lecture 3 bacteria 2

Question 1

what are glycocalyces

Answer 1

umbrella name for other structures that have a similar function like capsule and slime

Question 2

describe the features of capsules

Answer 2

Tightly attached, tight matrix; visible if treated with India ink

Question 3

describe the structure and functions of the slime layer

Answer 3

• loosely attached, easily deformed (e.g., Leuconostoc)
• assist in attachment to surfaces
• role in development and maintenance of biofilms
• virulence factors: protect against phagocytosis
• prevent dehydration/desiccation

Question 4

what are the similarities between capsules and slime layer

Answer 4

• both are sugars, capsule is more structured and tighter, whereas slime is more soft loose and less well defined
• both protective and adhere to different surfaces which can help the bacteria

Question 5

what is the s-layer and where is it found. what does it help the cell with

Answer 5

an additional protective layer commonly found in free-living Gram positive and Gram negative bacteria and archaea

may contribute to cell shape and help protect the cell from osmotic stress

Question 6

what is the s-layer composed of

Answer 6

crystalline layer of thick subunits consisting of protein or glycoprotein

Question 7

what are fimbriae and pili

Answer 7

filamentous protein structures ~2-10 nm wide

Question 8

what is the function of fimbriae

Answer 8

Fimbriae enable organisms to stick to surfaces or form pellicles (thin sheets of cells on a liquid surface).

Question 9

name the two types of pili and what they do

Answer 9

conjugative/sex pili facilitate genetic exchange between cells (conjugation).

type IV pili adhere to host tissues and support twitching motility (e.g., Pseudomonas and Moraxella).

Question 10

how many fimbriae are found per cell, how many pili are found

Answer 10

many fimbriae, only 1/a few pili

Question 11

what are 9 structural features of the cytoplasm . which are the 3 not usually found in eukaryotes

Answer 11

1. nucleoid
2. extra chromosomal dna
3. enzymes
4. regulatory factors
5. ribosomes
6. cell inclusions
7. gas vesicles
8. magnetosomes
9. cytoskeleton

7,8,9

Question 12

what kind of shape does FtsZ give the cell

Answer 12

spherical

Question 13

what shape does MreB give the cell

Answer 13

rod

Question 14

what shape does crescentin give the cell

Answer 14

virbroid shape

Question 15

what is the ParM protein and how does it help chromosomes divide

Answer 15

at the origin of replication, theres a protein called Par, binds on to origin, as chromosome divides, the two proteins are dragged to poles of cells. doing that bc between it is a build of cytoskeletal protein, and pushes the two proteins that are bound to the origin to the poles of cells, thereby segregating them to split them up

Question 16

do bacteria undergo mitosis and meiosis

Answer 16

no

Question 17

how do bacteria cells divide and what does it require

Answer 17

through fission

bacterial cell division, or fission, requires highly coordinated growth and formation of all the cell’s parts

Question 18

what is the bacterial DNA replication coordinated with

Answer 18

bacterial DNA replication is coordinated with the cell wall expansion and ultimately the separation of the two daughter cells

Question 19

explain how the process of septation works. what does it form?

Answer 19

as DNA synthesis terminates, the cell divides by a process called septation, the formation of the septum

the septum grows inward from the sides of the cell, at last constricting and sealing off the two daughter cells

Question 20

how does FtsZ direct septal growth in the bacterial cell

Answer 20

FtsZ subunit assembly circles around the septum in a treadmilling pattern, stepwise around the cell, that directs septal growth

Question 21

what does septation require? what is it managed by

Answer 21

Septation requires rapid biosynthesis of all envelope components, including membranes and cell wall.

the overall process of septation is managed by a protein complex called the divisome

Question 22

what is the difference in dna organization between eukaryotic and prokaryotic cells

Answer 22

Eukaryotic cells have a well-defined nucleus delimited by a nuclear membrane

prokaryotic cells have a nucleoid region that extends throughout the cytoplasm and is not enclosed by a membrane

Question 23

what is dna attached to in bacterial cells

Answer 23

in most bacterial species, the DNA is attached to the envelope at the origin of replication, on the cell’s equator

Question 24

explain how translation is prokaryotes is coupled to transcription

Answer 24

the ribosomes bind to mRNA and begin translation even before the transcription of the mRNA strand is complete

Question 25

explain the four steps of cell division in bacterial cells

Answer 25

1. in prokaryotes, a circular chromosome begins to replicate at its origin, or ori site 2. two replication forks are generated, which proceed outward in both directions. at each fork, DNA is synthesized by DNA polymerase, with the help of accessory proteins, this protein complex is called the replisome. 3. as the termination site is replicated, the two forks separate from the DNA 4. completion of replication triggers Z-ring formation

Question 26

what is the name of the protein complex that helps synthesize dna in bacterial cells

Answer 26

replisome

Question 27

how do bacterial cells efficiently divide

Answer 27

it starts to replicate again, before it divides in the 4th picture. so this happens if the bacteria is in a nutrient rich environment, its an efficient system to divide rapidly. they havent finished replicating the whole genome buy they have already started a new replication.

Question 28

what are the two types of daughter cells bacteria can generate

Answer 28

some bacteria generate two kinds of daughter cells: one stationary (sessile) and one mobile (swarmer)

Question 29

what form does the cell have to be in to divide? how can a swarmer cell divide?

Answer 29

in order to be able to divide, this cell has to be in the sessile form. swimmers can go to good areas to divide, ditch its flag, grow a stalk, stick itself to a surface, then on the top side of the bacteria it will grow a whole new cell that is a swarmer cell (with a flagella)

Question 30

what is polar agining increased by

Answer 30

stress

Question 31

what is a major form of asymmetrical growth

Answer 31

endospore formation

Question 32

what does the process of cell division determine about the poles in bacteria

Answer 32

the actual process of cell division itself determines that the poles of each daughter cell differ chemically from each other

Question 33

what are the 3 functions of vesicles

Answer 33

- attractors of partner hetertrophs - phage decoys - vehicles for DNA transfer

Question 34

what are contained in the membrane vesicles that microbial cells export

Answer 34

surprisingly, isolated microbial cells continually export bits of cytoplasm in membrane vesicles. these carry proteins and nucleic acids

Question 35

what are nanotubes? what do they allow for

Answer 35

nanotube have cell membrane that connects two cells. allows for cells to contain protein and mra, a way to exchange information between the two these nanotubes allow bacteria to directly share proteins and mRNA useful under hostile conditions, such as when exposed to antibiotics

Question 36

what are thylakoids

Answer 36

thylakoids: extensively folded intracellular membranes found in photosynthetic bacteria

Question 37

what are carboxysomes

Answer 37

carboxysomes: polyhedral bodies packed with the enzyme Rubisco for CO2 fixation

Question 38

what are gas vesicles

Answer 38

Gas vesicles: protein-bound gas-filled structures that increase buoyance

Question 39

what are magnetosomes

Answer 39

allow bacteria to orient themselves across a magnetic gradient

Question 40

what is an inclusion body and what is their function

Answer 40

inclusion bodies come out of the bacteria is because their are being produced in too high volumes inclusions function as energy reserves, carbon reservoirs, and/or have special functions

Question 41

what are inclusion bodies enclosed by, what do they reduce

Answer 41

thin membrane, osmotic stress

Question 42

what kind of storage polymers do cell inclusions have

Answer 42

glycogen: glucose polymer poly-β-hydroxybutyric acid (PHB): lipid polymer, stored as lipid droplets

Question 43

what are the 4 arrangements of flagella in bacteria

Answer 43

polar, lophotrichous, amphitrichous, peritrichous

Question 44

describe the structure of flagella

Answer 44

helical in shape consists of several components filament composed of flagellin increase or decrease rotational speed relative to strength of proton motive force

Question 45

what does ccw rotation of the flagella result in? what is this movement called? what is it caused by?

Answer 45

- CCW rotation - flagella bundle together - push cell forward - “run”

Question 46

what does cw rotation of the flagella result in? what is this movement called? what is it caused by?

Answer 46

- repellents (or absence of attractants) cause CW rotation - flagellar bundle falls apart - “tumble” - bacterium briefly stops, then changes directions

Question 47

what is a biased random walk

Answer 47

biased random walk is when you are moving towards a signal

Question 48

what is a random walk

Answer 48

random walk is when they are moving not with a signal and not towards a attractant

Question 49

what are the 5 types of taxis

Answer 49

- chemotaxis: response to chemicals - phototaxis: response to light - aerotaxis: response to oxygen - osmotaxis: response to ionic strngth - hydrotaxis: response to water

Question 50

what does an endospore do?

Answer 50

endospores essentially protect the bacterial genome in a dormant state when environmental conditions are unfavorable

Question 51

what are 4 characteristics of endospores

Answer 51

1. resistant to extreme temperatures and radiation 2. do not absorb gram stain, only special endospore stains 3. dehydrated; no metabolic activity 4. dormant; no growth or metabolic activity

Question 52

what are 5 structural features of an endospore

Answer 52

- many layers: exosporium (outermost), spore coats, cortex, core wall - contains dipicolinic acid and is enriched in Ca2+ both form the calcium-dipicolinic acid (DPA) complex - DPA complex help the cells to cope with dehydration and stabilize DNAdehydration and stabilize DNA - Core contains small acid-soluble spore proteins (SASP), which bind and protect DNA and function as carbon and energy source for outgrowth. - Core also contains the cytoplasmic membrane, cytoplasm, ribosomes and other cellular essentials.

Question 53

when are endospores formed

Answer 53

Formed during endosporulation or sporulation

Question 54

where are endospore present? where are they not present?

Answer 54

Present only in some gram-positive bacteria, (e.g., Bacillus and Clostridium), none in archaea, suggesting this process evolved in bacteria after split.

Question 55

what kind of dispersal are endospores ideal for?

Answer 55

Ideal for dispersal via wind, water, or animal gut

Question 56

name the 6 steps from dna from forming to releasing an endospore

Answer 56

1. dna replicates 2. membranes form around the dna 3. forespore forms additional membranes 4. protective cortex forms around the spore 5. protein coat forms around the cortex 6. spore is released.