Lecture 31 Development

Question 1

4 Important concepts of embryonic development

Answer 1

1. Universal mechanisms of animal development
2. Proteins can be substituted across species
3. Inductive signaling
4. Regional determination

Question 2

Unersal mechanisms of animal development use 5 pathways

Answer 2

1. Receptor tyrosine kinase
2. TGFB superfamily
3. Wnt
4. Hedgehog
5. Notch

Question 3

Receptor tyrosine kinase

Answer 3

-EGF ligands
- EGF receptors
FGF, and ephrins

Question 4

TGFB superfamily

Answer 4

• TGFB ligands and receptors
• BMP (DPP) ligands and receptors
• nodal ligands

Question 5

Wnt

Answer 5

• wnt ligand and frizzled receptor

Question 6

Hedgehog

Answer 6

• hedgehog ligand and patched/smoothened receptor

Question 7

Notch

Answer 7

• Delta ligand and notch receptor

Question 8

What defines the developmental program of multicellular organisms?

Answer 8

• Regulatory DNA

- multi cellular organisms are enriched in proteins mediating cell interactions and gene regulation

Question 9

Is inductive signaling just local?

Answer 9

No it can act over great distances and affect multiple cells

Question 10

regional determination

Answer 10

• once cells are committed to form a particular structure they can be taken out of resident area and transplanted to a different region but continue to behave like they did in other cite
• thoracic vertebrae developing like thoracic even though its been moved to cervical region

Question 11

Sequential induction

Answer 11

• builds a group of different cells
• B works on A and produces C
• C works on A and. B and produces D and E

Question 12

4 essential processes by which an embryo is constructed

Answer 12

1. Cell proliferation
2. Cell specialization (differentiation)
3. Cell interaction
4. Cell movement

All 4 processes must be working to achieve particular organism

Question 13

Developmental process greatly among different species.

Answer 13

• mouse have 21 day gestational periond

- elephants have 645 day

Question 14

Patterning

Answer 14

• cells that are produced by cleavage get organized into layers and groups of cell masses through what is know as gastrulation

Question 15

Organization of cells into layers and cell masses is know as?

Answer 15

• gastrulation

Question 16

Patterning occurs in what three dimensions?

Answer 16

• Anterior - posterior
• Proximal - Distal
• Dorsal- Ventral

Question 17

Differentiation

Answer 17

• cells begin to form specific and specialized structures

Question 18

Growth

Answer 18

• cell divisions that form more cells with identical functions as the parental cells

Question 19

Paradigm of development

Answer 19

• in every species and at every level of organization, complex structures are made by repeating a few basic themes with variations

Question 20

Gastrulation is the formation of what 3 key cell layers?

Answer 20

• Ectoderm
• Mesoderm
• Endoderm

Question 21

Gastrulation

Answer 21

• infolding of cells from outer layer to inner layer

- creating clusters of cells that have specialized function

Question 22

Hensens node

Answer 22

• organizing structure of gastrulation

- acts like a zipper

Question 23

Neural crest cells

Answer 23

• embryonic cell population that is localized between the developing neural tube and the non- neural ectoderm

Question 24

Stemness

Answer 24

• neural crest cells that can give rise to multiple differentiated cells exhibit stemness
• can renew itself

Question 25

How do neural crest cells form craniofacial structures?

Answer 25

- they migrate through restricted pathways to form the developing structures

Question 26

Cell migration

Answer 26

`- a tightly regulated process where the NCCs receive cues such as morphogens and growth factors that restrict their movement and determine fate

Question 27

Where do the cues for cell migration come from?

Answer 27

- adjacent cells

Question 28

Neural crest cells

Answer 28

- move out and give rise to tissues | - regions where they migrate are called rhombomeres

Question 29

Different signals are giving information to ectoderm and dermomyotome

Answer 29

- true

Question 30

The segmental plate mesoderm gives rise to what?

Answer 30

- epithelial somites

Question 31

Epithelial somites give rise to what?

Answer 31

-dermamyotome and sclerotome

Question 32

The dermamyotome gives rise to what?

Answer 32

- dermatome and myotome

Question 33

The sclerotome gives rise to what?

Answer 33

- ribs - vertebrae - base of skull; some facial muscles

Question 34

The dermatome gives rise to what?

Answer 34

- dermis

Question 35

The myotome gives rise to what?

Answer 35

epaxial skeletal muscle and hypaxial skeletal muscle

Question 36

Coordinate genes

Answer 36

regulate gap genes

Question 37

Gap genes

Answer 37

- self regulate - regulate pair rule genes - regulate homeotic selector genes

Question 38

Pair rule genes

Answer 38

- self regulate - regulate homeotic selctor genes - regulate segment polarity genes

Question 39

Homeotic selector genes

Answer 39

- regulate other genes

Question 40

Segment polarity genes

Answer 40

- regulate self | - regulate homeotic selector genes

Question 41

Homeosis

Answer 41

- replacement of one body part with another

Question 42

Drosophila Homeotic Genes

Answer 42

- gene products are gene regulatory proteins - All contain a highly conserved DNA binding homeodmain sequence 60 amino acids long - The corresponding segment in the 180 BP DNA sequence is called a homeobox hence the name hox complex

Question 43

Hox genes

Answer 43

- interspersed amongst large stretches of regulatory DNA regions - Hox genes are expressed sequentially according to their order in the HOx complex - Hox complex carries a permanent record of positional information (why head goes in the right spot) - There are hundreds of other homeobox genes in the genome, but they are scattered and not clustered in complexes

Question 44

How many hox complexes do drosophila have?

Answer 44

2

Question 45

How many hox complexes do mammalia have?

Answer 45

4

Question 46

T/F mouse complexes are located at 3 different chromosomes?

Answer 46

false (4)

Question 47

When do the lip forms?

Answer 47

between 4th-7th week of pregnancy

Question 48

When does the palate form?

Answer 48

between weeks 6 and 9