Histones - High Yield Topic Series

1. Poly A tail is usually present in 3' end of all pre-mRNA. But it is not present in the pre-mRNA of histone.

True

False

The poly A tail is a sequence of adenine nucleotides that is usually added to the 3' end of pre-mRNA molecules during RNA processing. However, in the case of histone pre-mRNA, this poly A tail is not present. This is because histone genes have a different mechanism of mRNA processing that involves cleavage and polyadenylation at a specific site within the coding region, rather than at the 3' end. Therefore, the statement that the poly A tail is not present in the pre-mRNA of histone is true.

Explanation

The poly A tail is a sequence of adenine nucleotides that is usually added to the 3' end of pre-mRNA molecules during RNA processing. However, in the case of histone pre-mRNA, this poly A tail is not present. This is because histone genes have a different mechanism of mRNA processing that involves cleavage and polyadenylation at a specific site within the coding region, rather than at the 3' end. Therefore, the statement that the poly A tail is not present in the pre-mRNA of histone is true.

2. Histone acetylation leads to

Euchromatin

Heterochromatin

Both of the above

None of the above

Histone acetylation refers to the process of adding acetyl groups to histone proteins, which are involved in DNA packaging. This modification loosens the structure of chromatin, allowing for easier access to DNA and promoting gene expression. Euchromatin is a less condensed form of chromatin that is actively transcribed, while heterochromatin is a highly condensed form that is transcriptionally inactive. Therefore, histone acetylation leads to euchromatin formation, making the correct answer "Euchromatin".

Explanation

Histone acetylation refers to the process of adding acetyl groups to histone proteins, which are involved in DNA packaging. This modification loosens the structure of chromatin, allowing for easier access to DNA and promoting gene expression. Euchromatin is a less condensed form of chromatin that is actively transcribed, while heterochromatin is a highly condensed form that is transcriptionally inactive. Therefore, histone acetylation leads to euchromatin formation, making the correct answer "Euchromatin".

3. Select the wrong statement ?

Histone methylation is in general associated with transcriptional repression

Histone acetylation tends to destabilize chromatin structure

Histone is rich in basic amino acids.

H1 is a component of Histone octamer.

H1 histone is a linker.

Explanation

H1 histone is a linker.

4. Anti histone antibodies are seen in

Drug induced lupus

SLE

Primary biliary Cirrhosis

Dermatomyositis

Anti-histone antibodies are antibodies that target histones, which are proteins involved in packaging DNA in the nucleus of cells. These antibodies are commonly seen in drug-induced lupus, a condition where certain medications can cause lupus-like symptoms in individuals who are susceptible. Drug-induced lupus is different from systemic lupus erythematosus (SLE), which is an autoimmune disease where the body's immune system mistakenly attacks healthy tissues and organs. While anti-histone antibodies can also be found in SLE, their presence is more strongly associated with drug-induced lupus. Therefore, the correct answer is drug-induced lupus.

Explanation

Anti-histone antibodies are antibodies that target histones, which are proteins involved in packaging DNA in the nucleus of cells. These antibodies are commonly seen in drug-induced lupus, a condition where certain medications can cause lupus-like symptoms in individuals who are susceptible. Drug-induced lupus is different from systemic lupus erythematosus (SLE), which is an autoimmune disease where the body's immune system mistakenly attacks healthy tissues and organs. While anti-histone antibodies can also be found in SLE, their presence is more strongly associated with drug-induced lupus. Therefore, the correct answer is drug-induced lupus.

5. Instead of poly A tail, which structure is present in the 3' end of the pre-mRNA of histone ?

Stem loop

Zinc finger

Leucine zipper

None of the above

In the 3' end of the pre-mRNA of histone, a structure called a stem loop is present instead of a poly A tail. A stem loop is a secondary structure formed when a sequence of nucleotides in the mRNA folds back on itself, creating a stem and a loop. This structure is important for the stability and regulation of the mRNA molecule.

Explanation

In the 3' end of the pre-mRNA of histone, a structure called a stem loop is present instead of a poly A tail. A stem loop is a secondary structure formed when a sequence of nucleotides in the mRNA folds back on itself, creating a stem and a loop. This structure is important for the stability and regulation of the mRNA molecule.