PCR

Question 1

PCR - Clinical Uses

Answer 1

• Prenatal diagnosis
• Detection of mutated oncogenes
• Diagnosis of infections
• Forensics

Adv = sensitivity! - only one strand of DNA is needed to detect a particular DNA sequence

Question 2

Reverse Transcriptase PCR

Answer 2

• Used to amplify DNA
• RNA is converted to DNA by reverse transcriptase
• Gene expression in the form of mRNA (rather than DNA sequence) can therefore be analysed

Question 3

PCR Process

Answer 3

Polymerase chain reaction is a molecular genetic investigation technique

Prep:

• requires 2 DNA oligonucleotide primers, which are complimentary to specific DNA sequences at either end of target DNA
• DNA sample added to test tube along with the 2 DNA primers
• a thermostable DNA polymerase (Taq) is added

PCR Cycle:
- mixture is heated to almost boiling point causing denaturing (uncoiling) of DNA
- mixture is then allowed to cool - complimentary strands of DNA pair up as there is an excess of primer sequences they pair with DNA preferentially
> Cycle repeated w amount of DNA doubling each time !

Question 4

Molecular Biology Techniques

Answer 4

SOUTHERN BLOTTING = Detects DNA

NORTHERN BLOTTING = Detects RNA

WESTERN BLOTTING = Detects proteins - uses gel electrophoresis to separate native proteins by 3D structure

SNOW (South > North > West)
DROP (DNA > RNA > Protein)

ELISA = Enzyme-linked immunosorbent assay

• a type of biochemical assay used to detect antigens and antibodies
• a colour changing enzyme is attached to antibody if looking for antigen and to an antigen if looking for an antibody
• sample therefore changes colour if either is detected