Topic.2.Development.powerpoint.2.1.Early-Development.comparisons.in.model.organisms

Question 1

Using a tadpole as an example, explain what each part would be for the following:
central, dorsal, left, right, anterior, posterior

Answer 1

belly would be the ventral
backside would be dorsal
head would be anterior
the tail would be posterior
right would be between anterior & dorsal
left would be between central and posterior

Question 2

In frog embryos, sperm will always enter at the ___ pole

Answer 2

animal

Question 3

In frog embryos, what triggers the rotation of the cell cortex which exposes the grey crescent?

Answer 3

sperm entry

Question 4

In frog embryos, what are grey crescents?

Answer 4

They are exposed non pigmented cytoplasm, they mark the future dorsal side

Question 5

T/F sperm enter on the dorsal side

Answer 5

False, sperm enter a side that reveals the grey crescent on the opposite side. The GC is on the dorsal side, so the opposite of the dorsal would be ventral.

Question 6

In frogs, grey crescent has ____ needed for the normal development of blastomeres. They regulate ___ in eggs.

Answer 6

Cytoplasmic determinants; gene expression

Question 7

what are blastomeres?

Answer 7

a cell formed by the cleavage of a fertilized ovum

Question 8

What is the name of the first stage of early embryonic development
after fertilization in sea urchins?

Answer 8

Cleavage

Question 9

What happens during cleavage stage in sea urchins?

Answer 9

miotic cell divisions with no significant (NO G1/G2)
It partitions the embryo into blastomeres(“smaller cells”)

Question 10

In sea urchins, what two poles can you find?

Answer 10

Vegetal pole: region where yolk (nutrients) is concentrated
Animal pole: opposite to vegetal pole

Question 11

What is the difference between cleavage of sea urchin and frogs?

Answer 11

Both have vegetal and animal poles, however, the distribution of yolk affects cleavage patterns in frog embryos. Frog embryos also have a cleavge furrow,

Question 12

T/F sea urchins have smaller blastomeres at the animal pole

Answer 12

False, frogs have smaller blastomeres because the vegetal side pushes up on the grey crescent, making animal blastomeres very small

Question 13

Compare cleavage in sea urchins vs frog

Answer 13

Sea urchins:
-yolk evenly distributed
-early cleavage results in cells of similar size
Frogs:
- yolk concentrated at vegetal pole
-cells at animal pole are smaller than those at vegetal

Question 14

Each cell within the ___, is a called a blastomere

Answer 14

blastula

Question 15

in sea urchins, what is the blastula stage?

Answer 15

-Produced after 5-7 cleavage divisions
-blastula consists of a hollow ball of cells with a fluid-filled cavity(or blastocoel)

Question 16

What are the differences in blastula in a sea urchin and frog?

Answer 16

Sea urchin- blastocoel takes up most of the cell
frog- blastocoel takes up top of the blastula

Question 17

holoblastic cleavage

Answer 17

frogs, mammals, sea urchins
cleavage furrow passes entirely through yolk

Question 18

meroblastic cleavage

Answer 18

birds, fish, reptiles
too much yolk and furrow can’t pass through the yolk, only occurs in a small area

Question 19

The embryo is called a blastula after it has divided a LOT. As cleavage continues, cells in ___ pole start dividing more rapidly than the __ pole. By the next day, continued cleavage has produced a hollow ball
of thousands of cells called the ____. With a fluid-filled cavity, called the ____

Answer 19

animal, vegetal, blastula, blastocoel

Question 20

T/F: Once a blastula is formed, there are transcription of zygote genes.

Answer 20

False, must have at least 4000 to be able to do so in frog embryos

Question 21

What allowed cleavage to take place which eventually makes a blastula?

Answer 21

Gene products(mRNA and proteins) deposited by the mother when she formed the egg

Question 22

What is gastrulation?

Answer 22

reorganization of blastula into a multi-layered organism
-ectoderm(outer layer of embryo)
-mesoderm(middle layer of embryo)
-endoderm(inner layer of embryo)

Question 23

Ectoderm

Answer 23

-epidermis of skin(sweat/hair)
-nervous and sensory systems
-pituitary gland and adrenal medulla
-jaws and teeth
-germ cells

Question 24

Mesoderm

Answer 24

-skeletal and muscular systems
-circulatory
-excretory and reproductive system(except germ cell)
-dermis of skin
-adrenal cortex

Question 25

Endoderm

Answer 25

-lining of the digestive tract and associated organs -lining of respiratory/excretory/ reproductive -thymus, thyroid, parathyroid gland

Question 26

In frog embryos, how is the location of gastrulation initiation established?

Answer 26

Sperm entry point

Question 27

Mesenchymal stem cells

Answer 27

multipotent, turn into lots of different cell types

Question 28

In sea urchins: Mesodermal mesenchymal cells

Answer 28

migrate from vegetal pole to blastocoel, will secrete calcium carbonate to form internal skeleton

Question 29

In SEA URCHINS: When primary mesenchyme cells begin to migrate, remaining cells of the vegetal plate ______ to form the archenteron (future gut).

Answer 29

invaginate

Question 30

archenteron

Answer 30

future digestive tract formed during gastrulation running from vegetal to animal poles

Question 31

In sea urchins: The vegetal plate is made up of endodermal cells, meaning what structure is also made up of it?

Answer 31

archenteron (future digestive tube)

Question 32

The filopodia job is to _ and _ the archenteron. They are cellular extensions that facilitate cell _ and _

Answer 32

contract and extend; attachment and migrate

Question 33

The filopoida is made up of ____

Answer 33

mesenchymal cells

Question 34

The point of invagination in sea urchin embryos is called

Answer 34

blastopore

Question 35

In sea urchins: blastopore on vegetal pole will become ____

Answer 35

anus

Question 36

What are two key features of frog gastrulation?

Answer 36

Blastopore: crease that forms on the dorsal side of late blastula Dorsal lip: involuted region of the blastopore

Question 37

during frog gastrulation, what happens when dorsal lip moves inward?

Answer 37

Animal pole cells spread over the outer surface of the embryo

Question 38

In frog gastrulation, what happens after dorsal lip moves inward?

Answer 38

blastopore extends via invagination, making a circle and becomes an opening into the Archenteron

Question 39

In frog gastrulation, the blastopore is plugged by___

Answer 39

yolk

Question 40

In protosomes(worms), the blastopore is plugged by yolk and becomes the ___

Answer 40

mouth

Question 41

In chick gastrulation, the embryo consists of what upper and lower layer?

Answer 41

Upper:epiblast lower:hypoblast

Question 42

T/F in chick gastulation, the embryo comes from the hypoblast

Answer 42

False, comes from the epiblast. The hypoblast cells form part of the sac that surrounds the yolk

Question 43

In chick gastrulation, we can find a primitive streak, what is it?

Answer 43

thickening found at the midline due to a concentration of migrating cells

Question 44

In mammals, the blastula forms the ____in the next stage of development

Answer 44

blastocyst

Question 45

The blastula forms the blastocyst by__

Answer 45

cells in the blastula arrange themselves in two layers: the inner cell mass, and an outer layer called the trophoblast.

Question 46

Inner cell mass (ICM):

Answer 46

group of cells that develop into the embryo

Question 47

Trophoblast:

Answer 47

outer epithelium of the blastocyst; eventually forms the fetal portion of the placenta

Question 48

In mammals, once the blastocyst reaches the uterus, how is it able to implant into endometrium?

Answer 48

Trophoblast: secretes enzymes that breakdown the lining of the uterus (endometrium) to facilitate implantation

Question 49

In mammals, after the blastocyst is able to implant(7 days) we should see the formation of _?

Answer 49

epiblast: formed by inner cell mass; gives rise to ect, meso, endoderm and gives rise to extraembryonic mesoderm hypoblast: formed by inner cell mass; contributes to extra embryonic membranes (such as yolk sac)

Question 50

In humans, day 10-11 and 13 what should we find?

Answer 50

extraembryonic membranes form days 10-11 and gastrulation begins day 13

Question 51

In humans,During day 10-11 what extraembryonic membrane should we see forming?

Answer 51

Chorion: extraembryonic membrane between fetus and mother; Is the fetal part of the placenta Gives rise to chorionic villi: allow transfer of nutrients from maternal blood to fetal blood.

Question 52

In humans after gastrulation we should see:

Answer 52

Amnion chorion ectoderm mesoderm endoderm yolk sac extraembryonic mesoderm-umbilical chord allantios

Question 53

Amnion:

Answer 53

Amnion: membrane that makes the amniotic sac; protection/cushion

Question 54

Allantois:

Answer 54

sac-like structure, involved in nutrition and excretion, webbed with blood vessels, collects liquid waste from the embryo, and exchanges gases used by the embryo

Question 55

gastrulation has produced what 4 extraembryonic membrane

Answer 55

Amnion, yolk sac, allantois, chorion

Question 56

Placenta:

Answer 56

temperorary organ that begins to develop after blastocyst implantation, connects the developing fetus to the uterine wall to allow nutrient uptake, gas exchange

Question 57

Placenta made up of what 3 layers

Answer 57

Amnion: innermost placental layer surrounding the fetus Allantois: the middle layer of the placenta Chorion: outermost layer of the placenta, comes into contact with the endometrium

Question 58

Yolk sac:

Answer 58

membrane outside the embryo, connected by a tube (the yolk stalk) through the umbilical opening to the embryo's midgut; helps with circulation;