Apoptosis/Cell death

Question 1

what is apoptosis?

Answer 1

“normal” or “programmed” cell death

Question 2

what is necrosis?

Answer 2

“accidental” or “uncontrolled” cell death

Question 3

what are the types of cell death?

Answer 3

Necrosis
Apoptosis
Autophagy
Ferroptosis
Oncosis
Necroptosis

Question 4

The word apoptosis comes from the Ancient Greek meaning?

Answer 4

the: ‘‘falling of petals from a flower’’ or ‘‘of leaves from a tree in autumn’’

Question 5

explain apoptosis in a more defined way

Answer 5

a mode of programmed cell death (PCD) that occurs under normal physiological conditions and the cell is an active participant in its own demise (“cellular suicide”).

Question 6

explain necrosis in a more defined way

Answer 6

a pathological cell death which occurs when cells are exposed to a serious physical or chemical insult (hypoxia, hyperthermia, ischemia).

Question 7

A table comparing forms of cell death

Answer 7

Necrosis Apoptosis Mitotic catastrophe

Passive Active Passive

Pathological Physiological or Pathological
pathological

Swelling, lysis Condensation, Swelling, lysis
cross-linking

Dissipates Phagocytosed Dissipates

Inflammation No inflammation Inflammation

Externally induced Internally or Internally induced
externally induced

Question 8

what is normal apoptosis

Answer 8

Apoptosis is the physiological cell death which unwanted or useless cells are eliminated during development and other normal biological processes.

It is important for the development of multicellular organism (embryonic development) and homeostasis of their tissues (adult).

Question 9

Why would a cell commit suicide?

Answer 9

Apoptosis is needed for ‘normal’ development
The resorption of the tadpole tail
The formation of the fingers and toes of the fetus
The formation of the proper connections between neurons in the brain

Apoptosis is needed to remove cells
Cells infected with viruses
Cells of the immune/neurological system
Cells with DNA damage
Cancer cells

Question 10

what is the importance of apoptosis?

Answer 10

During embryonic development, help to digit formation.
Lack of apoptosis in humans can lead to webbed digits called “ syndactyly ”.
Normal event in development of the nervous system

Question 11

refer to slide for malfunctioning of apoptosis

Question 12

state the two types of apoptotic pathway and explain their mechanisms

Answer 12

Intrinsic
Extrinsic

Intrinsic pathway > Cytochrome C> Caspases > Cell death
Extrinsic > Death receptor > Caspases > Cell death

Question 13

Efficient elimination of apoptotic cells requires specific cell signals, what are they?

Answer 13

Secreted “find-me,”
Exposed “eat-me,”
Lacking “don’t-eat-me”

Question 14

list the two EAT ME steps and explain them

Answer 14

Step 1 - Tethering - the phosphatidylserine (PtdSer) receptor Tim4 tightly binds PtdSer on the apoptotic cell and recruits it to the macrophage surface.

Step 2 – Tickling - Soluble proteins such as protein S/Gas6 or MFG-E8 bind PtdSer on apoptotic cells and activate their receptors (MerTK or integrin, respectively) on phagocytes, leading to Rac1 activation and actin polymerization.

Question 15

Both tethering and tickling are essential steps in the efficient engulfment of apoptotic cells. TRUE OR FALSE?

Answer 15

TRUE

Question 16

Apoptosis can be induced by intracellular and extracellular stimuli. TRUE OR FALSE

Answer 16

TRUE

Question 17

Apoptosis occurs at all ages of development and is used for morphogenesis and preservation of the organism. TRUE OR FALSE

Answer 17

TRUE