Protein Synthesis Flashcards
What is the genome?
Complete set of genes in a cell
What is a proteome?
Full range of proteins a cell is able to produce
Structure of RNA
Polymer made up of repeating mononucleotide sub-units
Forms a single strand in which each nucleotide is made up of:
-Pentose sugar ribose
-One organic base
- A phosphate group
Usually one nucleotide chain while DNA is usually 2
Describe the structure and role of mRNA
Thousands of mononucleotides arranged in a single helix.
mRNA carries the genetic code from the nucleus, through the nuclear envelope to the cytoplasm where it associates with a ribosome for translation.
Structure suits its function as it possesses genetic info in the form of codons. Sequence of codons determines the sequence of amino acids of a specific polypeptide
Describe the process of transcription
RNA Polymerase (enzyme) attaches to the DNA at the beginning of the gene.
Hydrogen bonds between the two DNA strands of the double helix break this causes it to unravel and expose the nucleotide bases.
One of the two strands is used as a template strand.
The exposed nucleotides on the template strand pair with their complementary bases from the pool in the nucleus.
RNA polymerase then moves down the strand joining the free nucleotides together to from a pre mRNA molecule.
Hydrogen bonds that had broken reform so the strands of DNA reform.
This process continues until the RNA polymerase reaches a stop signal where it detaches.
Does splicing occur in eukaryotic or prokaryotic cells?
Eukaryotic cells
Turns pre mRNA to mRNA
What occurs during splicing?
What’s the next step
mRNA contains introns and exons.
Introns do not contain information to code for proteins so they are removed.
The exons are then joined together.
The mRNA then moves out of the nucleus via a nuclear pore where it is then attracted to a ribosome
Steps of translation?
Ribosome becomes attached to the starting codon at one end of the mRNA molecule.
The tRNA molecule with the complementary anticodon to the first codon on the mRNA binds to the codon. This tRNA carries a specific amino acid.
The second tRNA does the same with the next codon also carrying its specific amino acid.
These two amino acids are joined by a peptide bond - this is done using an enzyme and atp which is hydrolysed to release energy.
The first tRNA molecule moves away and collects another amino acid simulatenously the ribosome moves along to the next codon.
Process repeats until the ribosome reaches a stop codon. The ribosome tRNA molecule and mRNA all release leaving a polypeptide chain.
