Broccoli: Lecture XVII

Question 1

What is a zygote?

Answer 1

the cell we derive from

Question 2

How does the zygote form?

Answer 2

fusion of the sperm and ovum along the oviducts

Question 3

What kind of single cell forms after the fusion of the sperm and ovum?

Answer 3

diploid cell

Question 4

What is the membrane of the diploid cell?

Answer 4

membrane pellucida

Question 5

What doe the membrane pellucida protecting the embryo from?

Answer 5

maternal tissue

Question 6

When does the embryo break maternal tissue?

Answer 6

when it arrive in the uterus, it breaks the maternal tissue to attach to the maternal endometrium

Question 7

How long does it take an embryo to travel from the oviduct to a uterus?

Answer 7

5 day in humans

Question 8

How many times does the embryo divide during its journey to the uterus?

Answer 8

into 32 blastomeres

Question 9

When does the morula stage of the embryo occur?

Answer 9

when it has divided into 32 blastomeres

Question 10

What kind of cells are the 32 embryonic cells called?

Answer 10

totipotent cells

Question 11

What happens when the embryo forms an internal cavity?

Answer 11

it becomes a blastocyst

Question 12

What are the “flat cells” of the blastocyst?

Answer 12

trophoblast cells that generate the walls of the blastocyte

they protect a mass of 50 internal cells called inner cell mass (ICM)

Question 13

What does the ICM do?

Answer 13

give rise to an entire individual

pluripotent stem cells that form organs

Question 14

What do the trophoblast cells do?

Answer 14

give rise to the embryonic part of the placenta

Question 15

What is the Leukemia Inhibitor Factor (LIF)?

Answer 15

molecule that maintains pluripotency

Question 16

What is pluropotency a unique property of?

Answer 16

ICM at the blastocyst stage

Question 17

When do adult stem cells form?

Answer 17

once the embryo forms the fetus

Question 18

What are adult stem cells?

Answer 18

organ-specific stem cells, which are organ specific meaning they cannot be differentiated

Question 19

Where are totipotent stem cells found?

Answer 19

only in the zygote in the morula stage (1-5 days)

Question 20

When are pluripotent stem cells found?

Answer 20

when blastocyst is formed (5-10 days)

Question 21

Adult stem cells are ___.

Answer 21

multipotent

Question 22

What does it mean is adult stem cells are multipotent?

Answer 22

they can differentiate into some cell types, but very few

Question 23

How are neuronal cells created?

Answer 23

ectoderm → neural plate (brain, spinal cord, and neural projections) & epidermal tissue (epidermis and epidermis sheets) → neural progenitors → neural tube

Question 24

What are BMP factors?

Answer 24

bone morphogenetic factors, which are expressed by the epidermis and specify the epidermal tissue

Question 25

What are fibroblast growth factors (FGF-2)?

Answer 25

the signal of BMPs protect neural progenitors by the FGF-2 FGF-2 are proteins that block the action of BMPs and specify the ectodermal cell to become neural progenitors

Question 26

How can we be use that the cultured cells are pluripotent?

Answer 26

we inject them into a blastocyst host in the blastocele cavity, which can the be replanted into a surogate mother

Question 27

What is a chimeric animal?

Answer 27

when an inoculated blastocyst attaches tot he endometrium and generates an embryo or fetus they are animals that are generated by 2 different cell types (1 with an ICM of the host blastocyst and the other from ESCs cultured in vitro and injected in the blastocyst)

Question 28

If ESCs are injected, as they are in vitro, into an adult animal, what would they give rise to?

Answer 28

tumor of embryonic origin because the cells will not have a signal to be able to differentiate and cause them to stop proliferating

Question 29

What is the tumor called that is produced when ESC are implanted into adult tissue?

Answer 29

teratoma

Question 30

What is a hypotoxic environment?

Answer 30

environment that does not have much metabolic supprt

Question 31

What are the minimal molecular signals that are sufficient to maintain cells in a pluripotent state?

Answer 31

culture condition in which there are fibroblasts and animal serum the 2 molecules found in these that are necessary for the pluropotency of the cells are PD0325901 and CHIR99021

Question 32

What is PD0325901?

Answer 32

small inhibitor of the FGF pathway

Question 33

What is CHIR99021?

Answer 33

inhibits the GSK3 pathway

Question 34

What do pluripotent cells express?

Answer 34

FGF4 receptor

Question 35

If FGF4 is expressed, what is caused?

Answer 35

iPS cells start to differentiate

Question 36

What are the 2 signals that activate the network of TFs that stimulate pluripotency?

Answer 36

β-catenin and STAT1/3

Question 37

What are the 3 pluripotency TFs?

Answer 37

Oct4 Sox2 Nanog

Question 38

What happens if Oct4, Sox2, and Nanog are not activated?

Answer 38

they do not specify inner cell mass and they lose their pluripotency

Question 39

Why is the ICM important in vivo and in vitro?

Answer 39

it creates a feed forward-loop that is essential to maintain the stable expression of proteins, which is required for the pluripotency state of the ESCs

Question 40

What is required to culture human embryonic stem cells?

Answer 40

FGF2 and activin without serum

Question 41

Describe the difference between human ESC and mouse ESC:

Answer 41

mice colonies have a dome shape, and human colonies are flat trypsin is used for mice for single cell suspension and humans cannot grow from a single cell

Question 42

What are epiblast stem cells?

Answer 42

made from the epiblast, which is a late stage where the blastocyst starts to generate an ectoderm and are found in mice

Question 43

In the 1st experiment, what were the 4 factors found to be necessary to start the conversion of adult fibroblasts into mouse embryonic stem cells?

Answer 43

Oct4 Sox2 Klf4 c-Myc

Question 44

In the 2nd experiment, what was found?

Answer 44

fully mature hepatocyte can be reprogrammed into iPScell through the TFs Oct4, Sox2, Klf4, and c-Myc

Question 45

What is cell reprogramming?

Answer 45

the idea that we can reprogram the identity of cells altogether

Question 46

What is a limitation in cell reprogramming?

Answer 46

it is not very efficient: the pluripotency switch occurs in 1 of 100,000 cells

Question 47

Why is efficiency so low?

Answer 47

it is not known

Question 48

What are the Yamanaka factors?

Answer 48

Oct4 Sox2 Klf4 c-Myc they can reprogram iPS cells into any type of cell

Question 49

What cells have a higher percentage of reprogramming?

Answer 49

progenitors of mature T & B cells

Question 50

Fibroblast-derived iPS cells have a ___ percentage to differentiate in blood stem cells compared to blood-derived iPS cells.

Answer 50

low this infers the cells have memory