Prokaryotes Flashcards
Name the 2 prokaryotic domains
- Archaebacteria
2. Eubacteria
_____________ are found in harsh environments
Archaebacteria
Examples of harsh environments in which archaebacteria are found
Very saline places; hot place
What group is referred to as the true bacteria
Eubacteria
What cell structures are lacking in prokaryotes?
Organelles
Do bacteria have ribosomes like other types of cells?
Yes
Describe the genetic material of bacteria. Where is it found?
DNA; it floats in the cytoplasm
What surrounds the outside of all bacterial cells?
Capsule
Cell walls of true bacteria contain _____________
peptidoglycan
Beside the circular chromosome, where else can DNA be found inside a bacterial cell?
cytoplasm
What is the size of most bacterial cells?
1-10 um
most bacteria act as a _________
decomposer
How can some bacteria be harmful?
diseases
What does motile mean?
can move
Motile bacteria may have one or more _______ for movement
flagella
What are bacterial pili?
Hair-like appendages used for reproduction
What are pili used for?
gene transfer and sticking to surfaces
What is spiral shaped bacteria?
spirillum
What is rod shaped bacteria?
bacilli
what is round shaped bacteria?
cocci
How do the walls of archaebacteria differ from true bacteria?
do not contain peptidoglycan
How do the cell membranes of archaebacteria differ from true bacteria?
archaebacteria cell membranes contain hydrocarbon instead of fatty acids
do archaebacteria and eubacteria have the same ribosomes?
no
Do archaebacteria require oxygen?
no
Methanogens live in _______ environments. What is lacking in this environment?
reduced; oxygen
How do methanogens get their energy?
methanogenesis
What is methanogensis?
the process in which a methanogen uses carbon as an electron accepter to produce methane
The _________ live in very salty environments
halophiles
___________ live in extremely hot environments
Thermophiles
Describe Gram staining
a method of differentiating bacterial species into two large groups by use of stain
Describe the cell wall of Gram positive bacteria
thick peptidoglycan layer in the cell wall
What color is the cell wall of Gram positive bacteria stained?
crystal violet
Describe the cell wall of Gram negative bacteria
thin peptidoglycan layer
What color is the cell wall of Gram negative bacteria stained?
red or pink
5 modes of nutrition in bacteria?
Autotrophs, Heterotrophs, Phototrophs, Chemotrophs, Lithotrophs
How do autotrophs get their nutrition?
They obtain their nutrition from inorganic compounds. Autotrophs will use hydrogen sulfide, ammonia or hydrogen gas to reduce carbon into necessary sugars.
How do heterotrophs get their nutrition?
organic sources of carbon such as sugars, fats and amino acids
How do phototrophs get their nutrition?
Phototrophic bacteria absorb light energy, then utilize this in photosynthesis to create cellular energy
How do chemootrophs get their nutrition?
These bacteria obtain chemical energy from their surroundings and convert it into ATP
How do lithotrophs get their nutrition?
use reduced inorganic compounds as the electron donor (H-donor) in anaerobic or aerobic respiration.
Explain obligate aerobes:
An obligate aerobe is an organism that requires oxygen to grow. Through cellular respiration, these organisms use oxygen to metabolise substances, like sugars or fats, to obtain energy.
Explain obligate anaerobes:
Obligate anaerobes are microorganisms that are killed by normal atmospheric concentrations of oxygen
Explain facultative anaerobes:
A facultative anaerobe is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent.
How do bacteria reproduce asexually?
binary fission
How do bacteria reproduce sexually?
genetic recombination
How does conjugation work
Conjugation is the direct transfer of DNA from one bacterial cell to another bacterial cell. The transferred DNA is a plasmid, a circle of DNA that is distinct from the main bacterial chromosome. The F plasmid is similar to a virus or a transposon in its ability to move independently of the main chromosome. The transfer of the plasmid take advantage of the complementary nature of double stranded DNA. One strand of the plasmid is transferred and the other remains in the original cell. Both strands have the complementary stranded added so that each cell ends up with a complete plasmid.
How do the new cells compare to each other after conjugation?
they are identical
How long can an endospore survive?
millions of years
Why are endospores such a problem in health care facilities and in the canning industry.
Dormant bacteria can suddenly become active after years of being inactive.
What are Pathogens?
Bacteria that can cause disease
what are toxins?
poisons
Difference between endotoxin and exotoxin
Exotoxins are toxic substances secreted by bacteria and released outside the cell. Whereas Endotoxins are bacterial toxins consisting of lipids that are located within a cell.
