RNA Flashcards
rna
- ribosomal nucleic acid
- found as a single strand in various shapes
difference between rna and dna
- rna has ribose, dna has deoxyribose
- rna has uracil not thymine
- rna is single stranded
shapes of rna
- mRNA: noodle
- rRNA: balls up into glob
- tRNA: looks like letter T
mRNA
- created in nucleus in process called transcription
- it is a copy of a gene that is capable of leaving the nucleus. it carries the code to the cytoplasm where it randomly bumps into a ribosome
- contains the codon
codon
3 nucleotide sequence of rna
rRNA
2 rRNAs join together to form 1 ribosome, the ribosome is the location of translation
tRNA
will pick up specific amino acid and bring it to ribosome. tRNA contains the anti codon
anti codon
3 nucleotide sequence of tRNA
overview of flow from gene to protein in eukaryotes
DNA (transcription) -> mRNA (translation) -> protein
how does transcription start
RNA polymerase binds to promoter region in the DNA that looks like TATA (= TATA box)
RNA polymerase
- unwinds DNA and builds complementary strand
- creates mRNA, pre-mRNA or the transcript
termination signal
- transcript detaches when it hits this
- AAAAAA
- this also releases mRNA
guanosine triphosphate (GTP)
added to the 5’ region of mRNA before it can leave the nucleus, known as the 5’ cap
poly A tail
- 150-200 A’s
- added to the 3’ end which controls the movement of mRNA through nuclear pore
SnRNP’s (small nuclear riboproteins)
cut out the introns so that several genes can be transcribed at once
(1 gene can be read many different ways producing many different products depending on how the gene is spliced)
start of translation
mRNA floats around cytoplasm until it hits the small subunit of a ribosome, at this point binding takes place
what happens after mRNA attaches to ribosome (translation)
first tRNA arrives with amino acid methionine attaches to mRNA.
-second rRNA subunit attaches
amino acids
- randomly brought to ribosome by tRNA
- put in very specific order by matching the mRNA codon to tRNA anticodon
how many tRNAs can fit on a ribosome at once?
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