concept 2b development

Question 1

ampulla

Answer 1

widest part of the fallopian tube

where fertilization occurs

Question 2

fertilization

Answer 2

sperm binds to the secondary oocyte and releases acrosomal enzymes that enable head of sperm to penetrate though the corona radiata and zone pellucida to penetrate the oocyte

Question 3

acrosmal apparatus

Answer 3

formed when the sperm comes into direct contact with the secondary oocytes cell membrane
tube like structure
extends to and penetrates the cell membrane
this allows the pronucleus to enter the oocyte once meiosis II is completed

Question 4

coritcal reaction

Answer 4

release of calcium ions
happens after penetration of sperm thought the cell membrane
calcium ions depolarize the membrane of the ovum
2 purposes: prevents fertilization of ovum by multiple sperm cells and increased calcium concentration increases metabolic rate of newly formed diploid zygote

Question 5

fertilization membrane

Answer 5

depolarized and impenetrable membrane

formed by the cortical reaction

Question 6

dizygote twins

Answer 6

fraternal twins
form from fertilization of 2 different eggs released during one ovulatory cycle by 2 different sperm
each zygote will implant in uterine wall and develops own placenta

Question 7

monozygotic twins

Answer 7

identical twins
form when single zygote splits into 2
have identical genetic make up
if division is incomplete may result in conjoined twins

Question 8

cleavage

Answer 8

rapid mitotic cell divisions of the zygote as it moves to uterus for implantation
many rounds of division occur but cell remains the same size
2 types: indeterminate and determinate

Question 9

indeterminate cleavage

Answer 9

results in cells that can still develop into complete organisms

Question 10

determinate cleavage

Answer 10

results in cells with fates that are already determined

these cells are committed to differentiating into certain types of cells

Question 11

morula

Answer 11

embryo has undergone several divisions
solid mass of cells
has about 8 cells

Question 12

blastula

Answer 12

morula undergoes blastulation
a hollow ball of cells with fluid-filled inner cavity called the blastocoel
trophoblast cells surround the blastocoel and give rise to the chorion and later the placenta
inner cell mass protrudes into the blastocoel and give rise to the organism itself

Question 13

chorion

Answer 13

extraembryonic membrane that develops into the placenta

developed from the trophoblastic cells when they implant into the endometrium

Question 14

chorionic villi

Answer 14

formed from trophoblasts

microscopic fingerlike projections that penetrate the endometrium

Question 15

umbilical cord

Answer 15

connects the embryo to the placenta

consists of 2 arteries and one vein encased in gelatinous substance

Question 16

yolk sac

Answer 16

supports the embryo until the placenta is functional

site of early blood cell development

Question 17

allantois

Answer 17

involved in early fluid exchange b/w the embryo and the yolk sac
umbilical cord is formed from remnants of yolk sac and the allantois
surround by the amnion

Question 18

amnion

Answer 18

a thin tough membrane filled with amniotic fluid

fluid serves as a shock absorber during pregnancy, lessening the impact of material motion on the developing embryo

Question 19

gastrulation

Answer 19

generation of 3 distinct cell layers
further development after cell mass implants
results in gastrula

Question 20

gastrula

Answer 20

embryonic stage characterized by the presence of ectoderm, mesoderm, and endoderm

Question 21

archenteron

Answer 21

central cavity in the gastrula stage of embryological development
it is lined by endoderm and ultimately gives rise to the adult digestive tract and the gut
opening is called the blastopore which develops into the anus

Question 22

primary germ layers

Answer 22

ectoderm
mesoderm
endoderm

Question 23

ectoderm

Answer 23

develops into: epidermis
hair
nails
epithelia of nose, mouth, and lower anal canal
lens of the eye
nervous tissue (including adrenal medulla)
inner ear
*“attracto”derm–> develops into the things that attract us to others

Question 24

mesoderm

Answer 24

develops into: musculoskeletal system
circulatory system
most excretory system
gonads
muscular and connective tissue layers of digestive and respiratory systems and adrenal cortex
*“means”oderm–> mean of getting around as an organism

Question 25

endoderm

Answer 25

develops into: epithelial linings of the digestive and respiratory tracts, including lungs 
pancreas
thyroid 
bladder
distal urinary tracts 
parts of the liver 
*linings of "endernal" organs

Question 26

selective transcription

Answer 26

only genes needed for that particular cell type are transcribed
how cells develop into distinctly different cell types
often related to the concept of induction

Question 27

induction

Answer 27

ability of one group of cells to influence the fate of other nearby cells
mediated by chemical substances called inducers which diffuse from organizing cells to responsive cells

Question 28

neurulation

Answer 28

development of the nervous system
after the 3 germ layers are formed
nervous system derived from the ectoderm

Question 29

stage 1 of neurulation

Answer 29

a rod of mesodermal cells called the notochord is developed along the long axis of the organism like a primitive spine

Question 30

stage 2 of neurulation

Answer 30

notochrod induces a group of overlying ectodermal cells to slide inward to form neural folds which surround the neural groove

Question 31

stage 3 of neurulation

Answer 31

neural folds grow towards one another until they fuse into a neural tube, which gives rise to the central nervous system
at the tip of neural fold are neural crest cells, which migrate to form the peripheral nervous system and specific cell types
ectodermal cells migrate over the neural tube and crest to cover the rudimentary NS

Question 32

teratogens

Answer 32

substance that interfere with development

cause defects or even death of developing embryo