Embryonic Development Flashcards
Specification
- initial stage of cell specialization
- cell is reversibly designated a specific cell type
- cells are unspecialized so unable to perform essential functions of mature tissues
Determination
- second step of cell specialization
- cell irreversibly commits to a specific function
- can occur during cleavage when a specific mRNA and protein molecule result in this
- may also occur due to secretion of specific molecules called morphogens from nearby cells
Differentiation
- final step of cell specialization
- includes changes a cell must make to develop into the determined cell type
- changes in cell morphology and behavior
What are the functions of DNA methylation?
- recruits additional binding proteins
- responsible for tissue specific patterns of gene expression
- means of heritable genomic imprinting
- blocks transcription
What is the function of histone acetylation?
activates genes by weakening histone binding and thus forming accessible euchromatin for transcription to occur
What are embryonic stem cells?
cells that have not yet differentiated
What is potency?
determines the tissues a particular stem cell can differentiate into
Explain totipotent
- cells with the greatest potency
- embryonic stem cells are this
- can differentiate into any cell type either in the fetus or placental structures
Explain pluripotent
- occurs in stage at which the cells start to differentiate into the 3 germ layers
- cells can differentiate into any cell type except for those found in placental structures
Explain multipotent
cells can differentiate into multiple types of cells within a particular group
Functions of adult stem cells
- necessary for growth and upkeep of body
- usually multipotent
Where can adult stem cells be isolated from?
- blood
- adipose
- marrow supplies
Functions of cell-cell communication
- promote differentiation of a competent responder cell via factor release from an inducer cell
- differentiation via diffusible chemical communication
- enables progressive increase in structural complexity
- signaling often occurs via gradients
What are growth factors?
- peptides that promote differentiation and mitosis in certain tissues
- common type of inducer in cell-cell communication
What are the different types of chemical signaling?
- autocrine
- paracrine
- juxtacrine
- endocrine
Define autocrine
signals that act on same cell that released the signal
Define paracrine
signals act on local cells
Define juxtacrine
signals act on adjacent cells via direct stimulation (ex. gap junctions)
Define endocrine
signals act on distant tissues after traveling through the bloodstream
What is migration?
- when cytoskeleton and membrane rearrange to move cell along extracellular matrix
- occurs during healing and immune response
What causes cell migration?
- chemical or mechanical signals from other cells
- extracellular matrix
What do neural crest cells differentiate into?
- thyroid (neck)
- thymus (chest)
- adrenal medulla (abdomen)
- chain ganglia (back)
- peripheral nerves
- glial cells
- melanocytes
- dentin (head)
Describe apoptosis
- programmed cell death
- initiated by internal genetic program or external signal
- during this process chromatin forms, the nucleus fragments and apoptotic blebs containing chromatin/nucleus fragments are phagocytized by neighbor cells
What is necrosis?
cell death from attack or injury
What is lysis?
cell bursting from osmotic pressure or viral infection
What is senescence?
- cell aging
- result of multiple molecular and metabolic processes
- often due to shortening of telomeres during cell division
What is regenerative capacity?
- ability of an organism to regrow certain parts
- liver has a high capacity
- kidneys have moderate capacity
- heart has low capacity
