Mmg Cell Walls And Membranes

Front 1

What wall is specialized only to bacteria?

Back 1

-a bacterial cell wall composed of peptidoglycan
-backbone of polymerized sugars and peptide cross-links

Front 2

Typically, what is the turgor pressure found in bacterial cells?

Back 2

-high, around 2 atm so cell wall protects it from osmotic forces

Front 3

How do antibiotics correlate to cell walls?

Back 3

-they attack it which is why eukaryotes can take these (no cell walls, just membranes)

Front 4

What do peptide cross-links do?

Back 4

-hold together the strands of glycan and form the rigid structure of the peptidoglycan
*cross-links vary between bacterial species

Front 5

How do you make a peptidoglycan?

Back 5

-insert N-acetlyglucosamine/N-acetylmuric acid/pentapeptide precursor into the growing part of the wall
-a precursor must be linked to a hydrophobic lipid carrier to cross the cytoplasmic membrane

Front 6

What is the hydrophobic lipid carrier that is able to cross the cytoplasmic membrane of bacteria (during formation of a peptidoglycan)?

Back 6

-bactoprenol

Front 7

What is the final step in the synthesis of petidoglycan?

Back 7

-Transpeptidation which includes the formation of prptide cross-links

Front 8

How does penicillin affect bacteria?

Back 8

-it inhibits the transpeptidation step of peptidoglycan synthesis (all penicillin derivatives work this way as well)

Front 9

How is cell shape generated?

Back 9

-cell wall material is put in different locations which deides what the cell will look like

Front 10

Where is the cell wall inserted to form a bacilli?

Back 10

-cell wall material inserted throughout cell cylinder

Front 11

How are streptococci formed?

Back 11

-insertion of cell wall material at the site of cell division

Front 12

How are corynebacterium formed?

Back 12

-insertion of cell wall material at the site of cell division and at the cell poles

Front 13

What creates high turgor pressure in cells?

Back 13

-most bacteria are in low solute environments, whereas they have high solute in their cells (more water comes in)
*without cell wall, membrane would lyse from continued osmosis

Front 14

How do halophilic archaea live in such high salt conditions?

Back 14

-pseudopeptidoglycan layers
-different plasma membrane composition
-make compatible solutes to increase internal solute concentrations

Front 15

What are some of the compatible solutes made by halophilic archaea to increase internal solute concentrations?

Back 15

-K+ ions
-sucrose
-glycerol
-amino acids

Front 16

What is the percent composition difference in gram + and - bacteria?

Back 16

-90% to 10%

Front 17

Which gram bacteria is more sensitive to penicillin and why?

Back 17

-Gram + because they have more peptide cross-links and interbridges (because they have so much peptidoglycan)

Front 18

Which acids in Gram+ cells have negative charges?

Back 18

-Teichoic acid
-Lipoteichoic acid
*What stain would you use to highligh a Gram+ cell?

Front 19

What are the cell walls of Mycobacterium like?

Back 19

-similar to Gram+ bacteria
-Mycolic acid residues are linked to the peptidoglycan

Front 20

What are mycolic acids?

Back 20

-long chain fatty acids (extremely hydrophobic)
-make up 60% of total cell wall mass)
-responsible for the "acid fast" properties of Mycobacteria
*free lipids, glycolipids, and peptidoglycolipids are also mycolic acids

Front 21

What part of a Gram- cell has the endotoxin?
What does this cause?

Back 21

-In the LPS layer (made up of polysaccharide and Lipid A)
-can cause fever and shock in patients

Front 22

Where is lysozyme found (not lysosomes)?

Back 22

-in saliva

Front 23

What does LPS stand for?

Back 23

-lipopolysaccharide

Front 24

Gram- cell walls have multiple phospholipid layers. How similar are they?

Back 24

-Not similar: each layer is different from the other

Front 25

What is porin?

Back 25

-means pores that allow charged products to pass through

Front 26

Which gram bacteria has peptidoglycan?
How about interbridge?
What is this interbridge made of?

Back 26

-both bacteria do (Gram+ has much more!)
-Gram+ has interbridge
-interbridge made of pentaglycine

Front 27

In terms of location, what does an O antigen mean?
How about H7?
K1?

Back 27

-O= outside sugars/a cell wall antigen
-H= flagella antigen
-K= capsular antigen

Front 28

Describe E coli O157:H7

Back 28

-cell wall antigen #157, flagella antigen #7
-causes foodborne illness (like spinach!)

Front 29

Describe E coli K1.

Back 29

-refers to capsular antigen #1
-encapsulated strain of E. coli
-causes neonatal sepsis

Front 30

What 2 simple eukaryotic groups aren't affected by penicillin even though they HAVE cell walls?

Back 30

-fungi and algae

Front 31

What does a fungi cell wall consist of?

Back 31

-80-90% polysaccharides
-chitin
-glycoproteins (glucans and mannans)

Front 32

What is chitin?

Back 32

-found in fungal and algal cell walls
-polymer of N-acetylglucosamine

Front 33

What do all algal cell walls consist of?

Back 33

-presominantly polysaccharides (similar to plants but diverse constituents)
-cellulose
-chitin
-pectins
-hemicellulose

Front 34

What are two special components that belong to two different algaes?

Back 34

-calcium carbonate in coralline algae
-silica (sand) in diatoms

Front 35

What two common membranes in eukaryotic (one is also in bacteria) cells are made of phospholipid bilayers?
What are in this layer?

Back 35

-Plasma membranes for both
-Organellar membranes for eukaryotes
-both embedded with proteins

Front 36

What causes these membranes to form and make them good barriers?

Back 36

-amphipathis nature

Front 37

How does the amphipathic nature of phospholipids lead to the bilayer?

Back 37

-fatty acids interact through hydrophobic interactions
-phosphate groups interact with the aqueous environment through h-bonds

Front 38

What are some other structures found in/around a cell membrane?

Back 38

-glycoproteins
-polysaccharides
-integral proteins
-integral glycoproteins
-peripheral proteins
*CHO's on these (look like little bird feet)

Front 39

What are sterols?

Back 39

-found in eukaryotic membranes
-rigid, planar molecules that provide rigidity to membranes

Front 40

What is different with Archaea membranes?

Back 40

-chemically unique: 'ether' linkages connect glycerol to isoprene NOT fatty acids
-can still form bilayers as well as monolayers which are very resistant to disruption

Front 41

How do membranes help photosynthetic prokaryotes?

Back 41

-by harvesting light energy

Front 42

Overall, what are some functions of a membrane?

Back 42

-selective permeability
-energy production
-anchor proteins needed for transport, bioenergetics

Front 43

What do transport proteins do?

Back 43

-bring solutes into cells against a concentration gradient (concentration usually higher in the cell)

Front 44

How is voltage created in a cell?

Back 44

-by creating an electrical gradient
-this is done by the import and export of charged ions (EX: H+ protons)