Gene Expression: Transcription and Translation

Flashcards for Chapter 7 Lecture Notes

Transcription

DNA -> RNA

Translation

RNA -> Protein

mRNA

Expressed intermediate of gene coding for a protein

tRNA

Adaptors translating mRNA sequence to amino acid sequence

rRNA

Form core of ribosome to catalyze translation reactions

miRNA

Regulate gene expression through binding mRNA sequences

ncRNA

Various regulatory functions (telomere maintenance, splicing, regulation of expression)

Prokaryote

Simultaneous transcription and translation of the same gene; no RNA processing required

Eukaryote

Transcription occurs in the nucleus and translation occurs in the cytoplasm; RNA processing is required and occurs in the nucleus

Promoter region

Specific sequence of DNA immediately upstream of transcription start site; recruits binding of transcriptional machinery

Initiation

Transcriptional complex binds to promoter of gene and starts transcription

Elongation

RNA polymerase catalyzes RNA nucleotides incorporation into a new RNA strand

Termination

Transcription stops, mRNA and transcriptional complex is released from the DNA

Sigma Factor

RNA pol contains subunit, sigma factor that recognizes the promoter

Eukaryotes Transcription

RNA pol II requires general transcription factors that bind to the promoter before transcription can begin

5’ Guanine Cap

Modified guanine with a methyl group is added to the 5’ end of mRNA during transcription

3’ Polyadenylation

Poly-A-polymerase (PAP) adds ~ 200 adenines to the 3’ end of mRNA

Exons

Coding regions; code for final product (protein)

Introns

Non-coding regions between exons of same gene

Intergenic Sequences

Non-coding regions that separate individual genes

Spliceosomes

Large complexes of small nuclear RNAs + proteins forming small nuclear ribonucleoproteins (snRNPs)