Cellular Communication and Mesoderm Induction

Question 1

What is juxtacrine signalling?

Answer 1

Communication between two cells that are touching

Question 2

What is bilateria life?

Answer 2

They have bilateral symmetry

Question 3

Do all bilateria have bilateral symmetry all their life?

Answer 3

No starfish lose it but all have it as larvae

Question 4

What is radiata life?

Answer 4

Not bilateral at any stage of their life, less complex than bilateria

Question 5

Give an example of a radiata organism?

Answer 5

A jellyfish

Question 6

What is Porifera life?

Answer 6

The least complex compared to radiata and bilateria

Question 7

Give an example of a proifera organism?

Answer 7

Sponge

Question 8

What are the three germ layers of bilateria?

Answer 8

Ectoderm, endoderm and mesoderm

Question 9

What is ectoderm?

Answer 9

The skin and nervous system

Question 10

What is endoderm

Answer 10

The mouth to anus tube down the middle (the gut)

Question 11

What is mesoderm?

Answer 11

The skeleton, blood, kidney and heart (everything in between)

Question 12

What kind of animals dont have mesoderm?

Answer 12

Simple ones

Question 13

What does tripoblastic mean?

Answer 13

All three germ layers

Question 14

What kind of axes do bilateria organisms have?

Answer 14

A anterior-posterior axis and a doso-ventral axis

Question 15

What are some examples of bilateria?

Answer 15

Humans, frogs, flies, worms

Question 16

What kind of axis do radiata organisms have?

Answer 16

One axis - the oral/aboval axis (one orfice for food and poop)

Question 17

What does dipoblastic mean?

Answer 17

Two germ layers - ecto and endo - no mesoderm

Question 18

What does monoblastic mean?

Answer 18

One germ layer - ecto

Question 19

What can be said about the tissues of porifera life?

Answer 19

No true tissues

Question 20

Evolution of which layer allowed more complex animals to form?

Answer 20

Mesoderm (the one missing from radiata compared to bilateria)

Question 21

What 3 things about xenopus laevis eggs that make them good for studying embryogensis?

Answer 21

1. They are big
2. Laid and develop outside the body
3. Large so make good amounts of proteins

Question 22

What defines the axis in a xenopus egg?

Answer 22

They factors (proteins and mRNAs) persent in different areas of the cytoplasm

Question 23

What pole of the xenopus egg is more dense with the local factors?

Answer 23

The animal pole

Question 24

What kind of animals are the animal and vegetal pole specific to?

Answer 24

Amphibians

Question 25

What causes the development of the animal pole?

Answer 25

The point of sperm entry

Question 26

What would have to be present in order for the sperm to cause the formation of the animal pole?

Answer 26

A receptor for the sperm that allows interactions between speicifc proteins on the animal pole membrane with the sperm

Question 27

What can be seen in the 32-cell blastula of the xenopus?

Answer 27

The cytoplasm that was present in the 1 cell is localised into the 32 cells and can tell because of their colour

Question 28

What would you call cells you remove from the 32-cell blastula?

Answer 28

Explants

Question 29

What happens to explants?

Answer 29

They undergo several cell divisions in culturew

Question 30

What do cells that have the animal pole cytoplasm go on to make?

Answer 30

Ectoderm (skin cells)

Question 31

Whar do cells that have the vegetal pole cytoplasm go on to make?

Answer 31

Endoderm (gut)

Question 32

What is decided at the 32 cell stage and what is not decided?

Answer 32

If the cells are ectoderm or endoderm but no mesoderm has been decided yet

Question 33

What do you get from an explant of a late stage blastula?

Answer 33

Mesoderm development

Question 34

What axes can be seen to develop in the late stage embryo?

Answer 34

The dorsal ventral axis

Question 35

What happens if you take different explants across the cell

Answer 35

You get different subsets of mesoderms

Question 36

What defines the dorsal ventral axis in the later stage blastula?

Answer 36

the different subsets of mesoderm

Question 37

What mesoderm defines the dorsal side?

Answer 37

Notochord and somites

Question 38

What mesoderm defines the ventral side?

Answer 38

Mesenchyme and blood

Question 39

What is the difference between fate and specification?

Answer 39

Let the cells develop in situ = fate, taking them out and seeing how they develop = specification

Question 40

If part of the cell develops different insitu (fate) compared to as an explant (specification) what does this tell you?

Answer 40

There must be something telling it do become the fate and if you remove it you lose the signal and therefore it doesnt become it

Question 41

What happens if you put endoderm and ectoderm near each other?

Answer 41

The cells of the ectoderm that are closest to the endoderm make mesoderm

Question 42

If the cells of the ectoderm make the mesoderm where is the signal coming from?

Answer 42

The endoderm

Question 43

What happens if you place ventral endoderm with ectoderm?

Answer 43

It makes notochord and muscle

Question 44

What happens if you place dorsal endoderm with ectoderm?

Answer 44

The ectoderm makes blood and other tissues

Question 45

What does the difference in ventral and dorsal endoderm changing the ectoderm tell you?

Answer 45

The signal being sent by the endoderm is different from dorsal to ventral

Question 46

What niewkoop?

Answer 46

fuck knows

Question 47

Sum up the example of cell communication in development?

Answer 47

The inductive signal originates in the endoderm and is recieved by the adjacent ectoderm which then becomes mesoderm but the type of mesoderm depends on what part of the endoderm the inductive signal is being trasmitted from (will be different along the dorsal ventral axis)

Question 48

Where is B-Catenin found?

Answer 48

In the dorsal end of the blastula

Question 49

What does B-catenin do?

Answer 49

It interacts with TCF/LEF transcrption factors to regulate gene expression

Question 50

What happens if you inject B-atenin in the ventral side of the blastula?

Answer 50

A second dorsal side will form

Question 51

What is Veg-t?

Answer 51

A transcription factor found in the vegetal end

Question 52

What does the cross-over between B-catenin and Veg-T regulate?

Answer 52

Nodal related proteins

Question 53

What are nodal related proteins?

Answer 53

TGF-B family small protein signals

Question 54

How are nodal related proteins involved in mesoderm induction?

Answer 54

Different levels of nodal related proteins (caused by the gradient between B-catenin and Veg-T) leads to different levels of nodal signals which means there is a different outcome in what mesoderm is made