A
What is PCR used for?
Amplifying DNA
What is the role of primers in PCR?
Initiate DNA synthesis
What type of molecule is analyzed in Northern blotting?
RNA
What determines the position of bands in blotting techniques?
Molecular size of DNA,RNA/protein.
What is STR
Repeating sequences of 2–6 base pairs
What does a cDNA library represent?
Only expressed genes or only exons
What does Western blotting detect?
Protein
What is used to detect proteins in Western blotting?
Antobodies
What type of ends are produced by staggered cuts?
sticky ends
Why is reverse transcriptase used in cDNA synthesis?
Converts RNA to DNA
What is the main purpose of Northern blotting?
Gene exprssion
What label is commonly attached to probes?
Fluorescent or radioactive tag
What is gel electrophoresis used for?
Separating DNA fragments by size
A Northern blot shows strong expression of a gene in liver cells but not in brain cells.
Question: What does this indicate about the gene?
The gene is tissue-specific and actively transcribed in liver cells.
Gene silencing mechanism is called
RNA interference
How is RNAi useful in research?
It helps determine gene function by silencing specific genes.
A researcher wants to study gene expression at different developmental stages. Which technique is most appropriate?
Northern blotting
A researcher performs Sanger DNA sequencing using dideoxynucleotides (ddNTPs). After electrophoresis, the following order of fluorescent bands is observed (from shortest to longest fragments):
T → A → C → G → G → T
What is the sequence of the original template strand?
A T G C C A
Why are ddNTPs able to stop DNA elongation?
They lack a 3′-OH group required for forming phosphodiester bonds.
A researcher wants to clone a human insulin gene and express it in bacteria. The scientist first collects pancreatic cells, which actively produce insulin. From these cells, RNA is extracted and converted into complementary DNA (cDNA) using reverse transcriptase. The resulting cDNA is then inserted into a plasmid and introduced into bacterial cells for protein production.
Why did the researcher specifically choose pancreatic cells for this experiment?
Because insulin gene is expressed in pancreatic cells.