Download Class26 2-15 Win17 Proliferation, Apoptosis

Unlikely human migration
(using sperm/egg technology)
Wednesday February 15th, 2017
Class 26 Learning Goals
Proliferation (case study: cleavage)
Apoptosis (case study: caspase)
Migration (case study: gastrulation)
•  After this class, you should be able to:
•  Predict a likely cleavage pattern based on adult body plan
•  Connect logical reasons for apoptosis to potential chemical
cues by a cellular signaling pathway
•  Describe a gastrulating embryo in terms of movements of
large numbers of cells
Polling Question #1
Part 1: Determinants
In the early fly embryo, a maternal determinant is
physically anchored to the region of the zygote that will
go on to become the anterior of the fly. This molecule is
an mRNA ( ) of the bicoid gene.
Which is the most likely distribution of the
Bicoid protein ( ) in early development?
1.
3.
2.
4.
Part 1: Determinants
Polling Question #2
An embryo inherited a mutation from the father fly in
the bicoid gene that creates an premature stop codon
very early in the coding region of this determinant.
Where is the Bicoid protein in this new mutant embryo?
1.
3.
2.
4.
5.
Part 2: Proliferation
Peer Instruction
In a few words:
What is happening
in this organism?
Why is this early stage called ‘cleavage’?
Besides development, where might
we expect to find cell proliferation?
Peer Instruction
Part 2: Proliferation
Explain the mechanism of cleavage in each example.
Radial cleavage:
Spiral cleavage:
Discoidal cleavage:
Example:
Example:
Example:
Yolk
Superficial cleavage:
Example:
Cells
Yolk
Un-separated nuclei
Polling Question #3
1. 
2. 
3. 
4. 
Radial cleavage
Spiral cleavage
Discoidal cleavage
Superficial cleavage
Which cleavage pattern is most likely occurring in the
development of this organism?
Polling Question #2
Part 2: Proliferation
Some organisms are under tremendous
selective pressure to develop quickly.
In these species,
which cleavage pattern is most likely?
1. 
2. 
3. 
4. 
Radial cleavage
Spiral cleavage
Discoidal cleavage
Superficial cleavage
Part 2: Proliferation
Rapid Cell Division Video
Part 3: Apoptosis
Peer Instruction
Why would an adult multicellular organism
intentionally destroy a few of its own cells?
How does apoptosis help to develop
the structure of this paw?
Part 3: Apoptosis
Apoptosis Video
How is the cell destroyed by apoptosis?
1.  The plasma membrane is destroyed lipid by lipid.
2.  Caspase is destroyed enzyme by enzyme.
3.  The cytoskeleton is destroyed filament by filament.
4.  The immune system is destroyed cell by cell.
5.  Many kinds of proteins are destroyed.
6.  The Electron Transport Chain is disrupted.
Which is true of this particular apoptotic pathway?
1.  Caspase has a single role in the cell.
2.  Apoptotic signaling is an example of positive feedback.
3.  The apoptosome is a negative regulator of apoptosis.
4.  Destruction of cells requires specific molecular
interactions with immune cells.
Part 3: Apoptosis
Polling Question #3
How is the cell destroyed by apoptosis?
1. 
2. 
3. 
4. 
5. 
6. 
The plasma membrane is destroyed lipid by lipid.
Caspase is destroyed enzyme by enzyme.
The cytoskeleton is destroyed filament by filament.
The immune system is destroyed cell by cell.
Many kinds of proteins are destroyed.
The Electron Transport Chain is disrupted.
Part 3: Apoptosis
Polling Question #4
Which is true of this particular apoptotic pathway?
1. 
2. 
3. 
4. 
Caspase has a single role in the cell.
Apoptotic signaling is an example of positive feedback.
The apoptosome is a negative regulator of apoptosis.
Specific molecular interactions with immune cells can
help to bring about apoptosis of other cells.
Part 4: Migration
Gastrulation Videos
Sea Urchin Gastrulation
Fruit Fly Gastrulation
Frog Gastrulation
Peer Instruction
Part 4: Migration
Ectoderm
Mesoderm
Endoderm
Blastocoel
Dorsal lip
Cross section
Blastopore
Pre-Gastrulation
Whole embryo
Initial Gastrulation
Blastopore
Explain these cell movements in the gastrulation of a frog.
Part 4: Migration
Ectoderm
Mesoderm
Endoderm
Presumptive gut
Cross
section
Whole
embryo
What is happening here?
Polling Question #5
What cellular developmental process is most
dramatic and obvious in frog gastrulation?
1. 
2. 
3. 
4. 
5. 
Differentiation
Proliferation
Movement
Apoptosis
Signaling
Migration Video
This video shows the closure of the dorsal
opening in fruit fly development.
Which of these are needed for dorsal closure?
1. 
2. 
3. 
4. 
5. 
Psuedopodia
Signaling to initiate actin polymerization
Adhesion proteins to hold cells together
Apoptosis
Proliferation of new cells
Polling Question #6
This video shows the closure of the dorsal
opening in fruit fly development.
Based on what you see in this video, which of
these are needed for dorsal closure?
1. 
2. 
3. 
4. 
5. 
Psuedopodia
Signaling to initiate actin polymerization
Adhesion proteins to hold cells together
Apoptosis
Proliferation of new cells
Summary
Proliferation
Apoptosis
Migration
Differentiation
Signaling
For Exam 4:
Exam 4: All questions are multiple choice (multiple T/F).
We will provide a purple Scantron sheet for you.
Concept Questions
• 
• 
• 
• 
Classify each of the following as needing either apoptosis, migration or
proliferation for optimum development:
–  Growing back an amputated limb
–  Developing a hole in a sheet of cells
–  Connecting two regions of tissue after a wound
–  Preventing widespread viral infection
–  Infecting a host
What is the likely cleavage pattern of a sea anemone? A monotreme? A
shark species in which the first-born eats the other siblings?
A spirochete (this last one is a trick question)?
Diagram the progression of molecular information between a death signal
from a T-cell and the eventual logical death of the cell.
–  Why is this a good idea?
–  What proteins, if mutated, might disable the ability to undergo apoptosis?
Describe two different kinds of cellular migration in this video.