MCB4403 Final Exam With
Complete Solution
How does the cellular structure of prokaryotes and eukaryotes differ? - ANSWER
Prokaryotes have fimbriae, pili, and flagella while eukaryotes have flagella and cilia
Prokaryotes have ____ ribosomes while eukaryotes have ______ ribosomes; what causes
this difference? - ANSWER Prokaryotes have 70S ribosomes while eukaryotes have 80S
ribosomes; Eukaryotes have 80S because they sediment faster than the more ancient
prokaryotic 70S
How does the gram negative cell envelope differ from the gram positive cell envelope? -
ANSWER Gram negative = Have two phospholipid bilayers, and have
lipopolysaccharides (LPS)
Gram positive = Have teichoic acids and lipoteichoic acids, have a very thick layer of
peptidoglycan
What endotoxic characteristic is specific to gram negative cells? - ANSWER Lipid A
Selective vs differential media - ANSWER Selective media allow certain types of
organisms to grow, and inhibit the growth of other organisms. ... Differential media are
used to differentiate closely related organisms or groups of organisms.
What is most impacted by penicillin? - ANSWER Gram-positive bacteria
Characteristics of bacillus anthracis - ANSWER found in soil, forms endospores,
aerobic, gram positive
bacterial growth curve - ANSWER lag phase, log phase, stationary phase, death phase
temperature dependent growth curve - ANSWER temperature range determines growth
and survival rates
Hershey-Chase Experiment (the waring blender experiment) - ANSWER convinced
scientific community that DNA and not protein was the carrier of genes
-used bacterial virus T2 and grew it containing different media: sulfur (protein) and
phosphorus (DNA)
-proves that DNA (phosphorous) was carrier of genes because protein (sulfur) did not
pass the trait onto offspring, while phosphorous (DNA) did
What is transformation? - ANSWER uptake of DNA from environment; only competent
cells can uptake DNA; DNA must both enter the cell and integrate into the host genome
(bacteria cannot be transformed with DNA from unrelated species)
,What is needed structurally for transformation of genetic material to occur? - ANSWER
PILUS is required to pull the donor cell close to the recipient; DNA must be in A SELF
REPLICATING VECTOR
Structures of viruses - ANSWER Very simple and consist of:
1) a protein coat (capsid)
- may be surrounded by a host-derived membrane (envelope)
2) a nucleic acid core
Viral shape is determined by what? - ANSWER viral shape is determined by its capsid
Viral capsid - ANSWER - outermost layer in non-enveloped viruses
- protect the nucleic acid core from environment
- made of subunits called capsomers
- capsomers spontaneously assemble into capsids
what are the three main shapes of capsomers? - ANSWER helical (tube), icosadehdral
(3D sphere with 20 triangular faces), and complex (alien)
viral envelope - ANSWER - much more common in animal than plant viruses
- Lipid bilayer is derived from the host's nuclear
or cytoplasmic membrane
- Envelope is susceptible to environmental
stress
You want to make homemade beer. Sadly, you do not own an autoclave and you're
worried about endospore contamination. Which process should you use for
sterilization? - ANSWER Tyndalization (= a sterilization method that kills all forms of
microbial life, including the spores)
pasteurization does not kill spores
Which of the following is true about yogurt production? - ANSWER Fermentation with
pure cultures of Lactobacillus bulgaricus and Streptococcus salivarius will produce
yogurt
Which commercial biochemical compounds are produced by microbes? - ANSWER
Vitamins, amino acids, MSG (monosodium glutamate), insulin, reverse transcriptase
A human is infected with a protozoan. Which of the following treatments is most likely
done? - ANSWER Target synthesis of folic acid because humans don't synthesize this
, but protozoans do
Which of the following is NOT a way that antivirals inhibit viruses? - ANSWER antivirals
inhibit cell wall synthesis
Why is phage therapy not commonly used in the USA? - ANSWER The early success and
commercialization of antibiotics overshadowed it.
Which assay would allow you to determine whether bacteria are susceptible to an
antibiotic? - ANSWER A minimum inhibitory concentration (MIC) assay and a disk
diffusion assay
Which of the following would NOT be a good target for a safe and effective bacterial
antibiotic? - ANSWER chitin biosynthesis and cellulose biosynthesis
Sulfa drugs were purified and used before antibiotics. Why are they rarely used today? -
ANSWER they have too many undesirable side effects and
bacterial resistance to them is widespread
What is the major contribution of Alexander Flemming? - ANSWER He was the first to
isolate penicillin from fungi
Why would an antibiotic that targets cell wall synthesis be safer for humans than one
that targets nucleic acids? - ANSWER Human cells do not have a cell wall, but bacterial
cells do
What is septic shock and what causes it? - ANSWER - Septic shock is the last and most
severe stage of sepsis.
- Sepsis occurs when your immune system has an extreme reaction to an infection
- Bacterial infections are the most common cause of sepsis.
- The source of the infection can be anywhere in your body
exotoxin - ANSWER - Proteins or metabolites that are released from living bacteria -
Mostly produced by Gram-positive bacteria
bacterial metabolites - ANSWER Primary metabolites include amino acids, nucleotides,
and fermentation end products such as ethanol and organic acids, which are
considered essential for proper growth of microorganisms.
What makes something an infectious disease? - ANSWER - Infectious diseases are
illnesses caused by germs (such as bacteria, viruses, and fungi) that enter the body,
multiply, and can cause an infection
- A pathogen infection that leads to significant harm to the host is called an infectious
disease
Complete Solution
How does the cellular structure of prokaryotes and eukaryotes differ? - ANSWER
Prokaryotes have fimbriae, pili, and flagella while eukaryotes have flagella and cilia
Prokaryotes have ____ ribosomes while eukaryotes have ______ ribosomes; what causes
this difference? - ANSWER Prokaryotes have 70S ribosomes while eukaryotes have 80S
ribosomes; Eukaryotes have 80S because they sediment faster than the more ancient
prokaryotic 70S
How does the gram negative cell envelope differ from the gram positive cell envelope? -
ANSWER Gram negative = Have two phospholipid bilayers, and have
lipopolysaccharides (LPS)
Gram positive = Have teichoic acids and lipoteichoic acids, have a very thick layer of
peptidoglycan
What endotoxic characteristic is specific to gram negative cells? - ANSWER Lipid A
Selective vs differential media - ANSWER Selective media allow certain types of
organisms to grow, and inhibit the growth of other organisms. ... Differential media are
used to differentiate closely related organisms or groups of organisms.
What is most impacted by penicillin? - ANSWER Gram-positive bacteria
Characteristics of bacillus anthracis - ANSWER found in soil, forms endospores,
aerobic, gram positive
bacterial growth curve - ANSWER lag phase, log phase, stationary phase, death phase
temperature dependent growth curve - ANSWER temperature range determines growth
and survival rates
Hershey-Chase Experiment (the waring blender experiment) - ANSWER convinced
scientific community that DNA and not protein was the carrier of genes
-used bacterial virus T2 and grew it containing different media: sulfur (protein) and
phosphorus (DNA)
-proves that DNA (phosphorous) was carrier of genes because protein (sulfur) did not
pass the trait onto offspring, while phosphorous (DNA) did
What is transformation? - ANSWER uptake of DNA from environment; only competent
cells can uptake DNA; DNA must both enter the cell and integrate into the host genome
(bacteria cannot be transformed with DNA from unrelated species)
,What is needed structurally for transformation of genetic material to occur? - ANSWER
PILUS is required to pull the donor cell close to the recipient; DNA must be in A SELF
REPLICATING VECTOR
Structures of viruses - ANSWER Very simple and consist of:
1) a protein coat (capsid)
- may be surrounded by a host-derived membrane (envelope)
2) a nucleic acid core
Viral shape is determined by what? - ANSWER viral shape is determined by its capsid
Viral capsid - ANSWER - outermost layer in non-enveloped viruses
- protect the nucleic acid core from environment
- made of subunits called capsomers
- capsomers spontaneously assemble into capsids
what are the three main shapes of capsomers? - ANSWER helical (tube), icosadehdral
(3D sphere with 20 triangular faces), and complex (alien)
viral envelope - ANSWER - much more common in animal than plant viruses
- Lipid bilayer is derived from the host's nuclear
or cytoplasmic membrane
- Envelope is susceptible to environmental
stress
You want to make homemade beer. Sadly, you do not own an autoclave and you're
worried about endospore contamination. Which process should you use for
sterilization? - ANSWER Tyndalization (= a sterilization method that kills all forms of
microbial life, including the spores)
pasteurization does not kill spores
Which of the following is true about yogurt production? - ANSWER Fermentation with
pure cultures of Lactobacillus bulgaricus and Streptococcus salivarius will produce
yogurt
Which commercial biochemical compounds are produced by microbes? - ANSWER
Vitamins, amino acids, MSG (monosodium glutamate), insulin, reverse transcriptase
A human is infected with a protozoan. Which of the following treatments is most likely
done? - ANSWER Target synthesis of folic acid because humans don't synthesize this
, but protozoans do
Which of the following is NOT a way that antivirals inhibit viruses? - ANSWER antivirals
inhibit cell wall synthesis
Why is phage therapy not commonly used in the USA? - ANSWER The early success and
commercialization of antibiotics overshadowed it.
Which assay would allow you to determine whether bacteria are susceptible to an
antibiotic? - ANSWER A minimum inhibitory concentration (MIC) assay and a disk
diffusion assay
Which of the following would NOT be a good target for a safe and effective bacterial
antibiotic? - ANSWER chitin biosynthesis and cellulose biosynthesis
Sulfa drugs were purified and used before antibiotics. Why are they rarely used today? -
ANSWER they have too many undesirable side effects and
bacterial resistance to them is widespread
What is the major contribution of Alexander Flemming? - ANSWER He was the first to
isolate penicillin from fungi
Why would an antibiotic that targets cell wall synthesis be safer for humans than one
that targets nucleic acids? - ANSWER Human cells do not have a cell wall, but bacterial
cells do
What is septic shock and what causes it? - ANSWER - Septic shock is the last and most
severe stage of sepsis.
- Sepsis occurs when your immune system has an extreme reaction to an infection
- Bacterial infections are the most common cause of sepsis.
- The source of the infection can be anywhere in your body
exotoxin - ANSWER - Proteins or metabolites that are released from living bacteria -
Mostly produced by Gram-positive bacteria
bacterial metabolites - ANSWER Primary metabolites include amino acids, nucleotides,
and fermentation end products such as ethanol and organic acids, which are
considered essential for proper growth of microorganisms.
What makes something an infectious disease? - ANSWER - Infectious diseases are
illnesses caused by germs (such as bacteria, viruses, and fungi) that enter the body,
multiply, and can cause an infection
- A pathogen infection that leads to significant harm to the host is called an infectious
disease
