3.2 HY Mechanisms of developement Flashcards
What is the difference between specification, determination and differentiation?
Specification- the initial stage of cell specialization, in which the cell is reversibly designated as a cell type.
Determination- the commitment of a cell to a particular function in the future. This is irreversible. Although it has committed to being a particular cell type, it is not yet that cell type.
Differentiation- This is the actual change in the cell that includes changing of the structure, function, and biochemistry of the cell.
What are two pathways that determination can occur?
- The presence of specific mRNA and protein molecules may be in separate cells during cleavage.
- Can also occur from secretion of specific molecules from nearby, called morphogens, which influence their development.
What are stem cells?
Cells that have not yet differentiated or that give rise to other cells that will differentiate.
What is:
Totipotency
Pluripotency
and Multipotency
Totipotent cells- have the greatest potency and can differentiate into any cell type, either in the fetus or in placental structures.
Pluripotent- can differentiate into any cell exceptthose found in the placental structure.
Multipotent- can differentiate into multiple types of cells within a particular group
What are the four types of cell-cell communication? (End in ~crine)
Autocrine
Paracrine
Juxtacrine
Endocrine
What’s the difference between apoptosis and necrosis.
Apoptosis- programmed cell death, that can occur for various reasons
Necrosis- process of cell death in which a cell dies as a result of injury. The substances may be leaked out, causing irritation of nearby tissues.
What are:
Apoptotic blebs
Apoptotic bodies
Apoptotic Blebs- first process of apoptosis, in which the cell undergoes changes in morphology and divides into many self-contained protrusions
Apoptotic Bodies- These break down the blebs and can be digested by other cells, allowing recycling of material.
What is inducer, responder, and competent, in terms of cell-cell communication?
What is reciprocal development?
Inducer is the cell that sends chemical signals to the other cell. They are often growth factors, which promote differentiation and mitosis in certain tissues.
The responder is the one that receives the response or chemical signal. However, they must be competent or have the correct structure to receive those signals.
The responder may signal other tissues to transform, known as reciprocal development.
Where do the following work?
Autocrine
Paracrine
Juxtacrine
Endocrine
Autocrine- affects the same sell that secreted the signal
Paracrine- signals act on cells in the local area
Juxtracrine- do not involve diffusion, directly stimulate the receptor in the cell next to it
Endocrine- involve secreted hormones that travel through the bloodstream to a distant target tissue
What is regeneration?
What is incomplete vs complete regeneration?
Regenerative capacity is the ability of an organism to regrow certain parts of the body. The stem cells must to go the part of the body that was damaged to regenerate.
Complete Regeneration- occurs in like salamanders, and their tail grows back. There are identical tissues
Incomplete regeneration- not identical in the structure or function. Human typically have incomplete regeneration.
What is senescence?
Biological aging, and is a normal part of aging.
This may be due to shortened telomeres
Telemeres reduce the loss of genetic information from the ends of chromosomes and help prevent the DNA from unraveling. However, they shorten each round of DNA syntehsis.
Telemerase is an enzyme, that is a reverse transcriptase that is able to synthesize the ends of the chromosomes, preventing senescence.
What is neurulation?
When does it start?
It is the development of the nervous system, and begins AFTER the formation of the three germ layers (ectoderm, endoderm, and mesoderm).
