Division and Differentiation in Human Cells

Question 1

somatic cell

Answer 1

-any type of cell in the body other than cells involved in the reproduction(diploid cell)
-divide by mitosis to produce more somatic cells

Question 2

Germline Cells

Answer 2

-Germline cells are gametes(ova and sperm) and the stem cells that divide to form gametes
-Diploid and have 23 pairs of homologous chromosome
-Can divide by mitosis to produce more germline cells(to maintain diploid number of chromosomes)
-Germline cells dividing by meiosis produce haploid gametes (ova and sperm).
-contain 23 single chromosomes.

Question 3

Homologous chromosome

Answer 3

These are Chromosomes which are:-
-Same size
-Same centromere position
-Carrying the same genes at the same
(location on the chromosome).

Question 4

Steps of Meiosis

Answer 4

Division 1- separates the homologous chromosome
Division 2-separates the chromatids

Question 5

Differentiation

Answer 5

-Cellular differentiation is the process by which a cell expresses certain genes to produces proteins characteristic for that cell type.
-This allows cells to carry out specialised functions.

Question 6

Write a short note explaining how genetically identical cells develop into different cell types such as neuron cells.

Answer 6

Unspecialised stem cells have the ability to express any gene. If the stem cell expresses the neuron specific gene it will produced neuron-specific proteins, characteristic of a neuron cell. Or any other cell.

Question 7

Stem Cells

Answer 7

-Stem cells are unspecialised somatic cells that have the ability to self renew and/or differentiate into a diverse range of specialised cells.
2 types:
-embryonic stem cell
-tissue stem cell

Question 8

Embryonic stem cells

Answer 8

-Embryonic stem cells are derived from an embryo about 4–5 days old (blastocysts).
-Cells in the very early embryo can differentiate into all of the cell types that make up the individual.
-They are said to be pluripotent.
-All genes in an embryonic stem cell can be switched on so these cells can differentiate into any cell type.

Question 9

Tissue Stem cells

Answer 9

-Involved in growth, repair and renewal of the cells found in that tissue.
-Tissue stem cells are said to be multipotent
-This means they can differentiate into all of the cell types found in a particular tissue type.
Can be found in:
-bone marrow
-heart
-muscle
-liver

Question 10

Blood Stem Cells

Answer 10

Located in the bone marrow
Give rise to:-
White blood cells
Lymphocyte
Phagocytes
Red Blood cell
Platelets

Question 11

Main uses of stem cells

Answer 11

Thereupatic uses- repair of damaged or diseased cells
Research uses- model cells to see how disease work

Question 12

Therapeutic

Answer 12

Therapeutic uses of stem cells involves the repair of damaged or diseased organs or tissues. For example they can be used in:
-cornea repair
-regeneration of damaged skin
can be done since stem cells can self renew

Question 13

How do we use the Stem cells to repair damaged or diseased organs or tissues

Answer 13

-stem cells are cultured/grown in laboratory
-stem cells are transplanted into the tissue/damaged area.

Question 14

Research uses of stem cells

Answer 14

-as model cells to study how disease develops
-as model cells for drug testing

Question 15

Ethical issue of embryonic stem cells

Answer 15

-The use of embryonic stem cells can divide opinion.
-Some people are FOR the use of embryonic stem cells
-Some people are AGAINST it, because it involves the destruction of the embryo.

Question 16

Cancer Cells

Answer 16

-Cancer cells divide excessively because they do not to respond to regulatory signals.
-This results in a mass of abnormal cells called a tumour.
-If cancer cells within the tumour fail to attach to each other, they spread through the body where they form secondary tumours.