Cell Determination&

Cell Differentiation

Overview of birth lineage and death

All cells are derived from a singl cell

Cell Determination

CELL DETERMINATION is the process by which portions of the genome are selected for expression in different embryonic cells. This involves developmental decisions that gradually restrict cell fate. Cells can progress from TOTIPOTENT to PLURIPOTENT to DETERMINED.

• From Egg To Tadpole next

• Blastula next

• Gastrulation next

• Huamn embryo development next

Animal cell undergoes simillar early embryonic development

A cell can be determined long before it show any obervious outwad sign of differentiation

• Gastrula Endoderm,Mesoderm,Ectodermnext• Embryo Transplation next• Misplaced tissue next

How do two cells with the same genome come to be different?

• Sister cells can be born different by an asymmetric cell division next

• Cell-to-cell interaction in cell fate

determination next

• Embryonic Induction next

Housekeeping gene

• Housekeeping Gene serving a fuction required in all the cell types of an organism, regardless of their specialized role.

luxury gene

• Luxury gene Gene performing specialized function in a definite type of cell, not required by all cell types of an organism.

Cell Differentiation

Differentiation – The process whereby an unspecialized early embryonic cell acquires the features of a specialized cell such as a heart, liver, or muscle cell.

Differentiated Cell RemainTotipotent

• Cloning of animal by nulear transfer

Principle of Cell Differentiation

• Each differentiated cell contains a complete genome.

• The differences between different types of cells are only duo to expression of different kinds of proteins, that is, a set of genes are switched on in a certain type of cell, meanwhile are switched off in another type of cell.

Cell differentiation is controlled by Transcription

• Tissue specific transcription factors These proteins cause the experssion of a whole block of proteins that together give cell its identity.

• Muscle Differentiation

Cell Differentiation is reversible

• Embryonic Stem cell (ES) can complete the whole process of differentia

tion in proper environment.next

• Differentiated cell can undergo dedifferentiation or transdifferentiation.

• Cancer cell can be induce to differentiate.next

Stem Cell• WHAT ARE THE UNIQUE PROPERTIES OF

ALL STEM CELLS? next

• WHAT ARE EMBRYONIC STEM CELLS? next

• WHAT ARE ADULT STEM CELLS? ext

• OBSTACLES THAT MUST BE OVERCOME next

All stem cells have three general properties

• Stem cells are capable of dividing and renewing themselves for long periods.

• Stem cells are unspecialized.

• Stem cells can give rise to specialized cells.continue

WHAT ARE EMBRYONIC STEM CELLS?

• Embryonic stem cells – Primitive (undifferentiated) cells from the embryo that have the potential to become a wide variety of specialized cell types.

• Human embryonic stem cells are derived from blastocyst

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Diseases that might be treated by ES cells

• Diseases that might be treated by transplanting cells generated from human embryonic stem cells include Parkinson’s disease, diabetes, traumatic spinal cord injury, Purkinje cell degeneration, Duchenne’s muscular dystrophy, heart disease, and vision and hearing loss. next

How are embryonic stem cells stimulated to differentiate?

How are embryonic stem cells stimulated to differentiate? continued

WHAT ARE ADULT STEM CELLS?

• Adult stem cell–An undifferentiated cell found in a differentiated tissue that can renew itself and (with certain limitations) differentiate to yield all the specialized cell types of the tissue from which it originated.

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Heart muscle repair with adult stem cells.

OBSTACLES THAT MUST BE OVERCOME

• Proliferate extensively and generate sufficient quantities of tissue.

• Differentiate into the desired cell type(s).

• Survive in the recipient after transplant.

OBSTACLES THAT MUST BE OVERCOME continued

• Integrate into the surrounding tissue after transplant.

• Function appropriately for the duration of the recipient’s life.

• Avoid harming the recipient in any way.

Blastula

The stages of cleavage in Xenopus

Early stages of mouse development

Early mouse embryo

Gastrulation

Layers of germ cell

Differetiation of Human Tissue

Embryonic Germ Layers From Which Differentiated Tissues

Develop

Development of the Preimplantation Blastocyst in Humans

40 weeks of huamn

My daughter

Misplaced toe

Two wing bud

The standard test for cell determination

Enuleate frog

Microinjection

Clone pig A

Clone Pig B

Clone Pig C

Birth of Dolly

Dolly,1 year old

Dolly with Reportor

Ainstan & Hitler

Dolly and Polly

Dolly,6 years old

Dolly with Wilmut

Two ways making sister cells different

Asymmetric division are particularly common at the beginning of development, when the fertilized egg divides to give daughter cells with different fates,but they also occur at later stages—in the genesis of nerbe cells,for example.next

Asymmetric division segregating P granules into the founder cel of the C.elegans germ line.

Caenorhabditis elegan

The linegae tree for the cells that form the gut of C.elegans.

The pattern of the cell divisions in the early nematode embryo.

Cell-signal path ways controlling assignment of different characters to the cells in a four-cell nematode embryo.

• Vertebrate embryos rely extensively

upon inductive interactions to

diversify the number of different

kinds of cells in the embryo.next

• Induction is the process by which one

group of cells produces a signal that

determines the fate of a second

group of cells.

• This implies both the capacity to produce a signal (ligand) by the inducing cells and the competence of the responding cells to receive and interpret the signal via a signal transduction pathway.

• The chemical characterist of inducer is protein.

The presence of organizing centers—the Mangold–Spemann experiment.a

The presence of organizing centers—the Mangold–Spemann experiment.b

Patterning by sequential induction

Development of Human Embryonic Tissues

Techniques for Generating Embryonic Stem Cell Cultures

Embryonic cell can be maintained

Creating chimeric mouse

Making chimeric mouse with ES cell

Patterns of stem cell division