Topic 19 Genetic Technology. Flashcards
(31 cards)
Describe the initial steps involved in DNA sequencing.
DNA sequencing begins with mapping the genome, where existing genomic information is utilized to locate specific genes.
This involves fragmenting the gene using restriction endonucleases (restriction enzymes) and inserting these fragments into bacterial artificial chromosomes, creating a genomic DNA library.
The fragments are then further broken down into smaller pieces, preparing them for sequencing.
Explain the role of restriction endonucleases in DNA sequencing.
Restriction endonucleases or restriction enzymes are crucial in DNA sequencing as they cut DNA at specific sequences, allowing for the fragmentation of genes.
This fragmentation is essential for inserting the DNA pieces into bacterial artificial chromosomes, which serve as vectors for cloning.
The precise cutting by these enzymes ensures that the resulting fragments are suitable for further analysis and sequencing.
Describe DNA profiling and its primary purpose.
DNA profiling is a forensic technique that identifies individuals based on their unique DNA characteristics.
It serves two main purposes: first, to identify individuals in criminal investigations by matching DNA found at crime scenes to suspects, and second, to determine genetic relationships among organisms, which can be useful in fields like paternity testing and biodiversity studies.
Explain the role of Polymerase Chain Reaction (PCR) in DNA profiling.
Polymerase Chain Reaction (PCR) is a crucial technique in DNA profiling that amplifies a specific DNA segment, producing millions of copies from a small sample.
This process begins with a mixture of DNA, primers, nucleotides, and Taq polymerase, an enzyme that withstands high temperatures.
The mixture undergoes cycles of heating and cooling to separate DNA strands, allow primers to bind, and enable polymerase to synthesize new DNA strands, ultimately generating enough DNA for analysis.
How does the process of gel electrophoresis contribute to DNA profiling?
Gel electrophoresis is a technique used in DNA profiling to separate DNA fragments based on size.
During this process, an electric current is applied to a gel matrix containing the DNA samples.
Smaller fragments move faster and travel further through the gel than larger ones.
This separation allows forensic scientists to visualize and compare DNA profiles, aiding in the identification of individuals or the determination of genetic relationships.
Define the significance of Taq polymerase in PCR.
Taq polymerase is a heat-stable enzyme derived from thermophilic bacteria found in hot springs, making it essential for PCR.
Its significance lies in its ability to withstand the high temperatures required to denature DNA during the PCR process without losing functionality.
This allows for efficient DNA replication at elevated temperatures.
Do the steps involved in PCR and their importance in DNA profiling.
The PCR process involves several key steps:
First, the DNA sample is mixed with primers, nucleotides, and Taq polymerase.
The mixture is heated to 95°C to separate the DNA strands.
Next, it is cooled to allow primers to bind, followed by raising the temperature to 70°C for DNA polymerase to synthesize new strands.
This cycle is repeated approximately 30 times, exponentially increasing the DNA quantity.
Describe the process of genetic engineering and its purpose.
Genetic engineering is a scientific process that involves the deliberate manipulation of an organism’s genetic material to alter its specific characteristics.
This is achieved by transferring genes into the organism, which can be sourced from various methods such as extracting from donor DNA, synthesizing from mRNA, or chemically creating from nucleotides.
The ultimate goal is to enhance or modify traits for applications in medicine, agriculture, and biotechnology.
What are the essential steps involved in gene transfer when producing a genetically modified organism (GMO)?
- Identify and obtain the required gene (it may be cut from a chromosome, synthesized from nucleotides, or made from mRNA via reverse transcription).
- Amplify the gene using polymerase chain reaction (PCR).
- Insert the gene into a vector (e.g., plasmids, viruses, liposomes).
- Use the vector to deliver the gene into target cells.
- Identify and clone cells with the new gene, often using marker genes.
Tools required:
* Enzymes: restriction endonucleases, DNA ligases, reverse transcriptase.
* Vectors: plasmids, viruses or liposomes.
* Marker genes for identifying modified cells.
What is gene editing, and how does the CRISPR/Cas9 system work?
Gene editing is a type of genetic engineering where the genome of an organism is altered by deleting, inserting, or replacing segments of DNA.
One common method is the CRISPR/Cas9 system:
* CRISPR = Clustered Regularly Interspaced Short Palindromic Repeats.
* Cas9 = CRISPR-associated protein 9.
Cas9 acts like molecular scissors to cut DNA at specific sites for editing.
How does the CRISPR-Cas9 system use guide RNA (gRNA) to edit genes?
- A guide RNA (gRNA) is synthesized in the lab to match the faulty gene.
- The gRNA is attached to Cas9, an enzyme with two active sites that cut DNA, forming the CRISPR-Cas9 complex.
- This complex enters the cell and searches for the matching DNA sequence.
- Once found, Cas9 cuts both strands of DNA at that specific point, creating a double-stranded break in the DNA.
- The cell attempts to repair the break, which enables gene editing where DNA can be deleted, inserted, or replaced.
This process allows scientists to fix genes that cause diseases (cystic fibrosis or sickle cell anaemia).
What are some applications of gene editing, and what are its advantages and social and ethical concerns?
- Treating genetic disorders by correcting faulty genes (e.g., cystic fibrosis, sickle cell anaemia).
- Gene therapy: introducing healthy DNA into a person’s cells to restore normal function.
- Improving crops: editing plant genes to enhance disease resistance.
- Preventing inherited diseases in embryos (though this raises ethical concerns).
Advantages and social and ethical concerns of gene editing:
* It is cheaper, faster and more accurate than previous genetic tools.
* People may use gene editing to alter traits like appearance or intelligence, leading to potential social inequalities.
* Gene editing might only be accessible to the wealthy, making healthcare increasingly unfair.
* Editing one gene could unintentionally disrupt other important genes and cause harmful effects.
* Some individuals may see gene editing as interfering with nature or going against religious beliefs.
Explain how plasmids are used in genetic engineering.
Plasmids serve as vectors in genetic engineering due to their natural occurrence, small size, and ease of manipulation.
The process begins with cutting both the plasmid and the target gene using the same restriction enzymes to create complementary ends.
These fragments are then incubated together, allowing base pairing to occur. DNA ligase seals the fragments, forming a recombinant DNA molecule that can be introduced into host cells for further study or application.
How is recombinant DNA created and what is its significance?
Recombinant DNA is formed by combining DNA from two different organisms.
The creation process involves cutting DNA with restriction enzymes, ligating it into plasmids, and introducing these plasmids into host cells.
This technology allows for the production of essential proteins, such as insulin, factor VIII, and adenosine deaminase.
Do explain the advantages of using genetically engineered bacteria for protein production.
Genetically engineered bacteria offer several advantages for protein production, particularly in the case of human proteins like insulin.
These bacteria can produce high-quality proteins rapidly and in large quantities, which is essential for medical applications.
Additionally, using bacteria reduces the risk of contamination associated with proteins derived from human donors, such as the potential transmission of diseases like HIV.
This method is not only efficient but also cost-effective, making it a preferred choice in biotechnology.
Discuss the various types of vectors used in genetic engineering.
In genetic engineering, several types of vectors are utilized to transfer genetic material into host cells.
Plasmids are the most common due to their simplicity and ease of use.
Other vectors include bacteriophages, which can infect bacterial cells, liposomes that encapsulate DNA for delivery, and yeast artificial chromosomes that can carry larger DNA fragments.
Describe the role of adenosine deaminase (ADA) in treating severe combined immunodeficiency (SCID).
Adenosine deaminase (ADA) is a crucial enzyme used in the treatment of severe combined immunodeficiency (SCID), a genetic disorder that severely weakens the immune system.
When gene therapy is not an option, ADA can be produced using genetically modified insect larvae.
This treatment helps to restore immune function by breaking down toxic metabolites that accumulate in the absence of ADA, thus improving the patient’s ability to fight infections.
How does genetic technology help in screening for breast cancer?
Genetic technology allows screening for genetic conditions such as breast cancer caused by faulty alleles of the BRCA1 and BRCA2 genes.
If a person is identified as a positive carrier, they may choose to undergo preventive procedures, such as a mastectomy, to reduce their risk of developing breast cancer.
How does bioinformatics contribute to the field of genetics and medicine?
In genetics and medicine, bioinformatics is used to build databases of gene sequences and complete genomes, facilitating the study of genetic relationships among organisms.
Define pre-implantation genetic diagnosis and its purpose in reproductive health.
Pre-implantation genetic diagnosis (PGD) is a technique used in conjunction with invitro fertilization (IVF) to test embryos for genetic disorders before they are implanted into a woman’s uterus.
The purpose of PGD is to identify embryos that carry specific genetic conditions, allowing parents to make informed decisions about which embryos to implant.
This process helps reduce the risk of genetic diseases being passed on to the child, thereby improving reproductive outcomes and family health.
Describe the procedures and differences between chorionic villus sampling and amniocentesis.
Chorionic villus sampling (CVS) and amniocentesis are both prenatal testing methods used to analyze fetal DNA for genetic disorders.
CVS is performed between 10 to 13 weeks of pregnancy, involving the collection of a sample of placental tissue called the chorion removed by a narrow needle (0.8 mm in diameter), which provides quicker results. The procedure is monitored by ultrasound scanning.
In contrast, amniocentesis is conducted between 15 to 16 weeks, where a sample of amniotic fluid containing fetal cells is obtained. Amniocentesis typically takes longer for results, as fetal cells need to be cultured.
Both tests carry risks and are used based on specific clinical indications.
Explain the use and describe the process of ultrasound scanning.
Ultrasound scanning is used to visualise the fetus and locate the position of the placenta, fetus and umbilical cord.
A suitable point for the insertion of the hypodermic syringe needle is chosen and this is marked on the abdominal skin surface. Generally, this position is away from the fetus, umbilical cord and placenta.
Explain the social and ethical issues surrounding genetic testing.
Genetic testing raises several social and ethical concerns, including the potential risk of harm to the fetus, such as miscarriage during procedures like CVS and amniocentesis.
The outcomes of genetic tests may lead to difficult decisions, including the possibility of abortion if a serious genetic disorder is detected.
Ethical debates also focus on the right to life and the implications of choosing to terminate pregnancies based on genetic information.
Additionally, the financial burden of raising a child with a genetic disorder poses significant societal questions about healthcare access and support.
