Polypeptide Synthesis Flashcards
Where does transcription take place?
In the nucleus
Process of transcription
- DNA helicase splits DNA to two strands
2.complementary RNA nucleotides attract to bases and form hydrogen bonds - RNA polymerase joins RNA nucleotides, creating phosphodiester bonds
- mRNA molecule moves out of nucleus through A nuclear pore
Where is noncoding DNA found?
Between genes and within genes
What are non-coding regions within a gene called?
Introns
What is RNA splicing?
The process of converting pre-mRNA to functional mRNA by removing introns and joining ends of exons
Where does splicing not take place and why?
In prokaryotes because introns are uncommon.
What do genes that don’t code for polypeptides do?
Code for functional RNA molecules e.g. Transfer RNA and ribosomal RNA
Where does translation take place?
In the cytoplasm
What is a genome?
All genes in a cell
What is a proteome?
All proteins produced by the genome of an organism
Why is the genetic code degenerate?
Most amino acids have more than one triplet.
Why is the genetic code non-overlapping?
No base is read more than once
Why is the genetic code universal?
It is the same in the vast majority of organisms on earth
What does the tRNA molecule consist of?
Amino acid binding site & an anti-codon which is complementary to the mRNA codon
Process of translation
- Small subunit ot ribosome binds with mRNA start codon.
- tRNA molecule with complementary anticodon attaches - held together by hydrogen bonding
- 2nd tRNA molecule moves into place with a complementary codon
- Peptide bond formed between amino acids.
- Ribosomes moves along and process continues (first tRNA molecule detaches)
- When ribosome reaches a stop codon, it detaches and the polypeptide chain is released
What is needed for the peptide bond to form?
Enzyme and energy provided by ATP
What is protein folding?
Physical process by which polypeptide folds into its characteristic 3D structure, which is essential to the protein’s function
What is the purpose of chaperone proteins?
Help other proteins fold correctly
When can the incorrect folding of proteins happen?
Can occur from hydrophobic groups on the amino acids join together.
