1.4 Cellular Differentiation

Question 1

describe ‘cellular differentiation’

Answer 1

Cellular differentiation is the process by which a cell expresses certain genes to produce a protein characteristic for that type of cell. This allows a cell to carry out specialised functions.

Question 2

in plants, what are the regions of unspecialised cells that can divide and/or differentiate into the specialised cells required by the plant called?

Answer 2

meristems

Question 3

in animals, what are the regions of unspecialised cells that can divide and/or differentiate into the specialised cells required by the animal called?

Answer 3

stem cells

Question 4

what does the term ‘pluripotent’ mean?

Answer 4

Pluripotent is the term used to describe cells in the very early embryo which differentiate into all the cell types that make up the organism.

All the genes in embryonic stem cells can be switched on so these cells can differentiate into any type of cell.

Question 5

what does the term ‘multipotent’ mean?

Answer 5

Multipotent is the term used to describe cells that can differentiate into all of the types of cell found in a particular tissue type (e.g. tissue stem cells as they are involved in the growth, repair and renewal of the cells found in that tissue).

e.g. blood stem cells located in the bone marrow can give rise to all types of blood cell

Question 6

what is the function of a red blood cell, skeletal muscle cell and palisade mesophyll cell and which genes are switched on?

Answer 6

Red Blood Cell
- to transport oxygen around the body
- haemoglobin gene = on
- nucleus digesting enzyme gene = on

Skeletal Muscle Cell
- to allow movement (through muscle contraction)
- actin gene = on
- myosin gene = on

Palisade Mesophyll Cell
- does photosynthesis
- photosynthesis enzyme gene = on
- chlorophyll gene = on

Question 7

what genes are most likely to be switched on in most types of differentiated cell?

Answer 7

genes for enzymes involved in vital functions (such as respiration, DNA replication and protein synthesis)

Question 8

describe ‘therapeutic uses of stem cells’ and give examples

Answer 8

Therapeutic uses of stem cells involve the repair of damaged or diseased organs or tissues.

e.g. for corneal repair and to regenerate skin for skin grafts

Question 9

describe ‘research uses of stem cells’ and give examples

Answer 9

Research uses of stem cells involves stem cells being used as model cells to study how diseases develop, for drug testing and to provide information on how cell processes work (such as cell growth, cell differentiation and gene regulation).

Question 10

explain ‘why some people have ethical concerns about the use of embryonic stem cells’

Answer 10

it involves the destruction of embryos which some people/religions say is the destruction of a life

Question 11

explain ‘why some people feel it is acceptable to use embryonic stem cells’

Answer 11

• can offer treatments for diseases and injuries
• may be able to treat or cure illnesses that cannot currently be treated or cured
• reduces the need for animal testing