Lecture 24: Transcription and Translation Flashcards
one mRNA can make
many proteins
Gene expression
process by which DNA directs synthesis of polypeptides through mRNA
Beadle and Tatum theory
proposed one gene one protein, ended up being one gene one polypeptide
Transcription and Translation are
coupled (occur at same time)
translation flow
pre-mRNA –> processed to mRNA –> transported to cytosol –> translated into proteins
pre-mRNA is
the primary transcript, aka hnRNA
transcription
synthesis of RNA under the direction of DNA
steps in transcription
- binding of RNA polymerase II
- unwinding of DNA
- initiation
- elongation
- termination
Binding in transcription
RNA polymerase II binds to promoter and begins to transcribe
stages of transcription in prokaryotic cells
initiation, elongation, termination
Steps of prokaryotic transcription
- RNA polymerase elongates RNA and transcribes one strand at a time
- RNA polymerase II untwists one turn of DNA helix at a time
- terminator sequence signals the end of transcription
Eukaryotic transcription difference
transcription factors are needed
transcription factors
proteins that recognize the sequence of nucleotides next to the promoter sequence
where does RNA splicing occur?
in the nucleus
5’ Cap
guanine modified nucleotide that protects mRNA from degradation and guides it to the ribosome for protein synthesis
