Stem Cells - Anita Hall

Question 1

Define Epigenetics and provide examples

Answer 1

Is the study of cellular and physiological alterations that are not caused by changed in DNA sequence. I.e. Dynamic alterations in the transcriptional potential of a cell.

Examples include;

DNA methylation
Histone modification

Question 2

What bases are usually methylated and give an example of a specific position

Answer 2

Cytosine and Adenine.

Position 5 on Cytosine is almost ubiquitous

Question 3

What percentage of methylation is seen in Mice, Drosophila and yeast?

Answer 3

2.5%, 0.03% and virtually none in yeast.

Question 4

Define Gene Expression Pattern.

Answer 4

The flow of genetic information from gene to protein; the process or the regulation of the process, by which the effects of a gene are manifested; the manifestation of a heritable trait in an individual carrying the gene or genes that determine it.

Good luck

Question 5

What are the main stages of the cell cycle? And what occurs at each stage?

Answer 5

Interphase:

1. G1: (growth) cell grows to accommodate new genetic information
2. S phase (synthesis) cell duplicates DNA for daughter cells
3. G2: (growth) cell grows again to create enough cytoplasm for daughter cells
4. Mitosis;

4a. Prophase: chromatin forms into chromosomes, centrosomes move to poles of the cell and nuclear envelope breaks down
4b. Prometaphase: nuclear envelope is gone, spindle fibres start to form and Chromosomes migrate to equator of cell
4c. Metaphase: chromosomes align along equator
4d. Anaphase: chromosomes are spilt into chromatids and are pulled toward the opposite poles by spindle fibres
4e. Telophase: chromatids are in newly formed nuclear envelopes ready for cell division

5. Cytokinesis: the work of actin rings creates a division pressure along cell membrane leading to division of the cytoplasm and two genetically identical daughter cells.

Question 6

What was the main outcome of John Gurdon’s experiments on frog cells in 1962?

Answer 6

Showed that it was possible to replace the nucleus of a frog egg cell with that of a somatic gut cell and led to normal development of frog offspring. Therefore the genome contains within itself the instructions to make any type of cell, but is hidden by differentiation

Question 7

What is the definition of a stem cell?

Answer 7

An undifferentiated cell of a multicellular organism which is CAPABLE of giving rise to indefinitely more cells of the same type and from which certain other cell types arise by differentiation. ?

Question 8

What does ‘potency’ relate to in terms of stem cell biology? ?

Answer 8

It refers to the number of different types of cells it can generate. More potent stem cells have a wider range of cells it can become.