Lecture 5 Flagella

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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

PROCESS WHEN MCP not bound by attractant-STEP 2

-CheA/CheW is active (phosphorylated)

PROCESS WHEN MCP not bound by attractant-STEP 3

-CheY is active -diffuses to flagellar motor and switches to clockwise (CW) rotation -tumbling occurs -concentration of attractant is measured every few seconds (receptors reset)

DESCRIPTION OF Bacterial Endospore

-Complex, dormant structure formed by some bacteria -Various locations within the cell

PROCESS WHEN MCP not bound by attractant-STEP 1

-MCP is methylated (CheR)

Twitching and Gliding Motility

-May involve Type IV pili and slime

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

Sporulation DESCRIPTION

-Process of endospore formation -Occurs in a hours (up to 10 hours) -Normally commences when growth ceases because of lack of nutrients or presence of harmful substances. -Complex multistage process

DESCRIPTION OF GLIDING

-SMOOTH MOVEMENTS

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

Bacterial Flagella DESCRIPTION

-Thin, rigid protein structures -composed of three parts -Pattern of flagellation varies

FUNCTION OF MCPs

-binds environmental chemicals -initiates a series of interactions with cytoplasmic proteins that affects flagellar rotation

Flagellar Synthesis

-complex involving many genes/gene products -new flagellin transported through the hollow filament using Type III-like secretion system -filament subunits self-assemble with help of filament cap at tip, not base

Formation of Vegetative Cell-GERMINATION STEP

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

DESCRIBE THE FILAMENT

-extends from cell surface to the tip -hollow, rigid cylinder of flagellin protein -acts as a syringe to inject its protein into another cell

FLAGELLA FUNCTIONS

-motility and swarming behavior -attachment to surfaces -may be virulence factors

DEFINITION OF CHEMOTAXIS

-move toward chemical attractants such as nutrients -away from harmful substances

DESCRIPTION OF TWITCHING MOTILITY

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

Formation of Vegetative Cell-ACTIVATION STEP

-prepares spores for germination -often results from treatments like heating

FORMS OF DNA

A FORM B FORM Z FORM

WHAT DO FLAGELLA NEED TO DO IN ORDER TO REPLICATE?

ATTACH

Regulated by a two-component signal transduction pathway

Activates sensor kinase CheA (with help of CheW) which autophosphorylates -CheA phosphorylates the response regulator CheY

WHAT FORM OF BACTERIA ARE FLAGELLA USUALLY FOUND ON?

BACILLI

HOW CHEMOTAXIS WORKS

Changing concentrations of chemical attractants and chemical repellents bind chemoreceptors of chemosensing system

MCP bound by attractant-STEP 2

CheA is inactive (not phosphorylated) -CheY is inactive -flagellar rotation is counter- clockwise (CCW) and running o occurs

BEHAVIOR IN PRESENCE OF REPELLENT

Chemotaxis away from repellent involves similar but opposite responses

NAME Three Parts of Flagella

FILAMENT HOOK BASAL BODY

TYPES OF Motility

Flagellar movement Spirochete motility Twitching motility Gliding motility

Mechanism of Flagellar Movement

Flagellum is 2 part motor producing torque Rotor -C (FliG protein) ring and MS ring turn and interact with stator Stator - Mot A and Mot B proteins -form channel through plasma membrane -protons move through Mot A and Mot B channels using energy of proton motive force -torque powers rotation of the basal body and filament

Bacterial Flagellar Movement

Flagellum rotates like a propeller very rapid rotation up to 1100 revolutions/sec -counterclockwise (CCW) rotation -causes forward motion (run) -clockwise rotation (CW) disrupts run causing cell to stop and tumble

WHAT TO FLAGELLA STIMULATE IN THE BODY?

IMMUNE RESPONSE

DESCRIBE THE HOOK

LINKS FILAMENT TO BASAL BODY -THIS PORTION BUILDS UP FIRST

MCP bound by attractant-STEP 1

MCP is not methylated (CheB)

DEFINITION OF Chemotaxis

Movement toward a chemical attractant or away from a chemical repellent

WHAT GOVERNS ROTATION OF FLAGELLA

Response regulator CheY governs rotation of flagella

DESCRIBE THE BASAL BODY

SERIES OF RINGS THAT DRIVE FLAGELLAR MOTOR

WHY DOES IT STIMULATE AN IMMUNE RESPONSE?

TO BE TAKEN UP BY MACROPHAGES

FLAGELLA DESCRIPTION

Threadlike, locomotor appendages extending outward from plasma membrane and cell wall

CAN FLAGELLA LIVE IN MACROPHAGES?

YES!

DEFINITION OF Methyl-accepting chemotaxis proteins (MCPs)

chemoreceptors in membrane

Formation of Vegetative Cell-OUTGROWTH STEP

emergence of vegetative cell

ENDOSPORE Resistant to numerous environmental conditions

heat radiation chemicals desiccation

MCP bound by attractant-STEP 3

regulatory system allows E. coli to respond to and adapt to very small amounts of attractant

WHO DOES CheA phosporylate

response regulator CheY

TYPES OF STIMULANT FOR CHEMOTAXIS

temperature light oxygen osmotic pressure gravity

BEHAVIOR IN PRESENCE OF ATTRACTANT

tumbling frequency is intermittently reduced and runs in direction of attractant are longer -Behavior of bacterium is altered by temporal concentration of chemical


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