Unit 13- Transcription Flashcards
Ribozymes
catalytic RNA
structure levels of RNA
- primary structure: seq of bases
- secondary structure: folding due to hydrogen bonding between complements of same strand
Characteristics of DNA
- composed of nucleotides
- sugar: deoxyribose
- H group
- nucleotides joined by phosphodiester bonds
- usually double stranded
- secondary structure: double helix
- stable
Characteristics of RNA
- composed of nucleotides
- sugar: ribose
- OH group (highly reactive)
- nucleotides joined by phosphodiester bonds
- usually single stranded
- many types of secondary structures
*easily degradable
ribosomal RNA (rRNA)
- prokaryotic and eukaryotic
- location (eukaryotic): cytoplasm
- function: structural and functional components of the ribosomes
Messenger RNA (mRNA)
- prokaryotic and eukaryotic
- location (eukaryotic): nucleus and cytoplasm
- function: carries genetic info for proteins (from DNA to ribosomes)
Transfer RNA (tRNA)
- prokaryotic and eukaryotic
- location (eukaryotic): cytoplasm
- function: helps incorporate amino acids into polypeptide chain
small nuclear RNA (snRNA)
- eukaryotic
- location: nucleus
- function: processing of pre-mRNA (alt splicing)
small nucleolar RNA (snoRNA)
- eukaryotic
- location: nucleus
- function: processing and assembly of rRNA
microRNA (miRNA)
- eukaryotic
- location: nucleus and cytoplasm
- function: inhibits translation of mRNA
small interfering RNA (siRNA)
- eukaryotic
- location: nucleus and cytoplams
- function: triggers degradation of other RNA molecs
piwi-interacting RNA (piRNA)
- eukaryotic
- location: nucleus and cytoplasm
- function: suppresses the transcription of transposable ele in reproductive cells
CRISPER RNA (crRNA)
- PROKARYOTIC
- function: assists destruction of foreign DNA
Long noncoding RNA (lncRNA)
- eukaryotic
- location: nucleus and cytoplasm
- function: variety
transcription components
- DNA template
- Raw materials (ribonucleotide triphosphates) needed to build a new RNA molecule
- proteins
transcribed strand
template strand
transcription unit
- A promoter (region that transcription factors,TFs,bind
- RNA-coding sequence
- Terminator
RNA transcription strand
- goes 5’ to 3’ and added to 3’-OH
- uses EITHER top or bottom strand of DNA
bacteria initiation
- ribonucleoside triphosphates (rNTPS) added to the 3’OH group end
- transcription apparatus
- bacterial promoters
- Initial RNA synthesis: no primer required
- Location of consensus sequence determines position of start site
transcription apparatus
bacterial RNA polymerase: five subunits make up core enzyme
- 2 copies of a
- single copy of B
- single copy of B+
- stabilizing enzyme: w
Sigma (o) factor: recognizes and binds to the promoter (after binding RNA pol. Enzyme —> creats holoenzymes)
RNA polymerase 1
- all eukaryotes
- Transcribes: large rRNAs
RNA polymerase 2
- all eukaryotes
- Transcribes: pre-mRNA, some snRNAs, snoRNAs, some miRNAs
RNA polymerase 3
- all eukaryotes
- Transcribes: tRNAs, small rRNAs, some snRNAs, some miRNAs
RNA polymerase 4
- plants
- Transcribes: some siRNAs
- methylation and chromatin structure