transcription Flashcards
what conclusions can be drawn from Beadle-Tatum experiments
concluded each gene dictase production on one enzyme; one gene, one enzyme –> one gene, one protein –> one gene , one RNA or protein
what is gene expression
process by which DNA directs protein synthesis; two stages being transcription and translation
prokaryotic gene expression
happen simultaneously (transcription and translation can happen at same time)
eukaryotic gene expression
transcription in nucleus and translation in cytoplasm; rna processing
what are retroviruses
make enzyme (reverse transcriptase) that ‘transcribes’ their RNA genome into double-stranded DNA copy (ex. HIV); exception to central dogma of biology because it uses reverse transcription to from RNA from DNA
what does reverse transcriptase do
enzyme that is responsible for the reverse transcription of retroviral single stranded RNA into double stranded DNA
RNA vs DNA
rna: single stranded, A, U, G, C, invoved in protein synthesis
dna; double stranded, helix, A, T, G, C, carries genetic info
tibonucleic acid
single stranded nucleic acid made of subunits of RNA nucleotides
mRNA
messenger RNA, transcript of gene, every three nucleotides = codon
tRNA
transfer RNA, ‘interpreter’ between nucleic acid language and protein language, anticodon binds to codon on mRNA, bound to specific amino acid corresponsonding to anitcodon
rRNA
ribosomal rna, component of ribosomes
synthesis of RNA
initiation
elongation
termination
promotor sequence
non-transcribed region short distance from 5’ end of gene; sequence that RNA polymerase binds to, regulates transcription rate, direct when and where transcription occurs
rna polymerase
enzyme that synthesizes RNA from a DNA template
transcription factors
proteins involved in the process of converting or transcribing DNA into RNA
terminator sequence
rna polymerase reaches terminator sequence at 3’ end of gene
different in prokaryotes and eukaryotes
how does the transcription rate compare to that of DNA replication
no proofreading so transcription has a higher error rate as RNA polymerase does not proof read like DNA polymerase
what are the modifications of mRNA that occur in eukaryotes
modify pre-mRNAs before nuclear exports:
- 5’ cap added
- 3’ poly A tail added
- introns spilced out
exons
regions of pre-mRNA (rna transcript) that are eventually translated into amino acids
introns
noncoding regions of pre mRNA that are removed
RNA splicing
process that removes intervening non coding sequences of genes (introns) from pre mRNA and joins protein-coding sequences (extrons) together in order to enable translation of mRNA into a protein
ribozyme
catalytic RNA molecule
snRNPS
small nuclear ribonuclear proteins, made of ribozymes & proteins
