Karteikarten
DNA Profiling
Karten in diesem Stapel (25)
- 1Where are there short sequences of DNa that are repeated many times?Introns, telomeres and centromeres
- 2What are the repeated sections of DNA known as?Satellite DNA
- 3What happens in the region known as a minisatellite?A sequence of 20-50 base pairs will be repeated from 50 to several hundred times
- 4How many locations do minisatellites occur at?More than 1000 locations in the human genome. The number of times they are present is also known as Variable Number Tandem Repeats (VNTRs)
- 5What is a microsatellite?A microsatellite is a smaller region of 2-4 bases repeated only 5-15 times. They are known as short tandem repeats (STRs).
- 6Where do satellites appear?In the same position on the chromosomes, but the number of repeats of each mini or micro satellite varies between individuals as different lengths of repeats are inherited from parents
- 7Will people ever have the same non-coding DNA?Only identical siblings
- 8How is an image of patterns in the DNA made?DNA profiling and can be used to identify family relations
- 9What is the first stage of DNA profiling?Extracting the DNA. This is done using a tissue sample. When the technique was first invented, a large amount of DNA was needed but now we only need a small fragment of DNA to use the Polymerase Chain Reaction (PCR).
- 10What is the second stage of DNA profiling?Digesting the sample. The DNA strands are cut into small fragments using restriction enconucleases/enzymes. These cut DNA at specific points on the base pairs and produce 'sticky ends'.
- 11What is the third stage of DNA profiling?Separating the DNA fragments. This is done with electrophoresis. This involves laying the cut DNA on a gel and passing an electric current through it. The DNA will spread out as it moves to the positive electrode (as DNA is negatively charged) and the smaller fragments will move further.
- 12What is the fourth stage of DNA profiling?Hybridisation. Radioactive or fluorescent DNA probes are added in excess to the DNA fragments. They are short DNA or RNA sequences complimentary to a known DNA sequence. They bind to this complimentary strand. These DNA probes identify the microsatellite. Excess probes are washed off.
- 13What is the fifth stage of DNA profiling?Seeing the evidence. If radioactive labels were added to the DNA probes, x-ray images are taken of the membrane. If fluorescence was used, a UV light can tell if the florescent tags glow. The fragments give a specific pattern of bars -the DNA profile - which is unique to every individual.
- 14In electrophoresis, where are DNA fragments actually placed?Into wells on a agarose gel strip which also contain a buffering solution to maintain constant PH. There are also DNA fragments of a known length used in one of the wells to use as a control.
- 15What happens to the gel after electrophoresis has been carried out?It is placed in an alkaline buffer solution to denature the DNA fragments, so the two strands of DNA separate, exposing the bases.
- 16What is 'Southern Blotting'?A technique in which these single strands of DNA are transferred onto a nitrocellulose paper of nylon membrane which is placed over the gel. The membrane is covered with several sheets of dry absorbent paper to rid of the alkaline solution that contained the DNA.
- 17How are DNA strands fixed in place?Once they are on the membrane in precisely the same place in which they were on the gel, the DNA fragments are fixed using UV light or heated to 80 degrees.
- 18What is the PCR?The Polymerase Chain Reaction is a way in which DNA can be profiled from just a small amount of original DNA.
- 19How is PCR started?An excess of the four nucleotides (A, T, C, G) are placed in a vial with smaller primer DNA sequences and the enzyme DNA polymerase. This vial is then placed in the PCR machine. The PCR machine can control its temperature quickly, going from one extreme to the other to trigger different stages of the process.
- 20How many copies of the original DNA does around 30 repeats of the PCR machine create?Around one billion copies - more than enough to carry out DNA profiling.
- 21What happens at step one in a PCR machine?At 95 degrees, the DNA fragment is separated into strands of DNA fragment.
- 22What happens at the second stage of the PCR reaction?At 55 degrees, complimentary DNA primers attach to the DNA strands
- 23What happens at the third stage of the PCR reaction?At 72 degrees, DNA polymerase attaches free nucleotides to the DNA strands to make them two new DNA fragments.
- 24Where is DNA Profiling and PCR used in real life?It is used a lot in forensic science such as crime investigations by using samples of DNA found at crime scenes. DNA can be obtained from blood, semen, saliva, root hairs or skin cells. DNA profiling can also be used to prove paternity.
- 25What is the most recent use of DNA profiling?Identifying those at risk of certain diseases as some non-coding microsatallites have been found to be associated with an increased risk of particular diseases including various cancers and heart disease.
Informationen
- Beschreibung
- A level Biology (Module 6) Karteikarten am DNA Profiling , erstellt von Emma Lloyd am 17/05/2017.
- Erstellt von
- Emma Lloyd
- Aufrufe
- 0
- Bewertung