Lecture 2: Cell Diff and Stem Cells Flashcards
Describe the blastocyst
- trophoectoderm surrounds inner cell mass (ICM)
- trophoectoderm: extra embryonic structures
- blastocyst: embryonic structures
What are the three fundamental aspects of developmental biology?
cell division, cell differentiation, morphogenesis
How is cellular differentiation controlled?
by differential gene expression (cells become different because they express different genes)
Self-renewal
seen in stem cells and functions to maintain the stem cell pool
Characteristics of differentiated cells
-specialised cells cannot divide to make copies of themselves
Definition of stem cells
undifferentiated cells that divide and give rise to cells that differentiate into specialised cells
What is a niche?
the microenvironment around stem cells that provides support and signals regulating self-renewal and differentiation (via direct contact, soluble factors and/or intermediate cells)
Where are stem cells found?
- embryonic stem cells: blastocyst
- tissue stem cells: fetus, baby and throughout life
- induced pluripotent stem cells: made in lab
Potency of a stem cell
a measure of how many types of specialised cells a stem cell can make
Multipotent vs pluripotent vs totipotent
- multipotent: can make multiple types of cells but not all types, ex: tissue stem cells
- Pluripotent: can make all types of cells, lacks potential (Extensively) to contribute to extra embryonic tissue, such as the placenta, example: embryonic stem cells from ICM
- totipotent: all types of cells plus cells needed during de elopement of embryo only (placenta, umbilical cord), example: early embryonic stem cells (8 cell stage embryo, morula) are totipotent
What can tissue stem cells produce?
can only make the kinds of cells found in the tissue they belong to
Characteristics of stem cells vs committed progenitors vs specialized cells
- stem cells: self renewal, divide rarely, higher potency, rare
- committed progenitors: “transient amplifying cells”, multipoint, divide rapidly, no self-renewal
- specialized cells: work, no division
Examples of tissue stem cells
- hematopoietic stem cells
- mesenchymal stem cells
How are induced pluripotent stem cells created?
created in the lab by genetic reprogramming (add certain genes to the cells)
How do induced pluripotent stem cells act?
-behave like embryonic stem cells and can make all possible types of specialized cells
What are the advantages and disadvantages of induced pluripotent stem cells?
- advantage: no need for embryos, genetically identical
- disadvantages: large numbers of somatic cells needed, long term studies still required
What factors are associated with turning an adult tissue cell into a pluripotent stem cell?
Oct4, Sox2, Klf4 and c-Myc
Cloning
- Reproductive cloning: live birth cloning
- therapeutic cloning: experimental cloning
- molecular cloning: DNA cloning
Reproductive cloning
- used to make two identical individuals
- very difficult to do
- illegal to do on humans
Therapeutic cloning
- used to make patient
- specific cell lines isolated from an embryo (not intended for transfer in utero)
- transfer of nuclear material from a somatic cell into an enucleated oocyte with the goal of deriving embryonic cell lines with the same genome as the nuclear donor
- little to no risk of rejecting transplanted cells/tissues–immunologically compatible with patient
Molecular cloning
- used to study what a gene does
- routine in the biology labs
Describe the process of reproductive cloning
-take an adult cell (containing DNA) and an egg cell with the nucleus removed and combine to make a clone
Somatic cell transfer (SCT)
- laboratory technique for creating a clone embryo with a donor nucleus
- reproductive cloning, therapeutic cloning
What are the applications of stem cells?
- regenerative medicine (replace cells that are irreversibly lost)
- drug testing and screening (stem cells directed to produce a specific cell type in the lab, huge amounts of identical cells)
- study disease processes (diseased cells used to model the disease)
