1. Ch. 19
Part 4

2. Do Now Review Primer Probe
Short length of DNA that attaches to one end of a single strand of DNA
Allows DNA polymerase to begin to make a complementary copy of a single template strand
Probe
Short length of DNA that attaches to one end of a single strand of DNA
Labeled in some way (fluorescence or radiation; phosphorus)
Emits beta radiation that can be detected
Indicates position of DNA

3. Gene Technology
Enables humans to make necessary products (commercial and medical)
Production of valuable human proteins:
Human Insulin
E. coli used to produce this protein
Bypasses ethical concerns and accessibility concerns of using animal insulin
Human growth hormone
Factor VIII
Blooding clotting protein
Inability to make this protein leads to hemophilia
Enzyme ADA
Adenosine deaminase
Used to treat Severe Combined Immunodeficiency Disease (SCIDs)
ADA vital for functioning of immune system

4. What Researchers Use to Make Proteins
Bacteria
Advantages:
Simple nutritional requirements
Large volume produced
Low space of production facilities
Process carried out anywhere
Few practical or ethical problems collecting protein this way
Disadvantages:
Do not modify proteins in same way eukaryotic cells do
Yeasts
Cultures of mammalian cells
BEST source
Transgenic animals

5. Examples of Eukaryotic Cells Being Used To Make Protein
GM Hamster Cells
Used to make Factor VIII
Kidney & ovary cells
Gene for Factor VIII inserted into GM hamster cell
Cells cultured in fermenter
Cultured cells constantly produce factor VIII
Protein is purified and treated before given to humans
GM Insect Larva
From Cabbage Looper Moth Caterpillar
Used to produce ADA protein for SCIDs
Given to patients awaiting gene therapy
Transgenic Animals
Genetically modified to produce human proteins in their products (milk)
Sheep
Goats

6. Transgenic Animals Sheep Goats Makes human alpha- antitrypsin
Used to treat emphysema
Goats
Makes human Anti- thrombin protein
Used to stop blood clotting
Anti-thrombin deficiency leads to increased risk of venous and arterial thrombosis

7. Genetic Screening
Analysis of a persons DNA to check for presence of a specific allele
Done to:
Adults
Fetus
Embryos
In utero
In vitro
Screen for faulty genes
Useful for disordered where there may be a hereditary disposition
Results can be used to prevent onset of disorder or to prepare treatments for disorder

8. Designer Baby Muscular dystrophy Thalassaemia Hemophilia
Pre-implantation genetic diagnosis (PGD)
Utilizes
Mixing sperm with oocytes in petri dish
Removal of cell from embryo during 8-cell stage
DNA analyzed and used to predict if embryo would have genetic disorder for which both parents were carriers for
Embryo WITHOUT the disease causing alleles is chosen as the one to be used for implantation
Embryos with the disease allele discarded (ethical concerns)
Popular technique to avoid pregnancies with:
Muscular dystrophy
Thalassaemia
Blood disease similar to sickle cell anemia
Common in Mediterranean
Decrease in disease due to genetic screening
Caused by mutated allele
Parents can be carriers
If fetus has the disease, therapeutic abortion is an option (termination of pregnancy for medical reasons)
Hemophilia
Huntington's Disease
Late onset disease
Symptoms appear at middle age (after children have been born)
No cure
Dominant allele (but some times disease does not develop)
Ethical dilemmas
2004 UK
Used to produce child with tissue match to older sibling who had genetic disorder
Stem cells from umbilical cord used in sick sibling
Ethical Concerns
Downs Syndrome
Cystic Fibrosis
Designer Baby

9. Ethics of Genetic Screening
UK Law, 2004
Allowed embryo to be chosen that did NOT have disease allele to produce baby
Allowed embryo to be chosen that was a tissue match for another child in the family that needed those cells
Does NOT allow addition of an allele into egg, sperm, or zygote
Decision to Terminate Pregnancies
Where to draw the line?
Minor chance vs. major
Other features such as gender

11. Fetal Genetic Screening Tests
Amniocentesis
Sample of amniotic fluid taken at weeks of pregnancy
Analysis of sample can check for genetic disorders- mainly chromosomal mutations
Ultrasound scanning used to view placement of fetus, placenta, and umbilical cord
Hypodermic syringe needle position marked on skins surface
Needle inserted and extracts amniotic fluid
Chance of miscarriage
Chorionic Villus Sampling
Carried out between 10 to 13 weeks of pregnancy
Early warning of genetic abnormalities in fetus (earlier than amniocentesis)
Ultrasound scanning used to located fetus and placenta
Hypodermic needle used to extract sample of fetal chronic villi fluid located in the placenta
Sample of fetal blood
Increase risk of miscarriage
Before 15 weeks, less risky than amniocentesis

13. Genetic Counselor/counseling:
Doctor who will help people interpret results of the genetic screening tests and help them make decisions
Difficult
Moral, ethical, scientific issues
Right to terminate life?

14. Gene Therapy
Process of inserting normal alleles of genes into people who suffered from genetic disorders
Cystic fibrosis
a hereditary disorder affecting the exocrine glands
Causes the production of abnormally thick mucus, leading to the blockage of the pancreatic ducts, intestines, and bronchi and often resulting in respiratory infection
Sickle Cell anemia
Difficulties with gene therapy
Getting normal alleles of genes into a persons cells
Making these normal alleles function properly in new cells
1st successful Gene Therapy
1990, Ohio, 4-year old girl with SCID (severe combine immunodeficiency disorder)
Isolated in bubble
Inability to make ADA protein (adenosine deaminase)
Patient’s T-lymphocytes removed & normal ADA alleles inserted into cells using virus vector
Cure not permanent; regular transfusion needed to maintain immune system function
Adult Stem cells from bone marrow used for gene therapy
2000, France  children getting transplant developed leukemia due to retrovirus used as vector

15. Vectors to Carry Normal Alleles into Patient’s Cells
Viruses
Retroviruses
Insert their genes into host’s genome randomly
May interfere with regulatory sequence of a gene in hosts’ cells  activate gene causing cancer
Lentiviruses
Insert genes randomly into host genome
Can be modified to inactivate replication
HIV disabled to act as vector
AAV (adeno-associated virus) acts as vector
Virus does NOT insert its genes into the host genome = not passed onto daughter cells
Problem with short lived cells (lymphocytes)
Successful with long-lived cells (neurons and liver cells)
Liposomes
Small spheres of phospholipids