PLTW Medical Interventions Unit 2

Single-Gene Disorder

Mutation in one gene, causes one protein to be made incorrectly

Multifactorial Disorder

Caused by a variety of mutations in several genes and introns as well as environmental factors. They are often the cause of several chronic disorders.

Chromosomal Disorders

Normal: 44 (22 pairs) autosomal chromosomes and 2 (1 pair) sex chromosomes.
Whole/partial missing/extra chromosome
Diagnosed with karyotypes (picture of the chromosomes)

Mitochondrial Disorders

Caused by mutations in mitochondrial DNA (not in the nucleus). Mitochondrial DNA is only passed down by the mother (only one copy of the gene). Deals with energy and metabolism. It usually affects all cells in the body, but not always.

Carrier Screening

Determines genotype of an individual when it cannot be determined using a pedigree or the phenotype. It is often used by perspective parents to see if they are carriers for a certain disease present in their families.

Preimplantation Genetic Diagnosis

Used following in vitro fertilization. Babies are tested for genetic defects and only healthy babies are inserted into the mother.

Amniocentesis

Done during the second trimester of pregnancy. Takes a sample of the amniotic fluid for genetic testing (requires use of an ultrasound)

Chorionic Villi Sampling

Done during the first trimester of pregnancy. It cannot detect neural tube defects. Takes a sample of chorionic villi on placenta wall for genetic testing (requires use of an ultrasound)

Ultrasounds

Takes video of baby in womb, can determine fetus' age and sex, as well as physical defects. It is also used to see the heartbeat and diagnose a pregnancy.

Newborn Screening

Newborn babies are tested for a variety of genetic disorders and defects. Tests vary from state to state.

Duchenne Muscular Distrophy

Sex-linked recessive disorder, causes body to not make protein dystrophin, causing muscle weakness.

Cystic Fibrosis

Autosomal recessive, Causes problem in CFTR Protein, causing
mucus to clog lungs, persistent cough, and other lung problems.

Huntington's Disease

Autosomal dominant, doesn't show symptoms until later
in life. Makes defective protein known as Huntington. It is a degenerative brain disease characterized by abnormal movements and a severe decline in thinking and reasoning skills.

Down Syndrome

Caused by a problem after/during conception (missing whole/partial chromosome 21). Characterized by small stature, physical defects, and mental retardation.

Leber hereditary optic neuropathy

Mitochondrial disorder creates a defective
enzyme responsible for converting oxygen, fats, and simple sugars to energy.
Characterized by vision loss.

Alzheimer's Disease

Early onset is autosomal dominant. Caused by a buildup
of beta-amyloid plaques and neurofibrillary tangles. Characterized by dementia and memory loss.

Polymerase Chain Reaction

Melt: Highest (94) temperature to separate strands
Anneal: Lowest(45) temperature to allow primers to bind
Extend: Middle temperature (72) to allow Taq polymerase to copy DNA
Final Extension: 10 minutes of extend to allow all DNA to copy.
Done in a thermocycler

Genotype

Genetic code for a gene

Phenotype

Expression of gene (Ex. Blue eyes, brown hair)

How much of their genetic code do all humans share?

99.9%

Single Nucleotide Polymorphisms

SNPs, Single nucleotide differences in the human genome that separate each individuals

What steps should you take for a healthy pregnancy?

300 extra calories per day, no under-cooked or unpasteurized foods, take prenatal vitamins, non-strenuous exercise, get plenty of sleep, no hot tubs or saunas, no alcohol, no smoking, no drugs, no caffeine, limit exposure to chemicals, take care of emotional health

12 week fetus

sex determinable, heartbeat, arms proportional, more movement

24 week fetus

senses present, nails develop

Why are older women more at risk for problems during their pregnancy, particularly genetic problems?

Older women's eggs are older, making fertilization more difficult and more complicated.

Gene Therapy

Replacing abnormal genes with healthy ones to cure/treat genetic disorders
Moral issues: Playing God, safety, abuse, going to far

Vectors

Delivery System for genes, frequently viruses

Retrovirus

Carries DNA as RNA, can hold up to 8,000 base pairs. It is possible to target specific cell types and new DNA will duplicate with the cell. However, it may cause an immune response, the RNA has to be translated into DNA before the gene is effective, it may enter into the wrong spot (can cause tumors), and only works on dividing cells.

Adenovirus

Carries DNA as double stranded DNA and can hold up to 7,500 base pairs. It affects dividing and non-dividing cells and can target specific cells. However, it can cause an immune response and does not integrate into host DNA, so the treatment is only effective for a few weeks.

Adeno-Associated Virus

Carries DNA as single-stranded DNA and can hold up to 5,000 base pairs. It does not make humans ill, infects dividing and non-dividing cells, can target specific cells, will integrate with the DNA of the host cell, and inserts into a specific region that does not harm humans 95% of the time. However, it requires a helper virus to replicate and fewer base pairs are transferred.

Herpes Simplex Virus

Carries DNA as double stranded DNA and can hold up to 20,000 base pairs. It does not disrupt the host cell's genes, and it lasts a long time, including through replication, as a circular piece of DNA. However, it only targets the nervous system, does not integrate into the host cell's DNA, and may cause an immune response.

Liposome

Carries DNA as a circular piece of double stranded DNA (plasmids) and has no limit on the number of base pairs. It can be engineered to integrate with the host cell's DNA. It cannot target specific cells, and it does not enter the cell wall as effectively as viruses. They are not very effective at integrating with the host cell's DNA even if they are engineered to do so, and some are toxic.

Naked DNA

Carries DNA as a circular piece of double stranded DNA (plasmids) and has no limit on the number of base pairs. It can be engineered to integrate with the host cell's DNA, is generally not toxic, and does not generate and immune response. However, it enters cells ineffectively, cannot target specific cell types, and is often ineffective at integrating with the host cell's DNA even if it has been engineered to do so.

Artificial Insemination

Medication is given to the female to increase fertility, and ovulation is ensured either with tests or medication. Then, selected sperm is inserted into the female with a catheter through the cervix.

Reproductive Technologist

Work with patients with fertility problems to help them have children. They council patients, give exams to determine cause of infertility, and perform treatments such as artificial insemination and in vitro fertilization to help couples have a child.

Andrologist

Diagnose and treat male reproductive and urinary system disorders, diseases, and injuries. They may conduct physical examinations, perform laboratory tests, or other medical interventions to diagnose these problems. They may treat these
problems using hormone therapy, medication, or surgery.

Embryologist

Work with physicians to treat patient's fertility problems. Some of their duties may include obtaining eggs from female patients, helping with in-vitro fertilization, record keeping, and testing eggs.

Genetic Testing Lab Steps

1. DNA (in cells) extracted from mouth with saline solution.
2. Spin in centrifuge to put DNA in pellet inside cells.
3. Re-suspend the cells in the liquid.
4. Add liquid to Chelex (opens cell membranes).
5. Centrifuge (DNA in supernatant, cell debris in pellet)
6. Do PCR
7. Two tubes, one digested and one undigested. Add HaeIII to digested.
8. Do PCR again.
9. Gel electrophoresis.

Denaturation

In DNA, the separation of the two strands of the double helix.
(Melt)

Anneal

To be capable of combining with complementary nucleic acid by a process of heating and cooling

Gene

A discrete unit of hereditary information consisting of a specific nucleotide sequence of DNA.

Genetic Counseling

A process of communication that deals with the occurrence or risk that a genetic disorder will occur in a family

Genetic Testing

The use of methods to determine if someone has a genetic disorder, will develop one, or is a carrier.

Genome

The complement of an organism's genes; an organisms genetic material.

Primer

A short piece of DNA or RNA that is complementary to a section of template strand and acts as an attachment and starting point for the synthesis strand during DNA replication

Restriction Enzyme

A degradative enzyme that recognizes specific nucleotide sequences and cuts up DNA.

Supernatant

The (usually) clear liquid left behind after a precipitate has been spun down to the bottom of a vessel by centrifugation

Thermal Cycler

An instrument that automatically cycles through different temperatures used to complete PCR reactions

Ultrasoundography

A noninvasive technique involving the formation of a two-dimensional image used for the examination and measurement of internal body structures and the detection of bodily abnormalities

Cloning

Using a somatic or body cell from a multicellular organism to make one or more genetically identical individuals

In Vitro Fertilization

A procedure in which gametes are fertilized in a dish in the laboratory, and the resulting zygote is implanted in the uterus for development

Sex Selection

Methods used to predetermine or diagnose the sex of an embryo for the purpose of selecting only those embryos of a particular sex for transplanting to the uterus of a woman