Week 9

Question 1

identical twins

Answer 1

splitting of the embryo

Question 2

fraternal

Answer 2

release and fertilization of 2 eggs

Question 3

polyspermy

Answer 3

the entry of multiple sperm nuclei into the egg, changes at the egg surface prevent this

Question 4

mitosis

Answer 4

cell division, creates 2 identical cells

Question 5

differentiation

Answer 5

cells become different from each other and they acquire specific functions

Question 6

patterning

Answer 6

arrangement of cells in proper positions, setting up the body plan

Question 7

cleavage

Answer 7

a period of rapid cell division without growth

Question 8

blastomeres

Answer 8

one large cell containing many smaller cells due to cleavage

Question 9

blastula (blastocyst in humans)

Answer 9

ball of cells with fluid filled cavity (blastocoel), the latest state an IVF clinic can maintain an embryo before transferring it to a uterus

Question 10

inner cell mass

Answer 10

contributes to the embryo, if we were to remove some of this cell mass, the embryo would still turn out normal because we haven’t told the cells what function they have yet

Question 11

trophoblast

Answer 11

contributes to the placenta, NOT the embryo, initiates implantation

Question 12

morphogenesis

Answer 12

process by which cells occupy their appropriate locations

Question 13

gastrulation

Answer 13

movement of cells from the blastula surface to the interior of the embryo

Question 14

organogenesis

Answer 14

the formation of organs

Question 15

gastrula

Answer 15

three layer embryo created by gastrulation rearranging the cells of a blastula

Question 16

ectoderm

Answer 16

forms the outer layer

Question 17

endoderm

Answer 17

forms the digestive tract

Question 18

mesoderm

Answer 18

partly fills the space between the endoderm and ectoderm

Question 19

cytoplasmic determinants

Answer 19

the zygote separating in the middle so that there’s unequal distributions of cytoplasmic material, which leads to different gene expression and determines what the cell does

Question 20

P granules

Answer 20

act as cytoplasmic determinants by moving to the posterior end of the zygote and therefore fixing germ cell fate at the earliest stage of development

Question 21

organizer

Answer 21

in an embryo that induce and pattern adjacent embryonic cells by changing the fate and generating an organized set of structures

Question 22

Hox genes

Answer 22

regulate body organization and control pattern formation in the late embryo, larva, and adult stages

Question 23

limb buds

Answer 23

all vertebrate limbs begin as bumps of tissue called limb buds

Question 24

ZPA

Answer 24

induces different Hot genes, which tells the cells what to be based on their position

Question 25

transcription factor combinations

Answer 25

control cell fates