Protein Synthesis Flashcards
what is the start codon?
AUG
how many termination codons are there and what are they?
There are 3 and they are UAG, UAA and UGA
Explain the role of messenger RNA in protein synthesis.
mRNA carries a copy of the genetic code instructions from the DNA in the nucleus to the ribosomes in the cytoplasm.
what do 5’ and 3’ mean?
The two ends of a strand of DNA or RNA strand are different from each other. That is, a DNA or RNA strand has directionality.
At the 5’ end of the chain, the phosphate group of the first nucleotide in the chain sticks out. The phosphate group is attached to the 5’ carbon of the sugar ring, which is why this is called the 5’ end.
At the other end, called the 3’ end, the hydroxyl of the last nucleotide added to the chain is exposed. The hydroxyl group is attached to the 3’ carbon of the sugar ring, which is why this is called the 3’ end.
Many processes, such as DNA replication and transcription, can only take place in one particular direction relative the the directionality of a DNA or RNA strand.
What is meant by the term transcription?
the process in which a gene DNA is copied to make RNA molecules
What is the finished product of transcription called?
mRNA
What enzyme catalyses Transcription?
RNA polymerase
What enzymatic activities does RNA polymerase have?
synthesis of mRNA. By forming phosphodiestar bonds between RNA molecules. Helipads activity
Where does transcription take place?
Nucleus
What is the DNA region called to which RNA polymerase bonds at the start of transcription?
Promoter region
Which strand does RNA polymerase transcribe?
Template strand
What is an intron?
a non coding region within a gene
What is splicing?
The removal of introns from the RNA transcript
Describe the process of Transcription.
1) an enzyme called RNA polymerase attaches to the DNA at a region called promoter
2) the enzyme helicase breaks the hydrogen bonds between paired bases and unwinds DNA
3) 1 strand of DNA, the template strand, is transcribe to make an mRNA molecule with the same base sequence as the DNA strand
4) RNA polymerase “walks” down the template strand in the 3’ to 5’ direction
5) RNA polymerase adds a matching complementary RNA nucleotide to 3’ end of the DNA strand
5) When the RNA polymerase reaches the termination region. It will stop
Name 2 types of molecules that are needed to translate an mRNA into a protein.
- Transfer DNA
* Ribosomal RNA
