Cell differentiation, Programming and Epigenetic control

Question 1

Somites

Answer 1

Paired blocks at the rostral end of the paraxial mesoderm

Question 2

Human embryos initially form X pairs of somites reduced to Y pairs

Answer 2

X- 40 - 44

Y - 37-38

Question 3

The notochord is located X to the somite and releases Y

Answer 3

X- ventral

Y- Shh

Question 4

Which cells secrete Wnt3a?

Answer 4

Dorsal-mediate somite cells

Question 5

Myotome is induced in _____ cells by ______ from the ____

Answer 5

Ventral-lateral somite cells, low levels of Shh and BMP4, lateral plate mesoderm

Question 6

Myoblast is a _____ cell of _______

Answer 6

Progenitor cell of skeletal muscle

Question 7

FGF stimulates_______ cell division

Answer 7

Myoblast cell division

Question 8

Myod1 is a ______ master _____ gene, induced by _____

Answer 8

Muscle-specific master regulatory gene, induced by Wnt3a

Question 9

Myod1 inhibits _____, activates _______ and promotes _____

Answer 9

1. Cell proliferation
2. Transcription of some muscle regulatory genes e.g. creatine phosphokinase/ Ach receptor
3. Muscle differentiation

Question 10

Mood belongs to

Answer 10

Family of myogenic regulatory factors which also includes Myf5, Myf6, MyoG

Question 11

MRF are _______ TF’s that regulate ______

Answer 11

Sequence-specific DNA binding, TF’s that regulate myogenesis

Question 12

Myod1 activity causes ______ to ______ to form ________

Answer 12

Myoblast to fuse together to form multinucleate myotubes -> myofibres -> basic cellular unit of skeletal muscle

Question 13

Titin

Answer 13

27k to 33k amino acids in length -> largest no. of exons 363, 17106bp

Question 14

Actin is a _________ protein, a is present in ____ beta and gamma are in ______

Answer 14

Ubiquitous protein, α– (high levels in muscle cells), β- and γ–actin (microfilaments), more than 30 genes

Question 15

Differential gene expression

Answer 15

Only a small % of genome is transcribed in each cell

Question 16

Enhancer

Answer 16

Cis-regulatory elements -> bind tissue-specific TF’s

Question 17

Epigenetic control

Answer 17

Transcription modification by DNA or associated histones

Question 18

5-methylcyotsine

Answer 18

Causes methylation preferentially at CpG dinucleotides close to trans. start site

Question 19

Enzyme that copies methylation pattern to newly synthesised strands

Answer 19

DNA methyltransferase

Question 20

2 ways methylation affects transcription

Answer 20

1 ) Blocking TF binding

2) Recruiting proteins that modify histone proteins to heterochromatin

Question 21

Histones that are core proteins of nucleosomes

Answer 21

H2A, H2B, H3 + H4

Question 22

Euchromatin

Answer 22

Trans. activation due to acetylation

Question 23

Transdetermination

Answer 23

3-5 founder mitotic cells can change their state of determination

Question 24

Somatic cell nuclear transfer (SCNT)

Answer 24

Reprogram genome of a differentiated cell by transferring nucleus into cytoplasm of an egg

Question 25

How are multiple cell types made in vitro?

Answer 25

Take inner cell mass cells of mammalian blastocyst + add chemical signals

Question 26

MyoD1

Answer 26

Basic-helix-loop-helix TF related to TF for skeletal muscle differentiation

Question 27

Which genes are sufficient to induce pluripotency?

Answer 27

Oct4, Sox2, Myc and Klf4