human and animal development

Fertilized egg

The initial single cell formed after the sperm fertilizes the egg.

Gestation period

The time it takes for the embryo to develop, varies by species (humans = 266 days, mice = 20 days, elephants = 645 days).

Neurulation

The process during embryo development where the neural tube forms, leading to the spinal cord and brain.

Organogenesis

The phase of development where organs are formed following neurulation.

Spina bifida

A developmental problem that occurs when the neural tube fails to close.

Epigenetics

Genetic changes not associated with changes in the DNA sequence, where genes are permanently switched on or off.

HOX genes

Genes that have a universal function in development, crucial for proper body plan layout.

Eyeless mutant

A mutation in the Pax-6 gene in Drosophila that leads to a lack of eyes.

Bilateral Anopthalmia

A condition caused by a mutation in the human homologue of Pax-6, resulting in bilateral absence of eyes.

Nature-nurture debate

The discussion regarding the relative contribution of genetics and environment to a phenotype.

Heritability

The probability that shared phenotypes are NOT explained by the environment or chance, reflecting genetic contribution.

Twin studies

Research comparing phenotypes in monozygotic (MZ) and dizygotic (DZ) twins to understand genetic versus environmental influences.

Genetic susceptibility

The concept that certain individuals may be predisposed to conditions, like schizophrenia, due to their genetic make-up.

IQ (Intelligence Quotient)

A standardized measure of intelligence, correlating with academic success.

Danish twin study (2017)

A study that estimated the heritability of schizophrenia as 79%, signifying a major genetic component.