Week 3 Gene expression and Control Flashcards
What is transcription?
The process of making an RNA copy (mRNA) from a DNA template.
What is the role of RNA in the central dogma?
RNA acts as the intermediary, carrying genetic info from DNA to ribosomes for protein synthesis.
What is the difference between DNA and RNA?
DNA is double-stranded and stable; RNA is single-stranded, less stable, and contains uracil instead of thymine.
What enzyme synthesizes RNA from DNA?
RNA Polymerase.
What is the function of the sigma (σ) factor in transcription?
It guides RNA polymerase to bind to the promoter and initiate transcription at the correct site.
What are the three phases of transcription?
Initiation, Elongation, Termination.
What is a promoter?
A DNA sequence where RNA polymerase binds to initiate transcription.
What are Rho-dependent and Rho-independent terminators?
Rho-dependent requires the rho protein; Rho-independent does not and relies on RNA secondary structures.
What is translation?
The process of synthesizing proteins from an mRNA template using ribosomes.
What does mRNA do in translation?
Carries genetic code from DNA in the form of codons.
What is the role of tRNA?
Carries amino acids to the ribosome and matches its anticodon with mRNA codons.
What is the role of rRNA?
Forms part of the ribosome and catalyzes peptide bond formation.
What are the three ribosome sites?
A-site (entry), P-site (peptide chain), E-site (exit).
What is a codon?
A three-nucleotide sequence that codes for a specific amino acid.
How many codons and amino acids are there?
64 codons, 20 standard amino acids – the genetic code is redundant.
What is an operon?
A cluster of genes transcribed as a single mRNA in prokaryotes.
What does the lac operon do?
Regulates the metabolism of lactose in E. coli based on glucose availability.
What are transcriptional activators and repressors?
Proteins that increase or decrease gene expression by binding to DNA near promoters.
When is the lac operon activated?
When lactose is present and glucose is absent.
What does the transcription unit include ?
Promoter, RNA Coding Region and terminator
