Cell Birth, Lineage, and Death (CH 21)

Question 1

Types of stem cells

Answer 1

pluripotent, unipotent, totipotent

Question 2

pluripotent

Answer 2

stem cell which has the ability to generate a number of different cell types as well as a copy of itself

Question 3

unipotent (progenitor) stem cells

Answer 3

stem cell which divides to produce a copy of itself and a cell that can only form one cell type

Question 4

totipotent

Answer 4

stem cell which has the ability to generate all cell types in the body (embryonic cells up to 8 cell stage)

Question 5

stem cells

Answer 5

unspecialized cells that can reproduce themselves and generate more specialized cells indefinitely

Question 6

precursor (progenitor) cells

Answer 6

cell with the potential to form different types of differentiated cells but with more limited potential than stem cells

Question 7

types of cell division

Answer 7

asymmetric and symmetric

Question 8

asymmetric cell division

Answer 8

cell undergoes growth and divides into two different daughter cells; may be different at birth or due to the micro-environment; differ in size, shape, composition, & patterns of gene expression

Question 9

symmetric cell division

Answer 9

cell divides into two identical daughter cells; increases the pool of stem cells

Question 10

three germ layers & their tissues

Answer 10

ectoderm - neural & epidermal tissue; mesoderm - muscle & connective tissue; endoderm - gut epithelial cells

Question 11

hallmarks of apoptosis

Answer 11

no cell lysis
phagocytosed by macrophages & organic component recycled
morphological changes:
nuclear & cytoplasmic shrinkage
breakup of nuclear envelope
DNA fragmentation (multiples of 180 base pairs)
membrane blebbing
translocation of phosphatidylserine from cytoplasmic to exoplasmic face of plasma membrane
increased caspase activity

Question 12

apoptosis

Answer 12

cell death that occurs in absence of trophic factors, physical damage, or cellular signals; cell undergoes morphological changes & is phagocytosed by macrophages

Question 13

necrosis

Answer 13

cell death caused by physical injury; cell bursts, spills contents, & produces inflammatory response

Question 14

caspase

Answer 14

proteases with conserved cysteine at active site; degrade cellular components (cytoskeleton & nuclear lamina) & activate other enzymes by cleavage

Question 15

formation of caspase

Answer 15

procaspase is activated by active caspase - cleaves prodomain & large/small subunits; caspase activation cascade; caspases activate enzymes that cleave cytosolic protein; caspases cleave nuclear lamin (or other intracellular proteins)

Question 16

initiator caspase

Answer 16

begin the cascade process - activate a series of caspases

Question 17

effector caspase

Answer 17

go on to cleave intracellular proteins & lead to cell death

Question 18

apoptosis pathway (by loss of trophic factor)

Answer 18

Bad - protein hat promotes apoptosis; binds to Bcl-2 & Bcl-xl; Bad prevents Bcl-2 & Bcl-xl from interacting with Bax; unbound Bax opens an ion channel, allowing ions to flow through outer mitochondrial membrance, releasing cytochrome c; cytochrome c forms complex with Apaf 1, recruiting/activating Procaspase 9 (initiator caspase); Procaspase 9 is cleaved to form Caspase 9, cleaves Procaspase 3 to Caspase 3; Caspase 3 goes on to cleave intracellular substrate & leads to cell death

Question 19

apoptosis pathway (regulated by presence of trophic factor)

Answer 19

trophic factor binds receptor; activated receptor activates PI-3 Kinase; PI-3 Kinase activates Akt kinase; Akt kinase (PKB) phosphorylates Bad - binding it (sequestered) to 14-3-3; Bad is sequestered to cytoplasm, unable to bind to Bcl, blocking death cascade