evolution and genetics 2

1953: J.D. Watson and F.H.C. Crick discover the structure of DNA.
2003: Completion of the Human Genome Project, paving the way for advancements in genetics.
2008: James Watson’s personal genome is sequenced.
Other important milestones include:
- 1955: Identification of 46 human chromosomes.
- 1961: Discovery of mRNA.
- 1975: Advancements in DNA sequencing.
- 1982: Establishment of gene bank databases.
- 1983: Development of PCR (polymerase chain reaction).

Genome: The complete set of DNA, including all of its genes and non-coding sequences.
Chromosomes: Structures within cells that contain DNA.
Genes: Segments of DNA that encode proteins or functional RNA.
Alleles: Different versions of a gene.
Genotype: The genetic constitution of an individual.
Nucleotides: The basic units of DNA, comprising four types - adenine (A), thymine (T), cytosine (C), and guanine (G).

DNA serves as the genetic information carrier:
- Base Pairs: A-T and C-G pairs constitute the rungs of the DNA ladder;
- Each human cell typically contains about 2 meters of DNA when fully stretched.
Length: The DNA double helix has a diameter of approximately 2 nm, whereas the total length of DNA in a human is estimated to be around 10 billion base pairs.

The DNA sequence represents inherited information:
- Example sequence illustrated demonstrating its complexity and length.
Post-genomic Era: The protocol of understanding the genetic code has shifted as science advances post-Human Genome Project.
Basic Functions of DNA:
- Replication: The process of creating two identical copies of DNA during cell division.
- Gene Expression: The process through which the information from a gene is used to synthesize a functional gene product, usually a protein.

Refers to the central dogma of molecular biology, which is the process of converting DNA into functional protein through mRNA.
The genetic code is read in groups of three nucleotides called codons, each codon representing a specific amino acid.
The translation complexity involves both exons and introns, where only exons (coding sequences) are retained in the final mRNA sequence for protein synthesis.
Genes often have intron-exon structures, where:
- Exons: Carry information for protein synthesis.
- Introns: Non-coding regions spliced out during RNA processing.

Genetic sequence variability is observed with SNPs (Single Nucleotide Polymorphisms) and VNTRs (Variable Number Tandem Repeats).
Roughly 1-2% of our genome encodes for proteins, with an estimated 20,000-25,000 genes coding enzymes.

Initiated in 1989 and finished by 2003, the Human Genome Project was a monumental effort to sequence the human genome.
Coordinated international effort that highlighted both a hierarchical and a ‘clone-by-clone’ approach to DNA sequencing.
The project uncovered genome sequences revealing that unrelated humans share 99.5% of their DNA, with differences amounting to around 15 million base pairs.
Significant similarities exist between humans and other species, such as sharing about 95% of their DNA with apes.

Mutations: Rare alterations in DNA that can lead to disease, often being monogenic disorders found in less than 1% of the population.
Examples: Sickle-cell anemia being linked to a single nucleotide error that alters hemoglobin structure.
Polymorphisms: Variations in the genetic code, most of which do not result in fatal diseases, highlighting the genetic diversity within the population.

The ongoing exploration of genetic codes, mutations, and polymorphisms continues to reshape our understanding of genetics, disease, and personal health.
Study outcomes from comparative genetics reveal profound insights into our biological similarities and differences, contributing to advancements in biomedical research and therapy.