MBG 3350 - Midterm 1 Exam Questions with Correct Answers Latest Update 2025/2026
DNA VECTORS - Answers Engineered derivatives of naturally occurring genetic elements. (Often
bacterial plasmids)
START CODON - Answers AUG
END CODONS - Answers UGA
UAA
UAG
METHYLATION - PROKARYOTES - Answers Protects the cells DNA from foreign DNA (virus,
phage, etc..)
METHYLATION - EUKARYOTES - Answers Decreases transcription rates and gene expression.
(Eg. the 2nd X chromosome in females)
Can be passed onto progeny
DNA BUILDING BLOCKS - Answers dATP, dTTP, dCTP, dGTP (dHTP in plants)
INVITRO - Answers DNA is not methylated __________.
VECTOR ENGINEERING - Answers 1. Isolate DNA from host
2. Insert foreign DNA into vector (usually a plasmid)
3. select successful transform ants
4. Propagate vector through cell cultures
CHOOSING A VECTOR - Answers -Does it have an origin of replication?
-Does it contain a selectable marker?
-Is there a unique RE site?
CULTURING E.COLI - Answers - Grow in rich medium at 37deg celsius, can be either liquid or
solid. If liquid grow with shaking.
- Will double population every 20mins
- Store forever at -70deg celsius with cryoprotectant
LB - Answers Lysogen broth
3 SITE SPECIFIC DNA METHYLASES - Answers Dam methylase
, Dcm methyltransferase
EcoKI methylase
ISSUES WITH RNA STORAGE - Answers Backbone is susceptible to hydrolysis because of
ribose 2'-OH atom
ISSUES WITH DNA STORAGE - Answers Bases can be lost by hydrolysis - especially purines
when conditions are acidic
PURINES - Answers Adenine and Guanine
PURIMIDINES - Answers Cytosine and Thyamine
PLASMID DNA ISOLATION - Answers - Chelation
- Lyse and denature
- Neutralize
- Remove debris
- Plasmid DNA recovery
CHELATION - Answers Use EDTA to engage divalent metals (To inhibit nucleases)
LYSE AND DENATURE - Answers SDS and NaOH respectively
NEUTRALIZE - Answers Use acetic acid and potassium acetate. (Precipitates everything but the
soluble plasmid DNA)
REMOVE DEBRIS - Answers Keep only the supernatant (contains DNA)
PLASMID DNA RECOVERY - Answers Use binding of DNA to silica bead in presence of high [salt].
Elute with neutral or acidic sol'n.
DAM METHYLASE - Answers Methylation of adenine in GATC
DCM METHYLTRANSFERASE - Answers Methylation of second cysteine in CCAGG and CCTGG
ECOKI METHYLASE - Answers Methylation of adenine in AAC(N6)GTGC and GCAC(N6)GTT
END A- - Answers An endonuclease gene which when inactivated increases transformation
efficiency and plasmid yield.
REC A- - Answers Required for homologous recombination and recombinant-dependant DNA
repair.
The mutant does not rearrange or delete plasmid DNA
DNA VECTORS - Answers Engineered derivatives of naturally occurring genetic elements. (Often
bacterial plasmids)
START CODON - Answers AUG
END CODONS - Answers UGA
UAA
UAG
METHYLATION - PROKARYOTES - Answers Protects the cells DNA from foreign DNA (virus,
phage, etc..)
METHYLATION - EUKARYOTES - Answers Decreases transcription rates and gene expression.
(Eg. the 2nd X chromosome in females)
Can be passed onto progeny
DNA BUILDING BLOCKS - Answers dATP, dTTP, dCTP, dGTP (dHTP in plants)
INVITRO - Answers DNA is not methylated __________.
VECTOR ENGINEERING - Answers 1. Isolate DNA from host
2. Insert foreign DNA into vector (usually a plasmid)
3. select successful transform ants
4. Propagate vector through cell cultures
CHOOSING A VECTOR - Answers -Does it have an origin of replication?
-Does it contain a selectable marker?
-Is there a unique RE site?
CULTURING E.COLI - Answers - Grow in rich medium at 37deg celsius, can be either liquid or
solid. If liquid grow with shaking.
- Will double population every 20mins
- Store forever at -70deg celsius with cryoprotectant
LB - Answers Lysogen broth
3 SITE SPECIFIC DNA METHYLASES - Answers Dam methylase
, Dcm methyltransferase
EcoKI methylase
ISSUES WITH RNA STORAGE - Answers Backbone is susceptible to hydrolysis because of
ribose 2'-OH atom
ISSUES WITH DNA STORAGE - Answers Bases can be lost by hydrolysis - especially purines
when conditions are acidic
PURINES - Answers Adenine and Guanine
PURIMIDINES - Answers Cytosine and Thyamine
PLASMID DNA ISOLATION - Answers - Chelation
- Lyse and denature
- Neutralize
- Remove debris
- Plasmid DNA recovery
CHELATION - Answers Use EDTA to engage divalent metals (To inhibit nucleases)
LYSE AND DENATURE - Answers SDS and NaOH respectively
NEUTRALIZE - Answers Use acetic acid and potassium acetate. (Precipitates everything but the
soluble plasmid DNA)
REMOVE DEBRIS - Answers Keep only the supernatant (contains DNA)
PLASMID DNA RECOVERY - Answers Use binding of DNA to silica bead in presence of high [salt].
Elute with neutral or acidic sol'n.
DAM METHYLASE - Answers Methylation of adenine in GATC
DCM METHYLTRANSFERASE - Answers Methylation of second cysteine in CCAGG and CCTGG
ECOKI METHYLASE - Answers Methylation of adenine in AAC(N6)GTGC and GCAC(N6)GTT
END A- - Answers An endonuclease gene which when inactivated increases transformation
efficiency and plasmid yield.
REC A- - Answers Required for homologous recombination and recombinant-dependant DNA
repair.
The mutant does not rearrange or delete plasmid DNA
