Name the three germ layers that form during gastrulation:
Name 3 examples of Ectoderm:
Epidermis of Skin
Cornea and Lens of Eyes
Name 3 examples of Mesoderm:
Name 3 examples of Endoderm:
How is calcium signaling involved in blocking polyspermy?
It triggers fusion of cortical granules with the plasma membrane.
What is acrosome?
Structure of the sperm head that contains enzymes to allow sperm to penetrate barriers surrounding egg.
What are cortical granules?
Enzyme filled vesicles activated during fertilization. Fuses with membrane of egg and releases it's contents to the exterior, causing formation of fertilization envelope.
What is protease?
Enzyme that cleaves peptide bonds
What is fertilization envelope?
Created by osmosis between plasma membrane and vitelline envelope that prevents polyspermy.
What is differentiation?
The process by which a unspecialized cell becomes a distinct specialized cell type. Usually by changes in gene expressoin.
What are deuterostomes?
A major lineage of animals that share a pattern of embyological development, including formation of the anus earlier than the mouth, and formation of the coelom by pinching off of layers of mesoderm from the gut. Includes echonderms and chordates.
What are protostomes?
A major lineage of animals that share a pattern of embryological development, including formation of the mouth earlier than the anus, and formation of the coelom by splitting of a block of mesoderm.
It includes arthropods, mollusks, and annelids.
What are cytoplasmic determinants?
Regulatory Transcription Factors that are distributed unevenly in the cytoplasm of the egg cells of many animals and that directs early pattern formation in an embryo.
What is Blastocoel?
Fluid filled cavity in the blastula of many animal species.
What is blastocyst?
Type of blastula in mammals.
Spherical structure composed of trophoblast cells outside and inner cell mass on the inside.
What is blastula?
A hollow ball of cells (blastomere cells) formed by cleavage of zygote and immediately undergoes gastrulation.
What is blastomere?
Small cell created by cleavage division in early animal embyos.
What is gastrulation?
Process by which some cells on the outside of a young embryo move to the interior of the embryo, resulting in three distinct germ layers.
What is trophoblast?
Exterior of a blastocyst.
What is the placenta?
Structure that forms in the pregnant uterus from material and fetal tissues. Exchanges nutrients and waste between mother and fetus, anchors the fetus to the uterine wall, and produces some hormones. Occurs in most mammals.
What is MyoD?
A transcription factor that is critical for differentiation of muscle cells.
What is organogenesis?
A stage of embryonic development, just after gastrulation in vertebrate embryos, during which major organs develop from the three embryonic germ layers.
What is embryogenesis?
The process by which a single-celled zygote becomes a multicellular embryo.
What is vitelline envelope?
A fibrous sheet of glycoproteins that surrounds mature egg cells in many vertebrate. Surrounded by a thick gelatinous matrix in some species.
What is yolk?
Nutrient rich cytoplasmt inside an egg cell; used as food for the growing embryo.
What are somites?
Paired blocks of mesoderm on both sides of the developing spinal cord in a veterbrate embryo. Give rise to muscle tissue, vertebrae, ribs, limbs, etc.
What is gastrula?
An embryo at the stage following the blastula, when it is a hollow cup-shaped structure having three layers of cells.
Why are eggs much larger than sperm?
The egg cytoplasm contains both storage proteins and lipids that aid in the development of the embryo.
What is the origin of the fertilization envelope?
The vitelline envelope.
The cortical granules is the signal to form the fertilization envelope
Expression of the MyoD gene in fibroblasts, or in several other cell types, will convert these cells to muscle-like cells. This is because the product of the MyoDgene affects what cellular processes?
It triggers expression of the MyoD gene itself.
It acts as a powerful transcription factor.
It binds to the enhancer elements of muscle-specific genes.
Define Apical-Basal axis:
apical refers to the tip
basal refers to the base or foundation
What is the radial axis?
It extends from the interior of the body out o the exterior.
What are MADS box genes?
They are similar to Hox genes in that they specify structure, but in plants. It is a transcriptional regulator. MADS box genes differ in base sequence, thus is not homologous with Hox genes.
Plants vs. Animal
Plants develop continuously, do not commit cells to gamete production until late in development and produce gametes by mitosis in haploid cells.
What is endosperm?
Similar to the placenta, the endosperm is the nutritive tissue developed by two eggs and one sperm, for the embryo.
What is the fate of the two cells found inside pollen grains prior to germination?