Lec. 2 Bacteria Flashcards
BASIC CHARACTERISTICS OF BACTERIA
•Prokaryotic cell structure
•Unicellular microorganisms
•Size range of most ≈ 0.5μ - 2.0μ
•Different species have different shapes, motility patterns
•Most bacteria have cell walls
•Some form endospores and capsules to protect from adverse environment
•Heterotrophic and autotrophic metabolism
•Reproduce asexually and parasexually
•Ubiquitous in environment, including colonization of higher organisms
-bacteria do not have a nucleus
-KNOW BACTERIAL STRUCTURE SLIDE 3
Unusual Giant Environmental Bacteria
- 600μ
- at 600 it can be seen with the naked eye
- in some Australian fish
Shape of Single Bacterial Cells
- coccus
- bacillus
- coccobacillus (In between the coccus & bacillus)
- spirillum (WAVY)
- spirochete (IT IS LIKE A CORK SCREW)
- vibrio
- Some bacteria are pleomorphic = have more than one form, usually cocci and bacilli
- these are important b/c they are used in diagnosis
Aggregations of bacteria
- diplococcus (two cocci come together as a pair)
- streptococci (long chains of cocci)
- tetrad (little packets of four in the same plane)
- sarcinae (pack of 8)
- staphylococci (cluster of grape)
- bacillus (can link up and look like sausages [you need in your life])
Which shaped bacteria aggregate and which typically don’t?
-cocci and bacilli may aggregate but vibrio, spirillum, and spirochete shaped bacteria do not usually aggregate; they exist as single cells
Flagella
- facilitate bacterial movement
- tail like things at the end
- can help them move to nutrients or away from harmful thing
axial filament
Axial filament is wound around the length of the bacterial cell between outer membrane an cell wall and attached at each end.
- kind of movement that comes out is a cork screw like movement
- similar structure to the flagella
Macroscopic aggregation bacteria
- usually called “colonies”
- diff species have characteristic forms & color when cultured on agar
Colony shape
-round
-irregular
-filamentous
-rhizoid
-curled
SLIDE 16
Colony edge/margin
-entire
-filamentous
-undulate (irregular)
-lobate (irregular)
SLIDE 16
colony elevation (looking it through the perti dish
-raised
-flat
-convex
-umbonate
-growth into medium
SLIDE 16
colony colors
•Depends on the species of bacteria
–Whether the species
produces a pigment
–How it reacts on culture
media with different
biochemical compositionsNutrition (metabolism) of prokaryotic cells
•Nutrients are absorbed directly through cell wall and plasma membrane
•Many species secrete enzymes to break down materials in the environment before absorbing them
•Many species secrete antibiotics to inhibit growth of different species (this is a territorial thing)
•Some species have flagella to aid movement toward nutrient sources
•Metabolism is the the entire set of chemical reactions necessary to maintain life
-discovery of these that revolutionized medical treatment
Energy source
check slide 23
- every living thing must have carbon and energy source
- carbon : CO2 or Organic molecules
- energy : Light or Chemical Reactions
MOST OF OUR ATTENTION WILL BE ON CHEMOHETEROTROPHS
Toxic Muck
- California’s Algae Problem is worse than ever
- happens mainly year farm water rushes there (has fertilizers and such)
- blue-green algae-related toxin warnings remain at Russian River
- Blue-green algae (cyanobacteria) are photoautotrophs that may produce toxins
- dog dies on Russian river, positive for toxic algae
- cyanobacteria is a very big public health concern
- it is an infection
- the way public health is dealing with it is by putting warning signs up
- especially worse in Aug.
Effects of cyanobacteria toxins
- Skin rash
- Gastrointestinal problems
- Respiratory failure, death
Aerobe **
can grow ONLY in the presence of oxygen
Microaerophilic **
can grow only in REDUCED oxygen
Anaerobe **
can grow only in the ABSENCE of oxygen
Facultative **
can grow in BOTH presence or absence of oxygen
CATEGORIES OF PROKARYOTES BASED ON METABOLIC OXYGEN NEEDS
•Why oxygen needs are important to know
–Determines where we
encounter the
microorganism in nature
–Determines where in
humans the
microorganism grows and
what disease it may cause
–Determines how the
microorganism is
diagnosed in the
laboratory
–May determine how the
infectious disease is
treatedHow bacteria protect themselves from the enviroment
•*Use flagella to move away from a dangerous chemical or physical threat*
•MAIN PROTECTION: Most bacteria have cell walls
–Protects against changes in
osmotic pressure
–usually composed of
peptidoglycan
•Formation of an endospore
–usually composed of
double cell membrane,
extra peptidoglycan,
calcium, and other
chemicals to form
protective wall around the
nucleic acids in the spore
–Protects against adverse
environment (heat,
dessication, chemicals)
•Formation of a capsule
–usually composed of
complex polysaccharides
–Protects against
phagocytosis (engulfment
and digestion) by immune
system cells of
human/animal hostGRAM Something
•Crystal violet (CV) is taken into cell wall/plasma membrane of all bacteria.
•CV is fixed into cell wall/plasma membrane of all bacteria.
•Decolorizer penetrates outer membrane and cell wall of Gram negative bacteria and CV comes out; CV is not removed from Gram positives because peptido glycan wall is thicker
•Safranin stains all bacteria. Since CV is much darker than safranin, it masks the pink color of safranin and Gram positive organisms appear purple, but Gram negative appear pink.
-this is important b/c it classifies bacteria into different groups
SLIDE 34
Acid-fast vs. non-acid fast
check slide 36
Reproduction in Bacteria
- Asexual reproduction is by binary fission; resulting individuals are genetically identical to original individual
- “Parasexual” reproduction results in an individual that is genetically different from the cell that started the process; however, haploid sperm and ova are not produced so it is not a true sexual process
Tranformation in bacteria
PARASEXUAL
check slide 41
- a way of getting genetic variation
Transduction
PARASEXUAL
- viruses that approach bacteria that are able to make a hole in the cell wall and incorporate its DNA into it
- therefore goes from one bacterial cell to another… leading to variation
Conjugation
PARASEXUAL
-Conjugation pilus… plasmid forms a little bridge between two cells and the plasmid is shared into a new cell that didn’t have plasmid before
SLIDE 44
Eukaryota
fungi, plantae, protista, animai
Prokaryota
bacteria & archaea
Plasmid
contains genetic material (that is separate from the chromosome)
Attachment pili (firmbriae)
- sticks out straight from the bacteria, but it is there to prohibit movement
- very important in some human disease, i.e. urinary track infection
archea
- bottom of volcanos
- places where there is no other life form known
- no archea has been known to give rise to human disease
Gram-negative vs. positive
- (-) has a thinner peptidoglycan than does gram (+) which has an extremely thick peptidoglycan
carbonflushsin
-dies acid fast pink
methylene blue
dies non-acid fast blue
Sperm from a hermaphroditic worm can fertilize the ova of a different individual worm or its own. If a tapework fertilitizes its own ova with its own sperm and offspring results, what type of reproduction would this be considered?
A. asexual
B. sexual
C. parasexual
D. none of the above
ANS: parasexual
