A gene that is lethal (fatal) for the zygote, the cell formed by the union of a sperm (male sex cell) and an ovum (female sex cell). The zygote would normally develop into an embryo, as instructed by the genetic material within the unified cell. However, a zygotic lethal gene scotches prenatal development at its earliest point.
A zygotic lethal gene is a mutated (changed) version of a normal gene essential to the survival of the zygote. The extent of the mutation can range from a change in a single base in the DNA to deletion (loss) of the entire gene.
‘When you hear hoof beats, think of horses, not zebras.’ For example, when someone develops a mild transient cough, a virus infection is the most logical and likely cause, and tuberculosis is a zebra.
Zeta-chain-associated protein kinase 70. A member of the protein tyrosine kinase family, ZAP-70 is normally expressed in T cells and natural killer cells and has a critical role in the initiation of T-cell signaling. ZAP-70 is expressed in T cells and tumors of T-cell lineage. A high level of ZAP-70 expression appears restricted to T-cell […]
- Z chromosome
A sex chromosome in certain animals, such as chickens, turkeys, and moths. In humans, males are XY and females XX, but in animals with a Z chromosome, males are ZZ and females are WZ.
Medical term for nosebleed. The nose is a part of the body that is very rich in blood vessels (vascular) and is situated in a vulnerable position on the face. As a result, any trauma to the face can cause bleeding, which may be profuse. Nosebleeds can occur spontaneously when the nasal membranes dry out, […]
- Prosopagnosia (face blindness)
a neurological disorder characterized by an inability to recognize faces. Prosopagnosia is also known as face blindness or facial agnosia and varies in severity among affected individuals. It is believed to arise from damage to an area of the brain known as the right fusiform gyrus. This damage can be caused by trauma, stroke, or […]