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Flashcards in lecture 1.6 Deck (44):
1

What are the different types of motility?

Flagellar movement
Spirochete motility
Twitching motility
Gliding motility

2

Chemotaxis=

move toward chemical attractants such as nutrients, and away from harmful substances or environments

3

Why would Bacteria/Archaea move in regards to chemotaxis?

Move in response to temperature, light, oxygen, osmotic pressure, and gravity
Changing concentrations of chemical attractants and chemical repellents bind chemoreceptors of chemosensing system

4

Describe Flagellar movement

very rapid rotation up to 1100 revolutions/sec
in general, counterclockwise (CCW) rotation causes forward motion (run)
in general, clockwise rotation (CW) disrupts run causing cell to stop and tumble

5

How fast does a flagellum rotate?

up to 1100 revolutions/sec

6

What does counterclockwise rotation cause in flagellum?

forward motion (run)

7

What does clockwise rotation cause in flagellum?

disrupts run causing cell to stop and tumble

8

look at movement of flagellum mechanism

See notes at home

9

Describe spirochete motility

Multiple flagella form axial fibril which winds around the cell
Flagella remain in periplasmic space inside outer sheath
Corkscrew shape exhibits flexing and spinning movements

10

Describe twitching

pili at ends of cell
short, intermittent, jerky motions
cells are in contact with each other and surface

11

Describe gliding

pili at ends of cell
smooth movements
cells are in contact with each other and surface

12

What happens , in regards to chemotaxis movement, in the presence of an attractant?

tumbling frequency is intermittently reduced and runs in direction of attractant are longer
(it is the opposite response if there is a repellent)

13

Biased Random Walk=

a random walk/series of motions with the goal of getting somewhere, but is random in the movement of how and when it will get there

14

What is a bacterial Endospore?

Complex, dormant structure formed by some bacteria
Various locations within the cell
Resistant to numerous environmental conditions

15

What are some of the enviromental conditions that an endospore is resistant to?

heat
radiation
chemicals
desiccation

16

Describe the endospore structure

Spore surrounded by thin covering called exosporium
Thick layers of protein form the spore coat
Cortex, beneath the coat, thick peptidoglycan
Core has nucleoid and ribosomes

17

exosporium=

thin covering surrounding the spore in an endospore

18

What makes an endospore so resistant?

Calcium (complexed with dipicolinic acid)
Small, acid-soluble, DNA-binding proteins (SASPs)
Dehydrated core
Spore coat and exosporium protect

19

sporulation=

process of endospore formation

20

Describe the process of sporulation

Occurs in a hours (up to 10 hours)
Normally commences when growth ceases because of lack of nutrients
Complex multistage process

21

What are the three stages of formation for a vegatative cell?

activation
germination
outgrowth

22

Describe the stage of activation in the formation of a vegetative cell

prepares spores for germination
often results from treatments like heating

23

Describe the stage of Germination in the formation of a vegetative cell

environmental nutrients are detected
spore swelling and rupture of absorption of spore coat
increased metabolic activity

24

Describe the stage of outgrowth in the formation of a vegetative cell

emergence of vegetative cell

25

What is common between Archaea and Eukarya

genes encoding proteins for DNA replication, transcription, translation

26

What is common between Archaea and Bacteria

genes for metabolism
have multi-genic operons

27

What is unique to Archaea?

unique rRNA gene structure
some are capable of methanogenesis

28

What are Archaea best known for?

growth in anaerobic, hypersaline, pH extremes, and high-temperature habitats (Also found in marine arctic temperature and tropical waters)

29

What are the common shapes of Archaea?

cocci, rods, branched/flat shapes

30

What shapes can Archaea not form?

no spirochetes or mycelial forms yet

31

How are Archaeal Cell walls different from Bacteria?

S layer may be only component outside plasma membrane
some lack cell wall
capsules and slime layers are rare

32

Describe the lipids used in archaeal membranes

isoprene units (five carbon, branched)
ether linkages rather than ester linkages to glycerol

33

Do all archaea have a bilayer structured cell memrane?

No, some are monolayer

34

Describe Bacterial/Eukaryotic lipds

Contain fatty acids in ester linkages to glycerol

35

Describe Archaeal lipids

Contain hydrocarbons derived from isoprene in ether linkages to glycerolw

36

Describe the differences between Bacterial/Eukaryotic lipids and Archaeal lipids

Bacterial have fatty acids and ester linkages
Achaeal contain hydrocarbons derived from isoprene and ether linkages

37

Describe archaeal cell envelopes

varied S layers attached to plasma membrane
pseudomurein (peptidoglycan-like polymer)
complex polysaccharides, proteins, or glycoproteins found in some other species

38

How do archeal cell walls differ from bacterial call walls?

Lack peptidoglycan
Most common cell wall is S layer
May have protein sheath external to S layer
S layer may be outside membrane and separated by pseudomurein
Pseudomurein may be outermost layer – similar to Gram-positive microorganisms

39

pseudormurein

peptidoglycan-like polymer
may be outermost layer – similar to Gram-positive microorganisms
S layer may be outside membrane and separated by pseudomurein

40

Describe the archaeal ribosome

bacterial/archaeal ribosome = 70S
16S small subunit, 23S and 5S in large subunit and 5.8S
more similar to eukarya than bacteria

41

Describe archaeal pili

not well understood as of yet
some composed of pilin protein and homologous to bacterial type IV pili proteins

42

What is the archaeal pili structure like?

pili formed have a central lumen similar to bacterial flagella, but not bacterial pili

43

What is archaeal pili used for?

may be involved in archaeal adhesion mechanisms

44

What are the differences of Archaeal Flagella to Bacterial Flagella

thinner
Flagellum are not hollow
Hook and basal body difficult to distinguish
Growth occurs at the base, not the end