3C Stem Cells/Using Stem Cells

Question 1

zygote

Answer 1

fertilized egg cell

Question 2

totipotent

Answer 2

an undifferentiated cell than can form ANY one of the different cell types needed for an entire new organism.

Question 3

blastocyst

Answer 3

an early embryo consisting of a hollow ball of cells with an inner cell mass of pluripotent cells that will eventually form a new organism

Question 4

embryonic stem cells definitiom

Answer 4

undifferentiated cells of the early human embryo with potential to develop into many different types of specialized cell

Question 5

morula

Answer 5

early embryo made up of a solid ball of 10-30 totipotent cells

Question 6

pluripotent (2)

Answer 6

• an undifferentiated cell that can form MOST of the cell types needed for an entire new organism (not tissues such as placenta)
• in development

Question 7

Stages of embryonic development

Answer 7

1. fertilization (totipotent)
2. start to divide, 2-cell stage embryo (totipotent)
3. forms dense ball (morula), 4-cell stage embryo (totipotent)
4. embryo is a hollow ball of cells, cell migration (totipotent)
5. five days after fertilization, forms blastocyst, all cells become pluripotent, will generate amniotic membrane

Question 8

Embryonic Stem Cells (3)

Answer 8

• earliest embryonic cells are totipotent
• by blastocyst stage (implanted in mother uterus) they are pluripotent
• pluripotent stem cells change to become more speacialized as the embryo develops

Question 9

Differences between totipotent, pluripotent and multipotent (3)

Answer 9

• zygotes are totipotent stem cells as they give rise to all cell types
• blastocyst contains pluripotent cells that give rise to embryonic cells (not extra embryonic tissue), so most cell types
• cells in the developing embryo are multipotent as they become only some cell types

Question 10

Differences between totipotent cells and pluripotent cells ( simple ) (3)

Answer 10

• totipotent cells can give rise to any cell
• pluripotent cells cannot give rise to all cells in the body
• totipotent cells can give rise to an entire human being, while pluripotent cells cannot

Question 11

Polygenic inheritance (3)

Answer 11

• idea of more than one gene for a single characteristic
• at a different loci
• giving rise to continuous variation

Question 12

Why is use of normal stem cells less controversial than embryonic stem cell therapy? (3)

Answer 12

• no destruction of embryos
• because embryos have the potential to become human life
• due to ethical/ religious reasons

Question 13

Therapeutic cloning/ somatic cell cloning (6)

Answer 13

1. Nucleus removed from patients adult cell
2. Nucleus removed from ovum
3. Nucleus from patients cell transferred into empty ovum
4. Mild electric shock to fuse nucleus with new cell
5. Mitosis gives a ball of cells
6. Stem cells removed and cultured to grow into required organ or tissue

Question 14

Induced Pluripotent Stem Cells (IPS) (4)

Answer 14

• remove differentiated cell to force cell to become pluripotent
• by using chemical stimulation
• reversing back to embryonic stage
• can divert its differentiation and create whatever you want it to be