electron: 0.2 nm
57
SEM technique
-sample frozen or dried, sprayed with a thin film of metal - electrons deflected from specimen onto detector - allows for excellent depth of field, resolution up to about 10nm
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