Transcription and Translation Flashcards
What is the purpose of transcription?
Making pre-mRNA using DNA as a template
What is the process of transcription?
1) DNA helicase acts on a region of DNA to separate both strands of DNA and expose the nucleotides.
2) One strand is used as template strand and pair with their complementary nucleotides contained in the nucleus.
3) RNA polymerase attaches at a start codon and moves along the strand to join nucleotides which form a pre-mRNA molecule.
4) Continues until the RNA polymerase is reached by the stop codon and it detaches.
What are the names of the nucleotide bases?
Adenine Thymine Guanine Cytosine (Uracil in mRNA)
Which nucleotides pair together?
Guanine - Cytosine
Thymine - Adenine
What is the difference between DNA and RNA nucleotides?
Thymine is replaced by Uracil
What is the difference between exons and introns?
Introns are non coding regions, meaning they do not code for proteins whereas exons do.
Through what process are introns removed?
Splicing
Why must splicing occur?
Introns prevent the synthesis of a polypeptide.
What happens after splicing?
- The mRNA molecule leaves through the nuclear pore as it is too large o diffuse out the nucleus.
- After leaving, it is attracted to the ribosome which becomes attached for translation to occur.
What is the process of protein synthesis?
1) Ribosome attaches to the starting codon on an mRNA molecule.
2) tRNA molecule moves to the ribosome and the anticodon on the tRNA pairs up with the codon and provides an amino acid.
3) Ribosome moves along to a second codon and brings a second tRNA molecule.
4) Every two amino acid is joined by a peptide bond using an enzyme and a hydrolysed ATP molecule.
5) As the ribosome moves to the third codon, the tRNA molecule is detached from the first codon.
6) Finishes at a stop codon.
