1.9 Protein synthesis Flashcards
Main point
Protein synthesis requires transcription of a gene into messenger RNA (mRNA) and translation of mRNA into an amino acid sequence at the ribosomes. In eukaryotic cells this occurs in the nucleus.
Transcription
what, where, lalal
The process of copying the genetic code from the gene DNA to produce a mRNA molecule
occurs in the nucleus for eukaryotic cells
DNA molecule is used as a template to make mRNA using the base pairing rule A-U, T-A, C-G, G-C
RNA is processed to produce mature mRNA
The mature mRNA moves out of the nucleus through the nuclear pores.
Translation
where
Occurs in the cytoplasm or on the surface of the endoplasmic reticulum.
Ribosome synthesise a specific chain of amino acids (polypeptides) according to the sequence of the bases on the mRNA molecule.
This involves (transfer) tRNA and ribosomal rRNA.
Transfer RNA (tRNA)
Transfers the specific amino acids to the ribosome by matching with the mRNA codons
Each tRNA has a set of three nucleotides on it called an anti codon.
The anticodon of a particular tRNA binds to a specific mRNA codon following the base pairing rules.
Each tRNA molecule carriers a specific amino acid that corresponds to its complementary mRNA codon.
Amino acids
The monomer unit of protein molecules
building blocks of proteins - 20 different amino acids in humans
a codon codes for 1 amino acid
mRNA transfers the DNA code from the nucleus to the cytoplasm
codon sequences are read from the mRNA to produce a polypeptide chain.
Differences between coding gene and template strands
only 1 strand of the DNA will get transcribed
the strand that gets transcribed is called the template strand serving as the template for the mRNA molecule
The strand that is not transcribed is called the coding strand it shares the same sequence as the mRNA molecule that is formed, except for the thymine bases which are replaced by Uracil.
How is mRNA read
The mRNA is read in groups of three bases called a codon
