BIOL 134 (11) Questions with CORRECT Answers
Question:
Why was the riboflavin solution yellow and the NaCl solution clear?
Answer:
Riboflavin absorbancy was the most around 450 nanometer wavelength which is
absorbing blue and the lowest was around 600 nanometers which is reflecting
yellow. NaCl solution is clear because it does not absorb visible light.
Question:
What do we know about Pseudomonas aeruginosa?
Answer:
It is a gram negative bacteria that can survive in diverse environments, can cause
infections, resistant to many antibiotics
Question:
Why are proteinase K and RNase used in the isolation of DNA?
Answer:
Proteinase K is used to break down the cell membrane, RNase degrades RNA. They
remove contaminants so you get a cleaner sample of genomic DNA.
Question:
How is genomic DNA removed from solution during the isolation of plasmid DNA?
Answer:
Genomic DNA is removed during plasmid isolation by raising the pH to denature all
DNA; when the solution is neutralized, the large, nicked genomic DNA becomes
insoluble and is pelleted by centrifugation, while the small, supercoiled plasmid
DNA stays in solution in the supernatant
Question:
What are the properties of restriction enzymes?
Answer:
Restriction enzymes cleave double stranded DNA at specific target sequences. After
the DNA has been cut the fragments can be joined to other DNA fragments to create
recombinant DNA molecules. The process of joining the molecules is called ligation
, Question:
What are the properties of plasmids used for gene cloning?
Answer:
Plasmids used for cloning have been genetically engineered to facilitate the
cloning process. They contain genes for antibiotic resistance and restriction
enzyme sites to facilitate cloning. They may also contain genes that allow for
identification of recombinant plasmids.
Question:
How does the blue/white screening system for recombinant plasmids work?
Answer:
The enzyme betagalactosidase breaks down XGal in the media to yield a product that
is blue incolor. So if the cells have the betagalactosidase enzyme then the
colonies will be blue. If there is no betagalactosidase enzyme the colonies will
be white. The lacZα gene is present in the multiple cloning site of the plasmid.
If an insert is present then the lacZα gene is not translated and the cells lack
betagalactosidase. So blue colonies contain plasmids with no inserts and white
colonies likely contain plasmids with inserts.
Question:
How are molecules separated during gel electrophoresis?
Answer:
During gel electrophoresis the molecules are separated by their size, shape, and
charge to mass ratio
Question:
Compare cut and uncut plasmids on a gel
Answer:
uncut plasmids will be supercoiled and travel farther on the gel and cut plasmids
will be linear and therefore higher on the gel
Question:
Compare cut and uncut gDNA on a gel
Answer:
uncut gDNA will appear high on the gel as a large thick band because it is long
and intact while cut gDNA shows as a smear across the gel because the enemy broke
the DNA into many different sized fragments
Question:
Why was the riboflavin solution yellow and the NaCl solution clear?
Answer:
Riboflavin absorbancy was the most around 450 nanometer wavelength which is
absorbing blue and the lowest was around 600 nanometers which is reflecting
yellow. NaCl solution is clear because it does not absorb visible light.
Question:
What do we know about Pseudomonas aeruginosa?
Answer:
It is a gram negative bacteria that can survive in diverse environments, can cause
infections, resistant to many antibiotics
Question:
Why are proteinase K and RNase used in the isolation of DNA?
Answer:
Proteinase K is used to break down the cell membrane, RNase degrades RNA. They
remove contaminants so you get a cleaner sample of genomic DNA.
Question:
How is genomic DNA removed from solution during the isolation of plasmid DNA?
Answer:
Genomic DNA is removed during plasmid isolation by raising the pH to denature all
DNA; when the solution is neutralized, the large, nicked genomic DNA becomes
insoluble and is pelleted by centrifugation, while the small, supercoiled plasmid
DNA stays in solution in the supernatant
Question:
What are the properties of restriction enzymes?
Answer:
Restriction enzymes cleave double stranded DNA at specific target sequences. After
the DNA has been cut the fragments can be joined to other DNA fragments to create
recombinant DNA molecules. The process of joining the molecules is called ligation
, Question:
What are the properties of plasmids used for gene cloning?
Answer:
Plasmids used for cloning have been genetically engineered to facilitate the
cloning process. They contain genes for antibiotic resistance and restriction
enzyme sites to facilitate cloning. They may also contain genes that allow for
identification of recombinant plasmids.
Question:
How does the blue/white screening system for recombinant plasmids work?
Answer:
The enzyme betagalactosidase breaks down XGal in the media to yield a product that
is blue incolor. So if the cells have the betagalactosidase enzyme then the
colonies will be blue. If there is no betagalactosidase enzyme the colonies will
be white. The lacZα gene is present in the multiple cloning site of the plasmid.
If an insert is present then the lacZα gene is not translated and the cells lack
betagalactosidase. So blue colonies contain plasmids with no inserts and white
colonies likely contain plasmids with inserts.
Question:
How are molecules separated during gel electrophoresis?
Answer:
During gel electrophoresis the molecules are separated by their size, shape, and
charge to mass ratio
Question:
Compare cut and uncut plasmids on a gel
Answer:
uncut plasmids will be supercoiled and travel farther on the gel and cut plasmids
will be linear and therefore higher on the gel
Question:
Compare cut and uncut gDNA on a gel
Answer:
uncut gDNA will appear high on the gel as a large thick band because it is long
and intact while cut gDNA shows as a smear across the gel because the enemy broke
the DNA into many different sized fragments
