Self And The Phenomenon Of Life: A Biologist Examines Life From Molecules To Humanity

Glossary 355

“9x6” b2726 Self and the Phenomenon of Life: A Biologist Examines Life from Molecules to Humanity

Genetic code: The information contained in the nucleotide sequence of DNA

that dictates the amino acid sequence of a protein.

Glycolysis: see Glycolytic pathway.

Glycolytic pathway: Metabolic pathway in the cytoplasm that converts

glucose to pyruvic acid, before the latter enters the mitochondria.

Gray matter: The outer layer of the brain containing the neuronal cell bodies.

So-called because of the grayish coloration. Gray matter makes up the cortex

of the brain.

Group selection: A theory of natural selection based on groups of individual

organisms whether or not they are genetically closely related.

Gyrus: The surface of the cerebral cortex that forms a ridge between two clefts.

Hebbian theory of learning: A theory that posits that the underlying mechanism

of learning involves changes in the neuronal synapse after repeated use.

Hippocampus: An inward extension of the temporal lobe of the brain important

for the formation of long-term memory. So called because of its seahorse shape.

Holism: A perspective in which an entity is taken as a whole with its compo-

nents intricately related. In a holistic view the total is greater than the sum

of the individual parts.

Hydrogen bond: The chemical bond responsible for the pairing of nucle-

obases in a DNA molecule.

Hypothalamo-pituitary-adrenal axis: A chemical channel in which hormone

from the hypothalamus stimulates the anterior pituitary gland, which in turn

sends hormone to the adrenal cortex (attached to the kidney) to secrete cor-

tisol, a stress hormone with widespread effects on the body and the brain.

Hypothalamus: The part of the brain that is mainly involved in the regulation

of the autonomic nervous system and the general well-being of an animal.

So called because it is situated below the thalamus.

Innate immunity: Inborn immunity that persists over generations. It is pres-

ent in plants and animals.

Insular cortex: The in-folding portion of cerebral cortex formed by the tem-

poral and the fronto-parietal lobes. Anterior insular cortex receives sensory

fibers from visceral organs.

Internal milieu: Internal environment of a cell and of an organism, which

remains constant despite external changes. The ability of an organism to

maintain its internal environment is referred to as “homeostasis.”

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