Chapter 7 Flashcards
Transcription
process in which RNA polymerase uses one strand of DNA as a template to synthesize a complementary RNA sequence
RNA polymerase
enzyme that catalyzes the synthesis of an RNA molecule from a DNA template using ribonucleoside triphosphate precursors
Do RNA polymerases need a primer?
no
Do RNA polymerases proofread their work?
no
messenger RNA (mRNA)
RNA molecule that specifies the amino acid sequence of a protein
each mRNA carries information transcribed for _____
just one gene which codes for a single protein
noncoding RNA
an RNA molecule that is the final product of a gene and does not code for protein
serve as enzymatic, structural, and regulatory components
ribosomal RNAs form the _______ of the ribosomes
structural and catalytic core
transfer RNAs (tRNAs)
act as adaptors that select specific amino acids and hold them in place as the ribosome links them to the growing protein
microRNAs (miRNAs)
regulate gene expression
small interfering RNAs (siRNAs)
provide protection from viruses and proliferating transposable elements
long noncoding RNAs (lncRNAs)
act as scaffolds and serve other diverse function, many of which are still being discovered
Promoter
DNA sequence that initiates gene transcription
includes sequences recognized by RNA polymerase and its accessory proteins
what does the sigma factor do
begins to open the DNA double helix to examine the exposed base pairs
which direction of DNA is used as its template
3’ to 5’ direction
general transcription factors
proteins that assemble on the promoters of eukaryotic genes near the start site of transcription and load the RNA polymerase in the correct position
RNA processing steps
capping
splicing
polyadenylation
RNA capping
modification of the 5’ end of a maturing RNA transcript by the addition of an atypical nucleotide