CARTA Glossary

Displaying 401 - 500 of 1063 defined words
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Germinal Zone A region where cell division and proliferation occurs during vertebrate central nervous system development consisting of 2 layers lining the ventricles (ventricular zone and subventricular zone).
Glia (neuroglia)

Non-neuronal cells in the central nervous system and the peripheral nervous system that do not produce electrical impulses. Their function is to ensure homeostasis, form myelin sheaths, and provide support and protection for neurons. Glia make up ~50% of our brain cells.

Global Neuronal Workspace (GNW)

A hypothesis that offers a simple connectomic scheme based upon the contribution of neurons with long-range axons to conscious processing. Their reciprocal interactions contribute to the formation of a global workspace, broadcasting signals from the sensory periphery to the whole brain, thus yielding “conscious” experience. The GNW hypothesis privileges cortical pyramidal cells with long-range excitatory axons, particularly dense in prefrontal, temporoparietal, and cingulate regions, that, together with the relevant thalamocortical loops, reciprocally interconnect multiple specialized, automatic, and non-conscious processors. Another important feature of this hypothesis is that the GNW activates in a non-linear manner, called ‘‘ignition,’’ upon access to conscious processing. Ignition is characterized by the sudden, coherent, and exclusive activation of a subset of workspace neurons coding for the current conscious content, with the remainder of the workspace neurons being inhibited.

Global nitrogen cycle

The biogeochemical cycle by which nitrogen is converted by fixation (gaseous nitrogen is converted into ammonia, which can be taken up by plants), ammonification (organic nitrogen from decaying animal and plant matter is converted into ammonium by bacteria and fungi), nitrification (ammonium is converted into nitrate by soil bacteria), and denitrification (nitrate is reduced into gaseous nitrogen). This cycle is central to the biogeochemistry of the Earth. Oceans also have an enormous nitrogen cycle.

Glucocorticoids

A class of corticosteroids that are involved in stress response and are also a part of the feedback mechanism in the immune system. E.g., Dexamethasone (a synthetic glucorticoid).

Glycans

One of the four classes of major biomolecules. Glycans consist of varying numbers of sugars (monosaccharides) attached to proteins or lipids or secreted as free glycans. Glycans are essential biomolecules whose functions can be divided into three broad categories: structural and modulatory properties (including nutrient storage and sequestration), specific recognition by other molecules, and molecular mimicry of host glycans.

Glycolipid

A type of a lipid (fat) with an attached glycan that functions to maintain the stability of the cell membrane and to facilitate cellular recognition. Glycolipids are crucial in immune response and tissue formation.

Glycoprotein

A class of proteins with covalently attached glycans. Glycoproteins play a part in important cellular functions like embryonic development, cell-to-cell recognition, cell adhesion, and immune functions.

Glycosylation

The process by which sugar molecules (glycans) are added to proteins, lipids, or other organic molecules. This post-translational modification plays a crucial role in the structure, stability, and function of many biomolecules.

Glycosyltransferases

Proteins with enzymatic functions that are involved in adding monosaccharides to other molecules.

Göbekli Tepe

An archeological site in Southeastern Turkey. Göbekli Tepe is a settlement dating to c. 9,500-8,000 BCE and is famous for its “monumental architecture” of large circular structures containing stone pillars (megaliths) decorated with reliefs. The structures were built by hunter-gatherers during the pre-pottery Neolithic and represent one of the first examples of monumental architecture.

Gram-Negative and Gram-Positive Staining

A characterization of bacteria based on how they differentially react with a chemical stain (crystal violet) based on their cell wall constituents.

Grandmother hypothesis

One of the explanations for the post-menopausal life stage of human females (and general long lives of humans), a life stage that does not exist in any non-human primate. It is hypothesized that the evolution of grandmothers is an advantage for humans. Grandmothers who invest energy into the offspring of their children reduce the reproductive cost of parenting through social kin-networking. This can further off-set the resource cost of childrearing and brain-building as parents are freed to provision for resources. An increase in resource procurement may reduce the inter-birth interval by allowing for earlier weening and more offspring production.

Gray Matter (Brain)

A major component of the central nervous system that includes regions of the brain involved in muscle control, sensory perception such as seeing and hearing, memory, emotions, speech, decision making, and self-control. Gray matter development peaks the third decade in humans.

Great apes

A taxonomic family denoting the extant chimpanzees, bonobos, gorillas, and orangutans. This is biologically invalid grouping given that chimpanzees and bonobos are more closely related to humans.

Green Revolution

The development and dissemination of crop variants and technology between the 1950s and 1960s that increased agricultural production around the world. Also known as the third agricultural revolution.

Greenhouse effect

The entrapment of heat close to Earth’s surface by greenhouse gas emissions.

Greenhouse gas emissions

The release of polluting gasses resulting from human activity, such as burning fossil fuels that contribute to greenhouse effect.

Grey ceiling effect

The proposed boundary of maximum brain size in hominins that can be supported by an ape-like lifestyle that was crossed by genus Homo through the adoption of cooperative breeding. Described by Isler and van Schaik (2011).

Guillain–Barré Syndrome (GBS)

A rapid-onset muscle weakness caused by an autoimmune response in which the body’s immune system mistakenly attacks and damages the peripheral nervous system. Initial symptoms typically begin in the feet and hands with changes in sensation, pain, and muscle weakness, which then spreads to the arms and upper body of both sides. Sometimes this immune dysfunction is triggered by an infection or, less commonly by surgery, and rarely by vaccination.

Gyrification

The process of forming the characteristic folds of the cerebral cortex.  The peak of such a fold is called a gyrus (plural: gyri), and its trough is called a sulcus (plural: sulci).

Gyrus (Brain)

A ridge on the cerebral cortex that, along with surrounding sulci (furrows) creates the folded appearance of the brain in humans and other mammals.

Hadza (Hadzabe)

An indigenous ethnic group of traditionally nomadic hunter-gatherers from the central Rift Valley and Serengeti Plateau of Tanzania. Tourism, encroachment by pastoralists, and land rights disputes critically threaten their way of life.

Handaxe

A prehistoric stone tool with two faces and is usually made from flint, basalt, sandstone, quartzite, or chert.

Haplogroup

A set of similar haplotypes that share a common ancestor.

Haploid

One set of unpaired chromosomes.

Haplotype

A set of alleles along neighboring positions on a chromosome that are inherited together.

HapMap collection

A map of informative subsets of single nucleotide polymorphisms (SNPs) found along a stretch of a chromosome used to identify blocks of genetic variation existing along human chromosomes.

Haptic

Sensory perception and manipulation of objects through touch and proprioception.

Health Disparity

Differences in the burden of disease, injury, violence, and health care as experienced by socially disadvantaged populations.

Hematopoietic stem cells

Stem cells that can become different types of blood cells.

Hemideletion

One of two paired chromosomes is affected by a deletion. The other chromosome is intact. 

Hemoglobin

A protein complex within red blood cells (RBCs) that binds to oxygen molecules in the lungs for delivery to tissues throughout the body. The same complex also binds carbon dioxide (CO2) and carries it back to the lungs.

Hemoglobin S

The abnormal hemoglobin protein in red blood cells (RBCs) that causes RBCs to assume a sickle, or crescent shape.

Hemoglobin Subunit Beta Gene (HBB)

A gene that provides instructions for making beta-globin, a protein component of hemoglobin. Sickle Cell Anemia is a disorder caused by a mutation in the HBB gene.

Herd Immunity

Sometimes also called “herd protection” or “indirect immunity,” this is when most of a population is immune to a specific contagious disease, which slows its spread to others that are not immune. However, because the level needed to reach this kind of immunity is so high (about 80-90% of the population), it invariably means that a lot of individuals must be infected (and often can die) before herd immunity can be achieved.

Heritability

A statistic used in the fields of breeding and genetics that estimates the degree of variation in a phenotypic trait in a population that is due to genetic variation between individuals in that population.

Heterochromatin

Tightly wrapped and inactive chromatin.

Heterozygotes

Have two different alleles at a locus.

Heuristics

Any problem solving strategy that involves the usage of generalizations as mental shortcuts to quickly come to adequate solutions for complex problems.

Hind limb

The back limbs and feet of a quadrupedal animal (also, the lower limbs/legs of a human).

Hindgut fermentation

A digestive process in which cellulose and other polysaccharides are broken down by symbiotic bacteria residing the colon of some mammalian species.

Hippocampus (Brain)

A part of the limbic system that plays important roles in the consolidation of information from short-term memory to long-term memory, and in spatial memory that enables navigation. Humans and other vertebrates have two hippocampi, one in each side of the brain. It is named after its resemblance to the shape of a sea horse (hippocampus in Latin).

Histo-blood groups

Meaning “tissue-related”, these blood group antigens originally evolved on epithelial cells prior to expression on erythrocytes (red blood cells). ABO is a classic example of a histo-blood group.

Histone Deacetylase Inhibitor (HDACi)

A drug that inhibits histone deacetylases or molecules involved in modifying histone proteins. Histone deacetylases typically function to reduce chromatin accessibility and gene expression. Therefore, administration of this drug allows for higher levels of gene expression.

Histone Modification

A covalent, post-translational modification (PTM) of histone proteins, which includes acetylation, glycosylation, methylation, phosphorylation, sumoylation, ubiquitylation. The PTMs made to histones can impact gene expression by altering chromatin structure or recruiting histone modifiers.

Histones

Chief protein components of chromatin and can be chemically modified as part of epigenetics.

Holocene

The current geological epoch, from about 11,700 years ago (after the end of the last Ice Age cycle) to the present that is marked by globally warmer and more stable climates.

Holocene Sea Rise

The early Holocene Sea Rise period (or EHSLR) is when the Earth underwent warming and meltwater release during the period between 11,650 and 7000 years ago, and consequently the volume of sea water increased. The sea levels rose from some 125 meters below the contemporary level to 2 meter above it, and then dropped to the present level. The coastlines moved inland and most contemporary islands, both large and small, were isolated off their mainlands.

Homeostasis

The state of steady internal, physical, and chemical conditions maintained by living organisms.

Hominid

A classification comprising all living and extinct “Great Apes” and humans.

Hominin

A classification of species comprising humans and our extinct relatives following the divergence from the common ancestor with chimpanzees.

Homo

The genus that comprises the species Homo sapiens, as well as several extinct species classified as ancestral to, or closely related to, humans.

Homo erectus

An extinct hominin species with fossil evidence from at least 1.9 million years to 70 thousand years ago and found from Africa to Indonesia. H. erectus may have been the first hominin to leave Africa. H. erectus DNA may be retrievable from other species due to archaic admixture.

Homo habilis

An extinct archaic species of the genus Homo dating to ~2.1 to 1.5 mya. H. habilis means “handy man” and was named so because of its association with stone tools.  H. habilis has intermediate morphology between Australopithecus and Homo erectus. There is ongoing debate if H. habilis should be moved to the Australopithecus genus.  Initial discovery was made by Mary and Louis Leakey at Olduvai Gorge in Tanzania between 1962 and 1964.

Homo naledi

An extinct hominin species whose fossil evidence dates to 335-236 kya. An assemblage of 15 H. naledi skeletons were first found in the Dinaledi Chamber of the Rising Star cave system in 2013 (since then, a second chamber has been found with H. naledi skeletons). The fossils possess a mix of “archaic” traits similar to genus Australopithecus (e.g. cranial and pelvic morphology) and “modern” traits characteristic of genus Homo (e.g. hand morphology). H. naledi lived contemporaneously with anatomically modern humans, Neanderthals, and Denisovans but is not likely a direct ancestors of humans living today.

Homo sapiens

The hominin species comprising all living humans. Meaning “wise man” in Latin, the name was introduced by Carl Linnaeus in 1758. The earliest fossil evidence of Homo sapiens appears in Africa around 300 kya (see Jebel Irhoud Hominins).

Homology

Similarity in DNA or phenotype because of shared evolutionary history from a common ancestor.

Homoplasy

Similarity in DNA sequence or phenotype that has evolved independently.

Homozygotes

Have two identical alleles at a locus

Hormone

A signaling molecule in multicellular organisms that contributes to the regulation of physiology and behavior.

Host

A living organism on or in which a parasite, pathogen, commensal or symbiont lives (see Parasitism).

Howiesons Poort

A lithic technology cultural period in the Middle Stone Age in Africa named after the Howieson’s Poort Shelter archeological site near Grahamstown, South Africa. Dates range from ~65.8 kya to 59.5 kya. Examples include composite weapons hafted with ochre and gum compound glue and microlith blades, bone arrows, and needles.

Human Accelerated Regions (HARs)

A set of 49 segments of the human genome that are conserved throughout vertebrate evolution but are strikingly different in humans. They are named according to their degree of difference between humans and chimpanzees. Some of these highly mutated areas may contribute to human-specific traits while others may represent “loss of function” mutations, possibly due to the action of biased gene conversion rather than adaptive evolution.

Human Arcuate Fasciculus

The specialized connections composed of axons linking Broca’s area and Wernicke’s area in the human brain and is a major anatomic feature supporting language function in humans.

Human-specific gene

A protein-coding gene that is present in humans but absent in other non-human ape species.

Hunting and gathering

A subsistence strategy in which most or all food is obtained by foraging and is in contrast to agriculture, which rely mainly on domesticated species.

Hunting hypothesis

An explanation for the dietary shift to meat procurement during human evolution as a catalyst favoring a suite of transformative biological and behavioral adaptations.

Hybridization

Breeding among recognized species.

Hydroxylase

An enzyme involved in the first step of aerobic oxidation of organic compounds.

Hygiene Hypothesis

A lack of early childhood exposure to infectious agents, symbiotic microorganisms and parasites believed to increase susceptibility to allergies and autoimmune diseases.

Hyperalgesia

Increased sensitivity to pain.

Hyperkatifeia

Pain, hypohedonia, dysphoria, anxiety, hyperalgesia, irritability, and sleep disturbances associated with drug abstinence following excessive drug taking.

Hypoallergenic

Having a decreased tendency to provoke an allergic reaction.

Hypocretin (Orexin)

A neuropeptide that regulates arousal, wakefulness, and appetite.

Hypohedonia

A diminished capacity for pleasure.

Hypoxia

A condition characterized by less than the normal amount of oxygen reaching the tissues; also, low partial pressure of oxygen at high elevations (hypobaric hypoxia).

I-type lectins

A class of lectins belonging to the immunoglobulin superfamily. e.g., Siglecs

Iberomaurusian

A type of lithic industry featuring a backed bladelet specific to the coasts of Morocco, Algeria, and Tunisia dating between 25,000 and 11,000 years ago.

Icon

A sign that shares perceived physical properties with the thing it refers to (its “referent”) (Kluender, 2020).

Idiosyncrasy

A mode of behavior or way of thought peculiar to an individual.

Imitation

Behavior copying. This term has been used to mean everything from social learning in general to the reproduction of action intentions but is now most commonly used in the narrow sense of copying the form or topography of observed movements.

Immediate Return Hunter-Gatherers

Those who do not store food, but consume it within a day or two of obtaining it. This means there is no opportunity to accumulate surplus.

Immune Cells

Cells that are part of the immune system. Most develop from stem cells in the bone marrow and become different types of white blood cells (the microglia of the brain originate in the yolk sack during embryonic development). Immune cells are broadly classified into innate and adaptive immune cells. Innate immune cells include neutrophils, basophils, mast cells, monocytes and eosinophils, dendritic cells, and macrophages. Adaptive immune cells include B-cells and T-cells. T-Cells and Natural Killer T-cells mediate important dialogues between innate (rapid) and adaptive (slower) immune responses. B-cells and T-cells can form long- term immunological memory.

Immune system

The biological defense system of an organism that protects against disease.

Immunity

The capability of multicellular organisms to resist harmful microorganisms from entering it and compromising its biological systems. The balanced state of adequate biological defenses to fight infection, disease, or other unwanted biological invasion, while having adequate tolerance to avoid allergy, and autoimmune diseases. It critically relies on recognition of both self and non-self.

Immunoglobulin domain/fold (Ig)

A type of region (domain) present in many different proteins that is self-stabilizing and folds independently.

Immunoglobulins

A type of protein that forms antibodies and other receptors both on cell surfaces and as soluble proteins of vertebrates. Comprised of a massive superfamily, immunoglobulins perform many different functions, including recognition, binding, or adhesion processes of cells.

Immunology

The branch of biology and biomedicine concerned with the study of immune systems.

Immunoreceptor tyrosine-based activation motif (ITAM)

A highly conserved region in the cytoplasmic domain of signaling chains of adapter proteins and receptors and typically result in activation of inflammatory responses.

Immunoreceptor tyrosine-based inhibitory motif (ITIM)

A conserved sequence of amino acids, including phosphorylated tyrosine, that is found intracellularly in the cytoplasmic domains of many inhibitory receptors.

IncRNA

Long non-coding microRNA

Indel

An insertion or deletion of a DNA sequence.

Index

A sign that depends for its reference on the physical presence of the thing that it refers (its “referent”) to at some point in space and time (e.g. smoke, a weather vane, a bullet hole, your index finger) (Kluender, 2020).

Induced pluripotent stem cells (iPSC)

Somatic (body) cells that are artificially reprogrammed to an embryonic-like stem cell state and differentiated into other types of cells.

Industrial revolution

The transition from agrarian and handcraft manufacture of goods to large scale industrial production starting 1760 in Great Britain and the United States.

Infant care

The practices and activities involved in ensuring the health, safety, and well-being of a newborn or young child, including feeding, hygiene, comfort, and emotional nurturing.

Infanticide The killing of infants by males or females.
Infection

The invasion of an organism’s organs or tissues by pathogens, their multiplication, and the reaction of the host tissues to the pathogens.

Infectious (disease)

The capability of producing infection or spreading disease to others. Synonymous with communicable and transmissible.

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