Lecture 2: Cell Diff and Stem Cells

Question 1

Describe the blastocyst

Answer 1

• trophoectoderm surrounds inner cell mass (ICM)
• trophoectoderm: extra embryonic structures
• blastocyst: embryonic structures

Question 2

What are the three fundamental aspects of developmental biology?

Answer 2

cell division, cell differentiation, morphogenesis

Question 3

How is cellular differentiation controlled?

Answer 3

by differential gene expression (cells become different because they express different genes)

Question 4

Self-renewal

Answer 4

seen in stem cells and functions to maintain the stem cell pool

Question 5

Characteristics of differentiated cells

Answer 5

-specialised cells cannot divide to make copies of themselves

Question 6

Definition of stem cells

Answer 6

undifferentiated cells that divide and give rise to cells that differentiate into specialised cells

Question 7

What is a niche?

Answer 7

the microenvironment around stem cells that provides support and signals regulating self-renewal and differentiation (via direct contact, soluble factors and/or intermediate cells)

Question 8

Where are stem cells found?

Answer 8

1. embryonic stem cells: blastocyst
2. tissue stem cells: fetus, baby and throughout life
3. induced pluripotent stem cells: made in lab

Question 9

Potency of a stem cell

Answer 9

a measure of how many types of specialised cells a stem cell can make

Question 10

Multipotent vs pluripotent vs totipotent

Answer 10

• 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

Question 11

What can tissue stem cells produce?

Answer 11

can only make the kinds of cells found in the tissue they belong to

Question 12

Characteristics of stem cells vs committed progenitors vs specialized cells

Answer 12

• 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

Question 13

Examples of tissue stem cells

Answer 13

• hematopoietic stem cells

- mesenchymal stem cells

Question 14

How are induced pluripotent stem cells created?

Answer 14

created in the lab by genetic reprogramming (add certain genes to the cells)

Question 15

How do induced pluripotent stem cells act?

Answer 15

-behave like embryonic stem cells and can make all possible types of specialized cells

Question 16

What are the advantages and disadvantages of induced pluripotent stem cells?

Answer 16

• advantage: no need for embryos, genetically identical

- disadvantages: large numbers of somatic cells needed, long term studies still required

Question 17

What factors are associated with turning an adult tissue cell into a pluripotent stem cell?

Answer 17

Oct4, Sox2, Klf4 and c-Myc

Question 18

Cloning

Answer 18

• Reproductive cloning: live birth cloning
• therapeutic cloning: experimental cloning
• molecular cloning: DNA cloning

Question 19

Reproductive cloning

Answer 19

• used to make two identical individuals
• very difficult to do
• illegal to do on humans

Question 20

Therapeutic cloning

Answer 20

• 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

Question 21

Molecular cloning

Answer 21

• used to study what a gene does

- routine in the biology labs

Question 22

Describe the process of reproductive cloning

Answer 22

-take an adult cell (containing DNA) and an egg cell with the nucleus removed and combine to make a clone

Question 23

Somatic cell transfer (SCT)

Answer 23

• laboratory technique for creating a clone embryo with a donor nucleus
• reproductive cloning, therapeutic cloning

Question 24

What are the applications of stem cells?

Answer 24

• 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)