Question

1) RNAi or dsRNA-mediated RNA interference is an example of a broader phenomenon that occurs widely in eukaryotes called __________.

a) RNA activation b) RNA ascension c) RNA translation d) RNA silencing e) RNA charging

2) Which of the following is an RNA nucleotide?

1. A phosphate group, thymine and ribose
2. A phosphate group, guanine and deoxyribose
3. Cytosine and ribose.
4. Uracil and deoxyribose
5. None of the above

3) You are looking at an electron micrograph of several transcriptional units for rRNA. How can you tell where the transcription initiation site is?

a) It is near the longest nascent transcripts.
b) It is near the middle of the Christmas tree.
c) It is near the shortest nascent transcripts.
d) It is always 40 μm from the center of the Christmas tree. e) It is outside of the Christmas tree

4)A pair of homologous chromosomes is called a(n) _________________________.

5) The synthesis on new RNA molecule proceeds in ______________________ direction.

Answer 1

1. RNA silencing

This is a method by which a particular gene is blocked by blocking the RNA it produces from being translated by forming a ds RNA which cannot translate into proteins.

2. None of the above

A nucleotide of the RNA must contain a phosphate group, and a ribose sugar. It should also have only any one of these four nitrogen bases – Adenine (A), Cytosine (C), Guanine (G) or Uracil (U)

3. It is near the shortest nascent transcripts

Nascent transcripts are basically mRNA. The Christmas tree model shows that the initiation site is situated towards the tip of the tree which is where the shorter nascent transcripts are observed. Thicker bottom of the tree shows the presence of longer nascent transcripts and is where the Terminator is present.

4. Bivalent or Tetrad

There are no usual situations where the homologous chromosomes are paired up other than when meiosis is happening more usually during metaphase I of meiosis I. Then they are present as a pair of homologous chromosomes or 4 chromatids (2 pairs of sister chromatids). So, they are named as such.

5. 5’ - 3’

The RNA polymerase acts on the template strand in the 3’ – 5’ direction. So the RNA produced will be in the 5’ – 3’ direction.