Domain: Bacteria Flashcards
What kind of organisms are Bacteria?
Bacteria are unicellular organisms -> prokaryotic cells!
Name 3 shapes of bacteria
- cocci - sphere
- bacilli - rod
- spiral
What is the function of the cell wall in bacteria?
- gives shape
- physically protects cell
- prevents cell from bursting in hypo-tonic environments
What is found in the cell wall of only bacteria
Peptidoglycan.
How does bacteria move?
Bacteria moves in response to chemical stimuli
positive chemotaxis -> towards stimuli
negative chemotaxis -> away from stimuli
What is the difference between gram-positive bacteria, and gram-negative bacteria?
Gram- Positive:
-thick layer of peptidoglycan around cell wall
-often responds to antibiotics
-typically less deadly
Gram-Negative:
-thin layer of peptidoglycan, plus an outer membrane surrounding this
-typically more deadly than gram-positive bacteria
-often does not respond to antibiotics
How do gram-positive bacteria look in a stain? Why?
purple, because the thick layer of peptidoglycan absorbs the stain.
How do gram-negative bacteria look in a stain? Why?
pink, because the outer membrane and thin layer of peptidoglycan do not hold the stain as well
What kind of capsule sometimes covers prokaryotes? What is it made from/what does it do?
Polysaccharide capsule
- Is made from sugars -> this allows it to:
- adherence
- dehydration protection
- resistance to host defenses
How does internal structure of prokaryotic cell differ from eukaryotic cell?
much simpler
- no complex compartmentalization
- have only single chromosome in a ring
- has ribosomes, but different in form and function
What is a plasmid?
Plasmid is a genetic structure in cell that can replicate independent of chromosomes - > “wayward DNA”
How do bacteria reproduce?
Binary fission -> parent cell splits in two, asexual.
What is an endospore?
Is a dormant structure produced by some bacteria that will remain in hibernation waiting for conditions to become right. Main goal is to survive long periods of time
-metabolically inactive and can remain
viable in harsh conditions for centuries
Why are bacteria so prolific?
- they reproduce via binary fission (asexual)
- they’re small
- have short generation time
Why do bacteria adapt so fast?
Because of short reproduction time.