Question

when DNA is cut with a restriction enzym, the resulting fragments have

2' hydroxyl group

3' hydroxyl group

5' phosphate group

5' hydroxyl group

two of the above

which type of gene is found mutated in cancer cells?

proto-oncogenes

tumor suppressor genes

dna repair enzyme genes

two of the above

all of the above

Answer 1

1. when DNA is cut with a restriction enzyme, the resulting fragments have.

1. 3' hydroxyl group and 2. 5' phosphate group.

Restriction enzymes or restriction endonucleases are enzymes recognises a specific sequence of nucleotide and cut DNA into fragments based upon this recognition.

When a DNA is cut with a restriction enzyme then either stickey ends or blund ends produced. The Restriction enzymes which cleaves the DNA asymmetrically and formed stickey ends they leads to production of several single stranded bases. The enzyme leaves a 5' overhang If the single stranded bases are end with a 5' phosphate group. The enzyme leaves a 3' overhang If the single-stranded bases end with a 3' hydroxyl group.

So, two of the above are correct answer.

2. which type of gene is found mutated in cancer cells?

All of the above

Proto-oncogenes are a group of genes which helps in cell growth, apoptisis (programmed cell death) and several other functions. When these genes are mutated these normal cells become oncogenes and contributes to cancer development. Example- KRAS, beta-carotene, cyclin-E.

Tumor suppressor genes are genes which involved in several processes like they slow down cell division, repair DNA damage or in apoptosis. When these genes gets mutated their is no control on cell decision or apoptosis is their, and the cell can grow out of control leads to the development of cancer. Example- RB (retinoblastoma), p53.

DNA repair genes are involved in correction of any damage which happened in replication machinery Or any other type of DNA damage. If these genes get mutated then the mistakes are not corrected which mey leads to cancer development.