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Questions and Answers
Programmed cell death is also known as necrosis.
Programmed cell death is also known as necrosis.
False
Humans possess approximately 1014 cells, with over 200 differentiated cell types.
Humans possess approximately 1014 cells, with over 200 differentiated cell types.
True
Cell death is irrelevant to the development of multicellular organisms.
Cell death is irrelevant to the development of multicellular organisms.
False
Abnormalities in cell death can lead to conditions such as cancer and autoimmune diseases.
Abnormalities in cell death can lead to conditions such as cancer and autoimmune diseases.
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Only embryonic stem cells have the ability to replace lost cells in adult tissues.
Only embryonic stem cells have the ability to replace lost cells in adult tissues.
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Apoptosis is an active process that leads to the death of a single cell.
Apoptosis is an active process that leads to the death of a single cell.
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The term apoptosis is derived from a Greek word that means setting leaves on fire.
The term apoptosis is derived from a Greek word that means setting leaves on fire.
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During apoptosis, necrotic cell death usually occurs and affects groups of cells.
During apoptosis, necrotic cell death usually occurs and affects groups of cells.
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Apoptosis typically results in healthy neighboring cells remaining unharmed.
Apoptosis typically results in healthy neighboring cells remaining unharmed.
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Apoptosis primarily occurs only in adult organisms.
Apoptosis primarily occurs only in adult organisms.
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Study Notes
Programmed Cell Death (Apoptosis)
- Apoptosis is an active process of cellular changes leading to cell death.
- It's a normal, controlled part of organism growth and development.
- The body uses apoptosis to eliminate unwanted or abnormal cells.
- The term "apoptosis" is derived from the Greek word for the falling of leaves from a tree or petals from a flower.
- It distinguishes this programmed cell death from accidental cell death caused by injury or inflammation.
Animal Development and Cell Balance
- Animals start as a single cell (fertilized egg) and, undergoing rapid proliferation, differentiate into a vast array of specialized cells.
- Humans have an estimated 1014 cells with over 200 distinct types.
- In multicellular organisms, cell death and proliferation are balanced throughout life.
- The complex process of development also involves maintaining a balance between cell death and proliferation.
Types of Cell Death: Apoptosis vs Necrosis
- Apoptosis is a programmed cellular suicide occurring in a normal or regulated manner.
- Necrosis, typically a result of severe cellular injury, leads to the death of groups of cells and often causes inflammation.
Apoptosis Stages and Characteristics
- Apoptosis involves a series of distinct cellular changes.
- Apoptotic cells shrink and form membrane blebs, with the nucleus breaking into fragments
- Apoptosis also involves the formation of apoptotic bodies, which are then phagocytosed by neighboring cells or macrophages.
- Neighboring cells remain healthy during apoptosis.
- Apoptotic cell death doesn't cause an inflammatory response.
Importance of Apoptosis
- Apoptosis is essential for balancing cell numbers in tissues undergoing turnover.
- Apoptosis serves as a defense mechanism to eliminate potentially damaged or dangerous cells.
- Apoptosis plays a crucial role during embryonic development, maintaining homeostasis in adults, and aiding in responses to disease states, and fighting infections.
- Cells infected by viruses often undergo programmed cell death to limit viral production and spread.
Cellular Renewal in Adults
- Cellular renewal, balancing cell death with cell replacement by stem cells, is essential in mature (adult) organisms and tissues.
- The capacity of stem cells to differentiate into various cell types is critical for tissue repair and regeneration.
Types of Molecules Involved
- Phosphatidylserine: A cell membrane component that signals apoptotic cells for removal.
- Growth factors: Essential for cell survival in many tissues
- Extracellular matrix: Plays a role in regulating cell-cell interactions and cell survival.
Intrinsic and Extrinsic Pathways
- Two pathways lead to apoptosis.
- The intrinsic pathway includes internal surveillance mechanisms or signals affecting cell pathways or DNA damage.
- The extrinsic pathway is initiated by signals from other cells and involves the interaction of "killers" with specific receptors.
- These pathways often interplay.
Common Causes of Apoptosis
- Developmentally defective cells.
- Excess cells
- Cells with perturbed cell cycles
- Virus-infected cells
- Chemotherapeutic treatments
The Bcl-2 Family
- The Bcl-2 family of proteins regulates apoptosis, with anti-apoptotic and pro-apoptotic proteins.
- Factors such as nutrient withdrawal and/or environmental changes that signal apoptosis
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Description
Explore the crucial processes of programmed cell death (apoptosis) and animal development. Understand how these processes maintain cellular balance in multicellular organisms. This quiz covers the definitions, differences, and significance of apoptosis and necrosis.
