Part II Flashcards
The cell membrane has a very broad range of _________ activities and is ________________
physiological; selectively permeable
The plasma membrane serves as a barrier to _________, _____ ______, and _______
sugars, amino acids, salts
What two things pass freely across the cell membrane?
water and gases
The cell membrane is permeable to all ______ - __________ molecules
water soluble
Most solutes must be brought into the cell through ___________
transporters
What two ions cannot pass through the cell membrane freely?
H+ and OH-
A ________ membrane is required for all living cells and ensures the directional flow of ____
charged; ions
The cell membrane is actively involved in _________ ________ by active transport process
importing solutes
True or False
The cell membrane is not actively involved in generating energy
False
True or False
The cell membrane is actively involved in exporting proteins for construction of molecular structures outside of the plasma membrane
True
True or False
The cell membrane is actively involved in exporting polysaccharides for capsule formation
True
The cell membrane is involved in processing signals across the membrane. This is needed for ______ _________, __________________, and synthesizing _______ factors
quorum sensing, chemiluminescence, virulence
The cell membrane responds to _________ changes to promote changes in lipids in order to maintain proper characteristics of cell
temperature
The cell membrane transports precursor molecules for the construction of _______________ and _________________
peptidoglycan; lipopolysaccharide (LPS)
True or False
The cell membrane does not participate in cell division
False. The cell membrane interacts with DNA to influence DNA replication
The cell membrane consists primarily __________ and proteins in a ______ __________
phospholipids; fluid mosaic
Membrane lipids account for __ to ___ of the total dry weight of BACTERIAL CELLS
2- 10%
Membrane lipids account for ___ to ___ of the total dry weight of PLASMA MEMBRANE
20- 40%
What are the three categories of lipids in the cell membrane?
Neutral lipids
Lipoconjugate
Polar lipids
Neutral lipids: free _____ _____ and ______ esters
fatty acids; sterol
Lipoconjugate: contains lipid plus ___________ ; ______________
polysaccharides (or proteins) ; Amphiphilic
What does amphipathic mean?
containing both hydrophobic and hydrophilic parts
Polar lipids consists of ________ and ___________
phospholipids; glycolipids
True or False
Phospholipids are the predominant form of lipid found in bacterial membranes
True
_______ serves as a backbone to support attachment of fatty acids, alcohols, or phosphates
Glycerol
Fatty acids are bound to a C-1 or C-2 position of _______
glycerol
True or False
The fatty acid in positions R1 and R2 can be different
True
True or False
The composition of fatty acids cannot change when the environment changes
False
Example: More fatty acids become saturated when growth occurs at high temperatures; this is to maintain fluidity
Phospholipid fatty acids (PFLA) are used to help ______ bacteria
identify
True or False
Archaea have the same PLFA as bacteria
False, BacTeria FAs are typically ESTER linked to glycerol, while archaea are typically ether linked to glycerol
What percentage of total phospholipids are found in the cell membrane?
65%-75%
Where are the rest of the phospholipids that are not located in the cell membrane?
In the outer membrane and cytoplasm
Phospholipids influence the _____ density on the membrane
charge
Phospholipids are important in ______ __________ processes (chemotaxis)
signal transduction
What are integral proteins?
proteins imbedded in the membrane; bound to FAs by hydrophobic bonding; removal by detergents
What are peripheral proteins?
attached at membrane surfaces to phospholipids by ionic interactions; removal by washing with salt solutions
What are aquaporins?
water channels that enhance rapid equilibration of water across the cell membrane
What are Bayer’s Patches?
adhesion sites
Bayer’s Patches connect what two membranes?
outer membrane and plasma membrane
Where is the periplasm located in Gram Negative bacteria?
between the cell membrane and the outer membrane
Where is the periplasm located in Gram Positive bacteria?
between the cell membrane and the peptidoglycan layer
Oligosaccharides are a component of the periplasm. What function do they serve?
involved in osmotic regulation
Cytochrome C is a component of the periplasm, what is its function?
cytochrome c oxidizes carbon compounds and delivers the electron to the ETC in the cell membrane
True or False
Hydrolytic enzymes degrade nutrients to smaller molecules that can be transported across the membrane by transporters
True
Is catalase a detoxifying agent?
yes
What is the location and function of Ton B
Location: originates in the plasma membrane and extends to the outer membrane (in E. coli)
Function: required for the uptake of certain solutes including iron siderophores and vitamin B12 against a huge concentration gradient
The peptidoglycan layer protects from lysis in what kind of solutions?
hypotonic solutions
NAG and NAM are attached to each other by __ - ____________
B - 1,4 linkages
The peptidoglycan layer is composed of _______ chains cross-linked by _________
glycan; peptides
Do archaea have a peptidoglycan layer?
No, archaea have a pseudopeptidoglycan layer
True or False
Attached to NAM is a tetrapeptide that crosslinks the glycan chains via peptide bonds
True
What is the difference in cross linking between Gram - and Gram +
Gram - cross linking is direct while Gram + cross linking usually involves a peptide bridge (pentapeptide bridge)
In Gram +, teichoic acids are attached to the peptidoglycan layer via…
covalent bonds between glycerol phosphate to NAM
How many FAs in Lipid A?
5-7 (NAG dimer)
The outer membrane of a Gram - bacteria is composed of what?
LPS, phospholipid, and a thin layer of peptidoglycan
True or False
LPS is not an endotoxin
False
Lipid A is the the membrane __________ region of LPS
anchoring
Does Lipid A illicit a strong immune response?
yes
The Core of LPS is attached to __ position on one of the _____ and is a chain of ______
6; NAGs; sugars (KDO and heptose)
O-antigen contains up to ___ repeats of _____ sugars
40, 3-5
True or False
O-antigen is connected to the Core
True
Porins form small __________ channels through the outer membrane to allow for _______ of small solutes
hydrophilic; diffusion
What are the three major porins in E. coli?
PhoE, OmpF, OmpC
True or False
OmpF is present under all growth conditions
True
PhoE is present only when ________ is in limited supply
phosphate
Gas vesicles are hollow structures made of __________
gas vesicle protein A (GsvA)
Gas vesicles are found mostly in what kind of microbes?
planktonic microbes
True or False
Gas vesicles provide buoyancy
True
Gas vesicles are impermeable to ______ but are highly permeable to _______
water; gases
Carboxysomes may serve to concentrate ______ inside the structure and thus increase the efficiency of ribulose diphosphate
carbon
What is FtsZ?
- involved in cell division
- forms septal ring that constricts cell
- without it it’s just long lines of filaments
What is MreB?
-contributes to shape of nonspherical bacteria (if knocked out E. coli become cocci)
What does Crescetin contribute?
contributes to vibroid shape
The Glycocalyx is the extracellular material external to the ____ _____
cell wall
True or False
The glycocalyx is composed of polysaccharides
True
What functions does the S layer serve?
may help prevent diffusion of proteins (if s layer is cell wall then not called glycocalyx)
True or False
The capsule is rigid, flexible, and impermeable
True
Where does the Slime adhere to?
the cell wall
What functions do the Glycocalyx serve?
- adhesion to other cells (or surfaces) to form biofilms
- protection from phagocytosis
- prevent dehydration
What does monopolar mean?
single flagellum at one pole (usually the old pole)
What does Lophotrichous mean?
bundle of flagellum at one pole
What does bipolar mean (flagella)
single flagellum at both poles
What does amphitrichous mean?
bundles of flagellum at both poles
What is subpolar?
flagellum located NEAR a pole
What does peritrichous mean?
flagella surround around the cell
In the basal body of flagellum, how many rings are in Gram positive and how many are in Gram negative?
- Gram + : 2 rings (M and S)
- Gram - : 4 rings (LPMS)
What proteins is the central rod of a flagella composed of ?
FlgB, FligC, FlgF
The rotor of the flagella contains what proteins?
FligG
What do FliM and FliN form?
C ring
C ring regulates the length of what?
the hook
FlgK and FlgL form a junction between what?
the hook and the filament
The flagellin is?
protein in filament (FliC)
CCW rotation the flagella moves in a _____________. CW rotation, the flagella bundle breaks apart and bacterium ________
straight line; tumbles
High concentration of chemoattractant _______ the frequency of tumbles. Higher concentration of chemorepellant ________ frequency of tumbles
decreases; increases
