DNA Technology: Genetic Screening & Probes | A-level Biology | OCR, AQA, Edexcel
27.2 هزار بار بازدید -
5 سال پیش
-
DNA Technology: Genetic Screening &
DNA Technology: Genetic Screening & Probes in a Snap! Unlock the full A-level Biology course at http://bit.ly/2K1CQsz created by Adam Tildesley, Biology expert at SnapRevise and graduate of Cambridge University.
SnapRevise is the UK’s leading A-level and GCSE revision & exam preparation resource offering comprehensive video courses created by A* Oxbridge tutors. Our courses are designed around the OCR, AQA, SNAB, Edexcel B, WJEC, CIE and IAL exam boards, concisely covering all the important concepts required by each specification. In addition to all the content videos, our courses include hundreds of exam question videos, where we show you how to tackle questions and walk you through step by step how to score full marks.
Sign up today and together, let’s make A-level Biology a walk in the park!
The key points covered in this video include:
1. Introduction to Genetic Screening
2. DNA Probes
3. Locating Specific Alleles
4. Screening for Many Diseases
Introduction to Genetic Screening
Many human diseases are caused by mutations to genes. DNA sequencing has allowed scientists to determine which mutations can cause or predispose individuals to a certain disease. Individuals who have a family history of disease may decide to undergo genetic screening. Genetic screening is the study of an individual’s DNA to identify whether an individual possesses alleles associated with a genetic disease. Scientists can genetically screen individuals by locating specific alleles of a gene using DNA probes.
DNA Probes
DNA probes are short sections of DNA that are complementary to a known DNA sequence. Probes are labelled so that they can be easily identified using fluorescence or radioactivity. Fluorescent probes can be visualised as they emit light at a different wavelength when light shines on them. Radioactive probes can be visualised as they expose X-ray film.
Locating Specific Alleles
DNA probes are used to locate a mutant allele which causes a specific disease using the following stages: 1) The sequence of the mutant allele is determined by DNA sequencing or by finding the DNA sequence in a genetic database. 2) A probe is made by synthesising a fragment of DNA that has a complementary base sequence to the mutant allele. 3) This DNA probe is labelled with a fluorescent marker. 4) The DNA probe is then amplified using PCR to produce many copies of the probe. 5) Many copies of DNA from the person being screened are then heated until they denature and separate into single strands. 6) The separated single DNA strands are then mixed with the DNA probes and the temperature is lowered. 7) If the individual contains the mutant allele, the probes will bind to the DNA fragments that are complementary in a process called hybridisation. 8) The DNA is then washed clean of any unattached probes. The hybridised DNA can then be detected because of the presence and intensity of fluorescence. 9) The hybridised DNA can then be detected because of the presence and intensity of fluorescence.
Screening for Many Diseases
Individuals can be screened for many different genetic diseases at the same time. This is done by fixing hundreds of different DNA probes in an array on a glass side. These DNA probes are complementary to sequences of DNA that are known mutations which cause genetic disorders. These DNA probes are designed to only fluoresce when they are bound to a DNA fragment by hybridisation. Many copies of DNA from the individual that is being tested are then added to the glass slide. If any of the DNA fragments are complementary to a specific probe then it will bind and the probe will fluoresce. This means that the tested individual is carrying that mutation.
Summary
Genetic screening is the study of an individual’s DNA to identify whether an individual is susceptible to or a carrier of a genetic disease
An allele that is associated with a specific disease can be located by using DNA probes
These DNA probes are short sequences of DNA that are complementary to the DNA sequence of the mutant allele
DNA probes are labelled with a radioactive or fluorescent marker to allow the DNA to be detected
A sample of DNA from an individual being screened is amplified and then denatured into single strands of DNA
Probes are added and if a probe is complementary to a fragment of DNA then it will bind in a process called hybridisation
Any fluorescence or radioactivity detected means that the individual contains the allele for that specific disease
Many genetic diseases can be screened for at the same time by fixing many different fluorescent DNA probes onto a glass slide
WHen complementary DNA fragments bind then the probe fluoresces, showing the individual contains an allele for that specific disease
The intensity of the fluorescence indicates whether the individual carries one or two mutant alleles
SnapRevise is the UK’s leading A-level and GCSE revision & exam preparation resource offering comprehensive video courses created by A* Oxbridge tutors. Our courses are designed around the OCR, AQA, SNAB, Edexcel B, WJEC, CIE and IAL exam boards, concisely covering all the important concepts required by each specification. In addition to all the content videos, our courses include hundreds of exam question videos, where we show you how to tackle questions and walk you through step by step how to score full marks.
Sign up today and together, let’s make A-level Biology a walk in the park!
The key points covered in this video include:
1. Introduction to Genetic Screening
2. DNA Probes
3. Locating Specific Alleles
4. Screening for Many Diseases
Introduction to Genetic Screening
Many human diseases are caused by mutations to genes. DNA sequencing has allowed scientists to determine which mutations can cause or predispose individuals to a certain disease. Individuals who have a family history of disease may decide to undergo genetic screening. Genetic screening is the study of an individual’s DNA to identify whether an individual possesses alleles associated with a genetic disease. Scientists can genetically screen individuals by locating specific alleles of a gene using DNA probes.
DNA Probes
DNA probes are short sections of DNA that are complementary to a known DNA sequence. Probes are labelled so that they can be easily identified using fluorescence or radioactivity. Fluorescent probes can be visualised as they emit light at a different wavelength when light shines on them. Radioactive probes can be visualised as they expose X-ray film.
Locating Specific Alleles
DNA probes are used to locate a mutant allele which causes a specific disease using the following stages: 1) The sequence of the mutant allele is determined by DNA sequencing or by finding the DNA sequence in a genetic database. 2) A probe is made by synthesising a fragment of DNA that has a complementary base sequence to the mutant allele. 3) This DNA probe is labelled with a fluorescent marker. 4) The DNA probe is then amplified using PCR to produce many copies of the probe. 5) Many copies of DNA from the person being screened are then heated until they denature and separate into single strands. 6) The separated single DNA strands are then mixed with the DNA probes and the temperature is lowered. 7) If the individual contains the mutant allele, the probes will bind to the DNA fragments that are complementary in a process called hybridisation. 8) The DNA is then washed clean of any unattached probes. The hybridised DNA can then be detected because of the presence and intensity of fluorescence. 9) The hybridised DNA can then be detected because of the presence and intensity of fluorescence.
Screening for Many Diseases
Individuals can be screened for many different genetic diseases at the same time. This is done by fixing hundreds of different DNA probes in an array on a glass side. These DNA probes are complementary to sequences of DNA that are known mutations which cause genetic disorders. These DNA probes are designed to only fluoresce when they are bound to a DNA fragment by hybridisation. Many copies of DNA from the individual that is being tested are then added to the glass slide. If any of the DNA fragments are complementary to a specific probe then it will bind and the probe will fluoresce. This means that the tested individual is carrying that mutation.
Summary
Genetic screening is the study of an individual’s DNA to identify whether an individual is susceptible to or a carrier of a genetic disease
An allele that is associated with a specific disease can be located by using DNA probes
These DNA probes are short sequences of DNA that are complementary to the DNA sequence of the mutant allele
DNA probes are labelled with a radioactive or fluorescent marker to allow the DNA to be detected
A sample of DNA from an individual being screened is amplified and then denatured into single strands of DNA
Probes are added and if a probe is complementary to a fragment of DNA then it will bind in a process called hybridisation
Any fluorescence or radioactivity detected means that the individual contains the allele for that specific disease
Many genetic diseases can be screened for at the same time by fixing many different fluorescent DNA probes onto a glass slide
WHen complementary DNA fragments bind then the probe fluoresces, showing the individual contains an allele for that specific disease
The intensity of the fluorescence indicates whether the individual carries one or two mutant alleles
5 سال پیش
در تاریخ 1398/04/16 منتشر شده
است.
27,216
بـار بازدید شده