# Microbial Physiology Exam 1 info

How are the outer membrane and peptidoglycan of Gram-negative bacteria connected?
a. TonB protein connect them.
b. The lipid moiety of the murein lipoprotein is embedded in the outer membrane, and the protein moiety is crosslinked to PG.
c. The outer membrane is loosely attached to PG
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How are nutrient molecules transported into Gram-negative bacteria?
a. All nutrient molecules diffuse across both the outer and cytoplamic membrane.
b. Hydrophilic molecules are transported through porins in the cytoplasmic membrane.
c. Nutrient molecules pass across the outer membrane to enter the periplasm through porins or specific proteins. Specific ABC or other transporters bring them across the cytoplasmic membrane.
What is incorrect about the cytoplasmic membrane?
a. Water, gases, and small hydrophobic molecules can diffuse through the phospholipid bilayer.
b. The phospholipid bilayer is permeable to proton.
c. Integral proteins and peripheral proteins of the cytoplasmic membrane carry out a broad range of physiological activities such as electron transport, solute transport, ATP synthesis, and transduction of environmental signals.
Which statement is incorrect on S layer?
a. The S layer is made of glycan or polysaccharides.
b. The S layer is a protein sheet that surrounds prokaryotic cells.
c. The S layer provides mechanical support against osmotic pressure.
d. The S layer confers resistance against low pH.
e. The S layer provides protection against virus and phagocytosis
Which is incorrect about archaea in comparison with bacteria?
a. Archaeal phospholipid uses ester linkages but bacterial phospholipid uses ether linkages.
b. Archaea do not have peptidoglycan.
c. Many archaea just use the S layer for mechanical stabilization of cells
d. Lysozyme cannot hydrolyze PG-like molecules present in some archaea.
e. Ribosomes in bacteria are quite different from those in archaea.
Which statement is correct about pili in bacteria?
a. Some pili are fibrous proteins on cell surface for binding of bacteria to certain types of surface or molecules.
b. Pili are usually made of carbohydrates.
c. Pili are the S layer of certain bacteria and most of archaea.
d. None of pili are involved in bacterial mobility.
The porins _____.
a. are located in the outer membrane of Gram-positive bacteria to allow small hydrophilic molecules to diffuse to the cytosol
b. allow small hydrophilic molecules to move into the periplasm of Gram-negative bacteria
c. are for transport of all kinds of molecules across the cell membrane