Nucleic Acids-Transcription and Translation Flashcards
What is mRNA?
Messenger RNA
When a polypeptide is required, what is converted into a molecule of mRNA?
The triplet code of it’s gene.
mRNA is like DNA in that it is a nucleic acid but what are the 4 differences?
-Single Stranded
-Contains Ribose
-Contains Uracil
-Easily Broken
Transcription is the first stage of what?
Protein Synthesis
What is the first stage of Transcription?
Helicase acts on a region of DNA to beak the hydrogen bonds between bases.
What is the second stage of Transcription?
RNA polymerase moves along one of the two DNA stands (template strands)
What is the third stage of Transcription?
RNA polymerase matches up complementary RNA nucleotides.
What is the fourth stage of Transcription?
C matches G
G matches C
U matches A
A matches T
What is the fifth stage of Transcription?
As the RNA nucleotides join together the pre-mRNA is formed.
What is the sixth stage of Transcription?
The DNA behind the RNA polymerase re-joins into a double helix.
What is the seventh stage of Transcription?
When the RNA polymerase reaches a ‘stop codon’ the chain is terminated and the pre-mRNA detaches.
What is tRNA?
Transfer RNA
What is the size of tRNA?
Small Molecule (~80 nucleotides)
How many strands and what is the shape of tRNA?
Single Stranded folded into a clover leaf shape with one slightly longer section.
What is the longer section attached to?
An amino acid.
What can each tRNA carry?
A different amino acid.
What are the 3 bases at the opposite end of the tRNA called?
Anti-codon
What does the anti-codon pair with?
The complementary codon on the mRNA
What does each amino acid have?
A different anti-codon
What is the first stage of Translation?
mRNA attaches the ribosomes at the start codon.
What is the second stage of Translation?
tRNA with a complementary anti-codon attaches to the mRNA.
What is the third stage of Translation?
This tRNA is attached to an amino acid.
What is the fourth stage of Translation?
The ribosomes moves along the mRNA bringing in 2 tRNA molecules at any one time.
What is the fifth stage of Translation?
An enzyme and ATP are used to join the amino acids with a peptide bond.
What is the sixth stage of Translation?
The first tRNA is released and can collect another amino acid.
What is the seventh stage of Translation?
The process is repeated until a ‘stop codon’ is reached.
What is the eighth stage of Translation?
Many ribosomes can travel along the mRNA at the same time-polysome.
