Medical Interventions unit 2

Denaturation

94°C

Strands separate

Annealing

64°C

Primers attach

Extension

72°C

TAQ polymerase adds bases

What gene were we testing for in the lab?

TAS2R38

How many bands for a nontaster? Dominant or recessive?

1 band

recessive

How many bands for a taster? Dominant or recessive?

2 bands

Dominant

CVS

Chorionic villus sampling

Sample taken from placenta

Weeks 10-12

Trans-cervical or trans-abdominal

Amniocentesis

Low risk but invasive 

Amniotic fluid contains fetal cells

Weeks 16-20

Waste and metabolites give information on fetal health

Low risk

Gene therapy

alteration of the genes of a person afflicted by a genetic disorder

Vector

An agent that contains modified genetic material and can be used to introduce new genes

Genome editing

uses tools in the cell to cut DNA and replace mutated genes

• can alter the DNA in stem cells

3 strategies of gene therapy

Insert

• A functional gene is inserted so the body can make a functional protein (defective gene is still present but its effects are masked)

Disable

• a dysfunctional gene is disabled

Repair 

• dysfunctional gene is repaired 

Plasmid

Liposome

Herpes Virus

Adeno-associated virus

Adenovirus

Retrovirus

Lentivirus

in vivo

Taking place inside a living organism

in vitro

Performed in a lab, outside a living organism

in vivo: Pros and cons

Pros

• patient receives benefits more readily

Cons

• more chance of immune response

• vector may enter non-affected cells

• cells cannot be easily tested to check progress

in vitro: Pros and cons

Pros

• less likely to cause immune response

• target cells can be harvested to ensure the vector entered

• cells can be tested before reintroduction

Cons

• patient has to wait to receive benefits

What gene causes CF and where is it?

CFTR gene, chromosome 7

What does a functional CFTR protein do?

Transports chlorine ions.

Preimplantation Genetic diagnosis

• screens the embryo for potential mutations before being implanted following in vitro fertilization

What maternal serums can be tested for during first trimester? Second trimester?

First: hCG & PAPP-A

Second: Quad screen →hCG, AFP, DIA, uE3

What is hCG? What do low and high levels mean?

A pregnancy hormone produced by the placenta.

Low: ectopic pregnancy, miscarriage

High: Pregnant with multiple babies, Tumors, down syndrome

What is PAPP-A? What do low and high levels mean?

A protein produced by the placenta →provides oxygen and nutrients to baby

Low: Down syndrome, Edwads syndrome 

High: lower risk of preeclampsia

What is a quad screen?

a blood test during pregnancy that tells you if the fetus is at increased risk for having certain genetic disorders →16-21 weeks (not diagnostic)

What is AFP? What do low and high levels mean?

Fetal protein-A, Large role in fetal development

Low: chromosomal abnormalities

High: Neural tube defects (defects of the brain, spine, or spinal cord)

What is UE3? What do low and high levels mean?

estriol →a form of estrogen

Low: high risk of down syndrome

What is DIA (inhibin-A)? What do low and high levels mean?

regulates cell division and differentiation in fetus

High: risk for down syndrome increases

What does cell free DNA screenings test?

Fetal DNA circulating through the mothers blood.

Anatomy ultrasound

• 18-22 weeks

• examine babies anatomical development, heart rate, etc

NT (Nuchal transluscency) ultrasound

• 11-14 weeks

• ultrasound that focuses on the back of the childs neck to examine developmental milestones of the brain and spinal cord 

• Usually paired with serum screening 

• Higher than 3.5mm = increased chance of chromosomal abnormality

Cystic fibrosis gene and location.

CFTR on chromosome 7

Cystic fibrosis causes and symptoms

CFTR cannot transport Chlorine ions to mucus ducts so mucus builds up. It also causes an influx of water into cells which makes mucus sticky and thick →trap pathogens

Can block respiratory passageways and pancreatic ducts

What does CRISPR stand for?

Clustered

Regularly

Interspaced

Short

Palindromic

Repeats

What is Cas-9

A restriction enzyme that cuts the DNA at a target sequence.

How does CRISPR target the gene of interest?    

It uses the guide RNA and identifies the matching sequence

Which diseases are candidates for treatment for the CRISPR-Cas9 system?     

• Huntigtons

• CF

• Sickle cell

Spacer DNA

Segments of viral DNA that previously infected the bacteria.

Interspaces palindromic repeats

What happens in a bacteria when a virus enters?

• CAS protein and guide RNA are produced →form a complex

• Complex locks onto a sequence called PAM and begins to unzip DNA

• Looks for a match to guide RNA and cas9 cuts viral DNA at this point

How is the CRISPR-CAS9 system modified for humans?

• Use only CAS 9

• Connect Guide RNA and tracrRNA (holds Guide RNA in place)

• Can modify the Guide RNA to target many genes 

• DNA feeds into complex and CAS9 cuts DNA at target sequence