Section 1- Prokaryotic Cell Structure/Function Flashcards Preview

Medical Microbiology > Section 1- Prokaryotic Cell Structure/Function > Flashcards

Flashcards in Section 1- Prokaryotic Cell Structure/Function Deck (53)
Loading flashcards...
1

3 domains of life

Bacteria
Archaea
Eukarya
All contain single-celled microbes
Archaea and Eukarya more closely related

2

Prokaryotes

Lack nuclear membranes

3

Archaea

Prokaryote

4

Bacteria

Prokaryote
Range from 0.2 to 2 microns in diameter
Seen mostly by electron microscopy

5

Eukarya

Eukaryote
Have nuclear membranes
Ex: paramecium, fungi, plants, animal

6

Virus

Non living
Smaller than bacteria

7

Coccus, Cocci

Spherical cells

8

Bacillus, bacilli

Rod-shaped cells

9

Spiral-shaped bacteria

Usually motile
Comma-like
Coiled
Ex: spirochete

10

4 main types of Prokaryotic cells

Coccus
Coccobacillus
Bacillus
Vibrio

11

Pleomorphic bacteria

Can have many different appearances

12

Diplococci

Cocci pair
One plane of division

13

Streptococci

Cocci chain
One plane of division, repeated

14

Staphylococci

Cocci bunch
3 planes of division, repeated

15

Binary fission- multiplication

How bacteria divide
Cell replicates DNA, membrane elongates to separate DNA molecules, cross-wall forms and membrane invaginates, cross-wall forms completely, daughter cells separate

16

Endospores

Produced by gram (+) Bacillus and Clostridium species
Each vegetative cell transforms into one endospore
Each endospore germinates to form one vegetative cell
*Dormant state for bacteria
Constitute a defense strategy against hostile or unfavorable conditions
Very resistant to drying, heat, radiation, and disinfectants
Can remain viable for 10-1000 years
Serious concern to food industry and hospitals (1000 cases/day)
Potential biological weapons of mass destruction (b/c create toxins)

17

Endospore Formation steps

DNA replicates, membrane invaginates to form forespore, membrane engulfs forespore in 2nd membrane, and vegetative cell's DNA disintegrates
Next, cortex of calcium and dipicolinic acid deposits between 2 membranes, spore coat forms around endospore, endospore "matures" (coat thicker), endospore released

18

Differential stains

Ex: Gram Stain
Acid-Fast Stain

19

Gram Stain

Gram (+) vs Gram (-)
Differentiates MOST bacteria
Steps: Crystal Violet, Gram's Iodine (Fixes stain), Decolorizer (Alcohol or Acetone), Safranin

20

Gram (+)

Stain purple
Ex: Staphylococcus aureus

21

Gram (-)

Stain red/pink
Ex: Escherichia coli

22

Gram stain NOT used for

Atypical cell walls
-Mycoplasmas
-Archaea
-Mycobacterial/Nocardia

23

Mycoplasmas

Only bacteria without cell wall
Sterols in plasma membrane

24

Archaea

Not bacteria
Wall-less or have walls of pseudomurein

25

Mycobacteria/ Nocardia

Acid fast bacteria (AFB)
Very waxy outer layer--> resistant
Ex: Mycobacterium tuberculosis, Mycobacterium leprae, Nocardia asteroides

26

Acid-Fast stain

AFB resist decolorization with acid-alcohol and stain raid, the color of the initial stain, CARBOL FUCHSIN
Other bacteria will be decolorized and stain blue with counterstain, METHYLENE BLUE

27

Central endospores

Bacillus
Endospore stain (green within red)
Stain everything but spore

28

Terminal endospores

Clostridium botulinum and Clostridium tetani

29

Clostridium botulinum

Causes botulism
Most potent toxin known
Disease is an intoxication by neurotoxin
Forms spores
Clinical sign=flaccid paralysis (no muscles contract)
Most affects infants less than 6 months b/c they are more susceptible to spores; HONEY often infected
150 cases/year

30

Clostridium tetani

Causes tetanus
Neurotoxin; causes spastic paralysis (all muscles contract)
Lockjaw first sign