transcription and translation Flashcards
why is transcription needed
DNA too large to pass out through the nuclear pores to attach to the ribsomes in the cytoplasm
define transcription
the process where DNA produces pre-MRNA
what are the enzymes used in transcription
Rna polymerase
what two jobs does RNA polymerase do
unzips the DNA helicase - braking the hydrogen bonds
catalyses the condensation of phosphodiester bonds between nucleotides
what happens when rna polymerase unzips the helix
hydrogen bonds break
what happens to the exposed h bonds
free RNA nucleotide will base pair with complementary bases
how do the nucleotides bond
rna polymerase catalyses a condensation reaction of phosphodiester bonds between base pairs
what bonds form between base pairs
phosphodiester
what does this lead to
splicing
what is splicing
removing introns
what does removing the introns form
mature MRNA
what is translation
where Mrna is turned into proteins
where does translation occur
in a ribsome
what happens in the ribsome
ribsome binds to MRNA and attaches to start codon
what then moves toward the ribsome
Trna molecule
what does this trna molecule have
a complementory anticodon
what does this anticodon do
pairs with the codon on the MRNA
what does each trna molecule carry
an amino acid
what the third step
anouther trna molecule binds to mrna condon carrying anouther amino acid
why do the trna molecules come
they are attracted to the ribsome
what does the ribsome do to ensure constant trna
it moves down the mrna
what then happens to the amino acids
they are then attached by a peptide bond
what then happens causing the first amino acid to be released
the ribsome moves along the mrna to the third condon causing the first Trna to be released
what causes it to stop
the stop codon
