Unit 3 Biology: signatures of life conceptual framework Chemical nature of the cell The nature of...
-
Upload
allan-beasley -
Category
Documents
-
view
214 -
download
0
Transcript of Unit 3 Biology: signatures of life conceptual framework Chemical nature of the cell The nature of...
Unit 3 Biology: signatures of Unit 3 Biology: signatures of lifelife
conceptual frameworkconceptual framework
Chemical nature of the cell
The nature of molecules
Interactions between molecules determine shape of biomacromolecules and produces binding sites for:•enzymes and substrates•Signals and receptors•Antibodies and antigens
Explains how:•various materials enter and leave a cell•Cells receive and respond to signals•How the immune system works•How vaccines work•How we design drugs
Molecular biology in Molecular biology in medicinemedicine
EL: To explore the application of molecular biology in medicine.
Molecular biologyMolecular biology
Applications of molecular biology in medicine, include:
Knowledge and manipulation of genetic material
the development of designer drugs to:◦ Prevent action of infective micro-organisms◦ Inhibit the action of specific chemicals in
the body
the production of hormones and plant vaccines
Inherited diseasesInherited diseases
Also known as genetic disorders
Exist because of defect in kind or amount of DNA in the affected organism
Many different types◦Eg a whole chromosome may be
involved or just a single gene (NB. We’ll only focus on single gene defects)
Inherited diseasesInherited diseasesKnowledge about the gene
responsible may allow:
◦Testing for the presence of the defective gene (eg breast cancer gene, phenylketonuria (PKU)
◦Special treatment to delay onset of the disease
◦Reducing severity of condition through treatment (eg cystic fibrosis) or special diet (eg galactosaemia, PKU)
Gene therapyGene therapy
The insertion of a normal functional gene into cells that contain a defect
Two types:◦ in vivo: gene therapy given directly to
patient◦ex vivo: gene therapy in which the
patient’s cells are manipulated outside the body and then returned into the individual
The specially prepared functional piece of DNA inserted into the cell is called a cloned gene
Viral Gene therapyViral Gene therapy
A vector is used to carry the gene into a cell
Most commonly used vectors are viruses ◦ Viruses with DNA replicate in the nucleus of
the cells they infect◦ Viruses with RNA replicate in the cytoplasm
of the cells they infect Exception is RNA viruses called retroviruses – they
also replicate in the nucleus
Most commonly used vectors in gene therepy are retroviruses and adenoviruses
RetrovirusesRetroviruses
Only used in cells that are reproducing when nuclear membrane breaks down and chromosomes of infected cell become accessible
Useful for cells that can be taken out an cultured outside the body (eg blood, bone marrow)
AdenovirusesAdenoviruses
DNA viruses – enters nucleus but remains separate from the host DNA
The cloned DNA is functional and produces functional protein
May be short-lived as this small piece of DNA doesn’t replicate when the host cell does
Viral Gene therapyViral Gene therapy
Still experimental in humans and can pose risks to patients safety, eg◦Temporary solution◦Insertion into wrong place on
chromosome, causing a different disease
◦Immune response to virus
Non viral Gene therapyNon viral Gene therapy
As yet, not very successful
Methods include◦Transporting DNA into cells in lipid
spheres◦Direct injection of DNA into cells◦Manufacture of artificial
chromosomes
Medical diagnosis: Pre-Natal Medical diagnosis: Pre-Natal TestingTesting
Used to determine if baby has a genetic defect
Done via:◦Ultrasound: physical defects◦Biochemical test on embryonic cells
or amniotic fluid: metabolic defect
Medical diagnosisMedical diagnosis
Obtaining a sample of embryo cells can be done through:◦Chorionic villus sampling:
at 6-8 weeks Removal of a small piece of chorion
tissue
◦Amniocentesis At 16-18 weeks Collecting a sample of amniotic fluid
surrounding the fetus
Medical diagnosis: Medical diagnosis: Presymptomatic testingPresymptomatic testing
Breast cancer: women with BRCA1 or BRCA2 gene have 80% risk of developing breast cancer (compared with 10% in rest of population)
Tests exist for the gene an women who test positive may either:◦have their breasts removed before
they develop the disease, or◦get regular mamograms
Rational drug designRational drug design
When a drug is designed to act against an infective agent:
◦The molecular structure of the active site of the infective agent is established
◦The drug is designed to have a complementary structure
◦The drug locks into the active site to prevent development of the disease
Rational drug designRational drug design
When a drug is designed to inhibit the action of a chemical in the blood:◦The molecular structure of
chemical is established◦The drug is designed to have a
structure that locks into the active site of the chemical
◦The chemical is inactivated
Rational drug designRational drug design
The delivery of vaccines in plant material as food involves:◦Determining the molecular structure of
the proteins in the infective agent that cause the immune response
◦Introducing the DNA that codes for these proteins into the plant genome
◦Growing and harvesting the plants
eg measles vaccine in powdered lettuce, cholera vaccine in rice
Manufacturing biological Manufacturing biological moleculesmolecules
Genetically engineering proteins that are deficient (eg insulin)
NanoparticlesNanoparticles
Nanoparticles are:◦Manufactured◦1-100 nanometers (one billionth of a
meter) in diameter◦Made of a double layer of phospholipids
to mimic plasma membrane of the cell
Used to deliver toxic drugs directly to target cells (eg tumour cells), reducing the chance of affecting healthy cells
Activity/homeworkActivity/homeworkComplete the Molecular Biology
exam questions
Chapter 4 Quick Check qu 1-16