B2 pages 26-35 cell division

Question 1

what is differentiation

Answer 1

the process where cells become specialised for a particular function

Question 2

what is interphase in the cell cycle

Answer 2

cell grows in size

-DNA replicates and organelles replicate.

Question 3

what is mitosis in the cell cycle

Answer 3

replicated chromosomes line up along the centre of the cell -Spindle fibres contract and the chromosomes get pulled to opposite poles
-Nucleus divides

Question 4

what is Cytokinesis in the cell cycle

Answer 4

cell membrane and cytoplasm divide

- 2 new identical daughter cells are formed.

Question 5

What is a stem cell

Answer 5

A cell that has not yet become specialised cell.

Question 6

what can a stem cell do

Answer 6

Can replicate many times

Has the potential to become specialised (i.e. different types of cell)

Question 7

name 3 types of stem cells

Answer 7

Embryonic stem cells
Adult stem cells
Meristems in plants

Question 8

what are Embryonic stem cells

Answer 8

are stem cells found in embryos are known as embryonic stem cells and can differentiate into almost every cell type under the right conditions in a lab.

Question 9

what are adult stem cells

Answer 9

are stem cells found in adult tissues (such as bone marrow, brain, muscle, liver stem cells). They can differentiate only into cells from the type of tissue where they are found. e.g. liver stem cells can only become liver cells.

Question 10

where are meristems in plants found

Answer 10

Found in root and shoot tips

Question 11

what can meristems in plants do

Answer 11

They can differentiate into any type of plant, and have this ability throughout the life of the plant

Question 12

what can meristems be used to make

Answer 12

They can be used to make clones of the plant- this may be necessary if the parent plant has
certain desirable features (such as disease resistance), for research or to save a rare plant from extinction.

Question 13

advantages of embryonic stem cells (unspecialised cells from embryos)

Answer 13

• Have the potential to develop into any type of cell/tissue.
• Cells can become any cell type.
• Used to treat human diseases.
• Painless

Question 14

disadvantages of Embryonic stem cells

unspecialised cells from embryos

Answer 14

• Unethical 􏰁 embryos cannot give permission.

- Possible harm/death to embryo.

Question 15

advantages of Adult stem cells

unspecialised cells from adult tissues e.g. bone marrow

Answer 15

• Plentiful supply
• No ethical issues (in
  collection) as the person
  can give consent.
• Safer method as it is well
  tried/tested

Question 16

disadvantages Adult stem cells

unspecialised cells from adult tissues e.g. bone marrow

Answer 16

• Painful to extract
• Fewer diseases can be treated
• Can only form the type of cells
  as the tissue they were taken
  from.
• Possibility of infection during
  extraction of stem cells.

Question 17

what have stem cells been used to treat

Answer 17

Stem cells have been used to treat conditions such as:
• Paralysis
• Diabetes
• Eyesight in the blind

Question 18

what does therapeutic cloning involve

Answer 18

Therapeutic cloning involves an embryo being produced with the same genes as the patient.

Question 19

what is therapeutic cloning used for

Answer 19

􏰂 The embr􏰃o prod􏰄ced co􏰄ld 􏰅hen be har􏰆es􏰅ed 􏰅o ob􏰅ain 􏰅he embr􏰃onic s􏰅em cells􏰇
􏰂 These co􏰄ld be gro􏰈n in􏰅o an􏰃 cells 􏰅he pa􏰅ien􏰅 needed􏰉 s􏰄ch as ne􏰈 􏰅iss􏰄es or organs􏰇􏰇

Question 20

what is an advantage of therapeutic cloning

Answer 20

The ad􏰆an􏰅age is 􏰅ha􏰅 􏰅he􏰃 􏰈o􏰄ld no􏰅 be rejec􏰅ed as 􏰅he􏰃 􏰈o􏰄ld ha􏰆e 􏰅he exact same genetic make-up as the individual.

Question 21

describe the stages in therapeutic cloning

Answer 21

nucleus from skin cell
human egg with nucleus removed
inject skin cell nuclei into enucleated egg
cloned embryo created
stem cells extracted
stem cells can form any cell type for possible organ repair and transplant