Cell differentiation and gene expression

Question 1

What is differentiation?

Answer 1

The production of many cell types within an organism

Question 2

What type of change is differentiation?

Answer 2

Stable, complex change

Question 3

what is determination?

Answer 3

The stability of cell differentiation even after the end of any inducing signal

Question 4

Is determination transmitted?

Answer 4

Determination is transmitted to daughter cells after division

Question 5

What is cell lineage?

Answer 5

The series of cell types evolving from a zygote to a mature cell type

Question 6

How does differentiation occur?

Answer 6

Occurs in steps

Question 7

What occurs in each step in differentiation?

Answer 7

At each step an immature cell type such as a precursor changes into a more mature cell type and this still may be a type of precursor

Question 8

What do branches represent?

Answer 8

Branches don’t represent cell division, just the possibilities of types of daughter cells that can be formed from precursor cells

Question 9

What can particular precursors do?(pluripotent)

Answer 9

Particular precursors can divide into more than one daughter cell types

Question 10

What do different cell types do?

Answer 10

Different cell types express different genes

Question 11

What does the whole process of gene expression lead to the synthesis of?

Answer 11

• The whole process leading to the synthesis of the final product of the gene:
○ Protein
○ Functional RNAs
○ Include processes like transcription and translation

Question 12

What is modulation?

Answer 12

Simple reversible change in gene expression, with no change in cell type

Question 13

What is modulation also known as?

Answer 13

Adaptation

Question 14

What type of change is modulation?

Answer 14

Temporary simple change

Question 15

Differentiation vs modulation

Answer 15

Differentiation is stable and is a complex change whereas modulation is temporary and is a simple change
Both involve gene expression

Question 16

How was dolly the sheep made?

Answer 16

• Differentiated mammary epithelial sheep cell fused into cytoplasm of sheep oocyte
• Fused cell divided many times and proliferated forming an embryo
• Put in the uterus of an ewe
• Embryo had all the genes for a whole sheep

Question 17

Was dolly the sheep fertile?

Answer 17

Yes

Question 18

what happens during one stage of lineage?

Answer 18

During one step of lineage, multiple genes that determine cell type are activated during expression while others are repressed

Question 19

What is the program of differentiation?

Answer 19

Set of expressed genes in a given cell type

Question 20

At What leverl is the program of differentiation controlled at?

Answer 20

Largely controlled during mRNA transcription

Question 21

How is differential transcription detected?

Answer 21

Detected by using individual probes by RNA-seq

Question 22

What does differential transcription reveal?

Answer 22

Reveals the difference in RNA between 2 cell types

Question 23

What are the two main levels of control?

Answer 23

Chromatin remodeling and methylation

Question 24

What does folding do in chromatin remodeling?

Answer 24

Folding interferes with transcription, as transcription machinery cannot access DNA

Question 25

What do different cell types have in chromatin remodelling?

Answer 25

Different cell types have different sections of genome as heterochromatin

Question 26

How is gene expression affected in different cell types during chromatin remodeling?

Answer 26

in different cell types, different parts of the genome are translated so gene expression varies

Question 27

What does methylation do?

Answer 27

Increases heterochromatin

Question 28

How does methylation work?

Answer 28

○ A methyl group binds to a cytosine(in a CpG) becoming methylcytosine
○ This is copied onto the opposite strand by maintenance methyl transferase

Question 29

Where does methylation occur?

Answer 29

DNA methylation occurs in whole stretches rich in CpG pairs

Question 30

What does methylation cause?

Answer 30

Methylation causes folding of chromatin

Question 31

What happens to methylation patterns?

Answer 31

Methylation pattern is remembered in daughter cells

Question 32

What is de nova methylation

Answer 32

§ CpG pairs are not always methylated

§ Unmethylated pairs can become methylated by a de novo methyltransferase

Question 33

How are different genes activated?

Answer 33

Different genes are activated by different transcription factors

Question 34

What do different cell types do?

Answer 34

Different cell types express different ranges of transcription factors

Question 35

What happens to some genes?

Answer 35

Some genes are transcribed in nearly all cell types

Question 36

What are master gene regulators?

Answer 36

A transcription factor that regulates transcription of a whole set of lineage specific genes, like a program

Question 37

What cell divide very rarely to repair DNA damage?

Answer 37

Endothelium and liver cells

Question 38

What is terminal differentiation?

Answer 38

Cells that cannot divide

Question 39

What can happen to terminally differentiated cells?

Answer 39

Terminally differentiated cells can be replaced by precursors somatic stem cells

Question 40

What is cancer not caused by?

Answer 40

Cancer is not caused by faulty differentiation

Question 41

What is deficient in cancer cells?

Answer 41

Differentiation is deficient in cancer cells

Question 42

What do tumor cells look like?

Answer 42

Look like precursors

Question 43

What is aniridia?

Answer 43

Aniridia is the lack of the iris of the eye due to a mutation in the transcription factor PAX6

Question 44

What is thrombocytopenia?

Answer 44

Thrombocytopenia is a platelet deficiency due to a mutation of GATA-1 which is needed for the differentiation of platelets.