1.13 Discuss cell differentiation.
1.14 Explain why each cell in a multicellular organism contains thousands of genes.
Explain why all cells in a multicellular organism contain the same DNA (except
1.15
for gametes).
1.16 Distinguish between cell division and cell differentiation.
In single cells, specialized structures perform specialized functions that contributes to
the cell working as a whole. (Examples of organelles, each organelle performs a specific
task for the cell.)
We have agreed that the reason that cells aggregate into multi-celled organisms is to
gain additional abilities that wouldn’t come about without cells working together. In
order to do so, cells take on specific roles within that organism. As a result, different
cells have different structures driven by their different functions.
Explain how this example supports the claim that
"The structure of a cell is related to its function."
Structure: Lots of ER and golgi and vesicles to produce and release protein (insulin)
Function: Produce and release protein insulin
Example
Panceratic cell
Structure: Contractile proteins and lots of mitochondria
Function: lots ready energy available to contract
Muscle Cell
Nerve cell
Epithelial/skin cell
Structure: one end with lots of receptors other with only one way out.
Function: Gather data and transmit a “signal” (only becomes a “message” when
working together as many nerve cells in the brain)
Structure: thin and flat
Function: protection/coating
We have also agreed that all cells in a single organism contain all of the same
DNA/genetic material of that organism. (We know this because we watch crime shows
where a fingerprint (aka skin cells) or hair cell has the full DNA of the individual). This,
among other scientific bodies of evidence, demonstrates that all cells (except eggs and
sperms) contain all of a single organism’s DNA.
So, the big question is how
do cells differentiate into different types
of cells (specialized cells) if they all contain the same DNA?
Fundamentally, we need to understand what makes one cell different than other.
So, what does make one cell different than another?
They make different proteins.
Central Dogma of biology: DNA  transcription mRNA translation  protein
nucleotide sequence in the DNA of a gene  nucleotide sequence in messenger RNA
(mRNA) transcription
nucleotide sequence in messenger RNA  amino acid sequence in a protein
translation
 structure and function of the protein
(e.g. normal hemoglobin vs. sickle cell hemoglobin)
person's characteristics or traits
(e.g. normal health vs. sickle cell anemia)
Different versions of same gene (alleles) code for different proteins which leads
to different versions of same traits (skin color)
Same gene, different allele expressed
Why do different CELLS of the same organism make different proteins? Same
overall DNA, different cell type.
Gene expression. Different genes expressed (genes can be turned on and
off) means different proteins made which means different functions and abilities.
Eye ball cells have eye ball proteins turned on and others off, muscle cells have
muscle cell proteins turned on and all others turned off.
What makes one cell different than the other?
The process of cell differentiation: the process of cell specialization that
results from variable gene expression. Influenced by external and internal
signals.
How does cell differentiation relate to being multi-cellular?
Necessary for cells to specialize in function so structure and
function essential to differentiation.
Write a comprehensive statement that relates the following terms:
DNA
Genes
Proteins
Traits
Gene expression
Differentiation