L1: Intro 2 Medical Genetics

Question 1

Why do different tissues exist?

Answer 1

Some genes are switchef on & some genes are switched off, e.g in muscle cells genes related to muscle contraction are activated, while in nerve cells genes responsible for signal transmission are switched on. Although all cells contain the same DNA, this selective expression of genes enables the development of various tissue types, such as muscle, nerve, and skin tissue.

Question 2

How does mRNA arise?

Answer 2

Arises during process of transcription where info in a gene’s DNA sequence is copied into RNA.
In the nucleus of eukaryotic cells, RNA polymerase binds to the promoter region of a gene, signalling start of transcription.
RNA polymerase moves along the DNA strand, unwinding it and synthesizing a complementary RNA strand from the DNA template. The RNA sequence is built using nucleotides, with adenine (A) in DNA pairing with uracil (U) in RNA, and thymine (T) pairing with adenine (A).
Once RNA polymerase reaches the termination signal on the DNA, transcription stops. The newly formed RNA strand is released.
The pre-mRNA undergoes processing, which includes capping at the 5’ end, polyadenylation (adding a poly-A tail) at the 3’ end, splicing where introns (non-coding regions) are removed, and exons (coding regions) are joined together.
After processing, the mature mRNA leaves the nucleus and enters the cytoplasm, where it is used in translation to produce proteins.

Question 3

What does the structure of ATP consist of?

Answer 3

Triphosphate (3 high energy phosphate groups), & adenosine (ribose - sugar & adenine - base)

Question 4

What is a nucleotide & give an example

Answer 4

Basic building block of nucleic acids like DNA & RNA, consists of 3 components which is a nitrogenous base (a purine - adenine or guanine, or a pyrimidine - cytosine or thymine (DNA) or uracil (RNA). A 5-carbon sugar which is either deoxyribose (DNA) or ribose (RNA). 1 or more phosphate groups which link nucleotides together to form the sugar-phosphate backbone of DNA or RNA strands (alternating sugar & phosphate groups form this -charged backbone due to phosphate groups & this is what makes DNA & RNA molecules -charged overall)
Example: ATP

Question 5

How is DNA compacted into a cell?

Answer 5

The 2 strands of DNA coil into a helix.
DNA wraps around proteins called histones which form structures called nucleosomes.
Nucleosomes coil further into solenoids.
Solenoids form a more compact structure called chromatin (functional state of DNA during most of cell’s life).
During cell division chromatin condenses further to form chromatids (arms of chromosomes)

Question 6

How many base pairs of DNA are in a single loop of chromatin?

Answer 6

100,000 base pairs of DNA

Question 7

What are autosomal pairs & what is the 23rd pair of the chromosome referred to?

Answer 7

There are 22 autosomal pairs (non-sex chromosomes) consisting of 1 chromosome inherited from mother & 1 from father & these chromosomes carry genes that determine traits & functions in the body.
23rd pair is the sex-determining chromosome (X or Y)

Question 8

What is a karyotype?

Answer 8

The complete set of chromosomes in an individual, organized and displayed in a systematic way typically by size, shape, and number.

Question 9

What are telomeres?

Answer 9

Protective caps at the ends of chromosomes that act as buffer regions made up of repetitive DNA sequences and proteins. Their primary function is to protect the chromosome ends from deterioration or fusion with neighboring chromosomes during cell division. Each time a cell divides, the telomeres shorten, which limits the number of times a cell can divide. When telomeres become too short, the cell either stops dividing or undergoes programmed cell death (apoptosis).

Question 10

How can specific sections of DNA be visualised?

Answer 10

Fluorescent labelling allows you to know the sequences of certain DNA segments, allowing scientists to create fluorescently labelled molecules that bind to specific areas on the chromosome to be observed under a microscope

Question 11

What are the 2 types of sex-linked inheritance?

Answer 11

Y-linked inheritance: only males affected as trait is carried on Y chromosome which isn’t present in females. All male offspring of an affected male will be affected
X-linked dominant: can affect both males & females, an individual with 1 copy of the dominant allele will show the trait. Females only need one copy of the dominant allele on one of their X chromosomes to express the trait. This means if a female inherits the dominant allele from either parent, she will be affected. Males have only one X chromosome, so if they inherit the dominant allele on that X chromosome, they will also express the trait.
Since males only pass their X chromosome to daughters, all daughters of an affected male will inherit the dominant trait, but none of his sons will (since sons inherit the Y chromosome from their father).

Question 12

What are autosomal recessive diseases?

Answer 12

Conditions caused by recessive alleles so trait is only expressed if individual has 2 copies of the recessive allele (1 from each parent). Carriers have only 1 copy which can be passed on

Question 13

What are the types of genetic diseases?

Answer 13

Chromosomal abnormalities e.g down syndrome (extra copy of chromosome 21/trisomy 21)
Single-gene disorders e.g adult polycystic kidney disease (APKD - affects kidney function caused by mutations in a single gene) cystic fibrosis (affects respiratory & digestive systems caused by mutations in CFTR gene), familial hypercholesterolemia (causes high cholesterol levels leading to cardiovascular disease), hereditary nonpolypodis colorectal cancer (HNPCC - increases risk of colorectal & other cancers), huntington disease (neurogenerstuve disorder caused by mutation in the HTT gene), sickle cell disease (blood disorder caused by mutation in harmoglobin gene), thalassemia (blood disorder caused by mutations affects hameoglobin production)
Multifactorial disorders e.g congenital heart defects, diabetes, certain cancers (influenced by multiple genes & environmental factors)
Mitochondrial disorders e.g diabetes mellitus & deafness (DAD), leber’s hereditary optic neuropathy (LHON) (caused by mutations in mitochondrial DNA affecting cellular energy production)

Question 14

How can you identify genetic mutations?

Answer 14

Identifying polymorphisms (variations in DNA sequences among individuals)
Mapping phenotype to genotype (linking observable traits (phenotype) to specific genetic variations (genotype)

Question 15

What technologies are involved in identifying genetic mutations?

Answer 15

Chromosome structure analysis using DNA hybridisation (identifies specific DNA sequences using complementary DNA probes that are labelled & bind to complementary DNA sequences)
Southern blotting using DNA probes & restriction fragment length polymorphism (RFLP - detects variations in DNA sequences by comparing lengths of restriction enzyme-digested DNA fragments)
DNA fingerprinting: involves amplifying & analysing specific DNA regions to generate a unique DNA profile which are typically used in forensic analysis & genetic identification
Genetic sequencing: allows for determination of the precise sequence of nucleotides in DNA to reveal mutations
Polymerase chain reaction (PCR): amplifies specific DNA sequences to analyse them in detail
Chromatography: separates DNA fragments based on size for further analysis

Question 16

Give an example of technology used in forensic science

Answer 16

DNA fingerprinting involves comparing PCR products from different samples to identify genetic matches commonly user in criminal investigations

Question 17

What are the types of genetic mutations in cancer cells?

Answer 17

Mutated growth signals: mutations in genes that lead to continuous activation of growth signals causing unchecked cell proliferation
Insensitive to antigrowth signals: ignoring signals that normally inhibit cell growth & so bypassing regulatory mechanisms
Evading apoptosis: mutations that prevent apoptosis allowing damaged cells to survive & proliferate
Enhanced replication: enabling them to divide more frequently
Angiogenesis: stimulate formation of new blood vessels (angiogenesis) to supply nutrients & oxygen supporting tumour growth
Tissue invasion & metastasis: invading surrounding tissues & spread to distant sites (metastasis) allowing cancer to affect multiple areas of the body

Question 18

How can cancer mutations be identified?

Answer 18

Conducting a biopsy & genetic analysis whereby tumour samples are analysed

Question 19

What are the different mutations in the CFTR gene that can cause cystic fibrosis?

Answer 19

Class 1: complete lack of CFTR protein production
Class 2: misfolded CFTR protein that can’t reach cell membrane
Class 3: disrupted regulation of CFTR channel which can’t open & close properly
Class 4: alters conductance of CFTR channel affecting its ability to transport chloride ions
Class 5: low levels of CFTR protein due to rapid degradation

Question 20

What are the major treatments for cystic fibrosis?

Answer 20

Potentiators: helps keep CFTR channel in open state (Class 3)
Correctors: assists CFTR protein in folding correctly & reaching cell membrane (Class 2)
Amplifiers: increases expression levels of CFTR protein (Class 1 & 5)
Combination of these can be used for patients with compound heterozygosity (mutations from both parents)

Question 21

What techniques can be used to diagnose down syndrome?

Answer 21

Amniocentesis: prenatal test where amniotic fluid is sampled from the amniotic sac surrounding the fetus containing fetal cells that can be analysed
Quantitative fluorescence-polymerase chain reaction (QF-PCR): fluorescent dyes are used to amplify & measure specific DNA regions & can detect extra copy by comparing amount of fluorescent signal from different DNA regions. Normal pattern shows 2 peaks indicating 2 copies of chromosome 21 whereas Trisomy 21 shows 3 peaks therefore 3 copies

Question 22

What is somatic cell therapy & its disadvantages?

Answer 22

Involves editing a patient’s cells in lab (in vitro) & then reintroducing them into the body to treat the disease e.g beta thalassemia by replacing defective cells with genetically corrected ones
High cost & need for personalised treatment

Question 23

What is involved in gene replacement therapy?

Answer 23

Inserting a normal gene into a patient’s cells by using vectors such as retroviral vectors (RNA viruses that integrate into the DNA of dividing cells. They can cause issues with integrating near other genes), adenoviral vectors (DNA viruses for non-dividing cells. Don’t integrate into the host genome but can still deliver therapeutic genes), lentiviral vectors (RNA viruses that can work in both dividing & non-dividing cells. Have a more stable integration but are complex to use)

Question 24

What are the difficulties in gene replacement therapy?

Answer 24

Achieving high level expression of the therapeutic.
Ensuring vectors reach & deliver genes to the target tissue efficiently.

Question 25

What can gene replacement therapy treat?

Answer 25

Haemophilia B by inserting a normal clotting factor gene into the liver cells of patients so that the liver can produce the necessary clotting factor, reducing the need for regular infusions of the factor

Question 26

Give an example of how gene replacement therapy can be used in vivo (administered directly into patient's body)

Answer 26

Treating otoferlin gene mutations (inherited hearing loss). Local administration of viral vectors are used to deliver a healthy copy of the otof gene directly to the inner ear's hair cells by targeting the cochlea to restore proper function to the hair cells which are crucial for hearing.

Question 27

What is CRISPR-Cas9 (Clustered regularly interspaced short palindromic repeats associated protein 9)?

Answer 27

Discovered in bacterial immune system in which the CRISPR sequences are interspersed with short DNA sequences from previous infections used to remember & defend against viral infections. Cas9 is an RNA-guided DNA endonuclease that introduces double strand breaks (dsDNA breaks) at specific locations in the genome & its directed to a specific DNA sequence by a guide RNA (gRNA) which binds to a complementary DNA sequence, allowing cas9 to make the cut

Question 28

Explain the process of gene editing with CRISPR-Cas9

Answer 28

gRNA matches to a specific DNA sequence in the genome directing the cas9 protein to the location. PAM (protospacer adjacent motif) is a short, conserved DNA sequence that cas9 binds to before making the cut to ensure specificity. Cas9 introduces a double-strand break at the site. Cells repair the double-strand breaks via 2 main pathways which are non-homologous end joining (NHEJ - insertions or deletions (indels) that can disrupt gene function, homology-directed repair (HDR - can be used to introduce specific changes if a DNA template is provided)

Question 29

What are the applications of CRISPR-Cas9?

Answer 29

Gene knockout: disabling a gene by introducing mutations Gene correction: replacing or repairing faulty genes with correct sequences Gene activation or silencing: by adding or removing transcription factors or other regulatory elements Gene replacement therapy Precision gene editing: modified versions of cas9 with altered cutting abilities or no cutting abilities to focus on transcriptional activation or repression Visualising genomic features: attaching fluorescent proteins to CRISPR components to visualise DNA sequences

Question 30

What is Hereditary angioedema (HAE) & how can CRISPR-Cas9 treat it?

Answer 30

Condition that causes sudden & severe swelling in parts of the body like throat which can be life-threatening. Caused by mutations in the C1 inhibitor gene which affects regulation of blood plasma proteins involved in inflammation & swelling. CRISPR-Cas9 is delivered into patient's cell to targets mutated C1 inhibitor gene, precise cuts are made at specific locations of the gene. Cell's natural repair mechanisms insert a correct copy of the gene at the cut site to correct the gene sequence & restore the normal function of the C1 inhibitor protein, thus reducing frequency & severity of angioedema attacks

Question 31

What are the 2 types of genetic tests?

Answer 31

Genome-wide association studies (GWAS): identifying genetic variants associated with specific diseases or responses to treatments across the genome Single nucleotide polymorphisms (SNPs): common genetic variations that can affect drug metabolism & efficacy

Question 32

How can precision medicine assess how well a patient is likely to respond to specific treatment?

Answer 32

By analysing mRNA & other biomarkers

Question 33

How can oncology be benefited significantly from precision medicine & give an example

Answer 33

A biopsy is conducted to get a sample of the tumour to know the cancer's cellular & molecular characteristics. The DNA from the biopsy is sequenced to identify specific genetic mutations or alterations associated with the cancer to help classify it more precisely. Data from the sequencing help predict how aggressive the cancer might be & how likely it is to respond to various treatments. Targeted therapies can be chosen based on the genetic profile of the cancer thus reducing side effects. Example: Non-small cell lung cancer (NSCLC) DNA sequencing can identify mutations in genes like EGFR or ALK. Targeted therapies like EGFR inhibitors or ALK inhibitors can be prescribed based on the specific mutation present

Question 34

How can risks of passing a condition to offspring be reduced?

Answer 34

Options such as pre-implantation genetic diagnosis (PGD) during IVF

Question 35

Explain the process of PCR

Answer 35

PCR is used to amplify/generate multiple copies of a specific DNA region. A thermal cycler is a machine used to control the temperature changes during PCR cycles At ~98.5 the double helix is separated into 2 single strands by denaturation. At ~50-65 depending on the primer (short sequences of nucleotides), specific primers bind to their complementary sequences on the single-stranded DNA. Primers are designed to flank the region of interest. At ~72 DNA polymerase extends the DNA strand from the primer using the original strand as a template. DNA polymerase adds complementary nucleotides to synthesise the new DNA strand. Process is repeated through 30-40 cycles & each cycle doubles amount if DNA leading ti exponential amplification

Question 36

Explain the process of Agarose gel electrophoresis

Answer 36

Used to separate DNA, RNA & proteins based on their size & charge. Agarose (polysaccharide) is dissolved in a buffer solution & poured into a gel mold to solidify. The DNA, RNA or protein samples are mixed with a loading dye & pipetted into wells in the gel. An electric current is applied across the gel causing the charged molecules to move through the agarose matrix. DNA & RNA are -charged do migrate to +electrode whereas proteins can be either + or - depending on their pH & environment. Larger molecules move slowly & travel shorter distances across the gel. The gel is stained with a dye (e.g ethidium bromide for DNA) that binds to the molecules & fluoresces under UV light. Bands representing different sizes of molecules are visualised & analysed

Question 37

What are the applications of Agarose gel electrophoresis?

Answer 37

DNA Fragment Analysis: determine the size of PCR products or restriction digest fragments. RNA Analysis: to check the integrity and size of RNA samples. Protein Separation: to analyze protein size and purity. Genotyping and Sequencing: to verify genetic markers and sequence variants.

Question 38

Explain the process of Dideoxy method of DNA sequencing/Sanger sequencing?

Answer 38

Uses chain-terminating dideoxynucleotides (ddNTPs) to determine the sequence of DNA. ddNTPs are modified nucleotides lacking a 3' hydroxyl group (-OH) on the sugar moiety preventing the addition of further nucleotides, terminating DNA strand elongation. Four types of ddNTPs are used each labeled with a different fluorescent dye or radioisotope: ddATP, ddCTP, ddGTP, and ddTTP. The DNA to be sequenced is used as a template & mixed with primers. A mixture is prepared containing DNA Polymerase to synthesize new DNA strands in the PCR process, dNTPs which are regular nucleotides (A, T, C, G) for elongation, ddNTPs that are chain terminators for sequencing used during the extension phase of DNA synthesis to terminate the growing DNA strand. The resulting fragments which are terminated at different points by ddNTPs. Load the reaction products onto a gel or capillary electrophoresis system to separate the fragments by size. These are detected based on the fluorescent or radioactive labels attached to the ddNTPs that when passed through a detector, the fluorescent dyes emit light at different wavelengths corresponding to the specific ddaNTP incorporated, allowing for identification of each nucleotide at the end of the fragments. Output is a chromatogram or sequencing trace showing peaks of different colors. Each color corresponds to a specific ddNTP, revealing the DNA sequence.

Question 39

What colour fluorescent dyes correspond to each ddNTP?

Answer 39

ddATP: red ddCTP: blue ddGTP: green ddTTP: yellow

Question 40

What are the benefits of modern techniques like Sanger sequencing?

Answer 40

Single-Tube Reactions: allow sequencing in a single reaction, simplifying the process. Fluorescent Labels: Provide real-time detection and automation, improving efficiency and accuracy.

Question 41

Explain the process of High-throughput DNA sequencing/Next generation sequencing (NGS)

Answer 41

modern technique that allows for rapid and cost-effective sequencing of entire genomes or specific regions of interest. The genomic DNA is broken into smaller fragments & each fragment is labeled with a unique barcode or tag allowing for identification and tracking of the fragments during sequencing. The tagged DNA fragments are attached to a large chip or flow cell, where they are spatially organized, & the DNA fragments are amplified on the chip. Each fragment is replicated to produce multiple copies, creating clusters of identical sequences. As each base (A, T, C, G) is incorporated into the growing DNA strand, it is tagged with a fluorescent dye. A specialized camera or imaging system detects the fluorescence emitted from each base. This detection occurs at each spot on the chip, corresponding to the DNA clusters. The pattern of fluorescence is recorded and used to determine the sequence of bases in each DNA fragment. The sequences obtained from overlapping fragments are aligned to a reference genome or assembled de novo, & the aligned sequences are analyzed to identify genetic variations, mutations, or other relevant information.

Question 42

What are the benefits of High-throughput DNA sequencing?

Answer 42

High-throughput: Capable of sequencing millions of DNA fragments simultaneously. Cost-Effective: Reduces the cost of sequencing compared to traditional methods. Comprehensive: Can sequence entire genomes, coding regions (exomes), or targeted regions to identify variants associated with diseases Metagenomics: Studying genetic material from environmental samples to identify microbial communities. Accuracy: Provides high-resolution data with fewer errors compared to earlier methods.

Question 43

Explain the process of Third-generation DNA sequencing/Single-molecule sequencing

Answer 43

allows for the direct sequencing of long DNA strands without the need for amplification, offering rapid and comprehensive genetic analysis. Unlike earlier methods that involve amplifying DNA fragments, third-generation sequencing reads individual DNA molecules directly. No amplification is required reducing errors introduced during amplification and preserves the original sequence. Single-stranded DNA molecules are passed through a nanopore, which is a tiny hole in a membrane. An electric current is applied across the membrane. As each base (A, C, G, T) passes through the nanopore, it causes a distinct change in the current. The specific changes in current are used to infer the DNA sequence, as different bases affect the current in unique ways.

Question 44

What are the advantages of Third-generation DNA sequencing?

Answer 44

Long Reads: Capable of sequencing long DNA strands, which is beneficial for analyzing complex genomic regions and structural variations. Portable: Devices using this technology can be compact and portable, allowing for on-site sequencing with minimal equipment. Real-Time Sequencing: Provides immediate results, making it useful for rapid diagnostics and field research.

Question 45

How is SARS-CoV-2 tested?

Answer 45

Real-Time Polymerase Chain Reaction (RT-PCR): Since SARS-CoV-2 is an RNA virus, the first step in RT-PCR involves using reverse transcriptase to convert viral RNA into complementary DNA (cDNA). This cDNA then serves as the template for the PCR amplification. During PCR, SYBR dyes or other fluorescent dyes bind specifically to double-stranded DNA. As the amount of double-stranded DNA increases, the fluorescence signal emitted by these dyes increases, allowing for the detection of the virus. The intensity of the fluorescence signal correlates with the amount of viral DNA present in the sample. By measuring this fluorescence, scientists can determine the presence and quantity of SARS-CoV-2 in the sample. Negative Sample: Shows no increase in fluorescence, indicating no detectable viral DNA. Positive Sample: Exhibits a significant increase in fluorescence as the PCR reaction progresses, indicating the presence of viral DNA. The level of fluorescence can also provide information on the quantity of viral particles.

Question 46

What are the advantages & disadvantages of RT-PCR?

Answer 46

High Sensitivity: RT-PCR is highly sensitive and can detect low levels of viral RNA, making it a reliable method for diagnosing infections. Specificity: The use of specific primers and reverse transcriptase ensures accurate detection of SARS-CoV-2. Limitations: Time and Resources: RT-PCR requires specialized equipment and can be time-consuming. Sample Quality: The accuracy of results depends on the quality of the sample collected.

Question 47

How can bacterial infections like Clostridium difficile be tested?

Answer 47

Clostridium difficile (C. difficile) is a bacterium that causes antibiotic-associated diarrhea and can lead to more severe conditions such as colitis. It is a common concern in hospital settings, especially where antibiotic use is prevalent. Stool Samples: Collected from patients who are exhibiting symptoms of diarrhea, particularly if they have been on antibiotics. PCR Ribotyping: To identify the strain of C. difficile present in the stool sample. PCR is used to amplify specific DNA regions. For C. difficile, the 16S-23S rRNA intergenic spacer region is often targeted for ribotyping. Fragment Analysis: The PCR products are separated by size using gel electrophoresis or other separation techniques. Different strains of C. difficile will produce distinct DNA band patterns. The bands on the gel correspond to different strains of C. difficile based on their ribotype. By comparing the band patterns with known ribotypes, the specific strain of C. difficile can be identified.

Question 48

What are the advantages of PCR ribotyping?

Answer 48

Specificity: PCR ribotyping provides a high level of specificity, allowing for precise identification of bacterial strains. Sensitivity: The method can detect low levels of bacterial DNA, making it suitable for identifying infections even in patients with mild symptoms. Rapid Results: PCR and ribotyping can provide results more quickly than traditional culturing methods, enabling timely management of infections.

Question 49

Give examples of cloned human genes & gene products

Answer 49

Insulin: Production: Human insulin can be produced using recombinant DNA technology. A gene encoding human insulin is inserted into bacterial or yeast cells, which then produce insulin that can be purified and used for diabetes treatment. Human Growth Hormone (hGH): Production: Recombinant DNA technology allows the production of human growth hormone in bacteria or yeast. This hormone is used to treat growth disorders in children and hormone deficiencies in adults. Follitropin Beta: Production: Follitropin beta, a form of follicle-stimulating hormone used in fertility treatments, is produced using recombinant techniques in mammalian cell lines. Human Albumin: Production: Human albumin, a protein used to treat liver disease and blood volume deficiencies, can be produced through recombinant DNA technology in yeast or mammalian cells. Antihemophilic Factors: Production: These are clotting factors used to treat hemophilia. They are produced using recombinant DNA technology in mammalian cells. Antibodies: Humanized Monoclonal Antibodies: These are antibodies engineered to target specific antigens while minimizing immune responses against them. They are produced using cell lines in bioreactors and are used in the treatment of various diseases, including cancer.

Question 50

Give examples of vaccines

Answer 50

Live-Attenuated Vaccines: These vaccines contain a live but weakened form of the pathogen. Examples include vaccines for measles, mumps, and rubella (MMR). Inactivated Vaccines: These vaccines contain pathogens that have been killed or inactivated. Examples include the polio vaccine (IPV) and hepatitis A vaccine. Subunit Vaccines: Contain purified components of the pathogen, such as proteins. Examples include the hepatitis B vaccine. Recombinant Vaccines: Produced using recombinant DNA technology to express antigenic proteins. Examples include the human papillomavirus (HPV) vaccine. Polysaccharide Vaccines: Contain polysaccharide capsules from bacterial pathogens. Examples include the pneumococcal vaccine. Conjugate Vaccines: Combine polysaccharides with proteins to enhance immune response. Examples include the Haemophilus influenzae type b (Hib) vaccine. Toxoid Vaccines: Description: Contain inactivated toxins produced by bacteria, which stimulate an immune response against the toxin. Examples include the tetanus and diphtheria vaccines.

Question 51

What are the applications of cloned human genes & gene products, & vaccines?

Answer 51

Treatment of Chronic Diseases: Insulin and hGH are used to manage diabetes and growth disorders, improving the quality of life for patients. Fertility Treatments: Follitropin beta is used to help individuals with fertility issues conceive. Blood Disorders: Antihemophilic factors and human albumin are critical for managing blood disorders and liver conditions. Cancer and Immune Disorders: Humanized monoclonal antibodies are used to target and treat various types of cancers and autoimmune diseases. Infectious Disease Prevention: Vaccines prevent the spread of infectious diseases and protect public health.

Question 52

Explain the process of how insulin can be produced via genetic engineering

Answer 52

Human Insulin Gene: mRNA to DNA: The gene coding for human insulin is first transcribed into mRNA in human cells. This mRNA is then reverse transcribed into complementary DNA (cDNA) to create a stable DNA copy of the gene. Cloning into Bacteria: The cDNA of the insulin gene is inserted into a plasmid vector, which is then introduced into bacteria (usually E. coli) through a process called transformation. This allows the bacteria to carry and replicate the insulin gene. Bacterial Growth and Induction Bacteria Growth: Cultivation: The bacteria containing the insulin gene are grown in large bioreactors under controlled conditions to maximize their growth and replication. Induced Expression: Induction: To trigger the production of insulin, specific conditions or chemical inducers are applied. This causes the bacteria to produce insulin protein as they continue to multiply. Protein Extraction and Purification Cell Lysis: Breakdown: Once the bacteria have produced sufficient insulin, the bacterial cells are lysed (broken open) to release the insulin protein into the solution. Protein Purification: Purification: The insulin protein is then purified from the bacterial lysate using various techniques, such as affinity chromatography, to ensure that it is free from contaminants and other bacterial proteins.

Question 53

What are the advantages of genetic engineering especially for the production of human insulin?

Answer 53

Consistency: Ensures a consistent and reliable supply of insulin. Cost-Effectiveness: Reduces the cost of production compared to extracting insulin from animal sources. Purity: Allows for high-purity insulin that is less likely to cause allergic reactions.

Question 54

Explain the process of how humanised monoclonal antibodies are produced

Answer 54

Mouse Antibodies: The process begins by immunizing mice with the target antigen, such as a cancer cell marker or a specific pathogen. This prompts the mice's immune system to produce antibodies against the antigen. Hybridoma Technology: Spleen cells from the immunized mice, which produce the desired antibodies, are fused with myeloma cells (cancer cells) to create hybridoma cells. These hybridoma cells can proliferate indefinitely and produce large quantities of the specific antibody. Reverse Engineering: Sequence Analysis: The antibody produced by the mouse is sequenced to identify the regions responsible for antigen binding and the regions that elicit an immune response in humans. Replacement: Non-essential regions of the mouse antibody, including those that may cause immune reactions in humans, are replaced with human antibody sequences. This process involves extensive genetic engineering to retain the binding specificity while minimizing potential immune responses. Optimization: Humanization: The modified antibody is further optimized to enhance its compatibility with the human immune system. This involves refining the sequence to ensure it functions effectively without triggering adverse reactions. Hybridoma Cultivation: The humanized antibody gene is introduced into hybridoma cells, which are then cultured in large-scale fermentation systems. These cells are capable of producing high quantities of the humanized antibody. Protein Purification: The produced antibody is extracted and purified from the cell culture using techniques like affinity chromatography. This step ensures that the final product is pure and free of contaminants.

Question 55

Explain the process of how live-attenuated vaccines are produced

Answer 55

Attenuation refers to the process of weakening a virus so that it can stimulate an immune response without causing the disease. The human virus is grown in a non-human host, such as chicken embryos or other animal cells. This new host causes the virus to undergo genetic changes and adapt to the new environment. During this adaptation, the virus accumulates mutations that allow it to replicate in the new host but reduce its ability to cause disease in the original human host. This makes it less virulent when reintroduced into humans, thus providing immunity.

Question 56

How is the rubella vaccine, & measles & mumps vaccine produced?

Answer 56

Rubella Vaccine: Produced using human cell strains. These cells are used to culture the virus and achieve attenuation. The virus is grown in human cell cultures until it is sufficiently attenuated and then harvested. Measles and Mumps Vaccines: These vaccines are produced by growing the virus in chick embryo cells. The virus is introduced into developing chick embryos, where it adapts to the avian environment. The attenuated virus is then harvested from the embryos. The virus is purified to remove any contaminants and other cellular components. This is crucial to ensure the safety and efficacy of the vaccine.