topic 6: prokaryotes

Question 1

living organisms are classified into 3 domains:

Answer 1

• Bacteria
• Archaea
• Eukarya

Question 2

which two domains consist of unicellular prokaryotes?

Answer 2

Domain Bacteria and Domain Archaea

Question 3

what is Domain Eukarya divided into?

Answer 3

the eukaryotes, divided into 4 Kingdoms:
- protists
- fungi
- plants
- animals

Question 4

prokaryotic micro-organisms

Answer 4

• bacteria
• archaea

Question 5

prokaryotic macro-organisms

Answer 5

do not exist

Question 6

eukaryotic micro-organisms

Answer 6

• fungi
• protists

Question 7

eukaryotic macro-organisms

Answer 7

• plants
• animals

Question 8

what are the micro-organisms categories?

Answer 8

• bacteria: unicellular prokaryotic micro-organisms
• archaea: unicellular prokaryotic micro-organisms
• protists: eukaryotic micro-organisms (e.g. protozoa, algae)
• fungi: eukaryotic micro-organisms (e.g. yeasts, mushrooms)
• viruses: non-cellular pathogens

Question 9

who discovered the antibiotic penicillin, and when was it discovered?

Answer 9

• Alexander Fleming
• 1929

Question 10

prokaryotes are divided into 2 domains:

Answer 10

bacteria and archaea

Question 11

what are 2 major categories of Domain Bacteria?

Answer 11

• Eubacteria
• Cyanobacteria

Question 12

what are Eubacteria?

Answer 12

includes pathogenic bacteria => cause diseases

Question 13

what are Cyanobacteria?

Answer 13

• non-pathogenic
• have chlorophyll, perform photosynthesis => produce oxygen
• live in lakes, oceans
• role in nitrogen fixation

Question 14

what does Domain Archaea include?

Answer 14

• Archaea (Archaeabacteria): live in extreme conditions

Question 15

what are examples of Archaea?

Answer 15

• halophiles: in salty lakes
• methanogens: in the digestive track, anaerobes, produce methane
• thermoacidophiles: in acidous, sulfur-rich hot spring, with optimum temperatures of 70-80˚C and pH 2-3

Question 16

in taxonomy of living organisms, species are broken down into?

Answer 16

• subspecies
• variety
• strain (in bacteria)

Question 17

how is a species named?

Answer 17

species name = genus + characteristic property

Question 18

what is an example of naming a species?

Answer 18

Staphylococcus aureus
- genus: staphylococcus
- property: aureus

Question 19

what does it mean for prokaryotes to have variable morphology?

Answer 19

a variety of shapes

Question 20

describe the morphology of prokaryotes

Answer 20

(1) spherical shape (cocci)
(2) rod-shaped (rods)
(3) spiral shape

Question 21

what is an example of a spherical shaped prokaryote?

Answer 21

Staphylococci, Streptococci
(cocci = spherical)

Question 22

what is an example of a rod-shaped prokaryote?

Answer 22

bacilli (E. coli)

Question 23

what is an example of a spiral shaped prokaryote?

Answer 23

• Vibrio cholerae: shape C or S
• Spirilla and Spirochetes

Question 24

what are the characteristics of a prokaryotic cells, different from a eukaryote?

Answer 24

• smaller in size
• absence of nuclear membrane
• absence of membrane-bound organelles (mitochondria/chloroplasts)
• no organized replicative cell cycle (mitosis)
• replicated by binary fission instead
• their cell wall has different composition from eukaryotic cells

Question 25

what are the structures in a prokaryotic cell, the essential and non-essential?

Answer 25

essential (present in ALL cells): - cytoplasm - cell wall - plasma membrane - nucleoid (region with circular DNA) non-essential (present in some): - fimbriae - capsule - sex pillus - flagella

Question 26

what are the functions of prokaryotic cell wall?

Answer 26

- maintains cell shape - protects the cell - prevents cell from bursting in hypotonic environment (osmotic pressure) - role in cell division

Question 27

compare the different cell wall compositions of eukaryotic, bacterial, and archaea cell walls

Answer 27

eukaryotic cell walls: - made of cellulose (plant cells) - made of chitin (fungi) bacterial cell walls: - contain peptidoglycan archaea cell walls: - contain polysaccharides and proteins - LACK PEPTIDOGLYCAN

Question 28

what is peptidoglycan?

Answer 28

a network of polysaccharides and polypeptide

Question 29

what is gram staining?

Answer 29

- staining technique used to classify bacteria in 2 major categories based on cell wall composition - uses crystal violet dye used for staining (violet color)

Question 30

what is gram-positive bacteria?

Answer 30

- their cell walls mainly consist of peptidoglycan - they absorb crystal violet => have a purple (violet) color

Question 31

what is gram-negative bacteria?

Answer 31

- their cell walls consist of a SMALL amount of peptidoglycan and a LARGE amount of lipopolysaccharides (LPS) - do not absorb crystal violet => have a pink color

Question 32

why are gram-positive bacteria violet in color?

Answer 32

the peptidoglycan in their cell walls traps crystal violet

Question 33

what are some examples of Gram (+) bacteria?

Answer 33

- staphylococci - streptococci - micrococci

Question 34

what are some examples of Gram (-) bacteria?

Answer 34

- Escherichia coli (E. coli) - Shigella - Salmonella

Question 35

what is an example of an antibiotic that targets the peptidoglycan and damages bacterial cell walls?

Answer 35

penicillin

Question 36

what are the functional differences between Gram (+) and Gram (-) bacteria?

Answer 36

Gram (+) bacteria: - resistant to physical stress - sensitive to lysozyme and penicillin Gram (-) bacteria: - resistant to lysozyme and penicillin

Question 37

what is more likely to be antibiotic resistant (antimicrobials/antibacterials)?

Answer 37

Gram-negative bacteria

Question 38

what is the capsule?

Answer 38

a polysaccharide or protein layer that covers some prokaryotes

Question 39

what is the capsule associated with?

Answer 39

increased virulence of wpathogenic bacteria

Question 40

what is virulence?

Answer 40

the ability of an infectious agent to produce disease (pathogenicity) => a measure of the severity of the disease it causes

Question 41

what are the functions of a capsule?

Answer 41

- protects bacteria from phagocytosis by leukocytes - protects bacteria from the digestion upon phagocytosis - protects bacteria from infection by phages and drying

Question 42

some prokaryotes have fimbriae, which are?

Answer 42

structures that aid with the attachment of bacteria to each other or to other cells that they infect

Question 43

what is a special type of fimbriae, what is it used for?

Answer 43

special type of fimbriae (longer than regular fimbriae) that allow prokaryotes to exchange DNA