Chapter 21- Manipulating Genomes Flashcards
Define a genome
All the genetic information contained by an organism
How many regions make up coding DNA?
20-25,000 (about 2% of total DNA)
What is coding DNA also called?
Exons
What is non-coding DNA called?
Introns
Define satellite DNA
Short sequences of DNA within introns that are repeated many times
What does VNTR stand for?
Variable number tandem repeats
What is a minisatellite?
A sequence of 20-50 base pairs that is repeated 50 to several hundred times
What is a microsatellite?
A even smaller region of just 2-4 bases repeated 10-15 times
What use does satellite DNA serve in DNA profiling?
Satellites always appear in the same positions on chromosomes, but lengths vary between individuals as different lengths are inherited from each parent.
The more closely related you are to someone the more likely it is that you have very similar patterns.
Define DNA profiling
Producing an image of the patterns in satellite DNA
Name the 5 stages of producing a DNA profile
Extracting
Digestion
Seperation
Hybridisation
Analysis of evidence
How is DNA extracted?
From a tissue sample- the PCR can give scientists enough DNA to develop a profile from a tiny sample
What is the enzyme used to cut DNA into small fragments, and at which stage of DNA profiling does this occur?
During digestion, special enzymes called restriction endonucleases cut DNA at the specific nucleotide sequence called the restriction site.
They make two cuts through each strand of the double helix.
Which stage of DNA profiling is electrophoresis used?
Separation (3)
Which gel is typically used in electrophoresis?
Agarose
Which part of DNA gives it a slight negative charge?
Phosphate groups
Where is the DNA placed in gel electrophoresis?
In wells suspended in a neutral pH solution containing a dye. The wells are located next to the negatively charged cathode
Why do some DNA fragments move faster than others through gel?
DNA molecules with a lower molecular mass will move faster through the gel than others
Which process is used to transfer the DNA from the gel to nylon membranes?
Southern blotting
What is a DNA probe, and which stage of DNA profiling is it used?
A small sequence of DNA or RNA complementary to a known sequence of profiled DNA. They are often fluorescent and bind to their complementary strands in the right conditions of temperature and pH.
This occurs in hybridisation.
How can we identify a relation between two individuals using DNA profiling?
The fragments give a pattern of bars- and although unique to each individual the more closely related two individuals the more similar their pattern of bars will be.
Describe Southern blotting
A nylon membrane is placed over the gel, and covered with several sheets of dry absorbent paper. This draws the alkaline solution containing the DNA through the membrane.
What does PCR stand for?
The polymerase chain reaction
What is the PCR used for?
A version of the natural replication process of DNA, amplifying a small section of DNA
