Microbiology: Prokaryotes

Question 1

Prokaryotes are broken up into what two chatagories?

Answer 1

• ## split into Bacteria and Archaea(has more incommon w/eukaryotes)

Question 2

Autotrophs

Answer 2

• organisms cpapble of using CO2 as their sole source of C.

- supply’s its own food.

Question 3

Heterotrophs

Answer 3

• use preformed organic molecules as sources of E

- uses others for food

Question 4

Phototrophs

Answer 4

use light as source of Energy

Question 5

Chemotrophs

Answer 5

• use oxidation of organic or inorganic matter as its source of Energy

Question 6

Describe Nitrogen fixation

Answer 6

• the process by which N2 is converted to ammonia

- nitrification-creates nitrates from ammonia

Question 7

Describe the structure of prokaryotes

Answer 7

1. single circular ds stranded DNA
2. No membrane bound nucleus
3. No Complex, membrane bound organelles
4. Ribosomes(50S+30S=70S), and
   Mesosomes(invaginations of the PM)
5. PM usually lacks steroids, has hopanoids instead.

Question 8

What is a phospholipid composed of?

Answer 8

• 1 Phosphate group
• 2 Fatty Acid chains
• A Glycerol backbone

Question 9

Why is a phospholipid amphipathic?

Answer 9

• it has both a polar (phosphate group) and nonpolar (FA chain) portion of the molecule

Question 10

Integral (intrinsic) proteins

Answer 10

• proteins that transverse the membrane from inside to outside the cell.

Question 11

Peripheral (extrinsic) proteins

Answer 11

entirely on the surface of the membrane

Question 12

Brownian motioin

Answer 12

random movement of molecules

Question 13

Electrochemical Gradient

Answer 13

• combination of the chemical concentration gradient and the electrical gradient

chemical conc. gradient
- gradual change in conc. of a compound over a distance

electrical gradient
- change in concentration of charge…

Question 14

A natural membrane is usually impermeable to …

Answer 14

large and charged

• polar molecules
• molecules with molecular weight graeater than 100.

Question 15

Facilitated diffusion

Answer 15

• diffusion down the electro-chemical gradient with the assistance of carrier or transport proteins

Question 16

Protoplast

Answer 16

• bacterial plasma membrane, and everything inside.

protoplast is surrounded by the bacterial envelope(includes the cell wall)

Question 17

What do we mean when we say the at most bacteria are hypertonic?

Answer 17

• Most bacteria have aquues solution in their cytosol that contains more particles than the aques solution surrounding them.

hypotonic- the opposite more stuff outside than in.

-If particles are prevented from crossing a barrier, water will cross in the opposite direction.

Question 18

What happens when water moves in of a hypertonic cell?

Answer 18

As the cell fills with water the hydrostatic pressure builds, it eventually equals the osmotic pressure and the filling stops …( Yet the water still moves back and forth)

Question 19

Cell walls of prokaryotes (bacteria ) are made of ???

Answer 19

Peptidoglycan

• more elastic than cellulose (cell wall of plants)
• It is pourous
• Penicillin is antibiotic that attacks the smino acid cross links
• Lysozyme - prod by humans attacks dissacharide linkages

Question 20

Describe Gram-Positive Bacteria

Answer 20

• Thick Peptidoglycan cell wall (prevents gram stain from leaking out)approximately 4X thicker than the PM
• ## cells show up purple

Question 21

Periplasmic space

Answer 21

• space between plasma membrane and the cell wall.

Question 22

Describe Gram-Negative Bacteria

Answer 22

• appear Pink when stained
• Thin peptidoglycan cell wall (allows most of gram stain to washed off
• outside the cell wall, gram-negative bacteria have a second phospholipid bilayer that is more permeable than the first.

Question 23

What are the layers of Gram-Positive Bacteria from cytosol outward?

Answer 23

1. Cytosol
2. Plasma Membrane
3. Periplasmic space
4. Cell Wall (peptidylglycan)
5. Capsule/slime layer

Question 24

What are the layers of a Gram -Negative bacteria from the cytosol outward?

Answer 24

1. Cytosol
2. Plasma Membrane #1
3. Periplasmic Space
   A. Space
   B. Peptidyl glycan (cell wall)
   C. Space
4. Plasma Membrane #2
5. Capsule/slime layer

Question 25

Define Plasmid, and Episome

Answer 25

Plasmid
- small circular DNA that exist and replicate independently of the bacterial chromosome.

Episome
- a plasmid that integrates into the chromosome

Question 26

Describe Conjugation

Answer 26

• type of genetic recombination

- requires that bacteria has a conjugative plasmid(one with a gene that codes for a sex pilus)

Question 27

Sex Pilus

Answer 27

• hollow protein tube that connects two bacteria to allow tha passage of DNA
• DNA flow is allows from the bacteria with the conjugative plasmid to the one without

Question 28

Describe the F plasmid

Answer 28

• F+, Fertility factor

- a episome

Question 29

Describe R plasmid

Answer 29

• donates resistence to certain antibiotics

Question 30

Define transformation

Answer 30

• the process where bacteria can incorporate DNA from their external environment into the genome
• ( DNA aquired directly from medium)
• can be DNA from lysed cells or added in a lab setting

Question 31

Define transduction

Answer 31

• Transfer of DNA via a virus

Question 32

Describe endospores

Answer 32

• some formed by gram-positive bacteria can lie dormant for hundreds of years
• resistent to UV radiation, chemical disinfectants, desiccation

Question 33

Describe fungi

Answer 33

• separated into divisions (not phyla)
• eukaryotic heterotrophs that obtain their food by absorption rather than by ingestion.
• secrete digestive enzymes outside of bodies and then absorb the products of digestion
• most possess cell walls called septa ( made of chitin)
• lack centrioles
• multicellular ( with the expection of yeasts)

Question 34

hyphae

Answer 34

• tangled mass of multiply branched thread like structures called hyphae.
• are haploid and lengthen through mitosis

Question 35

budding (cellular fission)

Answer 35

• smaller cell pinches off from the single parent cell

Question 36

under which conditions to asexuall reproduction occur compared to sexual reproduction.

Answer 36

• asexual reproduction normally occurs when conditions are good (if conditions are favorable for parent , then they wiill be for asexually produced offspring.)
• sexual reproduction normally occurs when conditions are tough

Question 37

What are 3 common shapes of bacteria?

Answer 37

• cocci(round), bacilli(rod) or spirilla(helical) shaped