 |
Basic Biology - How genes encode proteins
 The sequence of base pairs in a gene determines the protein product that gene can encode
The genes are located on the DNA which is found in the nucleus of the cell. Protein synthesis happens outside the nucleus in the cytoplasm on the ribosomes.
The processes that are involved in making proteins from our genes are called transcription and translation and the molecules that are involved in these processes are called DNA, mRNA, tRNA and proteins. The order of information transfer is DNA to mRNA to protein.
Transcription
Transcription is the process where messenger RNA (mRNA) molecules are synthesised from DNA molecules. Transcription takes place in the nucleus. During transcription only one of the strands of DNA corresponding to a gene (template strand) is copied into mRNA. This mRNA molecule will be complementary to the bases that compose the template strand. The mRNA molecules have short lives. They travel out to the cytoplasm where they direct the synthesis of a protein and then they are destroyed.
Transcription depends on complementary base pairings. A pairs with U, T with A, C with G and G with C. Only one of the DNA molecules is transcribed and therefore the resulting mRNA molecule is single stranded. The amount of transcription of any given gene can be directly controlled by the cell.
Once the mRNA molecules leave the nucleus and enter the cytoplasm, they are loaded onto the ribosomes. It is at the ribosomes that protein synthesis occurs by a process called translation. The ribosomes are composed of ribosomal RNA (rRNA) proteins and ribosomal proteins.
|
|
|
How genes encode proteins <<< 1/2 >>> |
|