Life Sciences Term 1

1) The importance of proteins

• Play essential roles in the cells of all living creatures
• They serve as building blocks of cells, control chemical reactions, and transport materials to and from cells
• Composed of long chains of amino acids
• The specific sequence of amino acids in a chain determines the exact function of the protein

2) The process of protein synthesis

Protein synthesis takes place in two steps namely transcription and translation. The two steps will now be dealt with in detail.

Transcription: 

• Takes place in the nucleus
• Double stranded DNA unzips
• When the weak hydrogen bonds break
• One strand is used as a template
• To form mRNA
• Using free mRNA nucleotides from the nucleoplasm
• mRNA is complementary to the DNA
• mRNA moves from the nucleus to the cytoplasm and attaches to the ribosome

Translation:

• Takes place in cytoplasm
• Each tRNA carries a specific amino acid
• When the anticodon on the tRNA
• Matches the codon on the mRNA
• Then tRNA brings required amino acid the ribosome
• Amino acids become attached by peptide bonds
• To form the required protein

Each protein is formed specifically to the genetic code stored on the DNA in the nucleus of every cell in the organism. Any change during this coding process will result in a gene mutation. 

The following table indicates how an amino acid’s anticodon on the tRNA, codon on the mRNA and base triplet on DNA are related. Note the difference regarding the thymine and uracil