Key Concepts in Biology, Genetics, and Public Health
Fundamental Concepts in Biology and Health
Antibiotic Resistance: How Bacteria Evolve
Resistance arises because bacteria, like all organisms, possess slight genetic differences. These differences can arise from mutations, alterations, or unnecessary DNA insertions (plasmids). Any use of antibiotics promotes the growth of resistant bacteria.
Among the most common useless uses is taking antibiotics for viral infections. Antibiotics do not kill viruses, which cause many common diseases. Doctors only prescribe them when there are associated bacterial infections.
Understanding Pandemics and Disease Spread
Microbes do not respect borders. An outbreak in one part of the world can easily reach people living in the other extreme. An infected person can travel across different countries during the incubation period before manifesting any symptoms, thus spreading the pathogen.
The Biology of Cancer and Tumor Growth
In normal cells, replacement occurs at the proper speed, producing new units from stem cells in the right amount, ensuring neither excess nor deficit.
Sometimes, however, cells begin to multiply uncontrollably. If these cells are also able to specialize and perform the function applicable to the tissue or organ, this unchecked growth produces tumors.
Sexually Transmitted Diseases (STDs)
STDs are infectious diseases caused by various pathogens, including:
- Bacteria
- Viruses
- Fungi
- Protozoa
- Arthropods
Their main mode of transmission is sexual contact. STDs are very common, and the number of affected people is increasing due to factors such as increased sexual freedom and inconsistent use of protection.
The Process of Cloning
Cloning typically involves Somatic Cell Nuclear Transfer (SCNT): taking an egg cell (oocyte), removing its nucleus, and implanting the complete genetic information (DNA) from a somatic cell (like a mammary cell) into it.
Cloning can also occur naturally or artificially in plants, various multicellular organisms, and unicellular organisms.
Mapping the Human Genome
The study of the human genome aims to:
- Identify all human genes.
- Locate their exact position on chromosomes.
- Sequence the nitrogenous bases characteristic of each gene.
- Determine the function of each gene.
Our genome contains over 30,000 genes and approximately 3 billion base pairs. Humans share 99.9% of these bases. The process involves sequencing DNA in fragments, assembling them into larger sequences, mapping them to chromosomes, and finally completing the entire genome sequence.