Question

How many enzyme activities are expressed by and involved in the movement of retro-homing elements in the Type II introns? What are the activities? How do they work?

A.

Two; the spliced intron expresses an endonuclease, which cuts the target DNA sequence for reverse splicing of the RNA intron into the DNA sequence, then a reverse transcriptase synthesizes the complementary DNA sequence using the intron as template

B.

Four; the spliced intron expresses an endonuclease, which cuts the target DNA sequence, then a special recombinase introduces the RNA sequence into the target DNA, a reverse transcriptase synthesizes the complementary DNA sequence using the intron as template, and then an RNAse activity removes the RNA sequence while the host DNA polymerase replaces the RNA with a DNA sequence.

C.

Three; the spliced intron expresses an endonuclease, which cuts the target DNA sequence, then a special recombinase introduces the RNA sequence into the target DNA, finally, a reverse transcriptase synthesizes the complementary DNA sequence using the intron as template.

D.

One; the spliced intron is incorporated into the target DNA by homologous recombination between the intron RNA and the target DNA catalyzed by a special recombinase expressed by the intron.

2.

Aging cells carry lower levels of the enzyme Telomerase, whereas cancer cells carry high levels of this enzyme. What intracellular molecule is its target? What does it do to the target? Does it harbor a prosthatic group to complete its action? What is it?

A.

DNA, extends the 3’-end, Yes, RNA

B.

RNA, extends the 3’-end, No, None

C.

RNA, cleaves into 21-base oligonucleotides, Yes, RNAse binding protein

D.

DNA, removes nucleotides from the 3’-end until it reaches the chi sequence, Yes, a protein by the name Rec A

E.

Protein, cleaves at the C-terminal of Aspartic acid, Yes, RNA

3.

Telomeres are beneficial to the target because of a particular reason:

A.

they are protein complexes that stabilize a chromosome

B.

they are protein complexes that stabilize a chromosome

C.

telomeres are 3’ extensions, which protect a chromosome from exonuclease digestion

D.

telomeres are covalently linked molecular caps that protect both ends of a chromosome

E.

telomeres are 5’ extensions that stabilize a chromosome from endonuclease digestion

these are the only information I have

Answer 1

1. How many enzyme activities are expressed by and involved in the movement of retro-homing elements in the Type II introns? What are the activities? How do they work?

One; the spliced intron is incorporated into the target DNA by homologous recombination between the intron RNA and the target DNA catalyzed by a special recombinase expressed by the intron.

2. Aging cells carry lower levels of the enzyme Telomerase, whereas cancer cells carry high levels of this enzyme. What intracellular molecule is its target? What does it do to the target? Does it harbor a prosthatic group to complete its action? What is it?

DNA, extends the 3’-end, Yes, RNA

What intracellular molecule is its target? DNA

What does it do to the target? extends the 3' end

Does it harbor a prosthatic group to complete its action? Yes

What is it? RNA

Telomerase add repeat sequence of telomere at 3'end of DNA which are complementary bases to the RNA template

3. Telomeres are beneficial to the target because of a particular reason:

telomeres are covalently linked molecular caps that protect both ends of a chromosome

They protect both the ends of a chromosome