Replication, Transcription And Translation Flashcards
What enzyme unwinds the DNA
Topoisomerase
What enzyme seperates the 2 strands of DNA
Helicase
When the DNA is seperated by helicase what does this create
2 DNA replication forks
What binds top the exposed bases of the DNA to prevent reannealing or snapping back together
Single stranded binding proteins
How is a short RNA primer made during replication
The primate enzyme then uses the original DNA sequences on the parent strand to synthesis a short RNA primer
Why are primers necessary in DNA replication
A primer is needed as DNA polymerase can only extend a nucleotide not start a new one
How does DNA polymerase begin to synthesis a new DNA strand
DNA polymerase begins to synthesis a new DNA strand by complementary base pairing using free floating nucleotides, which extends the RNA primer in a 5’ to 3’ direction
What happens to the RNA primer when the new DNA strand is completed
RNAse H recognises the primer on the DNA template and removed it by hydrolysing the RNA
What replaces the RNA primer
The RNA primer is replaced by newly synthesised DNA synthesised by DNA polymerase
What completes the DNA replication process
DNA replication is completed when the ligase enzyme joins the Okazaki fragments/short DNA pieces together to make one continuous DNA strand
What are the 4 stages of DNA transcription
Preparation
Production
Termination
Modification
What happens in the preparation stage of DNA replication
Topoisomerase unwinds the double helix structure removing the supercoils
DNA helicase seperates DNA apart to expose the nucleotides
Single stranded binding proteins coat the single DNA strands of either side to prevent the DNA from closing up
What happens during the production stage of DNA replication
TATA sequencing is the recognition signal for starting
AUG is the start codon
Free mRNA nucleotides line up along the exposed bases via complementary base paring
Uracil to thymine, guanine to cytosine
Coding Strand runs in a 5’ to 3’ direction
Template strand runs in s 3’ to 5’ direction
What happens during the termination stage of DNA transcription
RNA polymerase joins the mRNA nucleotides
Forms an antiparallel mRNA strand starting at the promoter
Transcription is stopped using a stop codon either UAA, UAG, UGA
What is the modification stage of DNA transcription also known as
Splicing
