Lecture 4,5,10+Textbook chap 12

Question 1

our genes control —– and chromatin controls —-

Answer 1

• cell identity
• gene expression

Question 2

heterochromatin

Answer 2

chromatin that remains tightly compacted after mitosis

Question 3

euchromatin

Answer 3

returns to a dispersed active state after mitosis

Question 4

Chromosomes contain

Answer 4

• chromatin fibres composed of DNA and associated proteins
• histones

Question 5

core complex of histones in nucleosomes

Answer 5

• two of each histone: H2A, H2B, H3, H4 forming an octamer

Question 6

Each histone has a —– that sticks out past the DNA

Answer 6

flexible amino-terminal tail (N)

Question 7

Histone modification includes

Answer 7

phosphorylation, acetylation, methylation or ubiquitination

Question 8

DNA or histone methylation (2)

Answer 8

• a methyl group is added to the 5-carbon position of cytosine residues in DNA by DNA methyltransferases
• histones are methylated on arginine and lysine residues by histone methyltransferases

Question 9

Histones can be acetylated on — by —-

Answer 9

• lysines
• histyl acetyl transferases and reversed by histone deacetylase

Question 10

Histone acetyltransferases lead to

Answer 10

open chromatin

Question 11

Histone deacetylases or histone methyltransferases lead to

Answer 11

closed chromatin

Question 12

Heterochromatin protein-1

binds+ associated with+ contains

Answer 12

• heterochromatin protein 1 can bind to methylated lysine 9 of histone 3
• the modification and HP1 are associated with closed chromatin
• contains a chromodomain which binds methylated histones

Question 13

The formation of a methylated lysine at the #9 position endows the histone H3 tail with an important property:

Answer 13

It becomes capable of binding with high affinity to proteins that contain a particular domain, called a chromodomain.

Question 14

X-ist

Answer 14

• non-coding RNA can silence a gene or entire chromosome
• does this by xist rna coating the future inactive X chromosome which triggers extensive histone methylation and chromosome inactivation

Question 15

stem cells are undifferentiated cells that are capable of

Answer 15

• self renewal: the production of cells with a similar capacity to proliferate and differentiate
• commitment: the production of cells commited to differentiate

Question 16

Totipotency

Answer 16

• The zygote: can form the whole embryo of extraembryonic tissues eg: amniotic sac
• the ability of a single cell to divide and produce all the differentiated cells in an organism, including extraembryonic tissues
• the ability of a living cell to express all of its genes to regenerate a whole new individual

Question 17

Pluripotency

Answer 17

ESC: can form all the tissues of the embryo
- Pluripotent stem cells can give rise to all cell types of the body (but not the placenta).

Question 18

Multipotent

Answer 18

• Multipotent stem cells can develop into a limited number of cell types in a particular lineage.

Question 19

Plasticity

Answer 19

the ability of a partially differentiated adult stem cell to change its genectic program and differentiate into cells of another tissue type

Question 20

Micro-environmental Reprogramming

Answer 20

The microenvironment provides signals and cues that induce changes in gene expression and cellular identity, facilitating the conversion of the bone marrow cell into a neural cell.