Developmental Biology Chapter 4 (and Fertilization

Hedgehog signaling pathway

A signaling pathway that regulates development in animals and is involved in cell differentiation.

Patch (PTCH)

A protein that inhibits the Smoothened (SMO) protein when Hedgehog is not present.

Smoothened (SMO)

A protein that, when activated by Hedgehog, can prevent the phosphorylation of Cubitus interruptus (CI), allowing it to act as a transcriptional activator.

Cubitus interruptus (CI)

A transcription factor regulated by the Hedgehog signaling pathway that can either function as a repressor or an activator depending on its phosphorylation state.

Kinase

An enzyme that catalyzes the transfer of phosphate groups from high-energy donor molecules, such as ATP, to specific target molecules.

Gain of function mutation

A mutation that increases the activity of a protein or the protein's expression, leading to effects such as enhanced signaling.

Loss of function mutation

A mutation that results in reduced or abolished protein activity, leading to loss of signaling.

Beta-catenin

A protein that plays a crucial role in the Wnt signaling pathway, functioning both in cell adhesion and as a transcription factor.

Destruction complex

A multiprotein complex that targets beta-catenin for degradation through phosphorylation.

Delta-Notch signaling

A communication pathway between cells that regulates cell differentiation and proliferation.

Cadherins

A class of type-1 transmembrane proteins that mediate cell-cell adhesion.

Epithelial to mesenchymal transition (EMT)

A biological process where epithelial cells lose their cell polarity and cell-cell adhesion, gaining migratory and invasive properties.

TGF-beta superfamily

A large group of proteins that are known to be involved in cell growth, differentiation, and embryonic development.

Neural crest cells

A population of cells that originate from the embryonic ectoderm and give rise to various cell types including neurons and glial cells.

Polyspermy

A condition in which an egg is fertilized by more than one sperm, leading to abnormal embryo development.

Fast block to polyspermy

An immediate, temporary change in membrane potential to prevent additional sperm from fusing with the egg.

Slow block to polyspermy

A longer-lasting physical barrier created by a fertilization envelope that prevents additional sperm from entering the egg after fertilization.

Acrosome

A cap-like structure that covers the head of a sperm and contains enzymes that help the sperm penetrate the egg.

Meiosis

A type of cell division that reduces the number of chromosomes in a gamete to half, resulting in four haploid cells.