Microbiology 260 (LCC) Exam 1 Question
And Answers
Calculate how many bacteria are present based on initial numbers and
generation time - -Bacteria double every generation time.
9pm = 17 million
9am = 280 trillion
In 36 hrs there would be a layer of bacteria 1ft deep over the entire earth
48 hours = 2.4 x 10^24 tons of bacteria
2+2=4 4+4=8 8+8=16...
- Compare/Contrast the functions of a fungal spore and bacterial
endospore - -One fungus spore can make many spores where bacterial
endospores can only make one endospore per cell (1:1)
- Contrast prokaryotic and eukaryotic ribosomes - -Prokaryotic (70S)
ribosomes are smaller than eukaryotic (80S) ribosomes. Eukaryotic
ribosomes are membrane bound to ER
- Contrast the structure of gram positive and gram negative cell walls
and describe the function of the cell walls - -Gram positive cell walls don't
have an outer membrane where as gram negative cells do, and the
Peptidoglycan layer is thin in gram negative cells and thick in gram
positive cells.
The cell wall prevents osmotic lysis
- Define biofilm and explain the advantage of biofilms to microorganisms
- -A biofilm is a complex community of one or more microorganism
species, forming as a slimy coating att. to a surface bc of prod. of an extra
polymeric substance that attaches to a surface or at the interface
between surfaces.
Advantages are that biofilms are resistant to antibiotics, exchange
plasmids, protect from the immune system, and communicate between
cells
- Define taxis and explain how it affects bacterial survival - -an oriented
movement toward or away from a stimulus, this affects bacterial survival
because it makes the bacteria move away something bad or move
towards food or light
- Define Tinea barbae - -barber's itch (beard area)
- Define Tinea capitis - -head/scalp
, - Define Tinea corporis - -body
- Define tinea cruris - -jock itch
- Define Tinea pedis - -athlete's foot
- Define Tinea unguium - -nails
- Describe quorum sensing - -Cells in biofilms communicate through
quorum sensing, by releasing chemicals called autoinducers. Bacterial
cells can sense when the cell population reaches a certain number
(quorum). When a quorum is reached certain genes are activated
- Describe the functions of (sex) pili - -Facillitate transfer of DNA from
one cell to another
- Describe the functions of fimbriae - -Help bacteria attach, contribute
to biofilms
- Describe the result of a hypertonic solution - -Water particles move out
of the cell, cell membrane shrinks and detaches from cell wall
- Describe the results of a cell being hypotonic - -Water particles move
into cell, cell wall counteracts osmotic pressure to prevent swelling and
lysis
- Describe the results of a cell being isotonic - -No movement, cell
membrane is attached to cell wall
- Describe the structure and function of a glycocalyx - -Surrounds the
cell, helps cells adhere to surfaces and each other, contributes to biofilms
and protects cell from phagocytosis
- Describe the structure and function of flagella - -tail-like structures not
usually seen under a light microscope. Help some bacteria move
- Describe the structures and functions of the prokaryotic plasma
membrane - -Surrounds the outside of the cell and is made up of a double
layer of phospholipids and controls the movement of various substances
into and out of the cell
- Differentiate between an imtermediate and definitive host - -An
intermediate host supports the immature or nonproductive form of a
parasite where as a definitive host supports the adult or sexually
reproductive form of a parasite
- Does this help you understand why E coli O157 :H7 has an O in it? - -
O157 means this is the 157th kind of O antigen found in E coli, the
And Answers
Calculate how many bacteria are present based on initial numbers and
generation time - -Bacteria double every generation time.
9pm = 17 million
9am = 280 trillion
In 36 hrs there would be a layer of bacteria 1ft deep over the entire earth
48 hours = 2.4 x 10^24 tons of bacteria
2+2=4 4+4=8 8+8=16...
- Compare/Contrast the functions of a fungal spore and bacterial
endospore - -One fungus spore can make many spores where bacterial
endospores can only make one endospore per cell (1:1)
- Contrast prokaryotic and eukaryotic ribosomes - -Prokaryotic (70S)
ribosomes are smaller than eukaryotic (80S) ribosomes. Eukaryotic
ribosomes are membrane bound to ER
- Contrast the structure of gram positive and gram negative cell walls
and describe the function of the cell walls - -Gram positive cell walls don't
have an outer membrane where as gram negative cells do, and the
Peptidoglycan layer is thin in gram negative cells and thick in gram
positive cells.
The cell wall prevents osmotic lysis
- Define biofilm and explain the advantage of biofilms to microorganisms
- -A biofilm is a complex community of one or more microorganism
species, forming as a slimy coating att. to a surface bc of prod. of an extra
polymeric substance that attaches to a surface or at the interface
between surfaces.
Advantages are that biofilms are resistant to antibiotics, exchange
plasmids, protect from the immune system, and communicate between
cells
- Define taxis and explain how it affects bacterial survival - -an oriented
movement toward or away from a stimulus, this affects bacterial survival
because it makes the bacteria move away something bad or move
towards food or light
- Define Tinea barbae - -barber's itch (beard area)
- Define Tinea capitis - -head/scalp
, - Define Tinea corporis - -body
- Define tinea cruris - -jock itch
- Define Tinea pedis - -athlete's foot
- Define Tinea unguium - -nails
- Describe quorum sensing - -Cells in biofilms communicate through
quorum sensing, by releasing chemicals called autoinducers. Bacterial
cells can sense when the cell population reaches a certain number
(quorum). When a quorum is reached certain genes are activated
- Describe the functions of (sex) pili - -Facillitate transfer of DNA from
one cell to another
- Describe the functions of fimbriae - -Help bacteria attach, contribute
to biofilms
- Describe the result of a hypertonic solution - -Water particles move out
of the cell, cell membrane shrinks and detaches from cell wall
- Describe the results of a cell being hypotonic - -Water particles move
into cell, cell wall counteracts osmotic pressure to prevent swelling and
lysis
- Describe the results of a cell being isotonic - -No movement, cell
membrane is attached to cell wall
- Describe the structure and function of a glycocalyx - -Surrounds the
cell, helps cells adhere to surfaces and each other, contributes to biofilms
and protects cell from phagocytosis
- Describe the structure and function of flagella - -tail-like structures not
usually seen under a light microscope. Help some bacteria move
- Describe the structures and functions of the prokaryotic plasma
membrane - -Surrounds the outside of the cell and is made up of a double
layer of phospholipids and controls the movement of various substances
into and out of the cell
- Differentiate between an imtermediate and definitive host - -An
intermediate host supports the immature or nonproductive form of a
parasite where as a definitive host supports the adult or sexually
reproductive form of a parasite
- Does this help you understand why E coli O157 :H7 has an O in it? - -
O157 means this is the 157th kind of O antigen found in E coli, the
