Warm Up (take out your homework)
• Draw 5 boxes
Interphase
Early
Mitosis
MidMitosis
Late
Mitosis
Final
Product
• Draw the process of mitosis in each phase,
and describe what is happening to the DNA in
each phase
Assessment
• Next Class: Growth and Development
Development: Growth & Differentiation
Essential Questions
• How are the bodys tissues and organs
formed?
• How can developmental problems lead to
cancer?
• How are technologies like stem cell therapies
and cloning organisms related to
developmental processes?
Todays Objectives
• Describe the role of differentiation in the
development of a multicellular organism.
• Describe the process that leads to
differentiation of cells in a multicellular
organism.
• Review key concepts of the unit so far (growth
& differentiation)
Concept Review
Development
Growth
Mitosis
Differentiation
Inside
Influences
Senescence
Outside
Influences
(Induction)
Vocab
• Zygote: a fertilized egg
• Phenotype: the observable traits of an
organism
Readings: Coordinating Growth
Differentiation and the Expression of Genetic
Info
1) What might happen if too little cell division
takes place?
– Injuries go unrepaired
2) Too much?
– A tumor can develop
2) Most of us go through every stage in the
same sequence.
So what?
So clearly there is some pretty good coordination of
development going on.
3) What are the two possible explanations for
why all cells with the same DNA don’t do the
same thing?
**DIFFERENTIAL GENE EXPRESSION**
– Environments inside the cells differ. A substance
in one part of the cytoplasm ends up in one
daughter cell and not the other. This may change
the activity of the genes in that cell.
– Something outside the cell differs. A nearby cell
may affect its neighbor’s gene expression.
4) Define induction and give an example.
An outside influence on differentiation that
occurs when a group of cells can cause a
neighboring group of cells to differentiate in a
certain way.
Example: eye tissue development
Sweat glands, teeth, limbs, and feathers
* See graphic
5) Why are we not 4 Foot wide brains?
-Different cell types use different parts of
their genetic material
6) How do environmental influences affect gene
expression ?
-Although all cells have the same genes,
environmental influences inside and outside the
cell cause certain genes to turn on and others to
turn off.
*Active gene is transcribed to mRNA for
protein synthesis
*Inactive gene is not transcribed
VOCAB GAME
• Try to get your partner to guess the
vocabulary word by giving him or her the
definition.
Development
Growth
Differentiation
Induction
Differential Gene Expression
Interphase
Mitosis
Senescence
Concept Review
Development:
Continuous permanent
changes from
fertilization to death
Growth: Increase in
number of cells
Mitosis: Cell division
Differentiation:
Changes in structure
and function of cells
Inside Influences
Senescence: Aging
leading to an
irreversible loss in
function
Outside Influences
(Induction)
Growth
• Growth is a key
component of
development in which a
multicellular organism
increases in size due to an
increase in the number of
cells.
• Mitosis produces an
increase in the number of
cells during development.
(http://geneticssuite.net/files/Cell%20multip
lication.jpg)
The Cell Cycle – Life of a Cell
•
Interphase
•
M Phase
–
Accounts for
90% of the life
cycle of a cell
–
Cell metabolism
is active, the cell
grows and DNA is
replicated
before the cell
divides
–
Consists of Mitosis (division of the nucleus) and Cytokinesis (division of the cytoplasm)
Mitosis results in how many daughter
cells?
A) 1
B) 2
C) 3
D) 4
How do the daughter cells of mitosis
compare with the parent cell genetically?
A) different
B) same
C) some parts are different, some parts are the
same
D) I’m not sure
DNA packaging in a eukaryotic cell
• DNA wraps around
proteins called histones to
form chromatin fibers.
Chromatin is the form in
which genetic material
takes during interphase.
• Chromatin further
condenses into a
chromosome during the
M phase of the cell cycle.
(http://www.tutorvista.com/biology/types-ofchromosomes)
Chromosome Structure
• A duplicated chromosome
consists of two sister
chromatids (present during
prophase and metaphase of
mitosis)
• Sister chromatids are joined at a
centromere
– Which is an attachment point
for spindle fibers during
mitosis
• A chromosome consists of one
chromatid after sister
chromatids are pulled apart
during mitosis
Chromososmes are present in a condensed,
visible (under the microsccope) form
during
A) All parts of the cell cycle
B) Interphase only
C) Mitosis only
D) I’m not sure
Interphase
• Includes:
•
•
•
•
Growth of cell
Metabolism is active
DNA is replicated
“Spaghetti Stage”
Early Mitosis
• Chromosomes Condense
• Nuclear envelope
(membrane) disintegrate
• Centrosomes migrate to
poles
• Spindle fibers appear
Mid-Mitosis
• Chromosomes line
up along the
equator (middle) of
the cell
Late Mitosis
• Sister chromatids
separate
• Spindle fibers pull
chromosomes to
poles
Final Result:
2 identical daughter cells
• Chromosomes go to
separate poles
• Chromosomes
unwind
• Nuclear envelope
reforms
• Cytokinesis
(cytoplasm division)
is completed
1.
2.
3.
4.
Differentiation
• During development,
differentiation is the
process by which cells
become specialized. In
other words, cells become
structurally and
functionally different.
• Different cell types
express (make proteins
from) different genes
within the DNA sequence
of the nucleus.
(http://scienceblogs.com/clock/2006/12/from_two_
lls_to_many_cell_di.php)
How does differentiation occur?
• During development of an embryo, both the
internal environment of cells and the external
environment of cells within the embryo differs.
• This causes individual cells within the embryo
to turn certain genes on and others off.
• Genes become turned on when they are
transcribed into mRNA for protein synthesis.
• Different cell types produce certain proteins
that are specific to the functioning of that cell
type.
T-R-I summarizations
Draw two 4-squares on one sheet of paper
T-R-I summarizations
Topic: Growth
Restriction
Illustration
Non-illustration
T-R-I summarizations
Topic: Differentiation
Restriction
Illustration
Non-illustration
Written Response
• Write a one paragraph response to the
following question:
– Explain the relationship between mitosis and
growth that occurs during development
– Remember: more depth = higher grade
Four-Two-One
• Test prep for next class
– Differentiation
Written Response
• Write a one paragraph response to the
following question:
– Compare and contrast growth,
differentiation, and senescencel
– Remember: more depth = higher grade