8.2.1 Most cells DNA not translated

Question 1

what is the process by which cells develop into a specialised structure suited to the role they are carrying out

Answer 1

cell differentiation

Question 2

what is differentiation

Answer 2

is the process by which stem cells become specialised.

Question 3

what is a stem cell

Answer 3

is an undifferentiated cell that can divide by mitosis an unlimited number of times and turn into other specific cell types

Question 4

what can stem cells do

Answer 4

after dividing can remain as stem cell of divide into specialised cells - differentiation

Question 5

what is the name for the process by which stem cells can differntatied into more speculated cells

Answer 5

potency

Question 6

name the 3 types of potency

Answer 6

Totipotency
Pluripotency
Multipotency

Question 7

what is a totipotent cell?

Answer 7

can divide and produce any type of body cell

embryonic stem cells

Question 8

How do totipotent cells become specialised

Answer 8

They translate only part of their DNA which results in cell specialisation

Question 9

where are totipotent cells found

Answer 9

early mammilian embryo - occur for limited time there

Question 10

why are there no totipotent cells present in the later stages of development

Answer 10

as cells lose their ability to differentiate into any cell type

Question 11

name and define the three types of stem cells

Answer 11

Totipotent – Can develop into any cell type, including the placenta and embryo.

Pluripotent – Can develop into any cell type excluding the placenta and embryo.

Multipotent – Can only develop into a few different types of cells.

Question 12

what are pluripotent cells

Answer 12

stem cells that are found in embryos and can become any type of cell

Question 13

what are pluripotent cells used in

Answer 13

research
treat Hyman disorders
used to regrow damaged cells e.g. burnt skin cells

Question 14

what are the issues with this treatment

Answer 14

doesn’t work

Stem cells continue to divide to create tumours

ethic issues - moral to make therapeutic clone to make embryos
- using embryos that are destroyed later

Question 15

what are multipotent and unipotent stem cells?

Answer 15

found in mature mammals and can divide to form a limited number of different cell types

Question 16

what are examples of multipoint cells

Answer 16

bone marrow cells

Question 17

difference between multipoint and unipotent cells

Answer 17

multi - can differentiate into a limited number of cells, whereas
unipotent cells can only differentiate into one type of cell.

Question 18

What happens to totipotent cells during embryonic development?

Answer 18

Certain parts of the DNA are selectively translated so that only some genes are ‘switched on’ in order to differentiate the cell into a specific type and form the tissues that make up the foetus.

Question 19

Give a unique feature of pluripotent cells and the use of this feature.

Answer 19

They can divide in unlimited numbers and can therefore be used to repair or replace damaged tissue.

Question 20

What is a unipotent cell? Give an example.

Answer 20

A cell that can only develop into one type of cell. This happens at the end of specialisation when the cell can only propagate its own type. An example is cardiomyocytes (heart cells).

Question 21

Which types of stem cells are found in embryos?

Answer 21

Totipotent and pluripotent.
Multipotent and unipotent cells are only found in mature mammals.

Question 22

Give some uses of stem cells.

Answer 22

Medical therapies (e.g. bone marrow transplants, treating blood disorders).
Drug testing on artificially grown tissues.
Research (e.g. on the formation of organs and embryos

Question 23

How are induced pluripotent stem cells produced?

Answer 23

From mature, fully specialised (somatic) cells. The cell regains capacity to differentiate through the use of proteins, in particular transcription factors.

Question 24

How can stem cells be used in the treatment of human disorders

Answer 24

• transplanted into patients to divide in unlimited numbers
• then differentiate into required healthy cells (to replace damaged cell)

Question 25

How are induced pluripotent stem (iPS) cells produced

Answer 25

1. Obtain adult somatic body cells from patient 2. Add specific protein transcription factors associated with pluripotency to cells so they express genes associated with pluripotency Transciption factors attatch to promoter regions of DNA, stimulating or inhibiting transcription 3. Culture cells to divide by mitosis Once made iPS cells can divide and differentiate into healthy cells to be transplated into the same patient

Question 26

Positives of using stem cells in treating human disorders

Answer 26

- can divide and differentiate into required healthy cells - save lives - embryos are often left over from IVF so would otherwise be destroyed - iPS cells unlikely to be rejected by patients immune system as they are their own cells - iPS cells can be made without destruction of embryo and adult can give permission

Question 27

Negatives of using stem cells in treating human disorders

Answer 27

- ethical issues with embryonic stem cells (destruction of a potential life) - immune system could reject cells and immunosupressant drugs are required - cells could divide uncontrollably leading to cancer

Question 28

How are induced pluripotent stem cells made?

Answer 28

-Produced from adult somatic cells - appropriate protein transcription factors are used to switch on the genes that were swtiched off to make the cell specialized

Question 29

How do IPS cells overcome ethical issues of using embryonicnstem cells

Answer 29

They dont cause destruction of an embryo and the sdult can give permission

Question 30

How can pluripotent cells treat human disorders

Answer 30

- they can replaaced damaged cells as they divide in unlimited numbers