Ch 3: Bacteria Flashcards Preview

BIO 246: Microbiology of Human Disease > Ch 3: Bacteria > Flashcards

Flashcards in Ch 3: Bacteria Deck (30):
1

What are prokaryotes? What are the types?

Prokaryotes are simple cells without a nucleus The types of prokaryotes are bacteria and archaea

2

What types of metabolism do Bacteria and Archaea (prokaryotes) have?

Heterotrophic: feed on organic substrates Autotrophic: Utilize inorganic substrates

3

Pathogenic bacteria use organic molecules of the host for energy and building blocks for reproduction. Bacterial pathogens are?

Heterotrophs

4

List the following in order from largest to smallest. Virus, yeast, bacterium, white blood cell.

White Blood Cell, Yeast, Bacterium, Virus

5

What structures are present on all bacterial cells?  What structures are only present on some bacterial cells?

All Bacterial Cells:

  1. Nucleoid Region
  2. RIbosomes
  3. Cell Membrane
  4. Cytoplasm

Some Bacterial Cells:

  1. Pilus
  2. Plasmid
  3. Actin Cytoskeleton
  4. Flagellum
  5. FImbria
  6. Cell Wall
  7. Glycocalyx

6

What is the flagellum?

Translates into "Whip"

Only present on some bacterial cells

Basal body acts as motor that rotates flagellum

7

What is chemotaxis?

chemical gradients influence bacterial movement

  1. tumble and runs
    • rotate counterclockwise: run (straight)
    • rotate clockwise: tumble (change direction)

8

How do we classify motile bacteria?

flagellar arrangement

9

What is the fimbria?

Protein filaments used for attachment and colonization

10

What is a pilus?

protein filament used for attachment and colonization

  • sex pilus: hollow tube used for conjugation

11

What is a glycocalyx?

sugar coat

  • slime layer or capsule

12

How does the glycocalyx (slime layer) help bacteria?

Helps bacteria form biofilms (plaque)

13

The glycocalyx helps form a capsule.  What does the capsule do?

Prevents the bacteria from adhering to phagocytes

14

What do bacteria transfer using a sex pilus?

Transfer plasmids

15

What is the cell wall

Structural support

-protection

-target for antibiotics

-Peptidoglycan: glycan sugar crosslinks to provide strength 

16

Who is Hans Christian Gram?

Invented Gram Stain

-differential staining technique for classifying bacteria

  • Gram-Positive: Stains PURPLE b/c have THICK cell wall
  • Gram-Negative: Stains PINK b/c have THIN cell wall

17

What are the characteristics of the gram-positive cell wall?

composed of a thick peptidoglycan layer with associated teichoic acids

18

what are the characteristics of a gram-negative cell wall?

composed of a thin peptidoglycan layer

 

Two membranes (Inner and outer) with:

  • porins: prevent entry of antibiotics like penicillin
  • lipopolysaccharides: endotoxin that causes inflammation

19

Which kind of bacteria has an irregular cell wall? What are the characteristics?

Mycobacterium has atypical cell wall

  • gram-positive cell wall but doesn't stain well
  • most of the cell wall is mycolic acid (Wax) which repels stains

20

What is significant about the mycoplasma bacteria?

Has NO CELL WALL

  • cell membrane contains sterols to make it stronger

21

What kind of crosslinks of peptidoglycan gives a bacterial cell wall its strength?

Peptide crosslink

22

What is contained in the nucleoid region of the bacterial cytoplasm?

Contains bacterial chromosome (single/circular DNA genome)

  • some bacteria have extrachromosomal DNA called Plasmids (multiple/circular)

23

How do bacteria reproduce?

Asexual cellular reproduction called Binary Fission

24

What are bacterial ribosomes?

Ribosomes perform protein synthesis

  • Translation: (mRNA⇒protein)

Contains two subunits

  • Large 50S and Small 30S together form the 70S Ribosome

25

WHat are the various bacterial cell shapes?

Cytoskeleton (actin filaments) produce the following cell shapes:

  1. Bacillus: rod shaped
  2. Vibrio: wave
  3. Spirillum: sprial
  4. Spirochete: really spiraled

26

What are the characteristics of the coccus (cocci)?

have no cytoskeleton

speherical shaped

 

27

What are the arrangements of cocci bacteria?

arrangements result from cytoplasmic division w/o separation of cell walls of daughter cells

Cell Division in One Plane:

  1. Diplococcus: two cells
  2. Streptococcus: variable number

Cell Division in Two Planes:

  1. Tetrad: 4 cells
  2. Staphylococcus: irregular cluster

28

How can you use cell morphology to tell the difference between Streptococcus and Staphylococcus?

Both are Gram-Positive so stained Purple

Streptococcus: chains

Staphylococcus: irregular cluster

29

What are endospores?

When growth conditions are unfavorable bacteria the vegetative cell undergoes sporulation and form endospores

This allows bacteria to survive in a dormant state until conditions change

When conditions are favorable the bacteria undergo germination and become a vegetative cell again

30

The Clostridium genus form endospores.  What would occure when Clostridium tetani is introduced into a host via a puncture wound?

endospores will germinate and produce neurotoxins