Unit 2 - The Cell Episode 1 Flashcards
First inventor of the compound microscope
PROBLEM: poor quality microscope
Zaccharias Janssen
made a better compound microscope after
Janssen
Joseph Jackson Lister
Three Important Parameters of Microscope
- Magnification
- Resolution/ Resolving Power
- Contrast
ratio of an object’s image to its real size
Magnification
computed by multiplying the magnification of the objective lens by the ocular lens
mostly used magnification of ocular lens: 10x
Total Magnification
measure the clarity of the image
it is the minimum distance between two points can be separated and still be distinguished as separate points
it is the ability of the lenses to distinguish fine detail structure
Resolution/ Resolving Power
the difference in brightness between the light and dark areas of an image
Contrast
measure of the light bending ability of the medium
Refractive Index
technique used to change the refractive index
Staining Technique
Lens System Parts
- Ocular Lens
- Objective Lens
- Coarse Adjustment Knob
- Fine Adjustment Knob
Illumination System Parts
- Light Source
- Condenser
- Iris Diaphragm
- Field Diaphragm
Body System Parts
- Base
- Body Tube
- Revolving Nose piece
Initial magnification
Objective lens
Further magnification
Ocular lens
moves mechanical stage noticeably
Coarse adjustment knob
sharpens the image
Fine adjustment knob
LPO → HPO
Parfocal / Parfocal Distance
focuses light on the specimen and controls the light for uniform illumination
Condenser
Regulate the intensity of the light
Light Source (Rheostat)
Uses visible light as source of illumination; cannot resolve structures smaller than about 2 μm; specimen appears against a bright background. Inexpensive and easy to use
Brightfield Microscope
used to observe various stained specimens and to count microbes; does not resolve very small specimens such as viruses.
Brightfield Microscope
Uses a special condenser with an opaque disk that blocks light form entering the objective lens directly; light reflected by specimen enters the objective lens and the specimen appears light against a black background
Darkfield Microscope
To examine living microorganisms that are invisible in brightfield microscopy, do not stain easily, or are distorted by staining
Darkfield Microscope
used in examining Spirochetes (prokaryotic organisms)
Darkfield Microscope
causative agent of syphilis
Treponema Pallidium
Uses a special condenser containing an annular (ring-shaped) diaphragm. The diaphragm allows light to pass through the condenser, focusing light on the specimen and a diffraction plate in the objective lens. Direct and reflected or diffracted light rays are brought together to produce the image. No staining required.
Phase-Contrast Microscope
it is used to facilitate detailed examination of the internal structures of living specimens
Phase-Contrast Microscope
forms halo around the image
very useful in examining living unpigmented cells
Phase-Contrast Microscope
Like phase-contrast, uses differences in refractive indexes to produce images. Uses two beams of light separated by prisms; the specimen appears colored as a result of the prism effect. No staining required
Differential Interference Microscope
TO provide Three-dimensional images
also called Nomarski Microscopy/ Nomarski Interference Contrast
Differential Interference Microscope
good in resolution compared to phase
contrast
it can give almost or nearly three
dimensional image
Differential Interference Microscope
Modulation Contrast
Hoffman
Differential Interference Contrast
Nomarski
Distinguishing Feature: Uses an ultraviolet or near ultraviolet source of illumination that causes fluorescent compounds (green-colored) in a specimen to emit light
Fluorescence Microscope
Principal Uses: For fluorescent-antibody techniques (immunofluorescence) to rapidly detect and identify microbes in tissues or clinical specimens
Fluorescence Microscope
Fluorescent compounds/ fluorescent dyes
Fluorochromes
Used in Mycobacterium tuberculosis
Auramine O (color yellow)
Used in Bacillus anthracis
Fluorescein Isothiocyanate (FITC)
causative agent of anthrax
Bacillus anthracis (Apple Green)
Distinguishing Feature: uses a photon to illuminate one plane of a specimen at a time
Confocal Microscope
Principal Uses: to obtain two-and three- dimensional images of the cell for biomedical applications
Confocal Microscope
ELECTRON MICROSCOPES
- Transmission
- Scanning
Distinguishing Feature: Uses a beam of electrons instead of light; electrons pass through the specimen; because of the shorter wavelength electrons, structures smaller than 2 μm can be resolved. The image produced is two-dimensional.
Transmission Microscope
Principal Uses: To examine viruses of the internal ultrastructure in thin sections of cells (usually magnified 10,000-100,000x)
Transmission Microscope
Distinguishing Feature: Uses a beam of electrons instead pf light; electrons are reflected from the specimen; because of the shorter wavelength of electrons, structures smaller than 2 μm can be resolved. The image produced appears three dimensional.
Scanning Microscope
Principal Uses: To study the surface features of cells and viruses (usually magnified 1000-10,000x)
Scanning Microscope
Used to isolate or fractionate cell components based on size and density
Cell Fractionation
This “__________________” results in a series of pellets, each containing different cell components.
differential centrifugation
1000 g ; 10 minutes
Pellets are rich in nuclei and cellular debris
20,000 g ; 20 minutes
Pellets are rich in mitochondria (and chloroplast if plant cells)
80,000 g ; 60 minutes/ 1 hour
pellets are rich in microsomes
150,000 g ; 3 hours
pellets rich in ribosomes
The lower the speed, the larger the components. The higher the speed, the smaller the components/ pellets are. They are ______________________
inversely proportional
THE THREE MAJOR DOMAINS
- Bacteria
- Archaea
- Eukarya
lack a membrane-bounded nucleus and mitochondria, are surrounded by a cell wall, and divides by binary fission
Bacteria
cell walls lack peptidoglycan
share some common characteristics with
bacteria
can be stained Gram + and Gram -
Archaea
cells contain an elaborate network of internal membranes, a membrane-bounded nucleus, and mitochondria
DNA is organized into true chromosomes, and a cell division takes place by means of mitosis
Eukarya
Class Order of Family Species (KPCOFGS)
Kingdom
Phylum
Class
Order
Family
Genus
Species
Acellular Microorganism
Viruses
Cellular Microorganisms
Prokaryotes
- Eubacteria
- Cyanobacteria
- Archaebacteria
Eukaryotes
- Parasites
- Fungi
single-cell prokaryotic microorganism
Bacteria
single-cell or multicellular eukaryotic
microorganisms
Fungi
Unicellular, eukaryotic microorganisms
Yeasts
single-cell or multicellular eukaryotic microorganisms (same with fungi)
Parasites
dependent on host cells for survival and therefore are NOT CONSIDERED CELLULAR ORGANISMS BUT RATHER INFECTIOUS AGENTS
Viruses
Unicellular organisms that lack a nuclear membrane and true nucleus
Classified as prokaryotes, having no mitochondria, ER, or Golgi Bodies
Bacteria
Vary in size, morphology and cell-to-cell arrangements and in the chemical composition and structure of the cell wall
Bacterial Morphology
bacterial cell wall differences provide the basis for the ______________
Gram Stain
the most fundamental test used in bacterial identification
Gram Stain
Most relevant clinically bacterial species range in size from ________ in width and ________ in length
0.25 to 1 μm; 1 to 3 μm
bacterium is some __________ larger than a virus, and _________ smaller than a eukaryotic cell
hundred-fold; ten-fold
___________ are far larger than bacteria
Parasites
Viruses < Bacteria < Parasites
small to large
circular bacterial shape
Cocci
ovoid bacterial shape
Coccobacilli
rod shaped bacteria
Bacillus
tapered, pointed ends bacterial shape
Fusiform
helical, like corkscrew
Spirochetes vary in length and in number of helical turns
Spiral
curved bacterial shape
curved
no defined shape
Pleomorphic
examples of pleomorphic bacteria
Rhizobium and Corynebacterium
T/F
All spirochetes are spiral; not all bacteria are spirochetes
True
T/F
All bacteria are helical, but not all helical bacteria re called spirochetes
True
Prokaryotes with no cell wall
Ureaplasma
Mycoplasma
Prokaryotes with CHO and Sterol compounds
Ureaplasma
Mycoplasma
units referring to sedimentation rates (unit of time) during high speed of centrifugation
Svedberg
named after _____________, Nobel prize winner and inventor of the ultracentrifuge
Theodor Svedberg
pairs
diplo-
chains
strepto-
grape-like structure
Staphylo-
Group of four
Tetrad
Group of eight
Sarcinae
Palisades
side by side
Cell Envelope comprises
- Outer Membrane
- Cell Wall
- Periplasm or Periplasmic Space
- Cytoplasmic or Cell Membrane
found only in **gram-negative bacteria **
function as the cell’s initial barrier to the environment
Outer Membrane
serve as primary permeability barriers to hydrophilic and hydrophobic compounds and contain essential enzymes and other proteins located in the periplasmic space
bilayered structure composed of Lipopolysaccharide
Outer Membrane
gives the surface of gram-negative bacteria a net negative charge
Lipopolysaccharide
very important in evading phagocytosis and actions of complement (host’s defenses against foreign substances)
Net Negative Charge
protein structures scattered throughout the lipopolysaccharide macromolecules
water-filled structures that control the passage of molecules/ nutrients (nucleotides, disaccharides, peptides, amino acid, vitamin B12 and iron) and other solutes, including antibiotics, through the outer membrane
Porins
number and types of____ vary with bacterial species
influence the extent to which various substances pass through the outer membranes of different bacteria
Porins
facilitate the attachment of the outer membrane to the next internal layer in the cell envelope, the cell wall
Murein Lipoproteins
referred to as the peptidoglycan murein layer
gives the bacterial *cell shape and strength *to withstand changes in environmental osmotic pressure that would otherwise result in cell lysis
Cell Wall
Composition of Cell Wall
A backbone composed of alternating sugar components N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) connected by B 1-4 linkage
linked in rows by 10-65 sugars (glycan) which builds the carbohydrate (CHO) backbone
NAG and NAM
linked by polypeptides (peptide/peptido)
NAG and NAM
unique element of bacterial cell wall
Diaminopimelic Acid (DAP)
interferes the linkage of your peptidoglycan
Penicillin
