DNA Transcription

Mind Map by meleking96, updated more than 1 year ago
Created by meleking96 over 5 years ago


Overview of the process of transcription in prokaryotes and eukaryotes, and the roles of RNA.

Resource summary

DNA Transcription
1 Prokaryotes
1.1 Use DNA as template for RNA strand
1.1.1 DNA directly copied into mRNA
1.2 Ribosomes translate new RNA strand while it's still being synthesized
1.2.1 Each ribosome follows the one before it: quickly bind many copies of same polypeptide Hard to correct mistakes in transcription because translation has already begun
2 Eukaryotes
2.1 Use DNA as template for pre-mRNA strand
2.1.1 pre-mRNA processed into mRNA Remove introns through RNA splicing RNA splicing catalyzed by snRNPs snRNPs=small nuclear ribonucleoproteins complexes of RNA and protein snRNPs form a phosphodiester bond between 2 exons intron loop removed introns degraded into ribonucleotides that can be recycled into other RNA structures Exons remain after splicing to make RNA relatively same size (same number bps) across species actually coding for proteins, which are same for multiple species
2.2 Transcription occurs in the nucleus
2.2.1 New RNA strand is modified, then exported into cytoplasm, where introns are removed Translation occurs in cytoplasm, where ribosomes are polypeptide then shipped to rough ER for folding Occurs separately from transcription, chance to remove errors
3 Only template strand of DNA is transcribed
3.1 New RNA nucleotides added 5' to 3' on NEW strand
3.1.1 This is 3'-5' on template strand
3.1.2 Result: new RNA strand, complementary and antiparallel to template DNA strand
4 Mechanics of Transcription
4.1 RNA polymerase attaches at promoter sequence
4.1.1 RNA polymerase moves along DNA, adding nucleotides to growing RNA strand Detaches when it reaches terminator sequence RNA bonds with itself, forming hairpin loop RNA polymerase reaches loop and detaches from RNA
5 Three Roles of RNA
5.1 1. messenger RNA (mRNA)
5.1.1 short-term carrier of genetic info
5.2 2. ribosomal RNA (rRNA)
5.2.1 part of ribosome's structure
5.3 3. transfer RNA (tRNA)
5.3.1 helps carry out translation
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