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BIOLOGY CHAPTER 14

QuestionAnswer
Applications of DNA technologies Gene cloning, DNA profiling and genetic screening are all powerful gene technologies that use DNA manipulation techniques
Gene Cloning Allows scientists to produce exact/identical copies of a gene of interest. Gene cloning is very different from the cloning of a whole organism. In gene cloning the end product is many copies of a specific gene. Two techniques are used: in vivo & in vitro
In vivo Involves the use of restriction enzymes, ligase & vector to incorporate the desired gene into the gene of a living organism, where it will replicate DNA code is universal, so the gene taken from one organism will express the same protein in the host
In vitro The PCR technique is used to produce multiple copies of the specific gene in a solution
Applications of gene cloning - Research into genes and gene expression Allows: Scientists to obtain the complete DNA sequences of different species Genetic code of different species to be compared Scientists to examine how genes are regulated by the environment or by master genes Mapping of genes associated with disease
Applications of gene cloning - Production of recombinant proteins achieved by introducing recombinant DNA (via plasmids) into bacteria or eukaryotes and allowing them to synthesise the protein. The main types of proteins produced by this technology are hormones, cytokines, enzymes and vaccines
Implications of recombinant DNA technologies for society - social • reduced costs of therapeutics made with bacteria • wider access to treatments • employment opportunities in the biotechnological industry • misuse for non-therapeutic processes, eg. performance enhancing drugs
Implications of recombinant DNA technologies for society - biological • human recombinant proteins more effective then proteins purified from other animals • risk of contamination by bacterial molecules • new, safer vaccines possible
Implications of recombinant DNA technologies for society - ethical • use of bacteria for therapeutics address the philosophical, cultural, or religious objections to animal use • manipulation or shifting of genes may be seen as unethical, regardless of purpose
Cloning organisms Involve methods of asexual reproduction in which the genetic information of the new organism comes from one ‘parent’ cell only. Clones are genetically identical to the parent cell
Embryo splitting Occurs when the cells of an early embryo are artificially separated Embryo is produced through in-vitro fertilisation Each single cell is then implanted into the uterus of a surrogate female parent where embryonic development continues
Somatic cell nuclear transfer - artificial cloning of mammals part 1 • obtaining the nucleus from a somatic (body) cell of an adult animal ― this is the ‘donor’ nucleus • removing the nucleus from an unfertilised egg cell, typically of the same species ― this is the “enucleated egg cell”.
Somatic cell nuclear transfer - artificial cloning of mammals part 2 • transferring the donor nucleus into the enucleated egg cell • culturing the egg cell with its donor nucleus until it starts embryonic development • transferring the developing embryo into the uterus of a surrogate animal where it completes development
Somatic cell nuclear transfer - artificial cloning of mammals part 3 • The genetic information in the cloned animal comes from the nucleus of the adult body cell and so the genotype of the cloned animal is determined by the donor nucleus, not by the egg into which the nucleus is transferred.
Gene therapy Insertion of a gene into cells or tissues to correct or replace defective gene function that leads to disease Application of cloning technology in medicine
Gene therapy methods Removing cells from the body, such as bone marrow stem cells, inserting genes into these cells and then returning the cells to the patient. Other forms of gene therapy deliver a gene directly into the affected tissue in the body using a suitable vector
Implications of gene therapy - social • increased life span and quality of life • equity of access • changing expectations of medical intervention
Implications of gene therapy - biological • immune response to viral vector • targeted gene delivery - getting it into the right cells • possible effects on other genes • regulation dosage • somatic V germ line cells
Implications of gene therapy - ethical • survival into reproductive years • influence on heritable characteristics • selection of disorders to treat - who chooses
DNA Profiling Technique used to produce an individual’s unique pattern of DNA bands on a gel, produced by analyzing short tandem repeats (STR) regions of the genome. It is often used in forensics to identify the perpetrator of a crime
short tandem repeats short, repeated sections of between 2 and six bases
techniques involved in DNA profiling • Use of restriction enzymes to extract DNA • STR’s are amplified using PCR • Differences in size of the STRs can be detected by standard gel electrophoresis • DNA sample is matched to that of a suspect of the lengths of the particular STRs
Genetic Screening Used to detect abnormalities or changes to genes Used to confirm or rule out suspected genetic conditions, to determine if a person carries a faulty gene that can be passed on to their offspring or whether a person is at risk of developing a disease
Genetic screening can be done in: • Embryos created through IVF can be tested preimplantation • Foetuses by amniocentesis (collection of fluid around the foetus) or chorionic villus sampling. These tests are invasive and increase the possibility of miscarriage • Postnatal
Methods involved in genetic screening PCR, restriction enzymes and gel electrophoresis
Implications of DNA profiling - social • privacy • reproductive decisions • storing peoples genetic information • discrimination, eg. insurance company refusing life insurance
Implications of DNA profiling - biological • accuracy possible false positives and false negatives • potential to correct mutations (gene editing) • intervention in evolution: altered inheritance
Implications of DNA profiling - legal and ethical • informed consent for DNA sampling • security of stored genetic data • legal access to genetic information • reliability of DNA as proof of guilt or innocence
Emerging infectious diseases • New or previously unrecognised diseases • Diseases that have increased in incidence, virulence (ability to cause disease) or geographic range over the past 20 years • Diseases that may increase in the near future
epidemic sudden increase in incidence in the number of cases of a disease above what is normally expected in that population in that area
pandemic an epidemic that has spread over several countries or continents, usually affecting a large number of people.
ELISA identifies the presence of specific proteins, such as antibodies. It uses an antigen from the pathogen to bind to antibodies present in the blood, which would have been produced by the immune system if the pathogen were present in the animal
Controlling disease •Prevention: education •Isolation and quarantine •Control carriers •Eradication of vectors: insect vectors such as mosquitoes may be eliminated to control vector-borne diseases •Vaccination: Effective in preventing in preventing future infections
Disinfectants used to kills pathogens on surfaces. They are non-specific antimicrobial agents, that is, they inactivate or destroy most biological agents (bacteria, viruses, fungi)
Antiseptics Antiseptics are used to kill pathogens on the skin. They are non-specific antimicrobial agents, that is, they inactivate or destroy most biological agents (bacteria, viruses, fungi)
Antibiotics naturally occurring molecules produce by fungi or bacteria kill bacteria without damaging the cells of the organism being treated target biochemical pathways and molecules specific to the microbe
Antiviral drugs part 1 • Preventing the virus from entering the cells by binding to receptors that allow the virus to enter. • Inhibiting enzymes that catalyse reproduction of the virus genome
Antiviral drugs part 2 • Blocking transcription and translation of viral proteins • Preventing the viruses from leaving the cell and so preventing the infection of other cells.
Rational drug design analysis of a disease to determine a structure of a pathogen and using this information to design a drug that will mimic or block the action of the disease-causing agent
Rational drug design step 1 identify the target molecule
Rational drug design step 2 determine the shape of the active or binding site
Rational drug design step 3 search existing drugs for one that fits the target OR computer aided design of new drug to fit the target
Rational drug design step 4 test drug binding to target molecule
Rational drug design step 5 test drug on cultured cells and animals models
Rational drug design step 6 clinical trials
Relenza Relenza targets a protein on the surface of the flu virus. It is used both to treat the early stages of influenza and to prevent influenza
Relenza process 1 New virion being released from a cell is bound by haemagglutinin to a receptor
Relenza process 2 Neuraminidase cuts the receptors to let the virus escape and infect another cell
Relenza process 3 Relenza blocks the active site on neuraminidase
Relenza process 4 now the virus cannot escape from the cell surface
Created by: emmawalton05