Topic 8B: Genome projects and gene technologies Flashcards
What is the human genome project?
The Human Genome Project was an international scientific effort to map the entire human genome, identifying all the genes and their functions.
What is the significance of sequencing a genome?
Sequencing a genome helps identify genes, mutations, and genetic variations, contributing to understanding diseases and developing personalized medicine.
How do scientists make DNA fragments using Reverse Transcriptase?
1)Most cells only contain two copies of each gene, making it difficult to obtain a DNA fragment containing the target gene. But they can contain many mRNA molecules that are complementary to the gene, so mRNA is often easier to obtain.
2)The mRNA molecules can be used as templates to make lots of DNA.The enzyme, reverse transcriptase, makes DNA from an RNA template.The DNA produced is called complementary DNA (cDNA).
3) For example, pancreatic cells produce lots of insulin. They have loads of mRNA molecules complementary to the insulin gene, but only two copies of the gene itself. Reverse transcriptase can be used to make cDNA from the insulin mRNA.
4)To do this, mRNA is first isolated from cells. Then it’s mixed with free DNA nucleotides and reverse transcriptase. The reverse transcriptase uses the mRNA as a template to synthesise a new strand of cDNA.
What is Polymerase Chain Reaction (PCR)?
PCR is a technique used to amplify a specific segment of DNA by using repeated cycles of denaturation, annealing, and extension to generate large quantities of a desired DNA fragment.
What is the role of primers in PCR?
Primers are short, single-stranded DNA sequences that bind to the complementary region of the target DNA, providing a starting point for DNA polymerase to extend and amplify the target sequence.
Why is Taq polymerase used in PCR?
Taq polymerase is used in PCR because it is a heat-stable enzyme that can withstand the high temperatures required for the denaturation step of the PCR process.
How is DNA amplified using PCR?
DNA is amplified through repeated cycles of heating and cooling, where the DNA is denatured, primers are annealed to the target DNA, and the DNA polymerase extends the DNA strand, creating multiple copies of the target region.
What is recombinant DNA technology?
Recombinant DNA technology involves transferring DNA fragments between organisms, creating new genetic combinations. (known as genetic engineering.
How is recombinant DNA created?
Recombinant DNA is created by using restriction enzymes to cut DNA at specific sequences, then ligating the fragments into vectors (e.g., plasmids) and inserting them into host cells.
What is a vector in recombinant DNA technology?
A vector is a DNA molecule (e.g., plasmid or virus) used to carry foreign genetic material into a host cell to create recombinant DNA.
What is transformation in genetic engineering?
Transformation is the process by which a cell takes up foreign DNA from its surroundings, often through methods like electroporation or heat shock.
What is a gene probe?
A gene probe is a short, labeled DNA or RNA sequence that is complementary to a specific target sequence in the genome, used to detect the presence of that sequence in a sample.
How are gene probes used in medical diagnosis?
Gene probes are used to identify specific DNA sequences associated with genetic diseases or infections, allowing for rapid and accurate diagnosis.
What is fluorescent in situ hybridization (FISH)?
FISH is a technique that uses fluorescently labeled gene probes to detect specific DNA or RNA sequences in tissues or cells, often used in genetic diagnostics and research.
What is genetic fingerprinting?
Genetic fingerprinting (or DNA profiling) is a technique used to identify individuals based on unique patterns in their DNA, often used in forensic analysis, paternity testing, and biodiversity studies.
How does genetic fingerprinting work?
Genetic fingerprinting works by comparing non-coding regions of the genome, which vary greatly between individuals, using techniques like PCR and gel electrophoresis to create a unique DNA profile.
What is STR analysis in genetic fingerprinting?
Short Tandem Repeat (STR) analysis involves examining regions of DNA that contain short, repeated sequences that are highly variable between individuals, making them useful for identification in forensic and paternity testing.
How is genetic fingerprinting used in forensics?
In forensics, genetic fingerprinting is used to match DNA samples found at crime scenes with suspects or to identify victims by analyzing their DNA profiles.
How can genetic fingerprinting help in paternity testing?
Genetic fingerprinting can compare the DNA profiles of a child and potential father to identify matching genetic markers, helping to confirm biological relationships.
Human Genome Project
An international research effort aimed at mapping and sequencing the entire human genome, identifying all genes and their functions.
DNA Fragments
Pieces of DNA that can be obtained through techniques such as restriction enzyme digestion or PCR amplification.
Polymerase Chain Reaction (PCR)
A method for amplifying specific segments of DNA through repeated cycles of denaturation, annealing, and extension.
Primers
Short, single-stranded DNA sequences used in PCR to bind to complementary regions of the target DNA and initiate DNA synthesis.
Taq Polymerase
A heat-stable enzyme used in PCR to synthesize DNA strands at high temperatures.
Recombinant DNA Technology
The process of combining DNA from different sources to create new genetic combinations, typically for the purpose of gene insertion or protein production.
Vector
A DNA molecule, such as a plasmid or virus, that is used to carry and insert foreign DNA into a host cell.
Transformation
The process by which a host cell takes up foreign DNA from its environment, resulting in genetic modification.
Gene Probe
A labeled DNA or RNA sequence that is used to detect the presence of a specific target DNA sequence within a sample.
Fluorescent In Situ Hybridization (FISH)
A technique using fluorescent gene probes to detect specific DNA or RNA sequences within cells or tissues.
Genetic Fingerprinting
A technique used to identify individuals based on unique patterns in their DNA, often using PCR and gel electrophoresis.
STR Analysis (Short Tandem Repeat)
A technique for analyzing highly variable regions of DNA, used in genetic fingerprinting for identification purposes.
Forensic DNA Analysis
The use of genetic fingerprinting to solve crimes by matching DNA samples from crime scenes with suspects.
Paternity Testing
The use of genetic fingerprinting to confirm biological relationships between a child and potential father.
How do scientists make DNA fragments using Restriction Endonuclease Enzymes
?
1)Some sections of DNA have palindromic sequences of nucleotides. These sequences consist of antiparallel base pairs (base pairs that read the same in opposite directions).
2)Restriction endonucleases are enzymes that recognise specific palindromic sequences (known as recognition sequences) and cut (digest) the DNA at these places.
3)Different restriction endonucleases cut at different specific recognition sequences, because the shape of the recognition sequence is complementary to the enzyme’s active site.
E.g. the restriction endonuclease EcoRI cuts at GAATTC, but HindIII cuts at AAGCTT.
4)If recognition sequences are present at either side of the DNA fragment you want, you can use restriction endonucleases to separate it from the rest of the DNA.
5)The DNA sample is incubated with the specific restriction endonuclease, which cuts the DNA fragment out via a hydrolysis reaction.
6)Sometimes the cut leaves sticky ends – small tails of unpaired bases at each end of the fragment. Sticky ends can be used to bind (anneal) the DNA fragment to another piece of DNA that has sticky ends with complementary sequences
How do scientists make DNA fragments using a ‘Gene Machine’?
- More recently, technology has been developed so that fragments of DNA can be synthesised from scratch without the need for a pre-existing DNA template.
- Instead, a database contains the necessary information to produce the DNA fragment.
- This means that the DNA sequence does not have to exist naturally — any sequence can be made.
- Here’s how it’s done:
* The sequence that is required is designed (if one doesn’t already exist).
* The first nucleotide in the sequence is fixed to some sort of support, e.g. a bead.
* Nucleotides are added step by step in the correct order, in a cycle of processes that includes adding protecting groups. Protecting groups make sure that nucleotides are joined at the right points, to prevent unwanted branching.
* Short sections of DNA called oligonucleotides, roughly 20 nucleotides long, are produced. Once these are complete, they are broken off from the support and all the protecting groups are removed. The oligonucleotides can then be joined together to make longer DNA fragments.
Why are DNA fragments important in Recombinant DNA technology?
To transfer a gene from one organism to another, you first need to get a DNA fragment containing the gene you want (the target gene).
What are the 3 ways that DNA fragments can be produced?
~A ‘Gene Machine’
~ Restriction Endonuclease Enzymes
~Reverse Transcriptase
