Chapter 3.2 Flashcards
What occurs during the initial stage of cell specification and determination
Specification
->cells is reversibly designated to a specific cell type
Determination
- > cell commits to a particular function in the future
- > after determination, the cell cannot become any other type of cell
What determines the process of determination? Discuss mRNA and morphogens
- presence of specific mRNA/protein molecules may result in determination
- morphogens may also be the result of determination
- > morphogens are molecules secreted from nearby cells
- > these molecules cause cells to follow a particular developmental pathway
During determination, has the cell produced the products it needs to carry out its function? If not, when does this happen
- no
- > this happens during differentiation
-during determination, cells just commit to a certain type
What occurs during differentiation
- cell must undergo changes that cause the cell to develop into the determined cell type
- > this includes changing structure, function and biochemistry of the cell to match the cell type
What is meant by the term potency
-it is the tissues a particular stem cell can differentiate into
What is meant by the term totipotent? Give an example.
- totipotent are cells with the greatest potency
- > include embryonic stem cells
- > totipotent cells can differentiate into any type of cell
What is meant by the term pluripotent cells? When do these cells exist?
- when the topitent cells differentiate into the three germ cell layers
- these cells can differentiate into any cell type except for placental structures
What is meant by the term multipotent cells?
- this is when the cells begin to become more specialized
- at this point cells can differentiate into multiples types of cells within a particular group
Do stem cells only exist in embryos
- no
- >they exist in full grown adults as well
What are autocrine signals
-they are signals that act on the same cell that secreted the signals in the first place
What are paracrine signals
-they are signals that act on a local area
What are juxtacrine signals
- they are signals that do not involve diffusion
- >rather a cell stimulating receptors of the adjacent cell
What are endocrine signals
-they are signals that involve the secretion of hormones
What are the function of inducers? Are they specific to a cell or can act across various cell types
- they are growth factors
- > peptides that promote differentiation and mitosis in certain tissues
- most growth factors function on only specific cell types in specific areas
- > therefore, most growth factors can code for particular tissue types
Give an example of cell migration involving neural crest cells
- neural crest cells form at the neural folds
- > they then go and migrate throughout the body to form different structures
- > those being Schwann cells, adrenal medulla, etc
What is the difference between apoptosis and necrosis?
- apoptosis is programmed cell death
- necrosis is cell death during injury
- > internal substances of the cell can be leaked and can cause an immune response
What comes first. Apoptotic blebs or apoptotic bodies?
- apoptotic blebs become apoptotic bodies
- >these bodies are then taken up by other cells
What does senescence refer to? What do telomeres have to do with this?
- senescence is biological aging
- > occurs as changes accumulate
- > results in failure of cells to divide, normally after 50 divisions
- failure to divide after 50 divisions may be due to shortened telomeres(ends of chromosomes)
- > telomeres shorten during each round of DNA synthesis
- > eventually they become too short and the cell is no longer able to replicate
Describe the enzyme telomerase. What is its role? Also describe its relationship to senescence
- it is a reverse transcriptase
- > that is able to synthesize the ends of chromosomes
- in terms of senescence
- > it prevents senescence
- > allows cells to divide indefinitely
