Quiz 9 Pierson
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- Gene expression is accomplished by what three processes?
- 1)Transcription 2)RNA processing 3)Translation
- How is transcription similar to DNA replication?
- Both involve enzymes that synthesize a new strand of nucleic acid that is complementary to DNA.
- Does RNA polymerase need a primer?
- No it does not.
- What happens as a result the RNA does not stay based paired to the template DNA?
- 1) Because this follows closely to the site of polymerization, multiple RNA pol can transcribe the same gene at the same time 2) Cell can synthesize large number of transcripts from a single gene in a short time.
- Name three components to the central dogma of molecular biology by Crick in 1958.
- 1) The flow of information is from loci to protein. 2) The flow is unidirectional. 3)Information here means the precise determination of a sequence.
- What is the definition of transcription?
- Transcription is the production of an RNA molecule using a DNA molecule as a template.
- Define transcript.
- A transcript is the RNA product of transcription.
- What are the four types of RNAs?
- 1)tRNA 2)rRNA 3)snRNA 4)scRNA
- What is the function of a tRNA?
- It transports amino acids to translation complex and aligns them at the correct location along the mRNA.
- What is the function of rRNA?
- They combine with proteins to make ribosomes and do most of the catalytic functions of ribosomes.
- What is the function of snRNA?
- snRNA (which stands for small nuclear RNA) combine with specific proteins to make ribonucleoprotein particles (snRNPs)
- What is the function of scRNA?
- scRNA stands for small cytoplasmic RNA and they direct protein traffic within a cell.
- What is more accurate: transcription or DNA replication?
- DNA replication is more accurate because in replication there is an error rate of 1 in 10^7 while in transcription the error rate is 1 in 10^4.
- What is one profound difference between replication and transcription?
- In replication we copy the entire genome only once every cell division but in transcription we selectively copy parts of the genome and make from a hundred to a thousand copies of any given section.
- Define promoter.
- A promoter is the DNA sequence that initially binds the RNA polymerase (together with any initiation factors required).
- In regards to RNA polymerase how do prokaryotes and eukaryotes differ?
- Prokaryotes have only one RNA polymerase while eukaryotes have three RNA polymerase.
- What is the function of RNA pol II?
- It is the polymerase responsible for transcribing most genes.
- What is the function of RNA pol I?
- RNA pol I transcribes large RNA precursor genes.
- What is the function of RNA pol III?
- RNA pol III transcribes tRNA genes, snRNA genes, and the 5S rRNA gene.
- What are the 5 units of protein called in core enzyme of bacteria?
- alpha alpha beta beta-prime omega
- What are the three stages of transcription?
- Initiation Elongation Termination
- Describe initiation in three steps.
- 1) Initial binding of RNA polymerase to promoter makes a closed complex where the DNA is double stranded and the enzyme is bound to only one face of the helix. 2) In second step, the closed complex turns into an open complex where the DNA strands separate. 3) Promoter escape
- When has an enzyme escaped the promoter?
- Once the enzyme gets further than 10 bp it is said to have escaped the promoter.
- What has to happen at the end of initiation to continue on to elongation?
- A stable ternary complex has to be formed.