Chapter 47: Development

Question 1

model organisms

Answer 1

organisms used for developmental research; easily available or bred

Question 2

fertilization

Answer 2

union of sperm and egg

Question 3

vitelline layer

Answer 3

extracellular matrix of unfertilized egg

Question 4

jelly coat

Answer 4

coat of unfertilized egg that protects egg and attracts sperm

Question 5

acrosomal reaction

Answer 5

reaction triggered by contact of egg with sperm

Question 6

acrosome

Answer 6

vesicle at sperm tip with hydrolytic enzymes break down jelly

Question 7

acrosomal process

Answer 7

structure w/ proteins that bind receptors on eggs

Question 8

depolarization

Answer 8

fusion leads to change in membrane potential

Question 9

polyspermy

Answer 9

multiple sperm fertilizing an egg; blocked by depolarization and fertilization envelope

Question 10

cortical reaction

Answer 10

initiated by fusion of egg and sperm; vesicles in cortex fuse with plasma membrane, leads to fertilization envelope

Question 11

fertilization envelope

Answer 11

slower response to block polyspermy; separates vitelline layer from plasma membrane and breaks up receptors so more sperm don’t bind

Question 12

activation of the egg

Answer 12

follows cortical reaction; increased respiration and protein synthesis, sperm nucleus fuses with egg nucleus

Question 13

cleavage

Answer 13

earliest division, rapid; cell division without growth

Question 14

blastomeres

Answer 14

individual cells formed by cleavage

Question 15

blastula

Answer 15

hollow ball of cells with a blastocoel

Question 16

blastocoel

Answer 16

internal cavity of blastomeres

Question 17

cytoplasmic determinants

Answer 17

proteins, mRNA, etc. in specific places that code for body polarity

Question 18

yolk

Answer 18

stored nutrients; help determine first cleavage

Question 19

vegetal pole

Answer 19

pole in which yolk is concentrated

Question 20

animal pole

Answer 20

pole opposite the vegetal pole

Question 21

animal-vegetal axis

Answer 21

anterior-posterior axis

Question 22

light gray crescent

Answer 22

area opposite sperm entry; sets polarity at fertilization

Question 23

shape of blastula

Answer 23

influenced by presence of yolk; 8 cells, unequal, offset by yolk

Question 24

gastrulation

Answer 24

the ball of cells turns into a structure with tissue layers and a gut

Question 25

gastrula

Answer 25

early gut

Question 26

3 germ layers

Answer 26

ectoderm, endoderm, mesoderm

Question 27

vegetal plate

Answer 27

future endoderm; invaginates and becomes archenteron

Question 28

archenteron

Answer 28

open cavity in the gastrula; blastopore is the opening and future anus in deuterostomes

Question 29

ectoderm

Answer 29

skin, nervous system, and other

Question 30

mesoderm

Answer 30

skeleton, muscles, circulatory system, excretory system, lining of body cavity, and others

Question 31

endoderm

Answer 31

lining of digestive tract, respiratory system, and others

Question 32

early organogenesis

Answer 32

cells differentiate to form organs; notochord, neural plate, neural tube, neural crest cells, somites

Question 33

cell differentiation and morphogenesis

Answer 33

continuation of organogenesis that leads to adult organs

Question 34

blastoderm

Answer 34

a disk that forms as two layers of cells on a large yolk

Question 35

hypoblast

Answer 35

cell layer of blastoderm on yolk

Question 36

epiblast

Answer 36

cell layer of blastoderm on top

Question 37

primitive streak

Answer 37

gastrulation by migration of epiblast cells toward yolk

Question 38

extraembryonic membranes

Answer 38

chorion, amnion, yolk sacs, allantois

Question 39

chorion

Answer 39

extraembryonic membrane that functions in gas exchange

Question 40

amnion

Answer 40

extraembryonic membrane that encloses embryo in fluid

Question 41

yolk sac

Answer 41

extraembryonic membrane that surrounds yolk

Question 42

allantois

Answer 42

extraembryonic membrane that sequesters waste products

Question 43

blastocyst

Answer 43

mammalian blastula consists of trophoblast and inner mass cells

Question 44

trophoblast

Answer 44

outer epithelium that initiates implantation; secretes enzymes to break down endometrium;

Question 45

inner mass cells

Answer 45

part that will become the embryo; form epiblast and hypoblast

Question 46

placenta

Answer 46

derived from trophoblast, mesoderm from the epiblast, and endometrial tissue; forms from embryonic and maternal tissue to exchange, nutrients, gases, wastes, etc.

Question 47

fetus

Answer 47

late embryo, after about 8 weeks in humans

Question 48

animals cells change shape

Answer 48

use of cytoskeleton; microtubules elongate and microfilaments narrow the apex

Question 49

cell adhesion molecules

Answer 49

used by cells to form stable tissues; glycoproteins on cell surfaces

Question 50

migration of cells

Answer 50

mediated by extracellular matrix

Question 51

cells differentiate

Answer 51

division of cells into different functions with specific body axes, gene expression, etc.; begins with cytoplasmic determinants

Question 52

induction

Answer 52

changes in gene expression based upon cell-cell interaction; pattern formation and positional information

Question 53

fate map

Answer 53

map of cell differentiation

Question 54

developmental potential

Answer 54

ability of a cell to become different types of cells; lost as cell lines develop

Question 55

totipotent

Answer 55

ability of a cell to differentiate into any function

Question 56

limb buds

Answer 56

beginning of limbs, covered in a layer of ectoderm

Question 57

apical ectodermal ridge (AER)

Answer 57

tip of bud; secretes growth factor that extends limb bud

Question 58

zone of polarizing activity (ZPA)

Answer 58

a group of cells in the posterior limb bud that controls the anteroposterior (AP) patterning of the limb