Lecture 2 - Cell Differentiation & Neural Induction II

Question 1

totipotent/omnipotent stem cells

Answer 1

can give rise to any cell type + placenta

Question 2

pluripotent stem cells

Answer 2

can give rise to any cell type but not the placenta

Question 3

multipotent cells

Answer 3

can develop into a limited number of cell types in a particular lineage

Question 4

Briggs & King Experiment (question)

Answer 4

do cells discard unneeded genes during cellular differentiation?

Question 5

Briggs & King Experiment (hypothesis)

Answer 5

if not, terminally differentiated cells would still have all of the genes necessary to make any other type of cell

Question 6

Briggs & King Experiment (test)

Answer 6

extract nucleus from skin cell in albino frog embryo and implant it in the center of wild-type frog egg that has been enucleated

Question 7

Briggs & King Experiment (result)

Answer 7

some eggs began forming albino tadpoles that eventually formed adult frogs

Question 8

Briggs & King Experiment (conclusion)

Answer 8

as cells become differentiated into specialized cells, they retain all genes needed to make any type of cell

Question 9

differential gene expression

Answer 9

all cells have the same DNA, they just don’t express all their genes at the same time (tissue specific gene expression)

Question 10

extrons

Answer 10

portions of gene that contribute code for mRNA molecule

Question 11

introns

Answer 11

don’t contribute info to final mRNA molecule, but regulates gene expression

Question 12

transcriptional factors

Answer 12

proteins that regulate gene transcription by binding to promoter

Question 13

activators

Answer 13

activate gene expression

Question 14

methylation

Answer 14

methyl group added to cytosine DNA by DNA methyltransferase (DNMT); represses gene transcription

Question 15

why methylation represses gene expression

Answer 15

prevents transcription factors from binding (attracts repressors)

Question 16

methylation & frog study

Answer 16

when implanted, egg had proteins to remove methyl group and make the gene active again

Question 17

mitotic lineage

Answer 17

sequence of cell divisions in mitotic cells during ontogeny that gives rise to a particular cell in the individual

Question 18

asymmetric cell division

Answer 18

daughter cells looks different than mother cell

Question 19

cell fate

Answer 19

depends on lineage

Question 20

mosaic specification of fate

Answer 20

cells follow a particular fate no matter what the neighboring cell is doing

Question 21

study with worms (question)

Answer 21

wanted to see if P1 was dependent on AB

Question 22

study with worms (test/results)

Answer 22

separate AB and P1, P1 gives rise to cells (not entire organism, eventually collapsed) > follow own fate

Question 23

SKN 1

Answer 23

posterior of egg, important for setting up pharynx in P1; w/o SKN-1 the cells fated to produce the pharynx will just form extra skin

Question 24

what happens if cells die during development? (worms)

Answer 24

laser ablation, killed cell did not come back (cells programmed to die still die)

Question 25

maternal effect

Answer 25

the influence that the mother has on the offspring’s phenotype that are separate from whatever genes she contributed to the egg

Question 26

origins of maternal factors

Answer 26

after sperm enters, maternal RNA & protein degrade throughout , methylation erased after fertilization