12. Transcription And Rna Processing B Flashcards
What are the similarities (2) and differences (2) in languages with DNA and proteins? Think what they are made of
They are both polymers with specific sequences of monomers DNA has four types of nucleotides - differ in nitrogen bases Protein strands are built with amino acids
What is transcription? What is it for?
The first step of gene expression. A segment of DNA is copied into RNA
What does the RNA polymerase do during transcription? Which direction does it go?
RNA polymerase copies the DNA template strand sequence (bottom strand) from the 5’ to the 3’ end.
Is which is in DNA and which is in RNA? - uracil and thymine. How does this impact transcription?
Thymine is in DNA and uracil is in RNA. The thymine nucleotide changes to a uracil nucleotide after the RNA polymerase copies the coding strand of DNA
When does RNA polymerase know when to stop? Think of a codon
The RNA polymerase stops copying the DNA coding stand once it reaches a ‘stop’ codon which is UAA, UAG or UGA
Which end of do the caps on either side of the copied mRNA go on? Think of if its the 5’ end or 3’ end and what the name of them are
A cap goes on the 5’ end and on the 3’ end the poly-a-tail is added
What is splicing?
Introns are removed from the pre- mRNA and exons are joined together
In eukaryotes cells, what happens after splicing occurs? Give two steps
The mature mRNA moves out of the nucleus through a nucleus pore. Then the mRNA is fed into a ribosome on the rough endoplasmic reticulum.
What are ribosomes made of? Hint: two ingredients
A mix of protein and rRNA
What does rRNA offer during transcription?
They allow mRNA to bind with tRNA (transfer RNA) so translation can occur
How does tRNA initiate translation from nucleotide language to amino acid language?
The ribosome reads a triplet codon one at a time on the mRNA strand. The Ribosome find the right tRNA to translate the mRNA codon, the correct tRNA has an amino acid attached to it. The triplet codons continue to be read and the amino acids covalently bond to form a polypeptide chain
define gene expression
the whole process of transcription and translation
