Cellular Differentiation, Stem Cells, And Modern Medicine

Question 1

What are totipotent cells

Answer 1

Cells that can develop into any cell type, including extra embryonic cell types

Question 2

What are pluripotent cells

Answer 2

Cells that can divide into any type cell type, excluding extra embryonic cell types

Question 3

Outline embryo development and how cells become more specialised and less flexible over time

Answer 3

An embryo begins as a small number of naive, totipotent cells
Embryonic stem cells can give rise to all cell types except trophectoderm (pluripotent)
Cells fate is progressively limited until it becomes terminally differentiated - can only give rise to the same cell type
Stem cells, germ cells are exceptions

Question 4

What is ICM

Answer 4

Inner cell mass - becomes embryo

Question 5

What is trophectoderm

Answer 5

A polarised transporting single cell layer that comprises the wall of the blastocyst

Question 6

Outline embryonic cells not being differentiated in terms of muscle gene

Answer 6

At this stage in development, the embryonic precursorcell could become any type of differentiated cell.
Muscle specific genes are not being transcribed

Question 7

Outline the fate determination of embryonic cells in terms of muscle gene

Answer 7

Embryonic precursor cell evolved into myoblast (determined cell)
This cell must not develop into a muscle cell.
Certain control genes which code for transcription factors become activated
MyoD protein synthesised (transcription factor)

Question 8

Outline the terminal differentiation of a embryonic cell in terms of muscle genes

Answer 8

Embryonic precursor cell -> Myobast -> part of muscle fibre
MyoD functions as transcription factor to produce more MyoD
Also acts as transcription factor for another transcription factor, which goes on to mediate production of Myosin, other cell cycle proteins, and cell cycle blocking proteins

Question 9

What is genomic equivalence

Answer 9

Differentiated cells contain all the DNA required to build an entire new organism

Question 10

Outline the experiment that was conducted to supper genomic equivalence

Answer 10

Frog eq cells nucleus removed with UV light
Donor nucleus from other frog embryo, and donor nucleus from fully differentiated (intestinal) cell transplanted into seperate egg cells.
Most of frog embry cross fully develop into tadpoles
Most of fully differentiated cross stop developing before tadpole stage, but some continue.

Question 11

What are embryonic stem cells

Answer 11

Harvested from inner cell mass (future embryo) of mammalian blastocyst embryos
Human embryonic stem cells are pluripotent
Cells derived from embryonic stem cells are genetically identical to embryo donor

Question 12

What are induced pluripotent stem cells

Answer 12

Cells made by reprogramming adult skin cells
Can be made from anyone, genetically identical to the source skin cell
Are pluripotent

Question 13

What is multipotent

Answer 13

Cells can give rise to 2 or 3 cell types.
Limited to differentiating into cell types of a specific lineage

Question 14

What are umbilical cord stem cells

Answer 14

Stem cells isolated from umbilical cord of new born babies
Stem cells are multipotent - immature blood stem cells
Less restricted that blood stem cells from adults

Question 15

Outline adult stem cells importance in renewal tissues

Answer 15

Stem cells are important for tissues such as blood and skin which need constant renewing
Blood stem cells (haematopoietic stem cells) found in bone marrow, can be used for marrow transplants

Question 16

Outline the development of embryonic stem cells to adult stem cells

Answer 16

A fertilise deg is totipotent - gives rise to all cell types
Embryonic stem cells are pluripotent - gives rise to all cells of body
Adult stem cells are multipotent - gives rise to cells of specific lineage

Question 17

What persuades stem cells to develop into different differentiated cell

Answer 17

Different cultural conditions are used to persuade stem cells to develop into different kinds of differentiated cells

Question 18

What is integrative gene therapy

Answer 18

Integrative gene therapy I based on the idea that it may be possible to alter genetic code of an individuals cells
Proposed as a way of correcting single gene disorders

Question 19

Outline the viral method of gene therapy

Answer 19

Insert RNA version of normal allele into retrovirus or other viral vector
Let virus infect bone marrow cells that have been removed from patient end and cultured
Viral DNA carrying normal allele inserts into chromosomes
Inject engineered cells into patient

Question 20

What are 2 methods of gene therapy

Answer 20

Viral delivery
CRISPR editing

Question 21

What is regenerative Medicine

Answer 21

Based on the idea that pluripotent stem cells can be used to repair or replaced damaged organs or tissues
Pluripotent stem cells can be made from skin or blood cells from patient (genetically identical) or matched donors, or from embryos
Stem cells encouraged to differentiate into specific cell types e.g. neurons, retinal cells
Differentiated cells transplanted into patients