MOLECULAR DIAGNOSTICS EXAM 1
QUESTIONS AND ANSWERS 100%
CORRECT
in one nucleotide of DNA what are the 3 major moieties (components) that make it up? -
ANSWER-- 5 carbon sugar
- phosphate group
- nitrogen bases
what is the overall charge of DNA and on which moiety is it found - ANSWER-DNA is
overall negative, it is found on the oxygen of phosphate backbone
name a method that uses the fact that DNA is charged to get that method to work? -
ANSWER-Agarose gel electroporesis
what types of bonds are formed during hybridization when a strand of DNA finds its
complement - ANSWER-hybridization is the formation of hydrogen bonds
name 3 differences between DNA and RNA - ANSWER-1. on sugar, RNA has an OC
on C-2' (ribose), and DNA has an H on C-2' (deoxyribose)
2. nitrogenous base: RNA uses Uracil in plase of thymine
3. RNA is typically single stranded and DNA is double
dNTPs - ANSWER-DNA building block
NTPs - ANSWER-RNA building block
ddNTPs - ANSWER-terminator for sequencing, not naturally occurring
Replication - ANSWER-building blocks: dNTPs
enzyme/cellular machine to add that building block: DNA polymerase
Transcription - ANSWER-building block: NTPs
enzyme/cellular machine to add that building block: RNA polymerase
Translation - ANSWER-building blocks: amino acids
enzyme/cellular machine to add that building block: ribosome
You work in a lab and you have been asked to do a DNA extraction from bacterial cells.
in one of the first steps you notice that you need to add the enzyme lysozyme. what is
the purpose of adding this? - ANSWER-it breaks down the peptidoglycan cell wall
, why might the temp in step 2 be changed in different PCR runs? - ANSWER-the
temperature depends and is adjusted based on the Tm of the primers (melting
temperature)
why does step 3 always occur at 72 degrees c? - ANSWER-72 degrees is the prime
temperature that taq DNA polymerase can polymerize DNA, the extension temp never
varies
what determines the length of time required for step 3? - ANSWER-the size of amplicon
determines the length of time for extension
Name 2 applications of restriction enzymes - ANSWER-1. clonning
2. DNA fingerprinting (RLFP)
if you were instead extracting DNA from human blood cells, would you need to add
lysozyme? briefly state why or why not? - ANSWER-No because the human blood cells
do not contain a peptidoglycan cell wall
what chemical is added to precipitate DNA at the end of DNA extraction protocol so it
can be concentrated? - ANSWER-alcohol (ethanol) is added to precipitate DNA to
prepare it to be concentrated.
After a DNA extraction you can check the success of your extraction by either a
spectrophotometer reading or running an agarose gel. list one reason why a
spectrophotometer reading is more commonly done - ANSWER-it is much faster and
cheaper to run
under what conditions might you choose to run an agarose gel instead (hint: what can
you learn from a gel that you dont get with a spec)? - ANSWER-agarose gel gives you
more information about the actual makeup of DNA, you can see the band sizes and
know the size of components based on how far they traveled. (check to see if its
smeared when you want to see your DNA [?])
after DNA extraction you can perform a quick spectorphotometer reading at what
wavelength do you measure the following
DNA__________ RNA _____________ contaminants_______________ - ANSWER-
dna: 260 nm
rna: 250 nm
contaminents: 280 nm
what concentrations of agarose should be used for optimal seperation of DNA
fragments of 100, 250, and 350 bp in length?
a. 0.5%
b. 0.8%
c. 2.0%
QUESTIONS AND ANSWERS 100%
CORRECT
in one nucleotide of DNA what are the 3 major moieties (components) that make it up? -
ANSWER-- 5 carbon sugar
- phosphate group
- nitrogen bases
what is the overall charge of DNA and on which moiety is it found - ANSWER-DNA is
overall negative, it is found on the oxygen of phosphate backbone
name a method that uses the fact that DNA is charged to get that method to work? -
ANSWER-Agarose gel electroporesis
what types of bonds are formed during hybridization when a strand of DNA finds its
complement - ANSWER-hybridization is the formation of hydrogen bonds
name 3 differences between DNA and RNA - ANSWER-1. on sugar, RNA has an OC
on C-2' (ribose), and DNA has an H on C-2' (deoxyribose)
2. nitrogenous base: RNA uses Uracil in plase of thymine
3. RNA is typically single stranded and DNA is double
dNTPs - ANSWER-DNA building block
NTPs - ANSWER-RNA building block
ddNTPs - ANSWER-terminator for sequencing, not naturally occurring
Replication - ANSWER-building blocks: dNTPs
enzyme/cellular machine to add that building block: DNA polymerase
Transcription - ANSWER-building block: NTPs
enzyme/cellular machine to add that building block: RNA polymerase
Translation - ANSWER-building blocks: amino acids
enzyme/cellular machine to add that building block: ribosome
You work in a lab and you have been asked to do a DNA extraction from bacterial cells.
in one of the first steps you notice that you need to add the enzyme lysozyme. what is
the purpose of adding this? - ANSWER-it breaks down the peptidoglycan cell wall
, why might the temp in step 2 be changed in different PCR runs? - ANSWER-the
temperature depends and is adjusted based on the Tm of the primers (melting
temperature)
why does step 3 always occur at 72 degrees c? - ANSWER-72 degrees is the prime
temperature that taq DNA polymerase can polymerize DNA, the extension temp never
varies
what determines the length of time required for step 3? - ANSWER-the size of amplicon
determines the length of time for extension
Name 2 applications of restriction enzymes - ANSWER-1. clonning
2. DNA fingerprinting (RLFP)
if you were instead extracting DNA from human blood cells, would you need to add
lysozyme? briefly state why or why not? - ANSWER-No because the human blood cells
do not contain a peptidoglycan cell wall
what chemical is added to precipitate DNA at the end of DNA extraction protocol so it
can be concentrated? - ANSWER-alcohol (ethanol) is added to precipitate DNA to
prepare it to be concentrated.
After a DNA extraction you can check the success of your extraction by either a
spectrophotometer reading or running an agarose gel. list one reason why a
spectrophotometer reading is more commonly done - ANSWER-it is much faster and
cheaper to run
under what conditions might you choose to run an agarose gel instead (hint: what can
you learn from a gel that you dont get with a spec)? - ANSWER-agarose gel gives you
more information about the actual makeup of DNA, you can see the band sizes and
know the size of components based on how far they traveled. (check to see if its
smeared when you want to see your DNA [?])
after DNA extraction you can perform a quick spectorphotometer reading at what
wavelength do you measure the following
DNA__________ RNA _____________ contaminants_______________ - ANSWER-
dna: 260 nm
rna: 250 nm
contaminents: 280 nm
what concentrations of agarose should be used for optimal seperation of DNA
fragments of 100, 250, and 350 bp in length?
a. 0.5%
b. 0.8%
c. 2.0%
