BIOL 1105 Lesson 20: Cellular Mechanisms of Animal Development

Why do researchers use model organisms to study development?

• Less complex

• Easier to study

• Avoid Ethical concerns

• Easy to draw parallels

What is depicted in this image?

A cell lineage map

What is the importance of cell division?

Essential for transforming a single-celled zygote into a multicellular organism

What is the second major development process?

Differentiation

WHat does differentaion involve?

The production of specialized cells

A cell which has not adopted a particular cell fate is called a….

stem cell

Differentiated cells arise from the _________________ of undifferentiated _________________.

(1) development, (2) stem cells

True or False: gene expression is gradually altered.

True; occurs over multiple cell divisions.

_____________ stem cells for all tissues of organism, plus extraembryonic tissues.

Totipotent

Individual ________________ form first few cleavages of the zygote

blastomeres

What is the name of the second potency level?

Pluripotent

True or False: a pluripotent stem cell is able to form extraembryonic tissues

False

__________________stem cells for all tissues of organism, except extraembryonic tissues.

Pluripotent

What is an example of a pluripotent stem cell?

Embryonic stem cells from Blastocyst inner cell mass

What is the restriction of multipotent stem cells?

Can only form certain cell types (Muscle, fat, and nerve)

Why are unipotent stem cells unique?

They can only form one cell type

What is an example of a unipotent stem cell?

Spermatogonia

Pattern formation creates the _____________ of an organism

body plan

What does pattern formation depend on?

differential gene expression

What genes are critical for pattern formation?

Hox genes

True or False: Hox Genes are highly conserved

True

Mutations in the Hox genes result in ________________ of embryonic segments.

misidentification

Morphogenesis is the generation of an organisms ____________________.

body form

Morphogenesis depends on…

• cell growth

• cell division

• Cell migration

• Changes in cell chape

• Apoptosis

What is the purpose of adhesion proteins?

Essential for cell movement as they bind and release the ECM

Cell shape and structure are associated with a given cell’s______________________.

function in the body

Apoptosis is a highly controlled process of _______________ that is activated by the expression of genes in a cell death pathway.

cell death

___________ is cell death caused by injury.

Necrosis

What is it called when the cell membrane bursts and contents are released after injury?

Necrosis

What involves reversing differentiation by resetting a differentiated cell to an undifferentiated stem cell state?

Nuclear programming

Somatic Cell Nuclear Transfer (SCNT) is an example of…

Nuclear Reprogramming

Both reproductive and therapeutic cloning require the _______________ changes to the cell’s DNA be _____________.

Epigenetic, reversed

Reproductive cloning generates genetically ___________________ organisms.

identical

_________________ cloning generates genetically identical tissues.

Therapeutic

During the process of therapeutic cloning, the _________of a differentiated cell is removed and inserted into an enucleated ________________. The cell is then allowed to develop into an embryo. However, rather than implanting the embryo into a surrogate mother, the embryonic stem cells that comprise the inner cell mass of the embryo, are ____________________________________. These pluripotent stem cells are then developed into healthy tissues that can be ____________________________________________to replace diseased or damaged cells.

nucleus, oocyte, harvested and cultured in the laboratory, transplanted back into the individual

What are some potential uses of reproductive cloning?

Reintroduction of extinct species and replicating important lines of livestock

What are some potential uses of therapeutic cloning?

Prevents rejection of transplanted organs/tissues and treats autoimmune diseases

What are two reasons why cloning is not commonly used in todays world?

• technical difficulties

• Ethical concerns

During _________________, The form of the anatomical structures is formed.

Morphogenesis

______________________ is the process in which a zygote undergoes to produce a new organism.

Cell Division

________________________ are changes in gene expression that result in cell specialization

Cell differentiation

_______________________ involves the cells' ability to detect positional information in the body plan.

Pattern formation

Which cell stages are skipped during early embryonic development?

G1 and G2

African Clawed Frogs (Xenopus laevis) represent a good model system for research on ___________________.

morphogenesis

True or False: Cell differentiation is a gradual process that occurs over multiple cell divisions, thus gradually altering gene expression. It is not like turning a light switch on and off.

True

True or False: A mutation in the Hox gene complex of the fruit fly (Drosophila melanogaster) could result in an extra pair of wings / appendages / etc. growing from the "wrong" body part.

True

Necrosis is triggered by _____________.

Injury

Apoptosis is triggered by ____________.

Expression of genes in the “cell death pathway”

During ________________ there is swelling and bursting, releasing the cell's content into the extracellular fluid.

Necrosis

________________ involves gradual degradation of cells, recycling cellular contents or digesting them.

Apoptosis

True or False: The process of development results in irreversible changes to the DNA sequence as cells progress from a single zygote to a multicellular organism.

False