Gene Expression Flashcards
Transcription
Copying the information in DNA into a single strand of mRNA
mRNA
carries genetic information from DNA to ribosomes for protein synthesis
tRNA
carries in new amino acids based on codon-anticodon pairings
rRNA
component of ribosomes where protein synthesis occurs
Template Strand
DNA strand that is read by the RNA polymerase to make mRNA
Coding Strand:
DNA strand that is complementary to the template strand; it will be
the same sequence as the new mRNA transcript
Promoter
Recognition and binding sites for RNA polymerase
- properly orients RNA polymerase on the DNA
- Leader
Coding region
Contains information that will be translated later
*Trailer
Terminator
Tells RNA polymerase to stop transcribing
What is the RNA polymerase holoenzyme made up of?
Core polymerase and Sigma factor
Core polymerase
Required for the elongation phase
Sigma factor
Required for the initiation phase, helps detect the promoter
Transcription: Initiation
protein that directs core RNA polymerase to the promoter, and stabilizes the initial open bubble of DNA
Transcription: Elongation
synthesis of the mRNA strand
Transcription: Termination
RNA polymerase
reaches the end of the coding region, and detaches from DNA
Translation
Using information carried in the mRNA to make proteins.
Leader:
Contains regulatory information for translation
Shine-Dalgarno
Contained within the leader, this is a sequence to help
initiate translation by properly aligning the ribosome on mRNA
Start codon
AUG, codes for methionine, the first amino acid in a protein
Stop codon
codes simply for ribosome to stop, not associated with an amino acid
Translation: Initiation
brings the two ribosomal subunits together, placing the first amino acid in position
Translation: Elongation
sequentially adds amino acids as directed by mRNA transcript
Translation: Termination
releases the completed protein and recycles ribosomal subunits
Polysomes
allows for the synthesis of
many protein molecules simultaneously from the same mRNA
molecule.
Gene expression in Prokaryotes
Coupling of transcription and translation:
Transcription and translation can occur simultaneously, located in cytoplasm
Gene expression in Eukaryotes
Translation does not occur
until transcription is complete transcr: nucleus, transla: cytplasm
Introns
material is removed from RNA
Exons
material is removed from proteins
