BCA lecture 1 Flashcards
preformationism
the belief that an organism’s development and growth were predetermined only by its genetic material, with all structures and organs present in a rudimentary form within the egg or sperm
Cell differentiation
single cell becomes a specialized cell type with specific functions in the body
embryogenesis life cycle
fertilization, cleavage, gastrulation, organogenesis, maturity, gametogenesis
mitosis
cell division resulting in the same number of chromosomes as the parent cells (1diploid cell into 2 diploid cells)
its purpose is for cell growth, tissue repair, etc
prophase, metaphase, anaphase, telophase
meiosis
cell division resulting in non-identical number of chromosomes as the parent cells (1diploid cell into 4 haploid cells)
its purpose is for sexual reproduction
same cycle as mitosis but twice
symmetry breakage in C. elegans
sperm entry point determines which end of the zygote will become the head and which will become the tail. this process determines the axis of asymmetry in the developing embryo
cleavage (explain 2 types)
start of cell division and cell differentiation
holoblastic: division of the entire egg cell
meroblastic: partial division of the egg, resulting in a smaller mass of cells attached to the yolk
blastocysts
a ball of cells containing trophectoderm (on the surface of the blastocyst which will give rise to the placenta) and ICM (or inner cell mass which contains pluripotent stem cells)
Hippo pathway
Activated Hippo signaling represses the Yap-Taz-Tead transcriptional complex, and in the ICM, the result is the maintenance of pluripotent ICM development through Oct4
Hippo ON:
High cell density (intern of morula)
Yap TF is inactive, retained in cytoplasm
Target genes are OFF
Target genes don’t inhibit ICM fate (the gene Oct4 is expressed)
Blastomere becomes ICM (Pluripotent Stem Cell)
Hippo OFF:
Low cell density (extern of morula)
Yap TF is active in the nucleus
Target genes are ON
Target genes inhibit ICM cell fate (the gene Oct4 is NOT expressed)
Blastomere becomes a Trophoblast
gastrulation
an embryo transforms from a one-dimensional layer of epithelial cells, a blastula, and reorganizes into a multilayered and multidimensional structure called the gastrula (forming the 3 layer of ecto, meso, and endoderm)
Primitive streak
a linear groove or indentation that forms on the dorsal surface of the embryonic disc, and marks the site where cells start to migrate and differentiate into the three germ layers. it is considered the starting point for embryonic axis formation and is a key factor in the establishment of embryonic polarity and bilateral symmetry
Epithelial-to-mesenchymal transition (EMT)
a process in which epithelial cells lose their cell-cell adhesion and polarity and acquire a mesenchymal phenotype, characterized by increased mobility and the ability to invade surrounding tissues. In the context of mesoderm formation, EMT is a key event in the formation of mesoderm from the ectoderm and the endoderm germ layers
Neurulation
process of formation of the neural plate and neural crest in the embryonic development of vertebrates
