Protein Synthesis Flashcards
What happens in transcription?
An mRNA molecule is produced that carries the genetic code from the DNA in the nucleus to a ribosome in the cytoplasm
Describe the first 3 stages Of protein synthesis
- DNA unwinds as RNA polymerase moves along a section that codes for a protein
- DNA molecule unzips when hydrogen bonds are broken
- Bases on the DNA strands are exposed
Describe stage 4 of protein synthesis
mRNA nucleotides move in and form complementary base pairs with one of the DNA strands
Describe stage 5 of protein synthesis
Strong chemical bonds form between the phosphate of one nucleotide and the ribose of the next nucleotide, building the mRNA strand
Describe stage 6 of protein synthesis
The weak hydrogen bonds that were holding the DNA and mRNA strands together break, allowing the mRNA primary transcript to leave the nucleus and enter the cytoplasm
Describe stage 7 of protein synthesis
Hydrogen bonds reform between the two DNA strands and the DNA molecule rewinds to form a double helix
What does the original DNA contain?
The codes to make proteins, but also non coding protein sections
Name the functions of different non coding regions of DNA
To regulate transcription- there are binding sites for other chemicals that can switch off neighbouring genes
To be transcribed to form RNAs that are not translated into protein, for example tRNA, rRNA and RNA fragments
Unknown - some regions make no sense and are thought to be the result of mistakes
What are the coding regions called?
Exons
What are the non coding regions called?
Introns
When are the introns cut out?
After the primary transcript has been produced
How is a mature mRNA strand produced?
The exons join together
What is the first stage of protein synthesis called and where does it happen?
Called transcription and happens in nucleus
