Section 3 - Module 11 Flashcards
What test is used for mutagenicity?
Ames test
What is Ames test?
Inclusions of rat liver enzymes to mimic the chemical modifications of potential mutagens in the human body
Discovery of Ames test?
Liver enzymes could make the chemical more or less mutagenic
Why do bacteriophages grow on some bacterial strains, but not others?
Because of ‘Type I” restriction endonucleases
What do “Type I” endonucleases do?
Recognize specific DNA sequences and cleave DNA
What type of restriction endonucleases are “restriction enzymes”?
Type II
What do “Type II” endonucleases do?
cleaves DNA within the recognition site
What type of restriction endonuclease is more useful in molecular biology?
Type II
The DNA restriction site is a __
palindrome
What is a palindromic sequences?
a sequence of nucleotide bases reads the same on the top strand as the sequence of nucleotide bases reads on the bottom strand of the DNA molecules in 5’ - 3’ direction
What is the resulting form of EcoRI restriction endonuclease?
“sticky” ends
1st endonuclease isolated?
EcoRI and BamHI
3rd endonuclease isolated?
HINDIII
What endonuclease is from the bacterium Escherichia coli?
EcoRI
What endonuclease is from the bacterium Bacillus amyloliquefaciens?
BamHI
What endonuclease is from the bacterium Haemophilus influenza?
HindIII
Why don’t bacterial restriction endonucleases attack the host’s own DNA?
Because the host methylates a base in every cop of the RE site within its own genome.
What can rejoin the DNA sequences cut by the Type II restriction endonuclease?
ligases, rejoining sticky ends
What is gel electrophoresis?
a method of sorting DNA (and RNA) sequence fragments by size. Uses electrical field to more charged DNA towards the positive electrode.
T/F. electrophoresis can occur in a liquid?
False. Electrophoresis must occur in a gel such as agarose
In gel electrophoresis what moves furthest towards the cathode?
Shorter molecules
What visualizes (stains) size-fractionated DNA?
DNA-binding florescent dye
What type of dye is EtBr?
intercalating (between bases)
Migration rate of a _____ DNA molecule is inversely related to log of its molecular mass (or # of base-pairs [bp]).
linear