Lecture 14: From one cell to an organism Flashcards
1. Introduce the field of developmental biology 2. Review cell processes essential for the making of an organism 3. Uncover the value of studying model organisms to illuminate conserved mechanisms in development 4. Understand major events in embryonic development 5. Understand the different approaches to study development
embryology
from one cell to an organism
tissue homeostasis
ability to replace old tissue with new
aging
decline in tissue functions
cell proliferation
producing many cells from one (multiple divisions)
cell specialization (differentiation)
creating cells with different characteristics
driven by differential gene expression
cell interaction (communication)
coordinating the behavior of one cell with that of its neighbors
cell-cell signaling
cell movement
rearranging the cells to form structured tissues and organs
major events of embryonic development
- Fertilization
- Cleavage
- Gastrulation
- Neurulation
- Organogenesis
fertilization
unites two haploid genomes (half of chromosomes), forming the diploid (2 sets of chromosomes)
one sperm fertilizes one egg (oocyte) - haploid nucleus (23 chromosomes)
activates embryonic development - driven by maternal components -> materials deposited in the egg by the mother
the embryo makes its own gene products later
oocyte (egg) maternal components
haploid nucleus (23 chromosomes)
biosynthetic machinery
mitochondria - energy
information (mRNAs and proteins)
essential for early embryonic development - stored in cytoplasm of oocyte
sperm
haploid nucleus (23 chromosomes in human)
centrosome (microtubule organizing center) MTOC
activates development when it enters the egg
cleavage
special type of cell division without cell growth
lacks G1 and G2 phases
cleavage divisions rely on maternal components
cleavage produces…
cleaving cells are called blastomeres (in some organisms, blastomeres can give rise to any cell type; others more specialized)
at the end of cleavage, the embryo is called a blastula
gastrulation
reorganizes the embryo and results in three distinct germ layers: endoderm (inside), mesoderm (middle), and ectoderm (outside) which give rise to the different cell types
morphogenesis
gastrulation is the first morphogenetic event in embryogenesis
morphogenesis refers to the generation of organized forms
morphogenesis is based on different behaviors or cells