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Stem Cells!
• Please have the cell differentiation ws out
• 1- 230 different types of cells.• 2- about 50 divisions from fertilized egg to
adult• 3- 100 billion cells make up the adult body• 4- types of cells that continue to divide: skin,
intestinal wall, blood (stem) cells, liver• 5- cells that do not continue to divide: nerve,,
kidney, heart, many others.
• 6a- a germ line is a cell line that, early in development, becomes differentiated from the somatic cell line and has the potential to form gametes.
• 6b- germ cells need to be separated early in development because they produce the gametes (sperm/egg). These gametes need to be unspecialized so they can eventually become the 230 specialized cells in the body. If you were even slightly differentiated then there would be issues in completing all of the 230 cells
• 7- Blastula is the stage before blastocyote. A blastula is a hollow ball of cells. A blastocyte is also a hollow ball but contains the inner mast cells or the embryoblast. The embryobast are the cells used for embryonic stem cell research.
• 8-Endoderm–Ectoderm–mesoderm
• 9- Once cells begin to differentiate even if they are not completely differentiated, they have some “programming” thus are not as viable as embryonic stem cells which are “clean slates” that can be “re-programmed” more easily.
Stem cell biology basics
A life story…
stem cell
What is a stem cell?
stem cell
SELF-RENEWAL(copying)
specialized celle.g. muscle cell, nerve cell
DIFFERENTIATION(specializing)
What is a stem cell?
Identical stem cells
Stem cell
SELF-RENEWAL(copying)
Stem cell
Specialized cells
DIFFERENTIATION(specializing)
1 stem cell
Self renewal - maintains the stem cell pool
4 specialized cells
Differentiation - replaces dead or damagedcells throughout your life
Why self-renew AND differentiate?1 stem cell
Where are stem cells found?
embryonic stem cellsblastocyst - a very early
embryo
tissue stem cellsfetus, baby and throughout life
Types of stem cell:1) Embryonic stem cells
Embryonic stem (ES) cells:Where we find them
blastocyst
outer layer of cells= ‘trophectoderm’
cells inside = ‘inner cell mass’
embryonic stem cells taken fromthe inner cell mass
culture in the labto grow more cells
fluid with nutrients
Embryonic stem (ES) cells:What they can do
embryonic stem cells
PLURIPOTENT
all possible types of specialized cells
differentiation
neuronsgrow under conditions B
Embryonic stem (ES) cells:Challenges
embryonic stem cells
skin
grow under conditions A
blood
grow under conditions C
liver
grow under conditions D
?
Types of stem cell:2) Tissue stem cells
Tissue stem cells:Where we find them
muscles
skin
surface of the eye brain
breast
intestines (gut)
bone marrow
testicles
Tissue stem cells:What they can do
MULTIPOTENT
blood stem cell
found in bone marrow
differentiation
only specialized types of blood cell:red blood cells, white blood cells,
platelets
Types of stem cell:3)Induced pluripotent (iPS)
stem cells
Induced pluripotent stem cells (iPS cells)
cell from the body
‘genetic reprogramming’= add certain genes to the cell
induced pluripotent stem (iPS) cellbehaves like an embryonic stem cell
Advantage: no need for embryos! all possible types ofspecialized cells
culture iPS cells in the lab
differentiation
Induced pluripotent stem cells (iPS cells)
cell from the body (skin)
genetic reprogramming
pluripotent stem cell(iPS)
differentiation
Stem cell jargon
Potency A measure of how many types of specialized cell a stem cell can make
Pluripotent Can make all types of specialized cells in the body Embryonic stem cells are pluripotent
Multipotent Can make multiple types of specialized cells, but not all typesTissue stem cells are multipotent
Cloning
CloningThere are two VERY different types of cloning:
Reproductive cloning
Use to make two identical individuals
Very difficult to do
Illegal to do on humans
Molecular cloning
Use to study what a gene does
Routine in the biology labs
gene 1
gene 2
Reproductive cloning
remove nucleus and take the
rest of the cell
egg
take the nucleus (containing DNA)
cell from the body
Cloneidentical to the individual
that gave the nucleus
Dolly the sheep
Molecular cloning: Principles
gene 1
gene 2
2) Make a new piece of DNA
gene 1
gene 2
1) Take DNA out of the nucleus
cell 1 cell 2
gene 1 gene 2
3) Put new DNA into a test cell and grow copies
gene 1
cell divides
Daughter cells contain same DNA:
Genes 1 and 2 have
been cloned
gene 2
insert new DNA
Molecular cloning: Applications
Normal mouseembryo
gene A missing
remove a gene to see if anything works differently
Loss of function
gene is involved ingiving the eye its colour
eye
Reporter geneadd a gene that shows
us when another gene is working
gene is active in blue areas only
Lineage tracingmark a group of cells to
see where their daughter cells end up
gene is passed on to cells all over the body
• Https://www.youtube.com/watch?v=sLepKx5z-r0 BBC stem cell
• HW: tissue review packet and animal tissue worksheet, has tissue engineering in it