Final Flashcards
_____ are hereditary units, each consisting of a sequence of DNA that occupies a specific location, or ______, on a chromosome and determines a particular characteristic in an organism.
Genes, locus
Genes occur in alternate forms called ______, which differ in their base sequences and result in alternative expressions of genetic traits that can be dominant or recessive.
alleles
Other reasons for differences in base sequences include DNA ________ resulting from environmental agents (ex: UV light, toxic chemicals) and deletions and other errors that occur during DNA ________.
mutations, replication
Variation in DNA sequences between individuals can be determined with the help of _________ ________.
restriction enzymes
What’s another name for a restriction enzyme?
Restriction endonuclease
Restriction enzymes are molecules that attach to double stranded-DNA at particular _________ sites, resulting in ________ of both DNA strands at or near those sites.
recognition, cutting/cleavage
How do restriction enzymes work?
They attach to double stranded-DNA at particular recognition sites, resulting in cutting/cleavage of both DNA strands at/near those sites.
Recognition sites are very specific sequences of nucleotide bases, usually _ to _ base pairs in length.
4 to 8
Recognition sites are frequently symmetrical, i.e. both DNA strands in the site have the same base sequence when read in a _’ to _’ direction.
5’ to 3’
Restriction enzymes are produced by many species of bacteria, mainly for the purpose of…?
For the purpose of cutting viral DNA that invades them
A _____ is a section of DNA that codes for a particular trait.
gene
Differences in DNA sequences between individuals can be visualized by using _________ __________.
restriction enzymes
Restriction enzymes are molecules produced by ______ that attach to DNA at particular “recognition sites” and cut the DNA
bacteria
Exonucleases – cut nucleic acids on the ____.
Endonucleases – cut nucleic acids within __________ _____
ends, polynucleotide chain
The restriction enzyme ______ binds to the sequence GAATTC.
EcoRI
EcoRI cuts unevenly, leaving overhangs (“______ ____”), which are useful in some laboratory applications
“sticky ends”
________ or ________ during replication can also create or eliminate recognition sites.
Mutations or deletions
Gel Electrophoresis is a technique used to separate molecules based on ______ & ____
charge & size
Gel Electrophoresis uses an _______ ______ applied to a gel ______.
electrical current, gel matrix
Gel Electrophoresis is used to separate ___, ___, and _______.
DNA, RNA, protein
The micropipette (P20) can dispense between \_\_ - \_\_ microliters The micropipette (P200) can dispense between \_\_ - \_\_\_ microliters
2-20
20-200
Electrophoresis is a separatory technique which utilizes an _______ ______ to separate biological molecules so that they may be identified, isolated, or further characterized.
electric field
The most common application is to separate _______ ______ or _______ molecules of different sizes.
Nucleic acids, protein
The DNA and RNA will migrate toward the ________ pole of an electric field.
postive (+)
Electrophoresis is commonly used to separate molecules based entirely or almost-entirely on their _____.
size
Which END of the gel box should DNA samples be loaded at?
The negative end so that they migrate toward the positive end.
How do different-sized DNA fragments migrate in an agarose gel?
Larger molecules will experience greater friction and move less effectively than smaller molecules
Smaller molecules will experience less friction and will move further down the gel than larger molecules
The use of _______ gels as a way to apply ______ has revolutionized electrophoresis of biological molecules and is termed gel electrophoresis.
porous gels, friction
The two most common types of gel are made of _______ and __________.
agarose and polyacrylamide
Agarose gel is used for ___ and ___.
DNA and RNA
Polyacrylamide is used for _______ and ________ ______.
protein and nucleic acids
The higher the concentration of agarose gel, the ______ the pores are within the gel.
smaller
The lower the concentration of agarose gel, the _______ the pores are within the gel.
larger
The size of an unknown DNA fragment may be estimated by comparison to a standard that is run on the same gel. The standard, also called a “_______,” is a sample of DNA containing several differently-sized fragments of known length.
marker
So how is a standard (‘marker’) used?
It is used to estimate the size of DNA fragments in base pairs
The DNA samples from the crime scene and the two suspects will be loaded and run on an agarose gel stained with ________ _______.
ethidium bromide (EtBr)
DNA migrates from _______ to ______ in electrophoresis.
cathode (+) to anode (-)
What is ethidium bromide?
An intercalating agent that binds to DNA and allows it to be visible under UV light
Prepare to cast a 50 ml 0.8% gel by calculating how much agarose you need.
0.8% (w/v) = __ g/100 ml or __g/50 ml
0.8, 0.4
What carries the electrical current?
The buffer
High agarose = ______ pores
Low agarose = ______ pores
Range: __% - __%
small
large
0.5-2.0 %
How much agarose needs to be added to 50ml to make a 1% gel?
1% = 1g/100ml = 0.5g/50ml → need 0.5g
How much agarose needs to be added to 100ml to make a 2% gel?
2% = 2 x 1g/100ml → need 2g
Observe banding patterns on a U.V light box called the __ ___________.
UV transilluminator
What are enzymes?
Biological catalysts that speed up reactions in various ways by directly binding the molecules (in contrast to heat)
Enzymes bind directly to a _________ molecule.
substrate
Enzymes are not _____ __, but __________.
not used up, but recycled
What two things do enzymes do?
1) lower activation energy
2) increase rate of reaction
