DNA, RNA & Protein Synthesis Flashcards
How is DNA & RNA made?
Polymerisation
- phosphodiester bond - between a free 3' OH group & 5' triphosphate
What are the ‘building blocks’ of DNA?
dATP, dCTP, dGTP, dTTP
e.g. deoxy-adenosinde-triphosphate
What are the ‘building blocks’ of RNA?
ATP, CTP, GTP, UTP
e.g. adenosine-triphosphate
What end are free nucleotides added to?
3’ end only
Why does DNA need to be replicated?
Must be replicated before division so that the daughter cells have a complete complement of the genome
What enzyme catalyses DNA replication?
DNA polymerase
Explain one of the tactics used to speed up the process of DNA replication.
- Eukaryotic genomes have many origins of replication
- Replication starts at several points in the genome
- bidirectional
What enzyme is used in removing incorrect nucleotides?
DNA polymerase
- further repair systems exist i. e. DNA polymerase has 3' to 5' exonuclease activity
How effective is DNA polymerase in proofreading and repair?
It decreases error rate from once every 10 power 4 to 10 power 5 base pairs to 10 power 9 to 10 power 10 base pairs
What are the 3 main classes of RNA?
- ribosomalRNA
- transferRNA
^^stable RNAs^^ - messengerRNA
Very briefly explain the role of rRNA (ribosomalRNA).
Combines with proteins to form ribsosomes where protein synthesis takes place
Very briefly explain the role of tRNA (transferRNA).
Carries the amino acids to be incorporated into the protein
Very briefly explain the role of mRNA (messengerRNA).
Carries the genetic information for protein synthesis.
What are the steps in transcription?
- RNA polymerase binding
- DNA chain separation
- Transcription
- Elongation
- Termination
what starts at nucleotide +1?
Transcription starts at nucleotide +1 ; the one before the first transcribed nucleotide is -1
