unit 6 part 2 (6.3-6.7) Flashcards
RNA transcription
process that copies a DNA template sequence into a new RNA sequence with RNA polymerase
RNA polymerase
enzyme that pries the DNA strands apart and synthesizes a new complementary RNA strand (mRNA)
Initiation (transcription)
promoter region has sequences where transcription factors bind, the TF proteins allow polymerase to attach
Elongation (transcription)
RNA Polymerase opens up transcription bubble and allows new RNA nucleotides to form hydrogen bonds with the DNA template. RNA polymerase adds bases to 3’ end of growing mRNA transcript///// one or many RNA polymerase can contribute in a convoy onto growing stand
Termination (transcription)
mRNA separates from the transcription complex after reaching terminator region
hairpin
tertiary structure formed by nucleotides that help separate DNA and RNA
mRNA
stores nucleotide sequence that is translated into protein sequences, carries info outside of the nucleus to ribosomes
tRNA
translates nucleic acid sequence into sequence of amino acids which are readily available in cytoplasm. anticodon base pairs with complimentary codons in mRNA which signals what amino acid is needed
rRNA
forms quartenary structure with other proteins to create functional ribosome, P site holds tRNA carrying the growing polypeptide chain, A site holds the tRNA holding the next amino acid to be added, E site is where the tRNAs leave
introns
noncoding sequences within genes
splicing
removal of introns from RNA sequence, remaining exons are reassembled to make mature mRNA
GTP
modified guanine cap on 5’ end of mature mRNA, stabilizes molecule and blocks any random chemical reactions from taking place in cytosol
Poly-A Tail
chain of adenine nucleotides that stablizes 3’ side and protects mRNA and helps ribosomes attach
poly a tail adding mechanism
proteins recognize specific sequences within mRNA and recruit poly-a polymerase to complete polyadenilation
alternative splicing
extra variation created in mature mRNA depending on which codons are considered introns
splicisome
structure made of five small RNA molecules and their proteins joined to a complex, binds to each INTRON and removes it, binds the remaining exons
translation
mRNA is read and generated into polypeptides (mRNA –> amino acids)
prokaryotic ribosomes
only has cytosolic ribosomes
eukaryotic ribosomes
has cytosolic ribosomes and ones bound to the endoplasmic reticulum
translation in prokaryotes occur…
while mRNA is being transcribed
initiation (translation)
rRNA interacts with the mRNA at the start codon (AUG) at A Site
elongation (translation)
amino acids are being added to growing polypeptide at P Sit, tRNA binds to exposed codon and new amino acid attaches to growing polypeptide
termination
where process stops (stop codon is read), newly synthesized polypeptide is released, rRNA subunites disassemble
retrovirus translation
when a viral RNA invades host cell, the reverse transcriptase copies viral RNA into viral DNA which is integrated into host cell’s genome and then transcribed and translation, resulting in new viruses
common ancestory and translation
translation is similar in all organisms, the same nucleotides are used and chemical compatibility
codons
nucleotide triplets that code for specific amino acids 5’ to 3’
mRNA editing is only in
EUKARYOTES
wobble
changing the 3rd base does not always change the amino acid
promoter
attachment and initiation point for RNA polymerase, marks the beginning of a gene
transcription unit
stretch of DNA that is transcribed into an RNA molecule
transcription factors
proteins that mediate binding of RNA polymerase and the initiation of transcription
transcription initiation complex
complex of transcription factors and RNA Polymerase bound to promoter
termination (transcription) in prokaryotes
in bacteria transcription proceeds through DNA terminator and it is transcribed as the terminator signal causing polymerase to dettach
termination (transcription) in eukaryotes
RNA polymerase transcribes a sequence on DNA for poludenylation and the proteins (transcription factors) cut free from polymerase
regulation of gene expression
process by which instructions in the DNA are selectively transcribed and translation into functional proteins, accounts for phenotypic differences between organisms