Stem Cells + Totipotency

Question 1

What are totipotent cells?

Answer 1

Totipotent cells are cells which can mature into any body cell

Question 2

What is an example of a totipotent cell (from women)?

Answer 2

An example of a totipotent cell is a single fertilised egg

Question 3

What happens to totipotent cells after they differentiate?

Answer 3

Totipotent cells differentiate and become specialised for a particular function

Question 4

Why do different types of cells, such as mesophyll and muscle cells, perform specific functions despite containing the same DNA?

Answer 4

This is because during the process of cell specialisation, only some genes are expressed.

This means only part of the DNA of a cell is translated into proteins.

Therefore allowing the cell to only make proteins that it requires to carry out its specialised function

Question 5

What are some essential proteins produced by all cells, regardless of specialisation?

Answer 5

Proteins required for processes like respiration and membrane synthesis are produced by all cells, as they are vital for basic cell function

Question 6

What happens to the DNA that is not translated into proteins during cell specialisation?

Answer 6

The unneeded DNA is not translated to conserve energy and resources, preventing the production of unnecessary proteins

Question 7

How does the cell prevent the expression of unnecessary genes? What are these preventions referred to as?

Answer 7

Cells prevent unnecessary gene expression by stopping transcription (blocking mRNA production) or translation. These are known as controlling factors

Question 8

Do specialised cells retain all the genes of the organism?

Answer 8

Specialised cells still retain all the genes of the organism

Question 9

What happens to xylem vessel and red blood cells as they specialise?

Answer 9

They lose their nuclei, and since the nucleus contains the genes, they cannot develop into other cells

Question 10

Is specialisation reversible in animal cells?

Answer 10

No, specialisation is irreversible in most animal cells

Question 11

In mature mammals, do any cells retain the ability to differentiate into other cells?

Answer 11

Yes, only a few cells retain this ability, and they are called stem cells

Question 12

What are stem cells?

Answer 12

Stem cells are undifferentiated, dividing cells that can divide to form identical copies of themselves in a process called self renewal

Question 13

Where are stem cells found?

Answer 13

Stem cells are found in adult animal tissues

Question 14

What is self renewal process in stem cells?

Answer 14

Self renewal is when stem cells divide to create an identical copy of themselves, allowing them to be constantly replaced

Question 15

What are the main sources of stem cells in mammals and where is each source located from? (8 marks)

Answer 15

1. Embryonic stem cells
2. Umbilical cord blood stem cells
3. Placental stem cells
4. Adult stem cells

Question 16

Where do embryonic stem cells come from, and what can they do?

Answer 16

Embryonic stem cells come from early embryos and can differentiate into any type of cell.

Question 17

Where are umbilical cord blood stem cells derived from, and how are they different from adult stem cells?

Answer 17

They come from umbilical cord blood and are similar to adult stem cells

Question 18

Where are placental stem cells found, and what do they do?

Answer 18

Placental stem cells are found in the placenta and develop into specific types of cells

Question 19

Where are adult stem cells found, and what is their role?

Answer 19

Adult stem cells are found in body tissues and are specific to certain organs or tissues, helping to maintain and repair them

Question 20

How are stem cells classified?

Answer 20

Stem cells are classified according to their ability to differentiate into different types of cells

Question 21

What are totipotent stem cells?
⇒ Give an example
⇒ State where it is found

Answer 21

Totipotent stem cells are cells which can differentiate into any type of cell
Found in early embryos
The ZYGOTE would be totipotent as it can form all body cells

Question 22

What happens as totipotent cells divide and mature?

Answer 22

As totipotent cells divide and mature, they become pluripotent stem cells, which are slightly more specialised

Question 23

What are pluripotent stem cells?
⇒ Where are they found?
⇒ State examples

Answer 23

Pluripotent stem cells are cells that can differentiate into almost any type of cell

Examples include embryonic and fetal stem cells

They are found in embryos

Question 24

How can pluripotent stem cells be used in medicine?

Answer 24

Pluripotent cells can be used to regrow tissues that have been damaged by accidents or diseases

Question 25

Give an example of how pluripotent cells can help in case of accidental damage. (burn victim)

Answer 25

Pluripotent cells can be used for skin grafts to treat serious burn damage

Question 26

Why are pluripotent cells significant in treating disorders?

Answer 26

They provide a potential source of regenerating damaged or diseased tissues, improving recovery and treatment outcomes

Question 27

What are multipotent stem cells? ⇒ Where are they found?

Answer 27

Multipotent stem cells are cells which can differentiate into a limited number of specialised cells They are found in adults

Question 28

What are two examples of multipotent stem cells?

Answer 28

Examples of multipotent stem cells include adult stem cells and stem cells from umbilical cord blood

Question 29

What are unipotent stem cells?⇒ Where are they from? ⇒ Where are they made in?

Answer 29

Unipotent stem cells are cells that can only differentiate into a single type of cell They are from multipotent stem cells and are made in adult tissue

Question 30

What is an example of unipotent stem cells ?

Answer 30

An example of unipotent stem cell is cardiomyocytes, heart muscle cells that can divide to repair heart muscle damage

Question 31

What are induced pluripotent stem cells? (iPS cells)

Answer 31

iPS cells are pluripotent cells produced from unipotent stem cells

Question 32

What are iPS cells very similar to?

Answer 32

iPS cells are similar to embryonic stem cells in form and function

Question 33

How are iPS cells created?

Answer 33

iPS cells are created by inducing genes and transcriptional factors within unipotent cells to express themselves, turning on genes that were previously turned

Question 34

What does the creation of iPS cells reveal about adult cells?

Answer 34

The creation of iPS cells shows that adult cells retain the same genetic information as embryonic cells, which can be reactivated

Question 35

What is a key feature of iPS cells?

Answer 35

A key feature of iPS cells is self - renewal, allowing them to divide indefinitely and provide a limitless supply

Question 36

Why are iPS cells significant in medical research and treatment?

Answer 36

iPS cells could replace embryonic stem cells, addressing many ethical concerns associated with using embryos in research and treatment