Topic 6.4 - Translation 𖦹⋆｡°✩ Flashcards
what is translation
the process by which an mRNA sequence is used to generate a polypeptide
where does translation occur
in the ribosomes
what type of ribosomes do prokaryotes have
cytosolic ribosomes
what type of ribosomes do eukaryotes have
cytosolic ribosomes and ribosomes bound to the rough ER
how does translation occur in prokaryotes
translation occurs while mRNA is being transcribed
what are the steps for translation in eukaryotes
༻ initiation - where the process starts
༻ elongation - where polypeptide starts
༻termination - where process starts
is translation similar in all organisms? how
yes. the nucleotides used to construct DNA/RNA molecules are common among organisms
what is evidence of common ancestry
the fact that the nucleotides used to construct DNA and RNA are common among organisms
what allows host-cell translation mechanisms to work with viral genomes
viral DNA molecules are chemically compatible with host-cell genomes, which allows host-cell translation mechanisms to work with viral genomes
what is translation
the final process in the flow of information from DNA -> RNA -> protein
what does translation involve
converting RNA information into a protein
what is the first step of translation
initiation - rRNA in the ribosome interacts with the mRNA at the first start codon
how are mRNA nucleotides grouped
they are grouped together and read in triplets called codons. each codon encodes a specific amino acid
how many naturally occurring amino acids are there
20, some are encoded for by more than 1 codon
how is translation terminated
via stop codons that do not code for amino acids but instead terminate translation
what is the function of tRNA molecules
bring the correct amino acid to the correct place, specified by the codon on the mRNA
what is the second step of translation
elongation - each newly arrived tRNA brings another amino acid to be added to a growing polypeptide chain
what is the function of rRNA
it adds the amino acids as the tRNA brings them
what is the third step of translation
termination - amino acids continue to be added to the growing polypeptide chain until a STOP codon is reached
what happens when translation is stopped
no more amino acids are added and the newly synthesized polypeptide is released
when is translation initiated
when the ribosomal subunits associate with an mRNA and read the first AUG codon
why can prokaryotes quickly adapt to their environments
because the ribosomes can bind before the mRNA molecule is even complete; translation can occur during transcription
what needs to happen to polypeptides before they are functional
they must be folded
why does mRNA need modifications
because the enzymes may remove amino acids from the interior of the chain
