Intrinsic Pathway

Question 1

What is the intrinsic pathway of apoptosis?

Answer 1

The intrinsic pathway of apoptosis is one of two pathways that initiate apoptosis and is activated by intracellular signals.

Question 2

Intrinsic

Answer 2

Intrinsic (mitochondrial) pathway of apoptosis (Fig. 1.25): It is activated by intracellular signals. • Role of mitochondria in apoptosis: – Mitochondrial damage is the major mechanism in a variety of physiological and pathological apoptosis. – Mitochondria contain proteins capable of induc- ing apoptosis. These include: cytochrome c and several proapoptotic proteins. Survival or apoptosis of cell is determined by permeability of mitochondria.Mitochondrial permeability is controlled by
BCL2 family of more than 20 proteins. This family
is named after BCL2, which was identified as an
oncogene in a B-cell lymphoma. These proteins
may be broadly divided into proapoptotic or anti-
apoptotic (prosurvival).
◆ Proapoptotic proteins: BAX and BAK
◆ Antiapoptotic proteins: BCL2, BCL-XL, and
MCL1. They prevent leakage of mitochondrial
proteins that trigger apoptosis. Growth factors
and other survival signals stimulate production
of antiapoptotic proteins.
If the balance shifts to proapoptotic proteins, the
apoptotic cascade is activated.

Question 3

What activates the intrinsic pathway of apoptosis?

Answer 3

The intrinsic pathway of apoptosis is activated by internal signals such as DNA damage, oxidative stress, and growth factor deprivation

Question 4

What is the role of the mitochondria in apoptosis?

Answer 4

The mitochondria play a key role in the initiation of apoptosis, and mitochondrial damage is a major mechanism in a variety of physiological and pathological apoptosis

Question 5

What are some proteins found in mitochondria that can induce apoptosis

Answer 5

Some proteins found in mitochondria that can induce apoptosis include cytochrome c and several proapoptotic proteins.

Question 6

How is the permeability of mitochondria controlled

Answer 6

The permeability of mitochondria is controlled by the BCL2 family of proteins

Question 7

What is the BCL2 family of proteins?
What is the difference between proapoptotic and antiapoptotic proteins?

Answer 7

The permeability of mitochondria is controlled by the BCL2 family of proteins.
The BCL2 family of proteins is a group of more than 20 proteins named after the BCL2 oncogene identified in a B-cell lymphoma

Question 8

What are some examples of proapoptotic proteins?
What are some examples of antiapoptotic (prosurvival) proteins?
What happens if the balance shifts towards the proapoptotic proteins

Answer 8

Examples of proapoptotic proteins include BAX and BAK.
Examples of antiapoptotic (prosurvival) proteins include BCL2, BCL-XL, and MCL1, which prevent the leakage of mitochondrial proteins that trigger apoptosis.
If the balance shifts towards the proapoptotic proteins, the apoptotic cascade is activated, leading to the destruction of the cell.