One of our main goals at Because Science is to make science as access as possible to everyone. Because of this, we have tried to define all words in our posts that may be confusing to someone not familiar to a particular field.


Acquired immunodeficiency syndrome (AIDS): A condition caused by human immunodeficiency virus (HIV), cripples the immune system and makes affected individuals highly susceptible to other infections

Allele: One of multiple alternatives of the same gene or locus, one individual can have the same two alleles or two different alleles on homologous chromosomes, alleles can confer the same phenotype or different phenotypes

Amoeba: Single-celled eukaryotic organism

Antibiotic: Antimicrobial medicine that specifically inhibits the growth of bacteria (not viruses or eukaryotic organisms)

Antimicrobial: Medicine active against microbes

Antiretroviral therapy (ART): Treatment of HIV-infected individual with a combination of drugs that target different aspects of viral replication, ART is extremely effective when drugs are given in combination and patients adhere to their treatment regimen

Autoimmune disease (autoimmunity): Disease caused by the immune system launching an abnormal response against its own molecules, cells, or tissues



Basin lakes: open and closed-basin lakes are lakes on Mars that form when valley networks on Mars enter a crater, filling it with water. Open basin lakes occur when the crater overflows, forming an outlet as well as an inlet channel, while closed basin lakes remain static.


Co-evolution: Two closely associated species influencing each other’s evolution (they evolve together in response to each other’s evolution)

Commensal relationship: A biological relationship in which two organisms benefit from each other or do no harm to each other, the microbiota is often referred to "commensals" of an organism

Comparative genomics: Field of biology where genomes of different individuals or organisms are compared

Cytoplasm: The space and material inside the cell, excluding the nucleus





Ebola: An RNA virus that is highly pathogenic in humans, causing severe internal bleeding and a high rate of mortality, it is a zoonotic virus with a reservoir in bats

Epidemic: Rapid spread of an infectious disease amongst a population at a particular point in time

Eukaryote: An organism made up of cells in which the DNA is packed in a distinct nucleus, includes animals, plants, fungi



Fitness: The intrinsic ability of an organism to survive in a particular environment

Fungus: Unicellular or multi-cellular eukaryotic organism, includes mold, yeast, and mushrooms



Genome: Collection of all genetic material in a single organism

Genotype: Genetic composition of an organism (influences phenotype)

Germ-free animals: Laboratory animals that have no microbes living in or on them



Host: An organism that is infected by another organism

Human  immunodeficiency virus (HIV): An RNA virus that infects humans and causes acquired immunodeficiency syndrome (AIDS), leading cause of death by an infection worldwide

Human leukocyte antigen (HLA): Set of genes coding for proteins presented on immune cells, display antigens such that the adaptive immune system can respond against it, human version of major histocompatibility complex (MHC)



Illumina: Computer system for analyzing genetic variation and biological function

Immune system: Organ system of body that has evolved to maintain homeostasis, fight infection and toxins



Locus (genetics): Particular location of a gene, particular DNA sequence, or stretch of chromosome



Major histocompatibility complex (MHC): Set of genes coding for proteins presented on immune cells, display antigens such that the adaptive immune system can respond against it, mouse version of human leukocyte antigen (HLA)

Microbiota: Microorganisms of a particular habitat, the microfauna and microflora of an ecosystem, for example the human microbiota is the collection of microbes that live in and on humans and live in a symbiotic relationship with their human host

Muscle fiber: The basic unit of a muscle, made from the union of multiple individual muscle cells. This means that, unlike most other cells in the body, they have multiple nuclei and many, many mitochondria!

Mutation: Change in DNA of an organism either by change in basepair, deletion/insertion/rearrangement of basepairs or short stretches of DNA, does not always induce change in phenotype

Mycobacteria: A family of bacteria that includes Mycobacterium tuberculosis (the cause of TB disease), Mycobacterium leprae (the cause of leprosy), and other species that don’t cause disease



Neuromuscular junction: A connection between a neuron and a muscle fiber. When the neuron is activated by a command from the brain, it releases chemicals that cause the muscle to change its length.

Neuron: Also known as a "brain cell". These cells take in information about the outside world, turn it into perceptions, make decisions about what to do based on those perceptions, and then tell the muscles how to move. They're busy little beavers!

New World: Western hemisphere

Nucleotides: Molecules that are the building blocks of DNA and RNA, the four nucleotides that make up DNA are adenosine (A), thymine (T), guanine (G), and cytosine (C), RNA is made up of A, T, G, and uracil (U), the order in which they are arranged conveys information in the genetic code

Nucleus: The component of the cell where genes are stored and where they are transcribed into RNA for translation into proteins by ribosomes.



Old World: Europe, Asia, and Africa



Pathogen: Infectious agent that produces disease upon entering its host

Phenotype: Physical characteristics or traits of an individual (partially influenced by genotype)

Physiology: Branch of biology that studies functions of organisms and their parts

Plasmodium: Group of species that cause malaria, have a complex life cycle that involves different stages present in mosquitoes and humans

Polymorphism: Different form of genotype within a population

Prokaryote: Single celled organism with no organelles or nucleus, genetic material and proteins are in the same volume surrounded by a coat, includes bacteria





Replicative capacity: Relative ease and speed with which an organism can replicate and spread

Reservoir: A species that carries an infectious pathogen without any obvious signs of disease, can transmit the pathogen to other species



Sequencing: Process of characterizing the genetic code of an organism

Seroprevalence: Amount of pathogen in organism/population

Simian immunodeficiency virus (SIV): Viruses closely related to HIV that infect non-human primates

Single nucleotide polymorphism (SNP): Difference in one base pair in a DNA sequence



Tuberculosis (TB): A severe lung disease caused by infection with the bacterium Mycobacterium tuberculosis, TB leads to the death of 1.5 million deaths per year on average, latent TB is when an individual is infected with M. tuberculosis but doesn’t progress to disease





Valley networks: fluvial river-like features found in the southern highlands. They tend to look very similar to terrestrial rriver systems in many ways.

Virulence: Ability of an infectious agent to cause disease









Zoonosis (zoonotic adj): Transfer of pathogen from one animal species to a different animal species