Mitochondria's Role in Apoptosis

Questions and Answers

What is the mitochondria commonly referred to as?

The protein powerhouse of the cell

The cell death regulator

The gene expression hub

The energy powerhouse of the cell (correct)

What is apoptosis defined as?

Unprogrammed cell death

Programmed cell death (correct)

Cellular differentiation

Cellular stress response

What is the main difference between apoptosis and necrosis?

Apoptosis occurs in embryological development, while necrosis does not

Apoptosis is controlled, while necrosis is uncontrolled (correct)

Apoptosis occurs in response to stress, while necrosis does not

Apoptosis is uncontrolled, while necrosis is controlled

What is an example of apoptosis in embryological development?

Development of the fingers and toes Signup and view all the answers

What is the current state of research in understanding apoptosis and necrosis?

There is still active research to elucidate the mechanisms Signup and view all the answers

What is the purpose of apoptosis in the development of fingers and toes?

To allow for the formation of separate digits Signup and view all the answers

What is the result of apoptosis in the development of hands?

The formation of a hand with five separated fingers Signup and view all the answers

What is a characteristic of necrosis?

It usually occurs in response to extreme stress Signup and view all the answers

What is the primary function of the mitochondria in apoptosis?

To play a big role in inducing cell death Signup and view all the answers

What can induce a cell to undergo apoptosis due to DNA damage?

Intensive DNA damage beyond repair capabilities Signup and view all the answers

What type of cells recognize infected cells and send signals to induce apoptosis?

Immune cells Signup and view all the answers

What is necessary for cells to continue surviving?

Signals that they are attached to other cells Signup and view all the answers

What happens to oxygen during the electron transfer chain in the mitochondria?

It is partially reduced, leading to reactive oxygen species Signup and view all the answers

What type of molecules can induce cell death by sending signals to the cell?

Growth factors Signup and view all the answers

What is the result of a cell losing connection to other cells?

Induction of apoptosis Signup and view all the answers

What type of species is the superoxide anion?

Reactive oxygen species Signup and view all the answers

What is the purpose of apoptosis in embryological development?

To remove excess cells Signup and view all the answers

What can reactive oxygen species do to a cell?

Induce cell death Signup and view all the answers

What is the primary function of antioxidant molecules in cells?

To trap reactive oxygen species and prevent oxidative damage Signup and view all the answers

What is the role of the BCL2 family of proteins in apoptosis?

To control the balance between pro-apoptotic and anti-apoptotic proteins Signup and view all the answers

What is the purpose of increasing the permeability of the outer mitochondrial membrane during apoptosis?

To allow cytochrome c to exit the intermembrane space and enter the cytoplasm Signup and view all the answers

What is the function of cytochrome c in the electron transport chain?

It helps shuttle electrons between the third and fourth complex Signup and view all the answers

What is the role of caspases in apoptosis?

To break down proteins with a cysteine residue in its active site Signup and view all the answers

What is the key difference between apoptosis and necrosis in terms of mechanisms?

Apoptosis is caspase-mediated, while necrosis is not Signup and view all the answers

What is the name of the protein family that regulates the permeability of the outer mitochondrial membrane?

BCL2 family of proteins Signup and view all the answers

What is the function of cytochrome c in apoptosis?

It activates caspases and initiates apoptosis Signup and view all the answers

What is the result of the imbalance between pro-apoptotic and anti-apoptotic proteins in the BCL2 family?

The mitochondria initiates apoptosis Signup and view all the answers

What is the significance of the name 'caspase'?

It refers to the cysteine residue in its active site Signup and view all the answers

Study Notes

Mitochondria and Apoptosis

Mitochondria are commonly known as the energy powerhouse of the cell due to their role in metabolic pathways like the Krebs cycle and the electron transfer chain.
However, mitochondria also play a role in apoptosis, which is defined as programmed cell death.

Apoptosis vs Necrosis

Apoptosis is a controlled type of cell death that usually has a purpose and confers an advantage to the organism.
Necrosis is an uncontrolled type of cell death that usually occurs in response to extreme stress, such as an extreme infection or trauma.
The distinction between apoptosis and necrosis can be unclear, and it's often said to lie along a spectrum between the two.

Role of Mitochondria in Apoptosis

The mitochondria play a big role in apoptosis, particularly in the initiation of programmed cell death.
Mitochondria have two membranes: the outer membrane and the inner mitochondrial membrane.

Factors that Induce Apoptosis

DNA damage can induce cell death, especially if the damage is intensive or the repair mechanisms are not equipped to deal with it.
Infection, especially by viruses, can induce programmed cell death.
Environmental stress, such as the deprivation of oxygen or nutrients, can also induce apoptosis.
The lack of cell-to-cell connections or growth factors can also trigger cell death.

Reactive Oxygen Species (ROS)

ROS are oxygen species that have acquired an unstable number of electrons, making them very reactive.
Examples of ROS include the superoxide anion, hydroxide radical, and hydrogen peroxide.
ROS can be formed inside cells as a byproduct of oxygen metabolism.
Cells have enzymes and antioxidant molecules to prevent unwanted reactions between ROS and important cell components.

BCL2 Family of Proteins

The BCL2 family of proteins regulate the permeability of the outer mitochondrial membrane.
There are two types of proteins in this family: pro-apoptotic proteins that push the cell towards apoptosis, and anti-apoptotic proteins that oppose apoptosis.
When the cell is healthy, the balance of these proteins is in favor of the anti-apoptotic proteins, which prevent the mitochondria from initiating apoptosis.

Cytochrome c and Caspases

Cytochrome c is a molecule normally found in the intermembrane space of the mitochondria.
When the outer mitochondrial membrane becomes more permeable, cytochrome c exits the intermembrane space and enters the cytoplasm.
Cytochrome c activates a family of enzymes called caspases, which are proteases that break down proteins.
Caspases have a controlled cascade of actions, activating other enzymes like nucleases that can break down DNA.
The eventual result is a large-scale degradation of polymers inside the cell.

Characteristics of Apoptosis

Apoptosis is caspase-mediated, unlike necrosis.
The degradation of polymers inside the cell can be recycled by surrounding cells through phagocytosis, allowing them to reuse amino acids and nucleotide bases.

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Description

Learn about the mitochondria's function in programmed cell death, also known as apoptosis, and its significance in the cell. This quiz explores the role of mitochondria beyond its energy-producing abilities.