BIOL-3080 2: Transcription

What is the product of transcription?

RNA that is complementary to one strand of DNA.

What is the function of mRNAs and what % of total RNA within a cell does it make up?

Messenger RNAs that code for proteins, only 3-5% of total RNA.

What is the function of rRNAs and what % of total RNA within a cell does it make up?

Ribosomal RNAs, form the basic structure of the ribosome and catalyze protein synthesis. Make up 75-80% of total RNA.

What is the function of tRNAs and what % of total RNA within a cell does it make up?

Transfer RNAs, are the adapters between mRNA and amino acids in protein synthesis. Make up 10-15% of total RNA.

What is the function of Telomerase RNA?

Serves as the template for the telomerase enzyme that extends the ends of chromosomes.

What is the function of snRNAs?

Small nuclear RNAs, involved in a variety of nuclear processes including the splicing of pre-mRNA.

What is the function of snoRNAs?

Small nucleolar RNAs, help to process and chemically modify rRNAs.

What is the function of lncRNAs?

Long noncoding RNAs, some serve as scaffolds and regulate diverse cell processes, including X-chromosome inactivation.

What is the function of miRNAs?

Regulate gene expression by blocking translation of specific mRNAs and causing their degradation.

What is the function of siRNAs?

Small interfering RNAs, turn off gene expression by directing the degradation of selective mRNAs and helping to establish repressive chromatin structures.

What is the function of piRNAs?

Piwi-interacting RNAs, bind to piwi proteins and protect the germ line from transposable elements.

What kind of polymerase does not require a primer to initiate synthesis?

RNA polymerase.

A major enzyme involved in transcription.

RNA polymerase.

Has an error rate of 1×10^4 rNTPs incorporated.

RNA polymerase.

Has an error rate of 1*10^7 dNTPs incorporated.

DNA polymerase.

What are the components of a holoenzyme?

5 subunits in a core enzyme and a sigma factor.

What is the function of the sigma factor?

Enables holoenzyme to bind selectively to different promoter sequences.

What are the two sequences recognized by sigma factors in E. coli?

-10 and -35 sequences.

Which strand on the DNA double helix does the transcribed RNA sequence mirror?

The coding strand.

Which strand on the DNA double-helix is used in transcription?

The template strand.

Why does DNA pol have a lower error rate than RNA pol?

DNA is the “hard copy” of genetic information and the consequence of mistakes during replication is therefore much graver.

What is the form of a final gene product?

A protein.

What is the only point at which the central dogma works in the opposite direction?

Reverse transcriptase between transcription and translation.

What are the subunits of a protein? What are they made up of?

Amino acids, each made up of three bases.

Of all the RNAs, which are the only ones to be synthesized?

mRNAs.

What does it mean that RNA polymerase can initiate RNA synthesis de novo?

Without the use of a primer.

What type of RNA is most abundant in cells?

rRNA, which makes up 75-80% of all RNA.