MB 351 - Lectures 9, 10, 11

Question 1

Atypical Cell Walls: -waxy lipid bound to peptidoglycan -what is this waxy lipid? and what kind of bacteria have this?

Answer 1

-Acid fast cell wall type -waxy lipid is mycolic acid -prevents the uptake of most dyes -mycobacterium and nocardia

Question 2

Most bacteria are either….think type of cell wall

Answer 2

gram negative or gram positive

Question 3

Atypical Cell Walls: -Lack cell walls

Answer 3

Mycoplasmas and Archaea

Question 4

Mycoplasmas

Answer 4

-lack cell walls -sterols in plasma membrane (lipids that protect from lysis)

Question 5

Archaea

Answer 5

-Wall-less or -Walls of pseudomurein (lack NAM and D-amino acids)

Question 6

Why do microorganisms move, and what is the movement called?

Answer 6

Tactic (taxis) response behavior -looking for nutrients (C&N) -avoiding predators -catching prey

Question 7

Stimuli that microbes move in response to: three of them

Answer 7

aerotaxis - move towards oxygen concentration phototaxis - photon intensity chemotaxis - chemicals that attract or repel microbes

Question 8

Peritrichous

Answer 8

flagella all over cell

Question 9

monotrichous and polar

Answer 9

single flagella

Question 10

lophotrichous and polar

Answer 10

a tuft of flagella coming from one pole

Question 11

amphitrichous and polar

Answer 11

flagella on both poles of the cell

Question 12

Various patterns of motility: RUNS

Answer 12

a run or swim is when a bacterium moves in one direction for a length of time. Runes are interrupted by tumbles. Then a run resumes. Tumbles are caused by reversal of the flagellar rotation

Question 13

Some bacteria with polar flagella will have reversible motors that allow them to move forward when it turns ______ and backwards when it goes ______.

Answer 13

CCW, CW -some are incapable of this, and may only travel in one direction (only CW flagella = unidirectional). They must stop, reorient in order to change directions

Question 14

Flagella (gram -) three basic parts

Answer 14

-filament made of flagellin proteins -wider hook -basal body, which anchors the flagellum to the cell wall and plasma membrane

Question 15

The basal body contains a small central rod inserted into a series of rings. What are these rings and where are they located?

Answer 15

-L ring is embedded in the OM and LPS -P ring is in the peptidoglycan -MS and C rings are embedded in the cytoplasmic membrane

Question 16

Which proteins function as the flagellar motor?

Answer 16

Mot proteins (bound to MS and C ring)

Question 17

Fli proteins function as?

Answer 17

function as the motor switch

Question 18

A __________ model has been proposed to explain rotation of flagellum.

Answer 18

proton turbine. Protons flowing thru the Mot proteins may exert forces on charges present on the C and MS rings, thereby spinning the rotor and the attached filament. 20,000 rpm

Question 19

-occur at the poles or can be evenly distributed over surface of cell -hairlike appendages that are shorter, straighter, and thinner than flagella -tend to adhere to each other and to surfaces, as a result, they are involved in forming _______

Answer 19

Fimbriae - also help bacteria to adhere to epithelial surfaces in the body biofilms

Question 20

Pili

Answer 20

-usually longer than fimbriae and number fewer only 1-2 per cell -Pili are involved in DNA transfer – connect two cells for the exchange of genetic material -also aid in the attachment to host cells during infection

Question 21

Pili involved in this kind of motility ________ and _________

Answer 21

-Twitching motility a special “type IV” pilus extends by the addition of subunits of pilin, makes contact with a surface and then retracts as the pilin subunits are disassembled. -called GRAPPLING HOOK MODEL (short, jerky, intermittent movements) -GLIDING motility - a smooth gliding movement of myxobacteria. Provides a means for microbes to travel in environments with low water content, such as biofilms and soil.

Question 22

Prokaryotic cells lack: Also, cytoskeleton proteins are _______ to eukaryotes.

Answer 22

nucleus, no carbohydrates and usually lack sterols in their plasma membrane -Sterols are essential in all eukaryotic cell membranes. They modulate membrane fluidity and permeability. Sterols and carbs serve as receptors present in eukaryotes. SIMILAR

Question 23

Plasma membrane contains

Answer 23

phospholipid bilayer with lipid-soluble proteins

Question 24

Due to lack of ________ in the plasma membrane of prokaryotes, they are less rigid than eukaryotic membranes.

Answer 24

sterols

Question 25

Phospholipid molecules contain:

Answer 25

polar head made of phosphate and glycerol that is hydrophilic (soluble in water), and nonpolar tails composed of fatty acids that are hydrophobic (insoluble in water)

Question 26

Fluid mosaic model

Answer 26

phospholipids and proteins (reception and transport proteins) are not static, but move quite freely

Question 27

Functions of the plasma membrane: three things

Answer 27

selective permeability, protein anchor, energy generating/conservation

Question 28

Selective permeability

Answer 28

Most important function of the cell membrane is to serve as a selective barrier through which materials enter and exit the cell. Only certain molecules and ions can pass through the membrane. This function allows the cell to concentrate certain metabolites and excrete waste materials.

Question 29

Protein anchor

Answer 29

Plasma membrane serves as the protein anchor, some proteins anchor together different layers of the cell envelope providing structure support. (Carrier proteins). Anchors for enzymes (ATP production, transport proteins).

Question 30

Energy conservation

Answer 30

microbial energy generating processes involve the generation of a PROTON MOTIVE FORCE (PMF) where protons are selectively moved across the membrane.

Question 31

Membrane Permeability Chart

Answer 31

Question 32

Enzymes made within the cell, then released outside of the cell to begin the process of extracellular digestion. Used since large macromolecules cannot normally pass through the cell. These _______ can be classified on the basis of what kinds of molecules they hydrolyze:

Answer 32

Exoenzymes

hydrolyze: carbohydrates, lipids, proteins, nucleic acids
ex. amylase hydrolyzes starch into mono- and dissacharide subunits. Iodine binds to starch, but not to its breakdown products (clear streak)