pt. 3 & Chapter 10

Question 1

what is the hierarchy of stem cells? (6)

Answer 1

totipotent
pluripotent = 3 germ layers
multipotent
limited differentiation potential
limited division potential
functional non-mitotic neuron

Question 2

what are the three ways stem cells can proliferate? (don’t describe them, only list)

Answer 2

1. single-cell asymmetry
2. population asymmetry
3. adult stem cell lineage

Question 3

describe single-cell asymmetry

Answer 3

one of the two daughter cells is less potent than itself (ex: pluripotent) and the other is as potent as itself (ex: totipotent)

Question 4

describe population asymmetry

Answer 4

• one daughter cell makes all its progeny as potent as itself
• other daughter cell makes all its progeny less potent than itself

Question 5

describe adult stem cell lineage

Answer 5

1. multipotent (form many types)
2. committed (1-2 types)
3. progenitor (transit amplification)
4. differentiated (specific)

Question 6

what is a progenitor cell?

Answer 6

makes the specific differentiated cell
- constantly being made

Question 7

how are the differentiated cell types determined when looked at bone marrow stem cells? (list the three main categories)

Answer 7

based on the surface tension (elasticity)
- low = neural
- medium = muscle
- high = bone
elasticity of the cells serves as a marker for cell type

Question 8

describe collecting stem scells from a morula

Answer 8

hard to do unless grown in vitro
- best for stem cells
- TOTIPOTENT

Question 9

describe collecting pluripotent cells from a blastocyst

Answer 9

from ICM
- more restricted for cell type it can become

Question 10

describe collecting pluripotent cells from a fetus

Answer 10

from primordial germ mass
- very restricted

Question 11

describe collecting pluripotent cells from an adult

Answer 11

not as pluripotent, but can still be induced in culture

Question 12

how are stem cells induced in culture?

Answer 12

somatic cell nuclear transfer
- take out nucleus & put into enucleated egg, grow in culture

Question 13

what are the three stem cell signals researchers look for when determining potency?

Answer 13

Oct4, Sox2, Nanog
- Oct4 binds to Sox2, this activates Nanog to turn on embryonic stem cell genes

Question 14

what did Yamanaka do?

Answer 14

added Oct4 to adult cells to see if they could dedifferentiate
- was able to do it through using different combinations of stem cell signals (all included Oct4, Sox2)

Question 15

what is a neuroblast?

Answer 15

precursor cell for neural cells

Question 16

what do the cells become if they have high BMP levels?

Answer 16

skin

Question 17

what do the cells become if they have medium amounts of BMP?

Answer 17

neural crest cells
- para NS
- symp NS
- glial cells

Question 18

what do cells become if they have low BMP levels?

Answer 18

neural tube
- brain
- spinal cord
- motor neurons

Question 19

what direction does the neural tube form during nerulation?

Answer 19

anterior to posterior

Question 20

what are the four steps of primary neurulation? describe them

Answer 20

ANTERIOR, BRAIN
1. shaping & folding = thickening of layers
2. elevation = edges raise
3. convergence = edges are pushed together
4. closure = neural plate sides fuse, crest cells migrate away

Question 21

what are the four steps of secondary neurulation? describe them

Answer 21

POSTERIOR, spinal cord
1. condensation = mesodermal cells pack together
2. transition = mesodermal cells change to ectodermal
3. cavitation = cells stick on two sides, creates hollow center
4. coalesce = formation of neural tube (ectodermal cells)

Question 22

describe the difference between an early gastrula and late gastrula

Answer 22

early = mountain range, hollow valley
late = cells have fused on the sides, hollow hole

Question 23

describe the cell layers of neural cells

Answer 23

pseudostratified (not separate layers)

Question 24

describe how researchers know where the cells are in the cell cycle based on location to the lumen

Answer 24

S phase = cells at top (outer) of neural tube
M phase = cells at bottom (lumen) of neural tube

Question 25

what are the three layers the neural cells divide into (don’t describe them, just list them)

Answer 25

ventricular zone (ependyma)
intermediate zone (gray matter, mantle layer)
marginal zone (white matter)

Question 26

now describe each of the three layers the neural cells divide into

Answer 26

ependyma = cells near lumen (center), does the most proliferation

mantle layer = contains cell bodies

white matter = axons, makes tracts that go throughout the body

Question 27

describe the difference between the dorsal and ventral horns

Answer 27

dorsal = signals come in
ventral = signals go out

Question 28

what is the thing that separates the dorsal and ventral horns?

Answer 28

sulcus limitans

Question 29

what are purkinje neurons?

Answer 29

secrete Shh
- connect to several cells
- moves body in coordinated way, balance

Question 30

what are bergamann glial cells?

Answer 30

synaptic plasticity
- build new neuron projections

Question 31

what does the granular layer do?

Answer 31

secrete BMPs

Question 32

describe the function of the following….
dendrites
soma
axon hillock
axon terminal (growth cone, microspikes)

Answer 32

dendrites = receive signal
soma = houses DNA
axon hillock = summate signals, decide on AP
axon terminal = where AP is sent to
- growth cone = moves to sense environment to grow
- microspikes = on the growth cone, part that senses

Question 33

what are the three primary vesicles of the neural tube?

Answer 33

forebrain, midbrain, hindbrain

Question 34

what are the five secondary vesicles of the neural tube? what primary vesicle do they come from?

Answer 34

telencephalon (forebrain)
diencephalon (forebrain)
mesencephalon (midbrain)
metencephalon (hindbrain)
myencephalon (hindbrain)

Question 35

describe the gene expression in the neural tube (two competing signals)

Answer 35

BMPs = roof plate
Shh = floor plate, comes from notocord
- form a gradient and work against eachother