Gene Expression Flashcards
gene expression
the process by which genes are expressed into polypeptide chains or RNA molecules which go on to affect the phenotype of an organism
central dogma
DNA > mRNA > protein
transcription
the synthesis of (pre)mRNA from a template strand of DNA, providing nucelotide-to-nucleotide transfer of information; nucleic acid to nucleic acid
translation
the syntheis of a polypeptide whose amino acid sequence is specified by the nucleotide sequence in the mRNA; nucleic acid to protein (language change)
template strand
the strand that is used as a template to build a complementary strand with matching base pairing; template strand and completementary strand are antiparallel
mRNA
messenger RNA; is transcribed and then carries the genetic information out of the nucleus in to be translated into proteins at ribosomes
codons
a triplet of nucleotides that code for 1 amino acid (or the stop signal); genetic information is encoded in a sequence of codons
reading frame
when translation occurs the codons are parsed out, if the sequence gets shifted the reading frame changes and the protein product may be different
stages of transcription
initiaion, elongation, termination
transcription unit
the segment of DNA that will be transcribed into mRNA
RNA polymerase
an enzyme that catalyzes RNA synthesis
RNA transcript
the RNA produced during transcription based on the genetic code of the template DNA
promotor
the region of a gene where RNA synthesis is initated, often includes a TATA box
TATA box
the binding sites of transcription factors, often in the promotor region of a gene
transcription factors
help eukaryotic RNA polymerase recognize promotor sequences forming a transcripton initiation complex
RNA processing
mRNA is modified before it leaves the nucleus; a 5’ cap is added to the 5’ end, a poly-A tail is added to the 3’ end, introns are excised
introns
regions of a gene that are not translated, they are excised in RNA processing
exons
regions of a gene that are translated, not excised
RNA splicing
process where introns are removed and exons are joined
spliceosomes
where RNA is spliced; but some RNA catalyzes it’s own splicing
ribozymes
RNA enzymes, can catalyze RNA splicing
alternative RNA splicing
introns allow for alternative mRNA product after splicing
