Apoptosis

Question 1

what is apoptosis

Answer 1

the controlled death of cells in the body. it removes cells without spilling their contents into the internal environment.

Question 2

what are the pathways of apoptosis

Answer 2

• mitochondrial pathway
• death receptor pathway

Question 3

mitochondrial pathway or intrinsic pathway

Answer 3

• initiated by detecting internal damage to cells.
• when detected they release cytochrome C into the cytosol. These bind to proteins and form an apoptosome.

Question 4

apoptosome

Answer 4

binds to proteins and activates caspase enzymes which will initiate apoptosis.

Question 5

death receptor pathway or extrinsic pathway

Answer 5

detect death signaling molecules by death receptor proteins on the surface of the cell.

When they bind to the death receptor surface proteins, caspase enzymes are activated which will initiate apoptosis.

Question 6

stages of apoptosis

Answer 6

1. caspases are activated ( mitochondria detect internal DNA damage and release cytochrome c ).
2. the contents of the cells is digested and organelles are broken down.
3. the cell and nucleus shrinks as the intracellular materials are broken down.
4. membrane blebbing and breakage occur as the cytoskeleton is digested. The membrane will wrap and detach itself from the cell is apoptotic bodies which contain broken down intracellular materials.

Question 7

what happens if the cell cycle is insufficient or disrupted?

Answer 7

the damaged cells can replicate exponentially which can therefore lead to the development of cancer and tumors.

Question 8

what happens when apoptosis decreases and why?

Answer 8

apoptosis may decrease due to inefficient cells being detected at the various checkpoints. As a result, cell growth can increase which will result in a tumor being formed.

Question 9

types of tumors

Answer 9

benign tumors
malignant tumors

Question 10

benign tumors

Answer 10

• slow growing
• generally enclosed in capsules that will prevent abnormal cells from separating and invading parts of the body.

Question 11

malignant tumors

Answer 11

some cells of benign tumors can mutate and invade tissues. They can also enter the bloodstream. therefore it can grow and travel over time.
these tumors are the only tumors that are seen as cancerous. this is due to the fact that they migrate.

Question 12

characteristics of tumors

Answer 12

• self sufficient
• antigrowth deactivation
• increased survival
• blood supply formation
• tissue invasion and metastasis.

Question 13

characteristics self sufficiency

Answer 13

tumor cells replicate without the use of chemical signals. instead, they produce their own signal or activate cell growth and replication pathways.

Question 14

characteristics antigrowth deactivation

Answer 14

they can disable mechanisms that prevent replication when they are not needed.

Question 15

characteristics increased survival

Answer 15

due to the fact that apoptosis doesn’t occur in tumor cells, they can divide and enhance their survival

Question 16

characteristics blood supply formation

Answer 16

they can form new blood vessels that maintains adequate nutrients and oxygen supplies.

Question 17

characteristics tissue invasion and metastasis

Answer 17

once they become cancerous they invade layers of tissue through the blood vessels.

Question 18

types of cell death

Answer 18

• necrosis
• apoptosis

Question 19

necrosis

Answer 19

a form of cell death that is unregulated and uncontrolled through an external force like trauma or infection. the cell will swell and rupture its contents into the internal environment. This can cause inflammation in the tissue.

Question 20

purpose of apoptosis

Answer 20

cells that are damaged are eliminated.
sculpts the body from tissue during the fetal stage

Question 21

Initiation stage of apoptosis in the intrinsic pathway.

Answer 21

a type of death ligand that will be released by a natural killer cell which would find a cell that needs to die and releases FasL. FasL will bind to a receptor on the surface ( FasR) which will draw two other FasR’s. These will attract the molecules FADD ( two of them ). then they draw in two molecules called Procaspase 8. Procaspase 8 will then have its top cut of to create an enzyme called caspase 8 which attaches to procaspase 3, which has its head cut of and turns into caspase 3 which cuts the cytoskeleton. which results in the cell collapsing. this occurs in the mitochondrial pathway

Question 22

execution

Answer 22

when the cytoskeleton is cut up during caspase 3, the cell will begin to shrink and starts blebbing whilst the chromatins and nucleus condense. The blebs break away from the cell body and chromatins and nucleus become fragmented.

Question 23

phagocyte

Answer 23

a number of white cells used to engulf foreign matter

Question 24

apoptotic vesicles

Answer 24

a bleb when it has broken away from the cell.

Question 25

phagocytosis

Answer 25

the cell debris in the apoptotic vesicles is engulfed by phagocyte through exocytosis

Question 26

cancer cells

Answer 26

cells that are unspecialised and grow rapidly and out of control which forms a tumor.

Question 27

malignant

Answer 27

invades normal tissue.