MIMG 101: Midterm 2 Final Exam
Questions with All Correct Answers
2025-2026 Updated.
Explain parts of a lac operon - Answer control locus: encodes proteins that bind repressor
and rna polymerase
repressor: acts as on and off switch, codes for repressor protein
structural locus: genes turned on and off by the operon
Example of inducible and repressible operon - Answer repressible: arginine operon (regulates
arginine amino acid synthesis), arginine represses operon by neg feedback
inducible: lac operon (regulates breakdown of lactose), repressed aka induced by lactose
AMES test - Answer test for mutagenicity of chemicals, used as a screen for carcinogen
potential, if the bacteria mutate often when they're plated on a certain chemical, that chemical
has high mutagenicity and may cause cancer
Fluctuation test - Answer proves existence of mutations occurring without selective pressure,
culture separate tubes of bacteria, then plate them on antibiotics, only mutated bacteria will
survie
Explain purposes of HGT for scientists and for organisms - Answer Organisms can gain new
metabolism, parthogens, and drug resistance. Scientists learn abt evolution and build
phylogenetic trees.
What are four ways genes are transferred horizontally - Answer Transformation: uptake and
incorporation of DNA from the environment
Transduction: transfer of DNA from one bacterium to another by a bacteriophage
Conjugation: temporary joining of two bacterial cells to copy DNA from donor to recipient cell
Transposon: a segment of DNA capable of independent replication and inserting the copy into a
new position in the genome (or another genome), can carry antibiotic resistance genes
How do we recognize genomic islands and what are they - Answer genomic islands are large
regions of the genome that came from HGT, scientists look for altered %G/C and direct repeats
flanking the section
How did scientists discover the inheritance material required in transformation - Answer In
1941, Avery and McCarthy treated lysates (genetic material) w RNase, Protease, and DNase.
,They found that transformation did not occur when DNase was added. DNA was the inheritance
material
What is transformation, explain the process in gram neg and gram pos bacteria? Who first
discovered it - Answer Transformation: the uptake of naked DNA from environment Frederick
griffin first discovered this when boiling virulent R bacteria made it avirulent then placing with
avirulent s bacteria made it become virulent again
In gram-, dd DNA separates to ss DNA in periplasm, ssDNA enters the cytoplasm
In gram+, only ss DNA enters the cell through a pore
What is the most important protein for homologous recombination in transformation - Answer
Rec A protein
What is competence, what are the different types - Answer Competence: ability to take up
DNA
Natural
Artificial: bacteria modified in the lab, common done on e coli
Acquired: bacteria gain competence in response to signals at high enough conc., ex: strep
pneumoniae
What is conjugation and how does it occur - Answer transfer of genetic material between
cells (usually plasmids), requires cell-cell contact, pilus of donor cell attaches to recipient cell
and conjugative pore opens, coupling protein allows ss dNA to enter recipient, DNA replicates,
recipient becomes a donor
What cellular structure is necessary for conjugation - Answer pilus, f plasmid
What traits are commonly conferred by plasmids in gram neg, what does the f plasmid contain -
Answer bacteria gain fertility, drug resistance toxins, metabolic pathways
f plasmid contains pilus formation genes, dna transfer genes, replication and Tn, IS genes
Diff btwn gram neg and gram pos conjugation - Answer In gram neg the cells' membranes
fuse to create a mating bridge, while in gram pos a conjugative pore spanning both membranes
opens, then both have rolling circle replication and transfer
HFR - Answer high frequency recombination,
when the plasmid can integrate a gene into a chromosome, rather than existing as an
independent circular dna, recipient cell does not become a donor
, Types of transposable elements - Answer Transposable elements are dna fragments mobile
within the genome, there are insertion sequences, transposons, and retrotransposons
Insertion sequences (IS elements) - Answer DNA segments that can move to new location on
same/different chromosome; consist of only one gene that codes for enzyme that just
transports it (transposase)
Transposons (jumping genes) - Answer DNA segments that can move to new location on
same/different chromosome; contain gene that codes for gene transport enzyme and also
another gene: replication, antibiotic resistance, etc.
What is transduction - Answer viral mediated transfer of DNA
Generalized transduction vs specialized transduction mutation - Answer 1. phage attaches to
bacteria and inserts own DNA, replicates and forms phages that lyse then break out of cell, by
accident one of the phages is actually host bacteria DNA w phage coat, when it infects a second
bacteria, the bacteria will receive DNA from the first bacteria and experiences genetic
recombination
2. occurs when phage DNA is excised incorrectly and contains a portion of host DNA, happens at
a higher frequency than general transduction
How does HGT help lyme disease causing bacteria - Answer Lyme disease causing bacteria
live on ticks. Ticks gained the dae gene thru HGT, this gene creates toxin that kills bacteria. Thus
ticks use dae gene to lower bacterial load.
What are ways to classify microbes - Answer 1. physical properties
2. metabolic processes, aka energy source
3. genetic material (most accurate)
Requirements of a gene used to track evolution, what meets the criteria - Answer universally
distributed, functionally homologous in the diff organisms, has an appropriate mutation rate
(rRNA meets criteria)
Who experimented to find relationship btwn archaea, bacteria, and eukaryotes - Answer Carl
Woese (1977) sequenced methanogens, nonmethanogens, and eukaryotes to find similarity,
archaea are more similar to eukarya than to bacteria
Examples of differences between archaea, eukarya and bacteria - Answer Bacteria and
eukarya have D glycerol in their cell membrane, archaea have L- glycerol and have esther linkage
on hydrophobic side chain
Questions with All Correct Answers
2025-2026 Updated.
Explain parts of a lac operon - Answer control locus: encodes proteins that bind repressor
and rna polymerase
repressor: acts as on and off switch, codes for repressor protein
structural locus: genes turned on and off by the operon
Example of inducible and repressible operon - Answer repressible: arginine operon (regulates
arginine amino acid synthesis), arginine represses operon by neg feedback
inducible: lac operon (regulates breakdown of lactose), repressed aka induced by lactose
AMES test - Answer test for mutagenicity of chemicals, used as a screen for carcinogen
potential, if the bacteria mutate often when they're plated on a certain chemical, that chemical
has high mutagenicity and may cause cancer
Fluctuation test - Answer proves existence of mutations occurring without selective pressure,
culture separate tubes of bacteria, then plate them on antibiotics, only mutated bacteria will
survie
Explain purposes of HGT for scientists and for organisms - Answer Organisms can gain new
metabolism, parthogens, and drug resistance. Scientists learn abt evolution and build
phylogenetic trees.
What are four ways genes are transferred horizontally - Answer Transformation: uptake and
incorporation of DNA from the environment
Transduction: transfer of DNA from one bacterium to another by a bacteriophage
Conjugation: temporary joining of two bacterial cells to copy DNA from donor to recipient cell
Transposon: a segment of DNA capable of independent replication and inserting the copy into a
new position in the genome (or another genome), can carry antibiotic resistance genes
How do we recognize genomic islands and what are they - Answer genomic islands are large
regions of the genome that came from HGT, scientists look for altered %G/C and direct repeats
flanking the section
How did scientists discover the inheritance material required in transformation - Answer In
1941, Avery and McCarthy treated lysates (genetic material) w RNase, Protease, and DNase.
,They found that transformation did not occur when DNase was added. DNA was the inheritance
material
What is transformation, explain the process in gram neg and gram pos bacteria? Who first
discovered it - Answer Transformation: the uptake of naked DNA from environment Frederick
griffin first discovered this when boiling virulent R bacteria made it avirulent then placing with
avirulent s bacteria made it become virulent again
In gram-, dd DNA separates to ss DNA in periplasm, ssDNA enters the cytoplasm
In gram+, only ss DNA enters the cell through a pore
What is the most important protein for homologous recombination in transformation - Answer
Rec A protein
What is competence, what are the different types - Answer Competence: ability to take up
DNA
Natural
Artificial: bacteria modified in the lab, common done on e coli
Acquired: bacteria gain competence in response to signals at high enough conc., ex: strep
pneumoniae
What is conjugation and how does it occur - Answer transfer of genetic material between
cells (usually plasmids), requires cell-cell contact, pilus of donor cell attaches to recipient cell
and conjugative pore opens, coupling protein allows ss dNA to enter recipient, DNA replicates,
recipient becomes a donor
What cellular structure is necessary for conjugation - Answer pilus, f plasmid
What traits are commonly conferred by plasmids in gram neg, what does the f plasmid contain -
Answer bacteria gain fertility, drug resistance toxins, metabolic pathways
f plasmid contains pilus formation genes, dna transfer genes, replication and Tn, IS genes
Diff btwn gram neg and gram pos conjugation - Answer In gram neg the cells' membranes
fuse to create a mating bridge, while in gram pos a conjugative pore spanning both membranes
opens, then both have rolling circle replication and transfer
HFR - Answer high frequency recombination,
when the plasmid can integrate a gene into a chromosome, rather than existing as an
independent circular dna, recipient cell does not become a donor
, Types of transposable elements - Answer Transposable elements are dna fragments mobile
within the genome, there are insertion sequences, transposons, and retrotransposons
Insertion sequences (IS elements) - Answer DNA segments that can move to new location on
same/different chromosome; consist of only one gene that codes for enzyme that just
transports it (transposase)
Transposons (jumping genes) - Answer DNA segments that can move to new location on
same/different chromosome; contain gene that codes for gene transport enzyme and also
another gene: replication, antibiotic resistance, etc.
What is transduction - Answer viral mediated transfer of DNA
Generalized transduction vs specialized transduction mutation - Answer 1. phage attaches to
bacteria and inserts own DNA, replicates and forms phages that lyse then break out of cell, by
accident one of the phages is actually host bacteria DNA w phage coat, when it infects a second
bacteria, the bacteria will receive DNA from the first bacteria and experiences genetic
recombination
2. occurs when phage DNA is excised incorrectly and contains a portion of host DNA, happens at
a higher frequency than general transduction
How does HGT help lyme disease causing bacteria - Answer Lyme disease causing bacteria
live on ticks. Ticks gained the dae gene thru HGT, this gene creates toxin that kills bacteria. Thus
ticks use dae gene to lower bacterial load.
What are ways to classify microbes - Answer 1. physical properties
2. metabolic processes, aka energy source
3. genetic material (most accurate)
Requirements of a gene used to track evolution, what meets the criteria - Answer universally
distributed, functionally homologous in the diff organisms, has an appropriate mutation rate
(rRNA meets criteria)
Who experimented to find relationship btwn archaea, bacteria, and eukaryotes - Answer Carl
Woese (1977) sequenced methanogens, nonmethanogens, and eukaryotes to find similarity,
archaea are more similar to eukarya than to bacteria
Examples of differences between archaea, eukarya and bacteria - Answer Bacteria and
eukarya have D glycerol in their cell membrane, archaea have L- glycerol and have esther linkage
on hydrophobic side chain
