Module 3 - Notes Flashcards
What are the distinguishing features between gram-positive, gram-negative, and acid-fast bacteria?
Gram-positive - Thick cell wall exposed to the outside world.
Gram-negative - Thin cell wall protected by another membrane
Acid-fact bacteria - a gram-positive with a wax layer
What are the distinguishing features between fungi and algae?
cell wall composition - Cellulose (algae) vs. Chitin (fungi)
Autotrophy/photosynthesis (algae) vs. heterotrophy/not photosynthesis (fungi)
Which option is NOT an example used to explain spontaneous generation?
A. Sand gave rise to scallops
B. Mud gave rise to frogs
C. Fungal spore deposited on a piece of melon gave rise to the same type of fungi
D. Rotting flesh gave rise to maggots
C. Fungal spore deposited on a piece of melon gave rise to the same type of fungi
What is spontaneous generation?
Inorganic matter gives rise to organic beings.
Life can arise from non-living matter
Which scientist provided experimental evidence against this theory using meat in an open container, meat in a cork-sealed container, and meat in a gauze-covered container to prove living matter did not arise from rotting flesh?
Francesco Redi
Why did people doubt Redi’s meat experiment to disprove spontaneous generation?
Because they thought the cork prevented the spirits from getting into the container and creating life.
How did Pasteur prove that life only comes from life?
He excessively boiled broth to kill any microorganisms and used a flask with a swan-neck to prevent outside air from entering the flask.
Which scientist coined the term cells?
Robert Hooke
What are the 7 components of the cell theory?
Living organisms are made up of 1 or more cells
Cells are the fundamental component of life
Cells arise from pre-existing cells
Activity of an organism depends on the total activity of the cells
Energy flow occurs within cells
Cells contain DNA and RNA
Cells of similar species have similar chemical composition
Who first proposed the Endosymbiotic theory?
Konstanin Mereschkowski
Who provided good microscopic evidence to support the endosymbiotic theory?
Lynn Margulis
What is the endosymbiotic theory?
infoldings in the plasma membrane of an ancestral cell gave rise to endomembrane components (nucleus & ER)
In the first endosymbiotic event, early eukaryotes consumed aerobic bacteria (mitochondria)
In the second endosymbiotic event, early eukaryotes consumed photosynthetic bacteria (Chloroplasts)
What does the endosymbiotic theory suggest about ancestry?
Both bacteria and Archaea gave rise to eukaryotes.
What is a prokaryotic cell?
Does not have a nucleus enclosed in a nuclear membrane?
Includes bacteria and archaea
Where is the DNA located in a prokaryotic cell?
in the center of the cell (Nucleoid)
What is this shape of bacteria called?
Coccus
(Cocci - plural)
Round
What is this shape of bacteria called?
Bacillus
(Bacilli - plural)
Rod
What is this shape of bacteria called?
Vibrio
(vibrios - plural)
Curved Rod
What is this shape of bacteria called?
Coccobacillus
(coccobacilli - plural)
Short Rod
What is this shape of bacteria?
Spirillum
(spirilla - plural)
Spiral
What is this shape of bacteria?
Spirochete
(sprochetes - plural)
long, loose, helical spiral
corkscrew with special flagella on the axis
What is it called when 2 cocci are together?
Diplococcus
What is it called when 4 cocci are arranged in a square?
Tetracoccus
What is it called when there is a chain of cocci?
Streptococcus
What is a cluster of cocci called?
Staphylococcus
What is a chain of bacilli called?
Streptobacillus
How large are bacterial cells in general?
1-10 microns on average.
Some are as small as 0.2 microns
How large are eukaryotic cells?
3-100 microns on average
When using a brightfield microscope, what features would differentiate a bacteria from a eukarya?
Membrane-bound nucleus & size
What is the purpose of prokaryotic inclusions?
Energy Storage for glycogens (sugars)
Some are gas vesicles to help float in water
Some are magnetosomes to help orient bacteria according to the magnetic field
What are endospores?
A dormant version of the cell
What type of bacteria produce endospores?
Exclusively produced by gram-positive bacteria
What are characteristics of endospores?
Resistant to extreme temperatures and radiation
Do not absorb gram stain
Dehydrated
Dormant - No growth or metabolic activity
What is the cycle of sporalization?
DNA replicates (Asymmetric division)
Membranes from around DNA (Engulfment)
Forespore forms additional membranes (maturation)
Protective cortex around the spore
Protein coat forms around the cortex (mother cell dies/lysis)
Spore is released
Spore germinates
Which type of microscopy can you use to see sporalization?
phase-contrast without staining
At which step can you inhibit spore formation?
A. Asymmetrical division
B. Engulfment
C. Germination
D. Maturation
A. Asymmetrical division
What is a eukaryotic cell?
membrane-bound nucleus
membrane-bound organelles
You have a new eukaryotic microbe. You analyze its ribosomes and observe two different forms of the ribosome, a 70S and an 80S. What is the best explanation for this observation?
The endosymbiotic theory
mitochondria and chloroplasts arise from bacteria
What is the cell envelope?
series of layers around the cytoplasm
What does the cytoplasmic membrane do?
Acts as a selective barrier
Generates concentration gradients
Anchors proteins for sensing, communicating and interacting
What is the composition of the cytoplasmic membrane in Bacteria & Eukarya?
Phospholipid bilayer
a tail and a head
Ester linkage
What is the composition of the cytoplasmic membrane in Archaea?
Bilayer or monolayer
Ether linkages
Phospholipids with side chains
What are the energy-independent forms of transport across the cytoplasmic membrane?
Diffusion
Facilitated Diffusion via proteins (dependent on concentration gradient)
What are the energy-dependent forms of transport across the cytoplasmic membrane?
Coupled Active Transport
ABC Transporter
Group Translocation
Which molecules enter the cytoplasmic membrane by simple diffusion?
Glycerol
H2
O
O2
What limits simple diffusion?
size and charge of the molecule
Hydrophilic and charged molecules are blocked
Hydrophobic molecules will go in but may not go out easily
What increases the rate of simple diffusion?
The greater the concentration gradient, the greater the rate is.
What is facilitated diffusion?
similar to simple diffusion but there is a channel embedded in the cell membrane that makes it more efficient.
It is easier than simple diffusion because you have greater selectivity or greater permeability for a specific molecule
What limits facilitated diffusion?
The size and charge of the molecule
What are the sources of energy for active transport?
ATP
high-energy-phosphate compound
substrate gradient & protonmotive force (PMF)
What are the 2 types of Coupled Active Transport?
Antiport
Symport
What is the source of energy for coupled active transport?
proton motor force & concentration gradient
How do the molecules move in antiport?
One molecule goes in
Once molecule goes out
How do the molecules move in symport?
Both molecules will bind and move either in or out of the cell.
What is the energy source for ABC transport?
ATP
How does the ABC transport method work?
The substrate outside the cell binds to the Substrate-binding protein
The carrier protein embedded in the cell wall opens to allow the substrate to pass into the cell when activated by ATP.
What energy source is required by group translocation?
a high-energy-phosphate compound
How does group translocation work?
a phosphoryl group transfers from protein to protein. Once the substrate-specific permease in the plasma membrane is phosphorylated, it allows the sugars to enter.
What is the purpose of the bacterial cell wall?
prevents osmotic lysis
maintains cell shape & rigidity
Which statement is correct about gram stains?
A. Gram-positive are pink because they have a thin cell wall whereas gram-negative are purple because they have a thick cell wall.
B. Gram-positive are purple because they have a thin cell wall whereas gram-negative are pink because they have a thick cell wall
C. Gram-positive are pink because they have a thick cell wall whereas gram-negative are purple because they have a thin cell wall.
D. Gram-positive are purple because they have a thick cell wall whereas gram-negative are pink because they have a thin cell wall.
D. Gram-positive are purple because they have a thick cell wall whereas gram-negative are pink because they have a thin cell wall.
What makes up the cell wall of a gram-positive bacteria?
Thick peptidoglycan cell wall
Teichoic acid (structural protein that helps anchor the cell wall)
What makes up the cell wall of a gram-negative bacteria?
Thin peptidoglycan cell wall
Outer membrane made of:
murein
lipid A
O antigen
lipopolysaccharide
How does peptidoglycan in gram-positive differ from the peptidoglycan in gram-negative?
The peptidoglycan structure has
in both:
NAG
NAM
and
Tetrapeptide
In gram-positive:
Pentapeptide
Of all the microbes, where will you find the peptidoglycan structure?
Only in bacteria
(except its absent in mycoplasma)
What is the dominant cell wall layer for archaea?
S-Layer (protein)
What cell wall structure does archaea have that is similar to peptidoglycan?
Pseudomurein (sugar)
What is peptidoglycan sensitive to?
lysozyme
Is Archaea sensitive to lysozyme?
No, they are resistant to it because they have different sugars than bacteria in their cell wall.
What is the best explanation for using beta-lactam to treat Chlamydia infection but not mycoplasma?
A. Chlamydia is an extracellular pathogen whereas mycoplasma is an intracellular pathogen
B. Chlamydia has peptidoglycan whereas peptidoglycan is absent in mycoplasma
C. Chlamydia has a metabolically inactive extracellular form whereas mycoplasma is always intracellular
D. Both lack cell walls therefore a beta-lactam cannot be used
B. Chlamydia has peptidoglycan whereas peptidoglycan is absent from mycoplasma
Can archaea have both S-layer and psuedomurein in their cell wall?
No.
They either have S-Layer or Pseduomurine but not both.
What is the cell wall in Fungi? (Eukaryotes)
Chitin
What is the cell wall in plants? (Eukaryotes)
Cellulose
Lysozymes are a defense mechanism in animals. What microbe does it target?
A. Archaua
B. Fungi
C. Viruses
D. Bacteria
D. Bacteria
because peptidoglycans are sensitive to lysozyme.
In which cell wall will you find lipopolysaccharide?
In gram-negative bacteria only
What purpose does the lipopolysaccharide layer serve?
Attachment
Mechanical Strength
Immune evasion
Protection
It is also a endotoxin
causes massive inflammation & can cause septic shock if it gets into your blood
What feature differentiates a gram-negative bacteria from a deep-branching bacteria?
A. The outer membrane is a bilayer made of lipopolysaccharide
B. The outer membrane is a bilayer similar to the inner membrane
C. The outer membrane is made of carotenoid glucoside esters with various branched-chain fatty acids
D. The outer membrane is made of mycolic acids
A. The outer membrane is a bilayer made of lipopolysaccharides
Why does gram staining not work in acid-fast bacteria?
It has a wax layer
It’s outer layer is mycolic acid
You want to use an antibiotic that targets the cell wall to treat an infection. Which group is the most resistant?
A. Acid-fast bacteria
B. Mycoplasma
C. Gram-negative bacteria
D. Gram-positive bacteria
E. Fungi
B. Mycoplasma
and
E. Fungi
If you don’t have a cell wall, you can’t kill it.
Mycoplasma will be the most resistant because it doesn’t have a cell wall.
Which structure is universally found in all cellular microbes?
A. Capsule
B. Cytoplasmic membrane
C. Nuclear membrane
D. Outer membrane
E. S-layer
B. Cytoplasmic membrane
The structure is universal but the composition is not.
What are the differences between the cell wall composition of bacteria, archaea, and eukaryotes?
Bacteria - peptidoglycan (murein)
Archaea - Protein (S-layer) or pseudomurein
Eukaryote - Chitin (fungi) or cellulose (algae)
What are the differences between the cell wall function of bacteria, archaea, and eukaryotes?
Bacteria - Cell shape & rigidity
Archaea - osmotic lysis, cell shape & rigidity
Eukaryote - Structural stability and stability
Where is the S-layer found in prokaryotes?
Bacteria - Typically the outermost layer if present
Archaea - sometimes its just outside the cytoplasm, not always the last layer
What is a capsule?
Outermost layer
Protects against the immune system
Tight matrix
Strongly attached to the cell
What is a slime layer?
Sticky polysaccharide coat
easily deformed
loosely attached to the cell
biofilm
What are Pili?
Thin, long filamentous protein structure on the bacterial surface
What are Fimbrae?
Short pili used for attachment
Which type of bacteria will you find pili and fimbrae?
Mostly in gram-negative and in some gram-positive bacteria
What is conjugative pili?
pili that forms a conduit for genetic material to pass through (Genetic exchange)
What are flagellum?
thin protein appendages that provide a quick way to move around
rotates at 1000 revolutions per second
If you have one flagellum attached at one end of the bacteria it is __________?
monotrichous
If you have one flagellum attached at each end of the bacteria it is ___________?
amphitrichous
If you have multiple flagella attached at one end of the bacteria it is ____________?
lophotrichous
If you have multiple flagella attached all over the surface of the bacteria it is __________?
peritrichous
A bacteria is described as being hairy when observed under the microscope. What is the structure?
A. Pili
B. LPS
C. Capsule
D. Flagella
A. Pili
What are the characteristics of flagellum?
hollow structure made of flagelin
driven by a proton motor force
assembles from the tip
parts include a hook and a basal body
What is an archaellum?
a structure in archaea that provides some motility
What are the characteristics of an archellum?
smaller than flagellum
not hollow
driven by ATP
Assembles from the base
What is twitching
allows bacteria and some archaea to move on harder surfaces
Stick and pull movement
ATP dependent
uses Type IV pili which extend, stick to a surface and then pull.
What is gliding?
allows bacteria to move on harder surfaces
continuous and smooth motion without external propulsion
uses glide proteins and an adhesion complex
Your bacterium moves and you did not detect a type IV pili or a flagellum. What type of motility is your bacteria most likely capable of?
A. twitching
B. swimming
C. gliding
D. Gliding, twitching, and swimming
E. no motility
C. Gliding
Type IV drive twitch
Swim by flagellum
What is meant by taxis?
sense and move
Ability to move towards or away from a gradient
What is chemotaxis
detects & moves due to a chemical gradient
What is Osmotaxis?
detects & moves due to an ionic strength gradient
What is Hydrotaxis?
detects & moves due to a hydrated environment/water
What is phototaxis?
detects & moves due to a light gradient
What is Aerotaxis?
detects & moves due to an oxygen gradient
What is Magnetotaxis?
detect & moves due to a magnetic field
You want to know if your bacterium is capable of sensing and moving in response to a hydrocarbon gradient. In a chemotaxis assay, your bacterium exhibits motility but moves in every direction. What is your best explanation?
The hydrocarbon does not induce a chemotaxis response
Are archaea capable of twitching and gliding?
No. They are only able to swim.
What does motility look like in eukarya?
Swimming
via flagellum & cilia
although it’s not the same type of structure as bacteria
it is a flexible whip made of microtubules and uses ATP as an energy source.
