Understanding the Human Genome and Genetic Engineering

The Human Genome

The genome of an organism is the set of all its genetic information. It consists of genes (2%), and the other 98% is composed of RNA genes, introns (extra DNA sequences not used to generate proteins), and junk DNA.

Thus, within the DNA, we can distinguish:

• Sets of nucleotides that form part of the genes: exons and introns.
  • Exon is the portion of DNA within a gene that encodes proteins.
  • Intron is the portion of DNA within a gene that is not used in protein synthesis.
• Junk DNA that does not belong to any gene. Most of the genome is actually non-coding DNA.

Genome and Complexity

Organisms with more genes per nucleotide are not necessarily more complex than organisms with fewer genes per nucleotide.

Genomics is the branch of biology that deals with the study of genomes. Proteomics is responsible for studying all the proteins encoded by the genome.

Developmental Genetics

Developmental genetics has made it possible to decipher the rules that govern the development of organisms. The development of an organism involves an initial cell multiplying (proliferation) and then the daughter cells specializing to become different tissues (differentiation).

• The proliferation requires cell division and replication of its genome.
• The differentiation requires the regulation of genome expression so that specific genes (those specific to each tissue) are expressed, and others are not.

Epigenetics

Epigenetics is the branch of genetics that studies how individual characteristics are not determined solely by the nucleotide sequence of DNA.

Manipulating Genes One by One: Biotechnology

Tools of Biotechnology

The tools for manipulating DNA are:

• To cut: Restriction enzymes. They are able to cut the DNA at specific sequences.
• To paste: DNA ligase. Allows joining of DNA fragments that have been cut by other enzymes.
• To copy: Plasmids. These are small circular DNA molecules found inside living bacteria.
• Transformation: Method to introduce plasmids inside bacteria.

Biotechnology: Protein Production

Other recombinant proteins marketed by the pharmaceutical industry include:

• Human interferon
• Growth hormone
• DNA polymerase I
• Vaccines based on recombinant proteins

In the food industry, examples include:

• Chymosin
• Bovine somatotropin and bovine growth hormone

In the detergent industry, examples include:

• Lipolase
• Subtilisin

The Polymerase Chain Reaction (PCR)

The polymerase chain reaction amplifies DNA samples rapidly.

Biotechnology: GMOs

Transgenic organisms are called genetically modified organisms (GMOs) that carry a foreign gene (transgene). Thus, super-degrading bacteria for oil slicks were obtained.