Apoptosis

Question 1

apoptosis

Answer 1

when normal cells die

Question 2

necrosis

Answer 2

where injury was extreme and sudden: ischemia following occlusion of a major artery, physical or chemical trauma, or overwhelming infection.

Question 3

In necrosis, At the stage called “high-amplitude swelling”

Answer 3

it can no longer maintain its ionic gradients or oxidative phosphorylation, and the cell runs out of energy.

Question 4

Necrosis is

Answer 4

intensely proinflammatory.

Question 5

The defining morphological feature of apoptosis is a

Answer 5

collapse of the nucleus

Question 6

Early in apoptosis cells ______, and the result is a

Answer 6

shrink remarkably, losing about a third of their volume in a few seconds.

peculiar, vigorous “boiling” action of the plasma membrane, which has been called zeiosis.

Question 7

the goal of all the
morphological changes of apoptosis is
to ensure that

Answer 7

the apoptotic cell gets taken up by a healthy cell, before it has had a chance to spill its dangerous contents.

Question 8

why is necrosis so inflammatory?

Answer 8

Lysis releases the cell’s intracellular contents into the extracellular, these internal lipids, proteases, and small molecules are intensely inflammatory.

They attract white cells, primarily macrophages, from around the body.

Question 9

The effect of the inflammatory process is

Answer 9

debris removal, injury resolution, and, if the stroma has been damaged, scar formation.

Question 10

in apoptosis, chromatin,

Answer 10

becomes supercondensed, appearing as crescents around the nuclear envelope and, eventually, spherical featureless beads.

Question 11

zeiosis

Answer 11

By this action the apoptotic cell usually tears itself apart into apoptotic bodies, some of which contain chromatin.

Question 12

Apoptosis is also accompanied by

Answer 12

changes in the plasma membrane, the most obvious of which involves the phospholipid phosphatidylserine (PS).

Question 13

All the PS in a normal plasma membrane is confined to the______

Answer 13

inner leaflet of the lipid bilayer

Question 14

flippase ensures that any

Answer 14

PS molecule that strays to the outer leaflet is quickly returned.

Question 15

Soon after apoptosis begins, the distribution of PS becomes

Answer 15

equal on both sides of the membrane, by a “scrambling” mechanism involving, as you’d guess, “scramblase.”

This means that PS is now exposed on the cell’s exterior surface.

Question 16

Phagocytic cells have receptors for PS, and

Answer 16

recognize, bind to, and ingest cells that have committed to the apoptotic pathway, consuming them while they are still alive.

In this way the apoptotic cell never has a chance to lyse and release inflammation-causing molecules to the extracellular space.

Question 17

a macrophage that recognizes a cell as apoptotic

Answer 17

does not become activated.

Question 18

So the removal of apoptotic cells

Answer 18

physiological and silent,

Question 19

______ are the most radiation-sensitive cells in the universe;

Answer 19

Lymphocytes

0.05 grey will kill one by apoptosis, while it takes 150 grey to kill a macrophage.

Question 20

If lymphocytes are exposed to radiation in the presence of a drug that blocks transcription, they

Answer 20

do not die.

Question 21

low-dose radiation does not kill lymphocytes;

Answer 21

it induces them to kill themselves.

Question 22

if one cell type has “death genes,” then

Answer 22

all cells in the body do, since they share the same genome.

Question 23

any cell in the body could be made to undergo apoptosis if

Answer 23

we could understand how to get it to turn on these genes, and any cell that intended to die might be prevented from doing so by a reverse strategy.

Question 24

morphogenetic death determines

Answer 24

the final shape of body parts and organs.

Question 25

Apoptosis: In the nervous system,

Answer 25

many more cells develop than the organism needs; those that form the correct contacts at the correct time are bathed in survival factors by the target they have innervated; if not, they are dispensable.

Question 26

Apoptosis In limbs,

Answer 26

the death by apoptosis of cells between the digits gives the final form to fingers and toes.

Question 27

Indeed, even the formation of as precise a structure as the brain depends on a

Answer 27

Darwinian-style selection of cells that have chanced to make the best connections. Other local conditions could determine cell survival.

Question 28

cell shape, as influenced by the local tissue geometry, affects

Answer 28

whether a cell will live or die.

Question 29

Mitosis is estimated to occur

Answer 29

25 million times a second in an adult human.

Question 30

In a steady-state system whenever a cell in a particular compartment divides,

Answer 30

another must die, or else the size of the compartment will change.

Question 31

But using the 1 mitosis = 1 apoptosis assumption we find that, in an average adult,

Answer 31

2 x 1012 cells die every dayan incredible number.

Question 32

for cancer progression, mutations that

Answer 32

inhibit death may be just as important as those that stimulate growth.

Question 33

death controlled by

Answer 33

pro- and anti-apoptotic Bcl-2 factors

Question 34

two pathways for apoptosis:

Answer 34

1. intrinsic: from the inside, typically mitochondria

2. extrinsic: cytotoxic T cells