Egg to Embryo

Question 1

What 5 features do most organisms undergo

Answer 1

Cleavage
Morphogenesis
Regional specification or pattern formation
cel differentiation
growth

Question 2

what is cleavage/ cell division

Answer 2

process by which a single celled zygote divides into blastomeres

Question 3

Morphogenesis what is it

Answer 3

the biological process by which a cell, tissue or organism develops its shape and structure

Question 4

What are the most important changes of form (in morphogenesis)

Answer 4

Gastrulation
Neurulation
Cavity formation

Question 5

WHat is gastrulation

Answer 5

embryo forms different tissue layers, 3 germ layers, from which future organs will be built

Question 6

What controls all these processes (morphogensis, grwoth, cell differentiatione etc)

Answer 6

Gene expression

Question 7

when does gastrulation start

Answer 7

day 15 or 16

Question 8

What is primitive streak

Answer 8

groove that forms on the surface of the epiblast and marks the start of gastrulation

Question 9

WHat does primitive streak establish

Answer 9

anterior-posterior axis of developing embryo

Question 10

where does the primitive streak begin and end

Answer 10

Begins = caudal (tail) region of bilaminar disc
Ends = cephalic (head) region

Question 11

What is the primitive node (organiser)

Answer 11

structure at front end of primitive streak that organises body development

Question 12

WHat happens as cells move through primitive streak

Answer 12

Epiblast cells mgirate into the streak
form 2 new layers = endoderm and mesoderm

Question 13

What causes ectoderm to necome neuroectoderm

Answer 13

signals from notochord and mesoderm induce the ectoderm to become neuroectoderm

Question 14

what does the neuroectoderm form first

Answer 14

forms neural plate
which becomes neural groove and neural folds

Question 15

wjhat do neural folds eventually form

Answer 15

fuse together forming neural tube
early form of brain and spine

Question 16

what condition happens if neural tube doesnt close properly

Answer 16

spina bifida

Question 17

when does neurulation start and end

Answer 17

start day 19
ends 27 or 28

Question 18

how does neurulation end with what

Answer 18

closure of posterior neuropore

Question 19

where is the neural crest

Answer 19

crest of neural folds

Question 20

where does neural crest migrate to

Answer 20

migrate from neuroectoderm into underlying mesoderm

Question 21

WHat tissues does neural crest form

Answer 21

melanocytes
glial cells and schwaan cells
cranial nerves
ondotoblasts
connective tissue and bones of face and skull

Question 22

where are somites

Answer 22

form both sides of neural tube from paraxial mesoderm

Question 23

what are somites made up of

Answer 23

sclerotome - cartilage, tendon, vertebral column
myotome - muscle precursors
dermatome - skin precursors

Question 24

what day to somites appear and how many are present day 30

Answer 24

appear day 20
day 30 has 35 somites

Question 25

what does lateral body folding do

Answer 25

turns embryo into cylinder rolls up gut tube and removed yolk sac amniotic cavity surrounds embryo allows organogenesis

Question 26

what happens in the phylotypic stage

Answer 26

embryo has body plan but hasnt differentiated yet

Question 27

what genes establish AP ais

Answer 27

Hox genes

Question 28

What signal controls the Hox gene

Answer 28

retinoic acid (derivative of vitamin A)

Question 29

what do hox genes ensure

Answer 29

right body parts develop in right place

Question 30

what do homeotic genes do

Answer 30

regulate development of structures programme transcription factors

Question 31

what happens if the homeotic genes are mutated

Answer 31

homeotic mutants display ectopic placement of body parts (legs growing out head of fly)