Zygotic lethal gene
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.
Read Also:
- Zebra
‘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.
- ZAP-70
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.
- Dihydroorotate dehydrogenase
Dihydroorotate dehydrogenase: An enzyme necessary to pyrimidine synthesis and therefore essential to the production of DNA and RNA. The drug leflunomide (Arava), an immunomodulatory agent, acts by specifically inhibiting dihydroorotate dehydrogenase.
- Reflex, Babinski
A reflex used to determine adequacy of the higher (central) nervous system. The Babinski reflex is obtained by stimulating the outside of the sole of the foot, causing extension of the big toe while fanning the other toes. The examiner begins the stimulation at the heel and goes forward to the base of the toes. […]