Microbiology Exam 2 UTA 2025
Questions and Answers
Uniporters - --CORRECT ANSWER--Transport in one direction across the
membrane
Symporters - --CORRECT 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 - --CORRECT 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 - --CORRECT ANSWER---Type of
group translocation
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 1
,-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 - --CORRECT ANSWER--Substance transported is
chemically modified during transport across the membrane, usually phosphorylated
ABC Systems - --CORRECT 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
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
,Shown in diagram at C
Cell Wall - --CORRECT 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 - --CORRECT ANSWER--An example of a few prokaryotes who
have a cell membrane with no outer layers
It's difficult to Gram stain
Sacculus - --CORRECT 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 - --CORRECT ANSWER--Has thin peptidoglycan (PG)
Gram- Positive - --CORRECT ANSWER--Has thick peptidoglycan (PG)
Peptidoglycan or Murein - --CORRECT ANSWER--Most bacterial cell walls are
made up of this [only in bacteria]
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, 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 - --CORRECT ANSWER--The bonds within
peptidoglycan between NAG and NAM
Peptidoglycan Is Unique to Bacteria - --CORRECT 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
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 4
Questions and Answers
Uniporters - --CORRECT ANSWER--Transport in one direction across the
membrane
Symporters - --CORRECT 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 - --CORRECT 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 - --CORRECT ANSWER---Type of
group translocation
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 1
,-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 - --CORRECT ANSWER--Substance transported is
chemically modified during transport across the membrane, usually phosphorylated
ABC Systems - --CORRECT 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
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 2
,Shown in diagram at C
Cell Wall - --CORRECT 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 - --CORRECT ANSWER--An example of a few prokaryotes who
have a cell membrane with no outer layers
It's difficult to Gram stain
Sacculus - --CORRECT 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 - --CORRECT ANSWER--Has thin peptidoglycan (PG)
Gram- Positive - --CORRECT ANSWER--Has thick peptidoglycan (PG)
Peptidoglycan or Murein - --CORRECT ANSWER--Most bacterial cell walls are
made up of this [only in bacteria]
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 3
, 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 - --CORRECT ANSWER--The bonds within
peptidoglycan between NAG and NAM
Peptidoglycan Is Unique to Bacteria - --CORRECT 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
....COPYRIGHT ©️ 2025 ALL RIGHTS RESERVED...TRUSTED & VERIFIED 4
