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Micro BIO 220 Part 1 > Lecture 2 > Flashcards

Lecture 2 Flashcards

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Biology 101 flashcards
1
Q

What are four structures that all Bacteria possess?

A

a cell membrane
cytoplasm
ribosomes
one (or a few) chromosome(s)

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2
Q

What are three structures that most Bacteria possess?

A

a cell wall
a surface coating called a glycocalyx
Cytoskeleton (only recently appreciated)

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3
Q

Which are present in only some Bacteria?

A 
flagella, pili, and fimbriae
an outer membrane
plasmids
Inclusions, microcompartments
endospores
intracellular membranes
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4
Q

What two structures generally control the morphology of a bacterial cell?

A 
Cell wall (rigid structure)
Cytoskeleton proteins (e.g. MreB, FtsZ) offer additional shape by altering cell wall synthesis
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5
Q

What are some common morphologies of bacterial cells?

A 
Coccus(ball-shaped),
 Rod/bacillus(short,plump rod), 
Vibrio (curved)
Spirillum (short, rigid spiral)
Spriochete (longer, flexible spiral)
Filaments/filamentous (straight or branching)
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6
Q

What does pleomorphic mean?

A
  • is the ability of some bacteria to alter their shape or size in response to environmental conditions
  • this can be caused by variations in cell wall structure
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7
Q

How does the general conservation of cell morphology and arrangement within a given species or group of microbes aid microbiologists in the study of microbes?

A

the morphology and arrangement of cells by microscopic observation is often a useful characteristic to help identify different types of bacteria.

-The number and orientation of division planes in cocci is often conserved.

Morphology is also generally conserved within a given species.

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8
Q

What is the major function of bacterial flagella?

A
  • Allows swimming motility

* note Bacterial (and archaeal) flagella are NOT similar in form to eukaryotic flagella

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9
Q

What energy source is used to power flagellar rotation?

A

Powered by proton motive force

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10
Q

Extra infromation about bacterial flagella?

A

360o rotation

Direction of rotation (CW vs. CCW) determines the direction of cell movement

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11
Q

What are four different types of flagellar arrangement on the cell?

A

Monotrichous: single flagellum
Lophotrichous: small bunches or tufts of flagella
Amphitrichous: flagella at both poles of the cell
Peritrichous: flagella dispersed randomly over the surface of the cell

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12
Q

What is chemotaxis?

A

Bacteria move in response to chemical signals

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13
Q

What are some examples of other types of taxes (plural of taxis)?

A

Positive chemotaxis: movement toward a stimulant

Negative chemotaxis: movement away from a repellant

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14
Q

Explain positive chemotaxis:

A

movement toward a stimulant

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15
Q

Explain negative chemotaxis

A

movement away from a repellant

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16
Q

Which direction of flagellar rotation (CCW or CW) results in “running”, and which results in “tumbling”?

A
  • CCW flagellar rotation results in FORWARD movement of the cell
  • Flagellar rotation reverses (CS), causes the cell to STOP and “tumble”, resulting an a change in orientation course
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17
Q

flagellar rotation, running relates to

A

CCW flagella rotation

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18
Q

How can the relative balance of running vs. tumbling result in chemotaxis toward an attractant?

A

SLIDE 23, Lecture 2 PPT Ask ???

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19
Q

How do the structure (i.e. number/cell and length) and functions of pili and fimbriae compare?

A

fimbraie is short compared to pili(Involved in attachment and adherence to surfaces
) , there is a lot of fimbaie compared to pili

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20
Q

Which of these structures can be involved in twitching motility and DNA exchange by conjugation? (pili or fimbriae?

A

Pili, Can retract and extent

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21
Q

What are two major types of glycocalyx, and what is the major macromolecular component of glycocalyx?

A

-Slime layer and Capsule

It is composed of polysaccharides, proteins or both

22
Q

What are some similarities between capsules and slime layers?

A
  • can be used for adhesion and biofilm formation
  • also, as a protective layer that can allow resistance to antibiotics and desiccation (drying out)
  • protection from phagocytosis by immune cells.
23
Q

What role does glycocalyx play in biofilm formation?

A

As cells divide, they form a dense mat bound together by sticky extracellular deposits.

24
Q

What are some differences between capsules and slime layers?

A
  • Varies in thickness and strength
  • Slime layers usually extend farther away from the cell, but are more loosely attached
  • Capsules are more tightly attached to the cell
25
Q

What is the major macromolecular component of the S layer, and what are two functions of this structure?

A

-Composed of a crystalline layer of thousands of copies of a single type of protein

26
Q

What are two functions of this structure of the S layer?

A
  • Extra protective coating found outside of the peptidoglycan cell wall in some Bacteria and Archaea
  • Can aid in attachment to surfaces, e.g. attachment to host cells in some pathogenic bacteria
27
Q

What are the two major components of peptidoglycan?

A

Sugars and amino acids

28
Q

What structure in Bacteria is made of peptidoglycan, and what are two important functions of peptidoglycan?

A

The Cell Wall, important functions: Provides strength to resist rupturing due to osmotic pressure, Important in conferring cell shape

29
Q

How does peptidoglycan thickness compare in Gram positive and Gram negative Bacteria?

A 
Gram positive bacteria
Thick cell wall
No outer membrane
// Gram negative bacteria
Thin cell wall
presence of an outer membrane
30
Q

What are some major differences in the cell envelope composition between Gram positive and Gram negative Bacteria?

A

Gram positive is thick, gram negative is thin.
Gram positive is cytoplasmic membrane only.
Gram negative: Two membranes…
Cytoplasmic membrane similar to Gram positives
Outer or periplasmic membrane

31
Q

What are some important characteristics of Gram Positive Cell?

A

Relatively thick (20-80 nm); many layers of interconnected peptidoglycan
Teichoic acid, lipoteichoic acid help maintain structure and negative charge
Cytoplasmic membrane only
No outer membrane
No periplasmic space

32
Q

What are some important characteristics of Gram negative cell?

A

Thin (1-3 nm) peptidoglycan cell wall
Two membranes…
Cytoplasmic membrane similar to Gram positives
Outer or periplasmic membrane

33
Q

What are some similarities between gram negative & positive?

A

??? there is still a plasma membrane and there is still a lipid bilayer that contains proteins, theres still layer of pepidglocan

34
Q

Be able to identify structures in G+ and G- cell envelopes shown in Figure 3.15 in the textbook.

A

gross

35
Q

What are four steps in the Gram stain procedure, and what types of Bacteria does this stain differentiate?

A
  1. crystal violet-it stains them all the same purple color
  2. gram’s iodine
  3. alcohol
  4. safranin (red dye)
36
Q

Be able to deduce what the result of a Gram stain would be if one of the procedures were omitted (e.g. what would happen if the iodine, alcohol wash, or safranin counterstain step were omitted)?

A

???

slide 34

37
Q

What is a major component of the cell wall of acid-fast bacteria, and what sort of cell envelope structure do acid-fast bacteria have (similar to G+ or G-)?

A

A major component of the cell wall of acid-fast bacteria is mycolic acid.

what sort of cell envelope structure do acid-fast bacteria have (similar to G+ or G-)???

38
Q

What is a component of the cytoplasmic membrane in bacteria such as Mycoplasma spp. that lack a cell wall, and what role does this component play? ASK

A

Mycoplasma is a genus of bacteria that lack a cell wall around their cell membrane. Without a cell wall, they are unaffected by many common antibiotics such as penicillin or other beta-lactam antibiotics that target cell wall synthesis. They can be parasitic or saprotrophic.

39
Q

What are the two major components of the cytoplasmic (or cell) membrane?

A

A phospholipid bilayer with proteins embedded, bacterial cell membranes contain primarily phospholipids (30%–40% of the membrane mass) and proteins (60%–70% of the membrane mass)

40
Q

What are some important roles of the cytoplasmic membrane?

A

-Provides a site for reactions
Contains enzymes of respiration and ATP synthesis, since prokaryotes lack mitochondria
-A major action of the cell membrane is to regulate the passage of nutrients into and out of the cell
-A selectively permeable barrier…
Water and small non-polar molecules can pass through
But not polar/charged molecules, even H+
Embedded proteins in the membrane mediate transport of specific molecules

41
Q

What are the relative permeabilities of the cell wall, cytoplasmic membrane, and periplasmic (or outer) membrane?
How might this play a role in differences in antibiotic or disinfectant resistance between Gram positive and Gram negative Bacteria?

A

Cell wall is the most permeable
Outer membrane is less permeable than the cell wall
Cytoplasmic membrane is the least permeable of the three
Transport is highly regulated

42
Q

What component of the bacterial cell envelope can act as an endotoxin, and in what structure and type of bacteria is this component found?

A
  • lipid A portion of LPS can be toxic to animals
  • found in the Periplasmic membrane of the cell
  • gram negative?
43
Q

What are two typical characteristics of the bacterial chromosome, and how do these compare to eukaryotic chromosomes?

A

single, circular

44
Q

• What is a similarity and difference between bacterial and eukaryotic cytoskeleton?

A
  • Cytoskeleton consists of fibers composed of actin- and tubulin-like proteins that alter cell shape and play important roles in cell division
  • Prokaryotic cytoskeleton is much less complex than eukaryotic cytoskeleton, although some component proteins are distantly related
45
Q

• What are inclusion bodies and microcompartments, and what roles do they play in Bacteria?

A

Inclusion bodies:
Non-membrane bound granules
Often used for storage of nutrients for later use, Magnetotatic bacteria have chains of magnetite crystals
Bacterial microcompartments: Found in a variety of Bacteria
Outer protein shell that contains specific enzymes that work together in a given metabolic pathway

46
Q

• What are endospores and in which genera and type (G+ or G-) of bacteria are these structures found?

A

found in gram +
-Cortex and spore coat protect against radiation and chemicals
-Metabolically active vegetative cells undergo process of sporulation to form spores
Typically in response to poor conditions for growth
-Dormant bodies that are more resistant than vegetative cells
Heat resistance due to calcium and dipicolinic acid contentDormant bodies that are more resistant than vegetative cells
Heat resistance due to calcium and dipicolinic acid content

47
Q

• What are some stresses that endospores can withstand, and how does this compare to vegetative cells?

A

because they are Dormant bodies that are more resistant than vegetative cells
:Heat resistance due to calcium and dipicolinic acid content
Resistance to radiation, freezing, and desiccation
Spores are already in a dehydrated state
Increased resistance to a variety of chemicals
Not affected by many antibiotics due to their dormant state

48
Q

Under what conditions are endospores formed? Is endospore formation and germination generally a reproductive process? Why or why not?

A

Typically in response to poor conditions for growth
e.g. substrate limitation
Spores germinate to reform vegetative cells when environmental conditions improve
NO not a reproductive process, Sporulation is not a reproductive function for most bacteria
One spore typically germinates to form one cell

49
Q

Why are Archaea not covered much in this course and textbook?

A

Prokaryotic (no nucleus) like Bacteria
Once thought to be restricted to “extreme” environments
Now known to be more widespread

50
Q

Know the steps of the Gram?

A

gram steps?

Micro BIO 220 Part 1 (18 decks)

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