Download Micro1-4th(part One) Lec- Pharm D

PharmD : Arwa Bdair
Subject: Structures of bacteria
Doctor: Randa Haddadin
PharmD PharmD PharmD PharmD PharmD PharmD PharmD PharmD PharmD PharmD PharmD PharmD PharmD PharmD
Sheet: 4(part1)
University of Jordan – Faculty of Pharmacy –Pharmaceutical Microbiology (1) – 1202341- Dr. Randa Haddadin– PharmD- 2nd Semester 2013
University Of Jordan
Faculty of Pharmacy
Microbiology for PharmD students
13th Of Feb 2013
Dr.Randa Haddadin
Arwa Bdair
Structures of bacteria
Structures of bacteria :
4th lecture
- Human body contains 70 S ribosome in
mitochondria … that is why some drugs which
target bacterial ribosomes may be toxic to human.
1. Cytoplasm of bacteria
2. Nuclear Region
- semi- fluid substance
- contains DNA , some RNA and proteins
- 80% is water , the rest 20% (proteins , lipids ..)
- In cytoplasm , anabolic & catabolic reactions take
place.
- ribosomes in the cytoplasm, are composed of
RNA with proteins in a spherical shape.
- Usually bacteria contain one circular ... some
bacteria contain plasmid , which is an extra
chromosomal DNA , circular and outside the
original chromosome. Plasmid enables bacteria to
resist antibiotics.
3. Inclusions
-ribosomes usually present in the cytoplasm in the
form of chains (polyribosomes)
- each ribosome is composed of two subunits
(small subunit and large subunit)
- ribosomes are measured according to their
sedimentation rate , which is done by
centrifugation
- Rate of sedimentation is measured by the unit 
Svedberg (S)
- 70 S means  the sedimentation rate equals 70
Svedberg.
- Human ribosome (Eukaryotes) ATS  80 S (60 S
large subunit, 40 S small subunit)
- small bodies, they may be granules or vesicles in
the cytoplasm
- the contain compacted materials such as
glycogen , polyphosphate (granules)
- gas filled vacuole (vesicle) , membrane enclosed ,
this air vacuole present in bacteria which live in
water , used for movement and changing depth
depending on the amount of air in the vesicles.
- some vesicles contain lipids to be used in
metabolism
4. Endospores
- Endospores present inside the bacteria , but
exospores are produced by Fungi
- prokaryotes 70S (30 S small , 50 S large)
- Fungi can spread exospores everywhere
there is a difference in the sedimentation rate
between eukaryotic ribosome and prokaryotic
ribosome , so by using this difference a certain
drug is used to target bacterial ribosome only.
- Bacteria may be at vegetative form
(metabolically active, alive , can do reproduction),
or at resting stage as endospores.
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Microbiology for PharmD students
13th Of Feb 2013
Dr.Randa Haddadin
Arwa Bdair
Structures of bacteria
4th lecture
→Bacillus and Clostridium can form endospores
(they are Gram +ve)
- Ca2+ deposit in endospores also elevate
resistancy.
→ Examples of Gram +ve bacteria ( Bacillus,
Clostridium , streptococcus and staphylococcus)
- Spores may live for thousands of years.
- The goal of spores formation is to survive during
harsh conditions , not for reproduction.
- If the surrounding conditions become good
enough for the bacteria, it will convert to the
vegetative form  the process is called
Germination.
- form within the cell
* Germination = spore  living bacteria.
-they have high resistance since they have low
amounts of water
- highly resistant to heat, alkaline and acidic media
, and it’s very hard to get rid of them
-they may be also resistant to radiations, but
Gama radiations can kill them
* Sporulation = living bacteria  spore.
------------------------------------------
* External structures of bacteria:Flagellum: used for movement.
- once the bacteria detect depletion of nutrients ,
sporulation starts.
Sporulation : conversion from vegetative form to
endospore formation
Naming according to the number of flagella:
Monotrichous = one flagellum.
Amphitrichous = two flagella, one on each side.
-Endospore is composed of
*core (contains DNA)
Lophotrichous = two or more flagella from one
side.
*cortex
Peritrichous = many, from all sides.
*coat
Atrichous = No Flagellum.
*some spores contain a layer called “exosporium”
* The type of bacteria who has flagella is usually
rod-shaped.
- Endospores contain dipicolonic acid , which is not
present in the vegetative form of bacteria. This
substance contributes to the high resistance of
endospores
* Flagellum is made out of the protein "
Flagelline", extends beyond the cell wall, and the
base of the flagellum is fixed to the cell
membrane.
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Microbiology for PharmD students
13th Of Feb 2013
Dr.Randa Haddadin
Arwa Bdair
Structures of bacteria
*** Chemotaxis:
Movement of the cell either toward something or
away from something depending on chemical
detection ( according to concentration).
4th lecture
2- Attachment Pili ( Fimbiae) , it helps the bacteria
to attach to surfaces which making it more
pathogenic.
-
The attachment of bacteria to the tissues
makes it hard to get rid of it.
* It may be positive chemotaxis  toward
nutrient.
*Glycocalyx :
* Or negative chemotaxis  away from toxic
substance "Repeler" .
- a polysaccharide-containing substance fount
external to the cell wall
* Bacteria contain receptors to detect
concentration gradient to decide where to go.
- two types:
*** Phototaxis:
* Positive  toward light.
* Negative  away from light.
- Axial filaments or Endoflagella:
- Present in the spiral bacteria, such as spirochete;
which moves around an axis.
* Pili:
-(Pilus: singular), composed of the protein piline ;
tiny hollow projections present on the bacteria
and it comes in two types:
1- D conjugation Pili ,( sex pili or also called F pili),
it connects two similar or different bacteria types
to transfer DNA , a weak bacteria may be
transferred to a resistant bacteria by transferring
certain plasmid types.
A) capsule: polysaccharide molecules present in a
loose gel
-function : protection
- example: Bacillus anthrax, some cells of this type
of bacteria have a capsule and other cells don’t …
then they concluded that when this bacteria is
present inside the human body it has a capsule,
and when its outside no capsule present.
(capsule protect the bacterial cell from immunity
detection)
B) Slim layer (Biofilm) :
-causes 60% of the infections
- thinner than capsule and less tightly bound to
the cell wall.
- when a certain type of bacteria exist in a large
number, they start to secrete polysaccharides as a
signal for the other bacterial cells to stick to a
surface.
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Microbiology for PharmD students
13th Of Feb 2013
Dr.Randa Haddadin
Arwa Bdair
Structures of bacteria
4th lecture
- During the surgery of introducing a prosthetic
device (ex: pace maker), some bacterial cells may
inter the body through the wound and form
Biofilm , infection produced is very hard to treat.
-biofilm protects bacteria from drying, increases
its resistance against chemicals and helps it to
capture nutrients.
(To be cont. in the next part)
Good luck in your Quiz
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