Microbiology: Prokaryotes Flashcards
Prokaryotes are broken up into what two chatagories?
- ## split into Bacteria and Archaea(has more incommon w/eukaryotes)
Autotrophs
- organisms cpapble of using CO2 as their sole source of C.
- supply’s its own food.
Heterotrophs
- use preformed organic molecules as sources of E
- uses others for food
Phototrophs
use light as source of Energy
Chemotrophs
- use oxidation of organic or inorganic matter as its source of Energy
Describe Nitrogen fixation
- the process by which N2 is converted to ammonia
- nitrification-creates nitrates from ammonia
Describe the structure of prokaryotes
- single circular ds stranded DNA
- No membrane bound nucleus
- No Complex, membrane bound organelles
- Ribosomes(50S+30S=70S), and
Mesosomes(invaginations of the PM) - PM usually lacks steroids, has hopanoids instead.
What is a phospholipid composed of?
- 1 Phosphate group
- 2 Fatty Acid chains
- A Glycerol backbone
Why is a phospholipid amphipathic?
- it has both a polar (phosphate group) and nonpolar (FA chain) portion of the molecule
Integral (intrinsic) proteins
- proteins that transverse the membrane from inside to outside the cell.
Peripheral (extrinsic) proteins
entirely on the surface of the membrane
Brownian motioin
random movement of molecules
Electrochemical Gradient
- 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…
A natural membrane is usually impermeable to …
large and charged
- polar molecules
- molecules with molecular weight graeater than 100.
Facilitated diffusion
- diffusion down the electro-chemical gradient with the assistance of carrier or transport proteins
Protoplast
- bacterial plasma membrane, and everything inside.
protoplast is surrounded by the bacterial envelope(includes the cell wall)
What do we mean when we say the at most bacteria are hypertonic?
- 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.
What happens when water moves in of a hypertonic cell?
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)
Cell walls of prokaryotes (bacteria ) are made of ???
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
Describe Gram-Positive Bacteria
- Thick Peptidoglycan cell wall (prevents gram stain from leaking out)approximately 4X thicker than the PM
- ## cells show up purple
Periplasmic space
- space between plasma membrane and the cell wall.
Describe Gram-Negative Bacteria
- 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.
What are the layers of Gram-Positive Bacteria from cytosol outward?
- Cytosol
- Plasma Membrane
- Periplasmic space
- Cell Wall (peptidylglycan)
- Capsule/slime layer
What are the layers of a Gram -Negative bacteria from the cytosol outward?
- Cytosol
- Plasma Membrane #1
- Periplasmic Space
A. Space
B. Peptidyl glycan (cell wall)
C. Space - Plasma Membrane #2
- Capsule/slime layer
Define Plasmid, and Episome
Plasmid
- small circular DNA that exist and replicate independently of the bacterial chromosome.
Episome
- a plasmid that integrates into the chromosome
Describe Conjugation
- type of genetic recombination
- requires that bacteria has a conjugative plasmid(one with a gene that codes for a sex pilus)
Sex Pilus
- 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
Describe the F plasmid
- F+, Fertility factor
- a episome
Describe R plasmid
- donates resistence to certain antibiotics
Define transformation
- 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
Define transduction
- Transfer of DNA via a virus
Describe endospores
- some formed by gram-positive bacteria can lie dormant for hundreds of years
- resistent to UV radiation, chemical disinfectants, desiccation
Describe fungi
- 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)
hyphae
- tangled mass of multiply branched thread like structures called hyphae.
- are haploid and lengthen through mitosis
budding (cellular fission)
- smaller cell pinches off from the single parent cell
under which conditions to asexuall reproduction occur compared to sexual reproduction.
- 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
What are 3 common shapes of bacteria?
- cocci(round), bacilli(rod) or spirilla(helical) shaped
