5. Fungi
Eukaryotic organisms
with rigid cell wall
Yeasts
Single-celled
Reproduce by budding
Superficial infections
Athlete’s foot
Ringworm
Thrush
Molds
Large, fuzzy,
multicelled organisms
Produce spores
Can cause systemic
infections
8. Q-2
Which of the following is semipermeable
A. cell membrane
B. cell wall
C. Nucleus
D. Ribosomes
9.
Cytoplasmic (Plasma)
Thin membrane
layer 5-10 nm, separates cell wall from cytoplasm
Acts as a semipermeable membrane: controls the
inflow and outflow of metabolites
Composed of lipoproteins with small amounts of
carbohydrates
11. Q-3
What are the contents of Mac Conkey’s
medium?
A. Peptone
B. Lactose
C. Neutral Red
D. All of the above
12. Differential media
A media which has substances incorporated in it
enabling it to distinguish between bacteria.
Eg: Mac Conkey’s medium
Peptone
Lactose
Agar
Neutral red
Taurocholate
Distinguish between lactose fermenters & non
lactose fermenters.
16. ANAEROBIC CULTURE METHODS
Anaerobic bacteria differ in their requirement
and sensitivity to oxygen.
Cl.tetani is a strict anaerobe – grows at an
oxygen tension < 2 mm Hg.
Methods:
Production of vacuum
Displacement of oxygen with other gases
Chemical method
Biological method
Reduction of medium
17. Production of vacuum:
Incubate the cultures in a vacuum desiccator.
Displacement of oxygen with other gases
Displacement of oxygen with hydrogen, nitrogen,
helium or CO2.
Eg: Candle jar
19. Chemical method
Alkaline pyrogallol absorbs oxygen.
McIntosh – Fildes’ anaerobic jar
Consists of a metal jar or glass jar with a metal
lid which can be clamped air tight.
The lid has 2 tubes – gas inlet and gas outlet
The lid has two terminals – connected to
electrical supply.
Under the lid – small grooved porcelain spool,
wrapped with a layer of palladinised asbestos.
21. Working:
Inoculated plates are placed inside the jar and
the lid clamped air tight.
The outlet tube is connected to a vacuum pump
and the air inside is evacuated.
The outlet tap is then closed and the inlet tube is
connected to a hydrogen supply.
After the jar is filled with hydrogen, the electric
terminals are connected to a current supply, so
that the palladinised asbestos is heated.
Act as a catalyst for the combination of hydrogen
with residual oxygen.
22. Gaspak
Commercially available disposable envelope.
Contains chemicals which generate H2 and CO2 on
addition of water.
Cold catalyst – in the envelope
Indicator is used – reduced methylene blue.
Colourless – anaerobically
Blue colour – on exposure to oxygen
24. Q-5
What is resolution
A. the ability of the microscope to
enlarge the object
B. the ability of the microscope to show
two nearby placed objects separately
25. Important Vocabulary :
magnification mag-ne-fe-'ka-shen n 1.
apparent enlargement of an object 2. the
ratio of image size to actual size
A magnification of "100x" means that the
image is 100 times bigger than the actual
object.
resolution rez-e-loo-shen n 1. clarity,
sharpness 2. the ability of a microscope to
show two very close points separately
26. Q-6
Which type of microscope has been
used for taking this picture?
27. A. Bright field microscope
B. Dark field microscope
C. Phase contrast microscope
D. Fluorosence microscope
28. Bright-field Microscope
Contains two lens systems for magnifying
specimens
Specimens illuminated directly from above or
below
Advantages: convenient, relatively
inexpensive, available
Disadvantages: R.P 0.2 µm at best; can
recognize cells but not fine details
Needs contrast. Easiest way to view cells is
to fix and stain.
31. Dark Field Microscopy
special condenser
diaphragm
occludes direct light,
passes wide angle
light
angle too wide to
enter objective
diffracted light scattered
enters objective
objects light on dark background
diffracted
light
32. Phase Contrast Microscopy
light rays through objects of different η → change in
phase, not intensity
special ring-shaped condenser diaphragm
special glass disc in objective
change phase differences to intensity differences
can view transparent
objects as dark on light
background (without staining)
Right; human brain glial
cells
33. Fluorescence Microscopy
Illuminate specimen with UV → visible fluorescence
(filter removes harmful UV)
View auto-fluorescent objects (e.g., chloroplasts)
Stain with specific fluorescent dyes, which absorb in
region 230-350 nm & emit orange, yellow or greenish
light
Images appear coloured against a dark background
35. Q-7
Steps of staining include
1. primary stain
2. decolorisation
3. counter stain
Which dyes are used for these steps?
In gram staining and acid fast staining
45. A. Hot air oven
B. Autoclave
C. Pasteurization
D. Ethylene oxide gas
46. Q-11
Which organism causes plague
A. streptococcus pneumoniae
B. mycobacterium tuberculosis
C. vibrio cholerae
D. yersinia pestis
47. Bubonic Plague or the Black
Death
Epidemic swept thru Europe in the Middle
Ages (13th and 14th centuries)
40 million people were killed
About 1/3 of the population of the continent
Etiological agent:
Yersinia pestis
2 Vectors
Rat
Flea
Gram (-) rod
49. Bubonic Plague Infection
1. Flea bite with Yersinia pestis
2. Bacteria multiply in the bloodstream
Bacteremia
3. Bacteria localize in lymph nodes,
especially axillary and groin areas
50. 4. Hemorrhaging occurs in lymph nodes, resulting in
“black and blue” swellings or Buboes (hence the name
Bubonic Plague or Black Death)
51. Bubonic Plague Infection
5. If untreated, about 50 % Mortality Rate
6. If bacteria spread to the lungs, it becomes
Pneumonic Plague and is now highly
contagious (Almost a 99 % Mortality Rate)
Hinweis der Redaktion
Uses of darkfield and Phase contrast microscopy
View unstained cells
Not subject to shrinkage, artefacts
Some bacteria do not stain easily, e.g., spirochetes (Borrelia, Leptospira, Treponema)
View living cells
Can observe processes, e.g., motility, predation