Cellular Mechanisms of Development

Question 1

Development

Answer 1

Gene directed changes of an organisms life cycle

Question 2

4 sub-processes in development

Answer 2

1. Cell division
2. Differentiation
3. Pattern Formation
4. Morphogenesis

Question 3

fertilization

Answer 3

process forms diploid zygote or the union of haploid egg + sperm

Question 4

What happens after fertilization

Answer 4

diploid zygote undergoes rapid mitotic division or cleavage

Question 5

What is the cell cycle and where does rapid mitotic division occur

Answer 5

G1, G0, S, G2, mitosis (mitotic division), cytokinesis

Question 6

What is the cell cycle controlled by? Explain in general.

Answer 6

Cell cycle is controlled by proteins: cyclins, cyclin dependant kinases. They control timing and the number of cell divisions

Question 7

Role of cyclin and cyclin-dependant kineses in adult cells and embryonic cells

Answer 7

adult cells: they control the cycle of mitosis through checkpoints (3, G1, S, G2)
Embryonic cells: inactivation and degradation of kinases allows cell to complete mitosis

Question 8

what is the difference between the cell cyle of adult and embryonic cells

Answer 8

adult cells: 3 cyclin proteins are active, G1 and G2

Embryonic cells: 1 cyclin protein is active, NO G1 and G2 so shorter, cyclin degradation required to complete mitosis

Question 9

Cleavage and in mammals

Answer 9

Rapid cell division

after fertilization, zygote divided in smaller cells called blastomeres

In mammals: several days, produces a ball of cells called blastocyst or blastula

Question 10

Steps from fertilization to blastula

Answer 10

fertilized egg, 2-cell stage, 4-cell stage, 8-cell stage, morula (compact mass of cells, zygote with many cells, size doesnt change), blastula (hasnt grown but hollow), early gastrula, gastrula

egg first divided in 2 blastomeres, then 8 and more blastomeres

Question 11

What does blastocyst or blastula made of

Answer 11

1. Trophoblast: outer layer to form placenta
2. Inner cell mass source of embryonic stem cells
3. Empty space called blastocoel

Question 12

Stem cells

Answer 12

cells capable of continued division, that can also give rise to differentiated cells (we can keep them forever, they have not differentiated yet)

Question 13

Recap, sperm-egg to human embryo and when are stem cells set aside

Answer 13

sperm cell and egg cell join, cell cleavage produces blastocyst, inner cell mass develops into human embryo

embryonic stem cells isolated from inner cell mass and continues to divide while remaining undifferentiated

Question 14

types of embryonic stem cells and where they are found

Answer 14

1. Totipotent: can give rise any cell type in organism, in total zygote
2. pluripotent: can give rise many different cell type, in inner cell mass
3. Multipotent: can give rise limited # cell type, in many organs: specialization potential limited to 1 or more cell lines
   * Unipotent: can give rise 1 single cell type

Question 15

Where are plant stem cells found and in what do they differentiate in

Answer 15

Meristems, they continually divide and differentiate into leaves, roots, branches and flowers.

Question 16

In plants, in what are totipotent cells found in

Answer 16

Roots, leaves, shoots from undifferentiated cells

Question 17

Do animal cells have to move for normal development?

Answer 17

Yes, this cell movement is called gastrulation

Question 18

Do plant cells have to move for normal development?

Answer 18

No, they only change orientation of cell division to control cell proliferation

Question 19

Gastrulation allows formation of 3 germ layers, whihc one will become the digestive system

Answer 19

ectoderm, mesoderm, endoderm (this one)

Question 20

What name is given to the cells that divide rapidly inside the embryo?

Answer 20

Blastomeres

Question 21

What is the name that an early embryo receives on Day 4 of development?

Answer 21

Morula

Question 22

Explain how the blastocoel is formed during blastulation; name the layer of cells on the outside and the inside the blastocyst

Answer 22

The blastomeres are nourished by uterine milk going through the zona pellucida. The blastomeres keep dividing and the increase in uterine milk in the morula forms a fluid-filled cavity called blastocoel. The outer cell mass of the blastocyst is called the trophoblast and the inner cell mass is called the embryoblast.

Question 23

On the third week of development, what important embryonic process occurs that allows to form the three (3) germ layers?

Answer 23

Gastrulation

Question 24

What is the role of the primitive streak in gastrulation?

Answer 24

The primitive streak allows the cells to move from the outside to the inside of the blastocyst and form the three germ layers.

Question 25

Name the three structures that are formed during Neurulation

Answer 25

Neural plate, neural tube and neural crest

Question 26

steps early embryogenesis

Answer 26

fertilization (fusion egg-sperm), cleavage (rapit mitotic div), gastrulation (mvt cells to form 3 germ layers), neurolation (neural plate, tube, crest), embryonic folding

Question 27

What is cell differentiation and why does it happen

Answer 27

Cell differentiation=cell fate (cell undergoes changes to make plan happen) due to differential expression of genes

Question 28

Which types of cells have been used to study differentiation and what cells do they give rise to

Answer 28

Human pluripotent stem cells give rise to types of blood, cardiac muscle and neural cells

Question 29

What comes before differentiation, explain

Answer 29

determination: molecular decision to become particular type of cell or cell commits particular developmental pathway (cell determined to become something specific)

Question 30

What are 2 de developmental pathways in cell determination

Answer 30

cytoplasmic determinants (pigment granules act as cd and detremines the cells fate) and cell to cell interactions or induction (cells from germ layer receives chem signal (FGF factor) from cells found in another germ layer to induce diff cell types

Question 31

What happens to cells when not determined vs determined

Answer 31

during dev, cells moved to diff location in embryo. If they dev according to new position they are not determined (didnt have plan yet)

Question 32

Why can cloning occur based on cell differentiation

Answer 32

de-differentiation

Question 33

how does cloning occur

Answer 33

1 or more organism genetically identical to parent that donated single cell.

Question 34

what type of cell can generate a complete new organsim

Answer 34

Totipotent

Question 35

what is the frog embryo experiment

Answer 35

less differentiated cell in egg with donor nucleus - most develop in tadpoles - older donor nucleus results lower% normal dev

Question 36

what did dolly the sheep show, and what process was used on her

Answer 36

differentiation in animals is reversible somatic cell nuclear transfer (from fully differentiated cell) (mammary cell fused with extracted egg cell by electric shock)

Question 37

problems of reproductive cloning

Answer 37

low success rate age associated disease lack of imprinting (not enough time to reprogram)

Question 38

nuclear reprogramming and 3 ways

Answer 38

reprogram adult cells to become pluripotent 1-fusion of es cells to differentiated somatic cells 2-culture of germ cells and adult stem cells after long time in culture 3-use specific transcription factors

Question 39

Steps of therapeutic cloning

Answer 39

``` isisi 1-isolate skin cell 2-scnt 3-insert nucleus of skin cells in enucleated eggs 4-blastocyst grows 5-get rid embryo and use stem cells 6-stem cells induced to grow any tissue ```

Question 40

difference therapeutic cloning and reproductive cloning

Answer 40

see notes but same begining (theraapeutic take nucleus from diabetic patient), but therapeutic cloning instead of implantic blastocyst in uterus to have healthy cloned baby, the embryonic stem cels are grown in culture and implanted

Question 41

what is allowed in terms of cloning

Answer 41

stem cell reaearch in unimplanted embryos

Question 42

what 2 genetic pathways control the establishment of polarity in drosophilia

Answer 42

bicoid and nano proteins (anterior/posterior) and dorsal proteins (dorsal/ventral), they activate genes for formation body structures

Question 43

an example of master regulatory gene that when activated determines a structure

Answer 43

Hox genes, gene that controls development of particular body part

Question 44

predominant homeotic gene family in plants

Answer 44

MADS-boxgenes: for root and floral development

Question 45

stages of early embryogenesis

Answer 45

fertilization, cleavage, gastrulation, neurulation, embryonic floding and organogenesis

Question 46

what happens after cleavage

Answer 46

rate of ell division slows and normal cell cycle restored

Question 47

Morphogenesis

Answer 47

process by which cells occupy appropriate location: includes gastrulation (mvt cells from surface to interior embryo) and organogenesis (formation of organs)

Question 48

Gastrulation

Answer 48

rearranges cell, by mvt from surface to interior, into 3 layered embryo called gastrula: ectoderm-endoderm-mesoderm

Question 49

3 germ layers and where

Answer 49

ectoderm: outer layer endoderm: lines digestive tract mesoderm: partly fills space between ectoderm and endoderm

Question 50

programmed cell death

Answer 50

cells shrivel and shrink during apoptosis: planned through genetic control