Please Define the Following Key Terms

question 44

Essay

Please define the following key terms. Show Who? What? Where? When? Why Important?
-Mary Wollstonecraft

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Definitions:

Yolk Sac

One of the extraembryonic membranes; a pouchlike outgrowth of the digestive tract of embryos of certain vertebrates (e.g., birds) that grows around the yolk and digests it. Embryonic blood cells are formed in the mammalian yolk sac, which lacks yolk.

Nuclear Equivalence

The principle suggesting that all somatic cells of an organism have the same genetic material and therefore, in theory, have the potential to develop into any type of cell or even a whole organism.

Differential Gene Expression

The process by which genes are turned on or off in different cell types, allowing for cellular diversity and function.

Teratogen

Any agent capable of interfering with normal morphogenesis in an embryo, thereby causing malformations; examples include radiation, certain chemicals, and certain infectious agents.