Biology - Recombinant DNA and Biotechnology - Quick Guides

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Study GuideBiology–Recombinant DNA and Biotechnology1. Recombinant DNARecombinant DNA biotechnologyis a way scientists use what we know about DNA to solve real-world problems. At its core, it involves changing an organism’s genes to give it new abilities or traitsthat are useful to humans.1.1 Biotechnology and Genetic EngineeringBiotechnology is often calledgenetic engineeringbecause it involves changing an organism’sgenes. When scientists add, remove, or modify genes, the organism’s DNA becomesrecombined.This newly formed DNA is calledrecombinant DNA.In simple terms, recombinant DNA is DNA that has been altered by combining genetic material fromdifferent sources.1.2 Why Recombinant DNA Is ImportantRecombinant DNA allows cells to makeproteins they would not normally produce. These proteinscan be used to:•Makemedicines, such asinsulin•Developvaccines•Improvehuman healthby treating or preventing diseases1.3 Using Recombinant DNA in the EnvironmentBacteria containing recombinant DNA can also be used outside the laboratory, but only undercarefully controlled conditions. These modified bacteria can:•Improvesoil fertility•Act asinsecticidesto protect crops•Helpclean up pollutionin the environment

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Study Guide1.4 Transgenic OrganismsAn organism that carriesextra genes from another organismis calledtransgenic.Scientists have created:•Transgenic bacteria•Transgenic plants•Transgenic animalsThese organisms are designed to perform useful tasks, such as growing faster, resisting pests, orproducing helpful substances.1.5 Gene Modification in HumansHuman cells can also be genetically modified. By adding or correcting specific genes, cells can bemade to produce proteins that help treathealth-related deficiencies. This approach is especiallyimportant in modern medical research and therapy.1.6 The Role of GenomicsScientists can modify genes because of advances ingenomics.Genomics is the study of an organism’sentire set of chromosomes, including:•How genes function•How species have evolved over time1.7 Genome Sequencing and Its ImpactIn2003, scientists completed the sequencing of thehuman genome. Since then, many otherorganisms have been sequenced, including:•Prokaryotes, such asE. coli•Eukaryotes, including both vertebrates and invertebrates

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Study GuideBy comparing genomes from different organisms, scientists gain a deeper understanding of:•Genetic similarities•Evolutionary relationships•How life on Earth is connected at the molecular level2. Pharmaceutical ProductsBiotechnology plays a major role in makingimportant medicinesthat help people with geneticdisorders and serious diseases. Many health problems happen when the body cannot make certainproteins. Thanks to biotechnology, scientists can nowproduce these missing proteins in thelaboratoryand use them as treatments.2.1 Treating Protein DeficienciesSome human gene defects prevent the body from producing essential proteins. For example:•Insulindeficiency leads todiabetes•Human growth hormonedeficiency causesdwarfism•Factor VIIIdeficiency results inpoor blood clottingToday, these proteins can be replaced using proteins made throughbiotechnology, instead ofrelying on natural sources.2.2 How Insulin Is Made Using BiotechnologyInsulin is made up oftwo protein chains. Scientists place the genes for these two chains into smallDNA rings calledplasmids, which are inserted into bacteria.The bacteria then produce the two protein chains separately. Afterward, scientistschemically jointhe chains togetherto form fully functional insulin that can be used as medicine.

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Study Guide2.3 Producing Human Growth HormoneHuman growth hormone is also produced using bacteria. However, because bacteria do not normallymake human proteins, scientists must usespecial techniquesto help the bacteria correctly producethe hormone. This allows patients to receive safe and effective treatment.2.4 Other Therapeutic Proteins Made by BiotechnologyBiotechnology is also used to produce many othertherapeutic proteins, including:•Tissue plasminogen activator (TPA)This protein helps dissolve blood clots. It is produced ingenetically modified mammalian cellsand is often used to treat heart attacks and strokes.•InterferonInterferon is an antiviral protein made inE. coli bacteria. It is used to treat certain cancers andsome skin diseases.•Antisense moleculesThese are special RNA molecules that bind tomRNA, blocking protein production. By stoppingthe synthesis of harmful proteins, antisense molecules can help treat specific diseases.For example, they can prevent human cells from producing key components of theHIV virusafterinfection.2.5 Biotechnology and VaccinesVaccines are another important application of recombinant DNA technology.•Thehepatitis B vaccineis made from viral proteins produced byyeast cellsthat carryrecombinant DNA.This vaccine is very safe because it containsno actual virus particles.•Experimental AIDS vaccinesare being developed using similar methods. One approachuses thevaccinia (cowpox) virusas a vector. This virus carries genes from several differentviruses, with the goal of helping the immune system develop resistance to multiple diseases.

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Study Guide2.6 Creating Safer VaccinesVaccines can also be made byremoving disease-causing genesfrom a pathogen. The weakenedorganism cannot cause illness, but it still triggers the immune system to respond. This allows the bodyto build protection without the risk of serious infection.3. Quiz Pharmaceutical Products1. QuestionWhich of the following statements about vaccines isFALSE?Answer Choices•Some vaccines are produced by eliminating disease-inducing genes from a pathogen,rendering it harmless.•Vaccines are harmful, and the dangers outweigh the benefits.•Vaccinescan be produced by using a virus as a vector.Correct AnswerVaccines are harmful, and the dangers outweigh the benefits.Why This Is CorrectThis statement isfalsebecause extensive scientific research shows that vaccines aresafe andhighly beneficial. They protect individuals and communities from serious, sometimes deadlydiseases. While vaccines may have mild side effects, their benefits in preventing illness, disability,and deathfar outweigh any risks.The other statements aretrue:•Some vaccines are made by removing or disabling harmful genes in a pathogen so it cannotcause disease.•Some vaccines use harmless viruses asvectorsto deliver genetic material that triggers animmune response.

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Study Guide4. Diagnostic TestingRecombinant DNA technology and biotechnology have completely changed the way doctors andscientistsdetect diseases. Today, many genetic disorders and infections can be identified early andaccurately by examining a person’s DNA.4.1 DNA Probes: The Basic ToolThe most important tool in DNA testing is theDNA probe.A DNA probe is asmall, single-stranded piece of DNAdesigned to find a matching(complementary) DNA sequence in a much larger DNA sample.Here’s how it works:•The probe searches for a specific DNA sequence•When it finds and binds to its matching DNA, it gives off asignal•This signal, similar to that produced by a radioactive marker, shows that the target DNA ispresentThis makes DNA probes very useful for detecting specific genes or genetic changes.4.2 Why PCR Is NeededFor DNA probes to work well, scientists need alarge amount of the target DNA. Often, the samplecontains only a tiny amount, which is not enough to detect easily.To solve this problem, scientists use thepolymerase chain reaction (PCR).4.3 Polymerase Chain Reaction (PCR): Making Millions of CopiesPCR is a powerful method used tomake many copies of a specific DNA segmentin a short time.In a highly automated machine:•The target DNA is mixed with enzymes, nucleotides, and primer DNA•The enzymes repeatedly copy the target DNA

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Study Guide•Each cycle doubles the amount of DNABecause this process grows exponentially,billions of copiesof DNA can be produced in just a fewhours, starting from only a few original molecules.4.4 Detecting Diseases Using DNA Probes and PCRBy combining DNA probes with PCR, scientists can detect many serious diseases with greataccuracy.These techniques are used to identify:•HIV, providing a direct test for the virus itselfThis test is often preferred over antibody tests because it detects the virus directly.•Lyme disease•Genetic disorders, including:○Cystic fibrosis–a respiratory disease where thick mucus blocks airways, makingbreathing difficult○Muscular dystrophy–a nervous system disorder that causes muscle weakness dueto nerve damage○Huntington’s disease–a nervous system disease marked by uncontrolledmovements and nerve degeneration○Fragile X syndrome–a disorder of the X chromosome associated with intellectualdisability4.5 RFLPs: Markers Linked to Disease GenesScientists often look for specific DNA segments calledrestriction fragment length polymorphisms(RFLPs).•RFLPs are sections of DNA that do not seem to have a direct function•They are locatednear genes associated with diseases•By finding these RFLPs, scientists can locate the nearby disease-causing geneIn this way, RFLPs act likesignposts, helping researchers track down harmful genes.

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Study Guide4.6 Detecting Microorganisms in the EnvironmentDNA probes are not only used in human medicine. They are also valuable for:•Detecting microorganisms in the environment•Identifyingviral and bacterial pathogensThis helps in disease control, environmental monitoring, and public health protection.5. Quiz Diagnostic Testing1. QuestionWhat is the purpose of the polymerase chain reaction (PCR)?Answer Choices•gene amplification•gene expression•gene recombinationCorrect Answergene amplificationWhy This Is CorrectThepolymerase chainreaction (PCR)is a laboratory technique used tomake many copies of aspecific DNA segment. This process is calledgene amplification.PCR allows scientists to start with a very small amount of DNA and produce millions of copies in ashort time. This is essential for tasks such as DNA analysis, medical testing, forensic science, andgenetic research.The other options are incorrect because:•Gene expressionrefers to using DNA to make proteins, not copying DNA.•Gene recombinationinvolves rearranging or combining DNA segments, not amplifying them.

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Study Guide2.QuestionFill in the blank:Using ________ and PCR, scientists are now able to detect the DNA associatedwith HIV.Answer Choices•DNA probes•plasmids•vectorsCorrect AnswerDNA probesWhy ThisIs CorrectDNA probesare short, labeled pieces of DNA that bind specifically to a complementary DNAsequence. When used together withPCR, which amplifies DNA, DNA probes make it possible toidentify and detect specific DNA sequences, such as those associated with HIV.The other options are incorrect because:•Plasmidsare circular DNA molecules used mainly to transfer genes in genetic engineering.•Vectorsare carriers (like plasmids or viruses) used to deliver DNA into cells, not to detectDNA.6.Gene Therapy: Fixing Problems at the Genetic LevelGene therapyis a medical technique that uses recombinant DNA technology to treat diseasescaused by faulty genes. The basic idea is simple:cells are taken from a patient,new genes are added, and the corrected cells are put back into thepatient’s body.These added genes contain instructions for makingproteins the patient’s body cannot produceproperly.

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Study Guide6.1 Why Gene Therapy Does Not Affect Future GenerationsGene therapy usesnonreproductive (somatic) cells, not egg or sperm cells.Because of this, the inserted genes:•Help only the treated patient•Are not passed onto future generationsThis makes gene therapy safer and more controlled.6.2 A Successful Early Example: ADA DeficiencyOne of the first successful uses of gene therapy occurred in theearly 1990s. It treated children wholacked an important enzyme calledadenosine deaminase (ADA).Here’s how the treatment worked:1.Lymphocytes, a type of blood cell, were removed from the children’s bone marrow.2.Scientists usedviruses as vectorsto insert normal ADA genes into these cells.3.The genetically altered cells were thenreinfused into the children’s bodies.4.Once inside the body, the modified cells beganproducing ADA normally.As a result, the enzyme deficiency was corrected, and the disease was successfully treated.6.3 Who Can Benefit from Gene Therapy?Scientists have identifiedover 4,000 disorders caused by defects in a single gene.Patients with these conditions may be good candidates for gene therapy, especially when traditionaltreatments are limited or ineffective.6.4Safety and Ethical OversightBecause gene therapy directly changes genetic material, it is carefully regulated. Today, astrict,multilayered review systemis in place to protect patients.Before any gene therapy experiment is approved:

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