Question

answer all the questions please

*3 2 1 OA- АаВЬСcl AaBbc | АаВЬСc| АаВЬС Emphasis Heading 1 1 Normal Strong Paragraph ly Styles 8) In mammalian female cells, the DNA of the Barr Body is characteristic of a) Heterochromatin b) Euchromatin c) Dispersed chromatin d) Paternal DNA ONLY e) Maternal DNA ONLY 9) When used to describe the RNA polymerases' activity, the term "processivity” refers to: a) The ability to recognize and bind to a promoter region b) The ability to remain attached to DNA c) The ability to add nucleotide triphosphates to a growing RNA chain d) The ability to correct errors in base mismatching e) The ability to detach quickly from DNA 10) Describe the structure of a nucleosome (be sure to include as much information as possible for full credit) 11) The enzyme that catalyzes the addition of additional bases on the ends of chromosomes is referred to as a) a centromere b) sister chromatid c) telomerase d) telomere e) kinase Foc a

Answer 1

1. Heterochromatin.

Barr body is the inactivated, highly condensed x chromosomes which are present in female cells. They are heterochromatin in nature hence they are inactive. In order to regulate the expression level of x chromosomes which are two in number in females, one of them is inactivated.

2. The ability to remain attached to DNA

Processivity of an enzyme refers to the ability of an enzyme to add nucleotides to the newly synthesized strand without dissociating from the template strand.

      3. The eukaryotic DNA into structural units called nucleosomes which are made up of DNA and histone proteins. Histones are the basic proteins that contain high amounts of basic amino acids such as arginine and lysine. They play a role in packaging .There are five types of histone proteins in eukaryotic chromosomes namely, H1, H2A, H2B, H3 and H4. H1 is called the linker histone and highly conserved and the last four histones in copies of two forms the histone octamer found at the centre of nucleosome. Two turns of DNA are wrapped around each octomer.Apart from its involvement in DNA packaging they also have a vital role in eukaryotic gene regulation which is brought about by acetylation and deacetylation of histone proteins.

4. telomerase

Telomerases are the ribonucleoprotein complexes containing a small RNA that serves as a template for addition of new six nucleotide repeats. Or Telomerase, the enzyme that synthesizes the telomere ends of linear chromosomes, is a specialized reverse transcriptase that contains an internal RNA template. Telomeres undergo cycles of shortening of the lagging strands due to the inability to complete synthesis.

5. missense mutation

Missense mutation is a type of point mutation which brings about change in the single nucleotides resulting in changing one amino acid into another amino acid in the protein.

Example for missense mutation

AUG-UGG-AAU-GUU-AUA

Met-Trp-Asn-Valine-Ile

After missense mutation

AUG-UGG-AAG-GUU-AUA

Met-Trp-Lys-Valine-Ile