Transcript Microbiology – Alcamp Lecture: Bacterial Structures

Microbiology – Alcamo
Lecture: Bacterial Structures
-Not all bacteria have all structures
Shapes of Bacteria
• _______ Different Shapes:
Bacilli
• _______ shaped
• Most occur singly, but some form long
chains called _____________
• Examples:
– __________ _________
– __________
– __________
Cocci
• Usually ______ shaped but can be oval
• Diplococci – cocci that remain in _____
– Examples – Gonorrhea, Menengitis
• Streptococci – cocci in __________
– Examples - Strep throat, Tooth decay
• Staphylococcus – irregular __________
__________ of cells
– Examples – Food poisoning, staph skin
infections
Spiral Bacteria
• __________ – curved rods - look like a
comma
– Example - Cholera
• __________ – corkscrew shape with
flagella
– Example – Rat Bite fever
• __________ – corkscrew shape but no
flagella
– Example - syphilis
Flagella
• Used by some bacteria to achieve
_________
• Made of long rigid strands of protein
called __________
• Protein strands are permanently
________
• Permits the flagellum to rotate and
________ the bacterium forward
Flagella
•
Complicated structure: Filament
attached to hook-like shaft which is
inserted through cell wall and attached
to cell membrane
Flagella
_______trichou
s
_______trichou
s
_______trichou
s
Axial Filament
•
•
•
Only ____________
One flagella attached at both ends of
flexible spiral MO
Motion effected by cell spinning around
filament
Pili
•
•
Look like short flagella but have nothing
to do with _________
Very tiny protein “Hairs” that enable MO
to ________ to surfaces - like “Velcro”
Pili
• Pili aid in transfer of ___________
__________ between bacteria
• Pili anchor bacteria to surfaces like
_________ ________
• Can __________ MO’s disease effect
• Example - gonorrhea
Capsule
• Some bacteria secrete a layer of
_____________ and ___________ that
stick to its surface
• Sticky and gelatinous
• Serves as a buffer between the bacteria
and its environment
– Protects bacteria against ______________
– Protects bacteria against host’s _________
_____________
White Blood Cell
Glycocalyx
•
Some bacteria produce a _______ _______
•
Complex _____, made inside cell wall secreted
as liquid, polymerizes to jelly like substance
_________ – S. mutans attaches itself to teeth
by using the sugar a person eats – creates an
acid that breaks down tooth enamel
•
Cell Wall
• All bacteria have a cell wall except
mycoplasmas
• Semi-rigid structure, _________, gives
_________
• Amount of chemical “_____________”
determines characteristics of cell wall
• If a lot: Thick, G+ stain reaction, sensitive
to penicillin and lysozyme in tears, saliva,
mucous
•If small: thinner, G- stain reaction, not
sensitive to penicillin or lysozyme
•If MO is pathogenic, disease more
difficult to cure
Cell Membrane
•
•
•
•
Boundary layer of the cell ________ of cell wall
Contains _________, controls _________
________ in and out of the cell
Triple layer structure, 60% proteins, 38% lipids
(phospholipid bilayer), 2% sugars
Antimicrobials (detergents, alcohol, some
antibiotics) __________ cell membrane
cell membrane animation
Cytoplasm
Gelatinous mass of
________
carbohydrates
________
nucleic acids
________
ions
________
Important Structures in
Cytoplasm
• Ribosomes – ________ __________
• Inclusion Bodies – globules of starch
or lipids – ________ _________
• Bacterial Chromosome – closed loop of
DNA ________ a membrane or proteins
(nucleoid region)
• Plasmids – smaller, separate _________
__ ______ – few genes but do give
bacteria drug resistance (R genes)
Endospores
•
Some Gram + bacteria produce highly
resistant structures - ___________
–
–
–
–
Bacteria grow, mature and reproduce as
_____________ cells
Then the bacterial chromosome replicates
and the cell membrane grows in to _______
______ a developing spore
Next, thick layers of peptidoglycan form to
_________ the cell
Finally, the cell wall of the vegetative cell
disintegrates and the spore is __________
Endospores
• Very resistant to poor environmental
conditions:
– ________ _____________– boiling water
– ____________ – 70% alcohol
– Spores have even been recovered alive
from an Egyptian mummy’s intestines
• Examples of spore formers – anthrax,
botulism, tetanus
•“__________” is spore formation DNA + some cytoplasm wrapped in
spore case formed by cell membrane
•“__________” occurs when good
environmental conditions return –
vegetative cell
Kingdom Classification
Archaeobacteria
• Have existed on earth longer than any
other living organism
• They are different from eubacteria:
– No ______________ in cell wall
– Different _________ in cell membrane
– Different ribosomal ________
– Now archaeobacteria and eubacteria are
classified as different kingdoms
Archaeobacteria
• 3 Types:
– _______________ – rods that live in
anaerobic conditions and produce
methane gas – common in marshes and
the guts of cows and humans
– ________________ – resistance to acid
and high temperatures – live in hot springs
and ocean vents
– ___________ ____________– thrive in high
salt environments (Great Salt Lake)