U8T4 – Stem Cells, Epigenetics and siRNA

Stem Cells, Epigenetics and siRNA

1 / 25

After fertilisation, zygotes ( fertilised eggs) divide by which process?

Binary Fission

Mitosis

Meiosis

Sexual Reproduction

2 / 25

In humans, the zygote ( fertilised egg ) divides into a ball of cells called a Morula. What word describes the cells contained in a morula?

Totipotent

Pluipotent

Multipotent

Unipotent

3 / 25

The morula hollows out into a hollow sphere, with a small group of cells at the bottom called teh inner cell mass which go on to develop into an embryo. What do the outer cells go on to make?

Skin

Arms and Legs

Head

Placenta

4 / 25

What word describes the inner cell mass now?

Totipotent

Pluripotent

Multipotent

Unipotent

5 / 25

Cell differentiation is the process of stem cells becoming more specialised into different types of cell. e.g. Muscle, bone etc. But what is the cause of this differentiation?

All genes are expressed (turned 'on'), but in a particular order.

All genes are expressed (turned 'on'), but some are turned off again later.

Some genes are expressed (turned 'on'), others are not.

Some genes are expressed, but in a random order.

6 / 25

What is the difference between 'totipotent' stem cells and 'Pluripotent' stem cells?

Totipotent cells can only make placental tissues.

Pluripotent cells can make placental tissue as well as bodily tissues.

Pluripotent cells can only make placental tissues.

Totipotent can make placental tissue, as well as all bodily tissues.

7 / 25

Which type of stem cells are not found in adults?

Pluripotent

Multipotent

Unipotent

Somatic Cells

8 / 25

Cardiomyocytes are an example of what type of stem cell?

Totipotent

Pluripotent

Multipotent

Unipotent

9 / 25

What are iPS cells?

Induced Placental Stem Cells

Infected Pluripotent Stem Cells

Induced Pluripotent Stem Cells

10 / 25

iPS cells can be made from adult somatic cells. What are somatic cells?

All human cells.

All human body cells except gametes.

All human body cells except unipotent stem cells.

All human body cells except multipotent and unipotent stem cells.

11 / 25

What substances can be used to take mature, differentiated adult cells, and de-differentiate them back into pluripotent stem cells ?(usually only found in embryos).

Hormones

Enzymes

Transcription factors

cAMP second messenger model.

12 / 25

What is an advantage of using iPS cells to treat degenerative disorders, instead of embryonic stem cells?

Unlike embryonic stem cells, there is no loss of 'potential life' with iPS cells.

Every single type of cell in humans can be made by iPS cells.

The use of viruses to make iPS cells carries a risk of cancer.

iPS cells from one patient may be rejected by another.

13 / 25

What is 'Epigenetics'?

The study of the genetic factors that effect Epileptic seizures.

The effect of epinephrine on DNA.

An environmental factor that causes a change to the base sequence of a gene.

An environmental factor that causes 'marker' molecules to be added on to the DNA.

14 / 25

A methyl group has the structure CH3. Methylation is the addition of a methyl group onto what?

ApT site

Histone protein

Deoxyribose

CpG site

15 / 25

Which area of DNA is particularly affected by methylation?

Intron

Exon

Promoter Sequence

Termination Sequence

16 / 25

What effect will having a high methylation of a promoter sequence , have on expression of that gene?

Increase

Decrease

Stay at a steady level

Stay at whatever it was before

17 / 25

Can extra methylation be removed from the DNA?

Yes

No

18 / 25

Acetylation is the addition of a C2H3O group which contains a double bonded oxygen. Where does acetylation occur?

Histone proteins

CpG site

Base sequence

Centromere

19 / 25

What effect will increased acetylation have on a gene?

Increase expression

Decrease expression

Stay at a steady level

Stay at whatever it was before.

20 / 25

What causes epigenetic markers to be added or removed from DNA?

Exposure to carcinogens.

Inherited mutations from parents.

Exposure to environmental conditions such as a balanced diet.

Exposure to ionising radiation.

21 / 25

What does the 'si' stand for in siRNA?

Small In-Vitro

Small In-Vivo

Small Irrational

Small Interfering

22 / 25

SiRNAs are formed when large double stranded molecules of RNA are cut up into small section which then do what?

The small double stranded sections bind to DNA polymerase preventing it from working.

The small double stranded sections bind to RNA polymerase, preventing it from working.

Small double stranded sections become single stranded and combine with an enzyme to form a RISC complex

Small double stranded sections become single stranded and bind to DNA.

23 / 25

Which molecule does the SIRNA / protein complex (RISC) bind to?

Double stranded DNA

Single Stranded DNA

tRNA

mRNA

24 / 25

What does the RISC complex do to the mRNA?

Cut the mRNA up at the sequence complementary to the siRNA

Extend the mRNA by adding the new siRNA section on.

Shorten the mRNA by removing the siRNA complementary section.

Nothing

25 / 25

What effect will siRNA have on expression of a gene?

Increase expression

Decrease expression

Stay at a steady level

Stay at whatever it was before.

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