Chapter 18 flashcards

What is Necrosis

Accidental cell death from acute injury or disease, leading to the breakdown of cell structures and loss of function.

What is Apoptosis

A programmed cell death process that occurs in a regulated manner, allowing for the removal of damaged or unnecessary cells without causing inflammation. Characterized by DNA fragmentation, chromatin condensation, fragmentation of the nucleus and cell.

What does proliferation mean?

The process of cell growth and division, resulting in an increase in the number of cells. It is essential for tissue growth, repair, and regeneration. It is the reproduction of cells.

What is the difference between pluripotent stem cells and transdifferentiation

Pluripotent stem cells can differentiate into almost any cell type, while transdifferentiation refers to the process where one specialized cell type is converted directly into another without reverting to a pluripotent state.

Since 50% of developing neurons are eliminated by programmed cell death, what happens to those that survive?

Those that survive have made the correct connections with their target cells, which secrete growth factors that signal cell survival by blocking the neuronal cell death program.

How is apoptosis done?

Apoptotic cells express “eat me” signals such as phosphatidylserine. Apoptotic cells and cell fragments are recognized and phagocytosed (engulfed) by macrophages (type of white blood cell) and neighbouring cells, and rapidly removed from tissues. The 3 genes responsible are Ced-9, Ced-4, Ced-3.

How is necrosis done?

Necrotic cells swell and lyse (cell membrane breaks down); the contents are released into the extracellular space and cause inflammation.

What is a protease

An enzyme that breaks down proteins by hydrolyzing peptide bonds, playing a crucial role in various biological processes such as apoptosis and cellular signaling.

What is a caspase

A type of protease involved in the apoptosis process, responsible for dividing specific proteins to execute cell death. An example is Ced-3. Activation of an initiator caspase starts a chain reaction that activates executioner caspases, leading to cell death.

What inhibitis apoptosis?

Bcl-2 is a protein that regulates cell death by inhibiting the apoptotic process, promoting cell survival. Also, cancer cells often overexpress Bcl-2, allowing them to evade apoptosis and continue to proliferate.

What is the apoptosome complex

A protein structure formed during apoptosis that activates initiator caspases, leading to the execution phase of cell death. It is typically formed by the aggregation of cytochrome c, Apaf-1, and caspase-9.

What is the inhibitor of apoptosis (IAP) family

A group of proteins that prevent apoptosis by inhibiting caspases, thereby promoting cell survival. IAPs bind to and inhibit the activity of caspases, allowing cells to resist apoptotic signals.

What is ubiquitylation

The process of attaching ubiquitin molecules to a protein, marking it for degradation by the proteasome or altering its function.

What does p-53 do in cell apoptosis

p53 induces apoptosis in response to DNA damage or stress. It activates transcription of genes encoding proapototic BH3, PUMA and Noxa and inhibits anti-apoptotic factors, promoting cell death to prevent the propagation of damaged cells.

What initiates a major pathway that promotes cell survival

The activation of the PI 3-kinase which phosphorylates PIP2 to make PIP3, which activates Akt. Akt phosphorylates BH3, Bad and FOXO transciption factors which makes them inactive, in turn inhibiting apoptosis.

What is the extrinsic pathway

The extrinsic pathway is a mechanism of apoptosis triggered by external signals, such as death ligands and polypeptides in the TNF (tumor necrosis factor), binding to death receptors on the cell surface, leading to the activation of caspases (8 and 9) and Bid that execute cell death.

What is autophagy?

Autophagy is a cellular process that degrades and recycles cellular components, helping to maintain cellular homeostasis and respond to stress by removing damaged organelles and proteins. For example, in starvation conditions, degradation of components provides energy. Autophagic cell death does not require caspases, but are characterized by an accumulation of lysosomes.

What is necroptosis

Necroptosis is a programmed form of necrosis or inflammatory cell death that occurs when apoptosis is inhibited, characterized by the activation of receptor-interacting protein kinases (RIPK1 and RIPK3) and the formation of a necrosome (RIPK1,RIPK3,MLKL). The necrosome triggers cell swelling, membrane rupture, and the release of pro-inflammatory factors.

What are stem cells

Stem cells are undifferentiated cells capable of self-renewal and differentiation into various specialized cell types. They play a crucial role in development, tissue repair, and regeneration. They divide to two daughter cells, one being a stem cell and one being a differentiated (specialized) cell.

What is a niche

A niche is a specialized microenvironment where stem cells reside, providing necessary signals and support for their maintenance, self-renewal, and differentiation. Also it controls the balances between self-renewal and differentiation

How does Hematopoietic stem cell transplantation help with damaged cells

Hematopoietic stem cell transplantation (bone marrow) helps repair damaged cells by replacing dysfunctional cells with healthy stem cells. This process restores normal blood cell production and immune function. It is useful after chemotherapy treatment since it replaces cells damaged by the toxic chemo drugs.

Why are Embryonic stem cells special?

Embryonic stem cells are unique because they are pluripotent, meaning they can differentiate into any cell type in the body. They are derived from early-stage embryos and have the potential for extensive applications in regenerative medicine and research.

What is somatic cell nuclear transfer

Somatic cell nuclear transfer is a laboratory technique used to create a cloned embryo by transferring the nucleus of a somatic cell into an enucleated egg cell. This method is significant in cloning and regenerative medicine, as it allows for the generation of embryonic stem cells that are genetically identical to the donor organism. It is used to reproduce the genetic material of a specific organism, enabling studies on development and disease.

What is therapeutic cloning

Therapeutic cloning transfer, often associated with somatic cell nuclear transfer, is a process used to create cloned embryos for the purpose of generating embryonic stem cells. This technique allows for the production of cells that are genetically identical to the donor, which can be used for regenerative medicine and research. It is used to produce cells for treating diseases and injuries and it bypasses the problem of tissue rejection since it uses the patients’ cell then transfers it back.

Induced pluripotent stem cells

Are adult cells reprogrammed to an embryonic-like state, allowing them to differentiate into various cell types. This technique provides an alternative to embryonic stem cells for research and therapy.