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