Protein Synthesis and the Human Genome: A Deep Dive

Protein Synthesis: From DNA to Protein

1. Transcription: Copying the Genetic Message

Transcription is the process of copying part of the genetic message from DNA to RNA so that it can be used to synthesize a specific protein.

Stages of Transcription:

• The double helix of DNA unwinds.
• Complementary nucleotides position themselves opposite one of the two strands.
• Only one of the DNA strands is copied.
• An RNA strand is produced with a sequence of bases that is complementary to the DNA bases.

2. Translation: Building the Protein

Stages of Translation:

• The message copied as RNA is identical to the message in the DNA (except it contains uracil instead of thymine).
• This RNA, known as messenger RNA (mRNA), is a single-chain molecule that can leave the nucleus.
• The mRNA positions itself on the ribosomes.
• Transfer RNA (tRNA) transports the amino acids to the ribosomes in the order indicated by the mRNA's message.
• Each particle of tRNA is specific to a particular type of amino acid.
• The ribosomes link amino acids together in the appropriate order. The mRNA is read by the ribosomes that translate it into a protein.
• Each protein is synthesized according to the genetic information in the molecules of mRNA, which corresponds to segments of DNA.

3. The Genetic Code: The Language of Life

The genetic code is the relationship between the sequence of nitrogenous bases in DNA (mRNA) and the sequence of amino acids that make up proteins.

• Nitrogenous bases are arranged in groups of three, called codons, that code for a specific amino acid.

Characteristics of the Genetic Code:

• It's universal, meaning it is the same for all living things.
• It is a linear sequence of nitrogenous bases.
• The sequence is a continuous line with no breaks between the codons.

4. The Human Genome: Our Complete Genetic Blueprint

The human genome is an organism's complete set of genes.

Key Steps in Understanding the Human Genome:

• Determining the complete sequence of nitrogenous bases of its DNA.
• Locating the position of all its genes on the chromosomes.
• Understanding the relationships between its genes.
• Finding and identifying previously unknown genes.

The Human Genome Project

At the beginning of the 1990s, a project called the Human Genome Project was started.

By April 2003, all the sequences of nucleotides in the human genome were located.

The human haploid genome consists of 23 chromosomes, 3 billion pairs of nitrogenous bases, and approximately 30,000 genes. Notably, 99.9% of genes are identical in every person.