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Microbiology Exam 2 UTA Questions And Answers With Verified Solutions 100% Correct!!! (RATED A+)
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Microbiology Exam 2 UTA Questions And Answers With Verified Solutions 100% Correct!!! (RATED A+)
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Microbiology Exam 2 UTA QuestionsAnd Answers With Verified Solutions
100% Correct!!! (RATED A+)
Uniporters - ANSWER✔✔ Transport in one direction across the membrane
Symporters - ANSWER✔✔ Functions as co-transporters; the two molecules travel
in the same direction; 1. Energy is released as one substituent moves down its
concentration gradient 2. This energy moves a second substrate against its
gradient into the cell
Anitporters - ANSWER✔✔ Transport a molecule across the membrane while
simultaneously transporting another molecule in the opposite direction; the
actively transported molecule moves in the direction opposite to the driving ion;
1. Antiporter binds substrate A on the cytoplasmic side of the membrane
2.Antiporter opens to the outside, where the concentration of A is less 3.
Substrate A leaves its binding site, and substrate B then binds to its site 4.
Antiporter opens to the inside of the cell. Substrate B is released in exchange for
substrate A
The Phosphotransferase System in E.coli - ANSWER✔✔ -Type of group
translocation
-Best studied system
-Moves glucose, fructose, and mannose
-Five proteins required
-Energy derived from phosphoenolpyruvate (PEP)
-The product Glucose 6-P is used in glycolysis
,Group Translocation - ANSWER✔✔ Substance transported is chemically modified
during transport across the membrane, usually phosphorylated
ABC Systems - ANSWER✔✔ -ATP-Binding Cassette systems
- >200 different systems identified in prokaryotes
-Often involved in uptake of organic compounds (e.g. sugars, amino acids),
inorganic nutrients (e.g sulfate, phosphate), and trace metals
-Typically display high substrate specificity
-Contain periplasmic binding proteins
3 components: Periplasmic binding proteins, Membrane- spanning transporter,
and ATP-hydrolyzing protein (i.e ATPase); also requires ATP energy
Shown in diagram at C
Cell Wall - ANSWER✔✔ How prokaryotes protect the cell membrane? For most
species, the cell envelope includes at least one structural supporting layer and the
most common structural support is _______?
This confers shape and rigidity to the cell and helps it withstand turgor pressure,
can see it for example in E.coli
Mycoplasmas - ANSWER✔✔ An example of a few prokaryotes who have a cell
membrane with no outer layers
,It's difficult to Gram stain
Sacculus - ANSWER✔✔ The bacterial cell wall, or this, consists of a single-
interlinked molecule; for example disaccharide or peptidoglycan
Needed to maintain high pressure and solubility in order to maintain its shape
Gram- Negative - ANSWER✔✔ Has thin peptidoglycan (PG)
Gram- Positive - ANSWER✔✔ Has thick peptidoglycan (PG)
Peptidoglycan or Murein - ANSWER✔✔ Most bacterial cell walls are made up of
this [only in bacteria]
The molecule consists of:
-Long polymers of two disaccharides called: N-acetylglucosamine (NAG or G) and
N-actelymuramic acid (NAM or M)
-The peptides can form cross-bridges connecting the parallel glycan strands
-Can have Lysine (Gram -) or Diaminopimetic acids (Gram +) amino acids
-Cross-linked differently in G+ and G- bacteria
-5 more Glycine in G+
-Peptide bonds are covalent; more peptide bonds in G+
-No inter bridge between G and G
, Beta (1,4) Glycosidic Bonds - ANSWER✔✔ The bonds within peptidoglycan
between NAG and NAM
Peptidoglycan Is Unique to Bacteria - ANSWER✔✔ -Thus the enzymes responsible
to its biosynthesis make excellent targets for antibiotic
-Penicillin inhibits the transpeptidase that cross-links the peptides
-Vancomycin prevents cross-bridge formation by binding to the terminal Ala-Ala
dipeptide
-Unfortunately, the widespread use of such antibiotics selects for evolution of
resistant strains
Dispersed Zonal Peptidoglycan Growth - ANSWER✔✔ Wall synthesis direction in
bacilli ex: E.coli (pulse label, 5% doubling time)
Usually growth from the center
Septal Zonal Peptidoglycan Growth - ANSWER✔✔ Ex. cocci (staphylococcus,
streptococcus)
Usually growth from the center
Polar Peptidoglycan Growth - ANSWER✔✔ Growth in one direction
Ex. actinomycetes, rhizobiales
Cell Envelope of Bacteria - ANSWER✔✔ Most bacteria have additional envelope
layers that provide structural support and protection
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