B2.3 Cell specialisation

Question 1

Cell differentiation

Answer 1

Where newly formed cells become more specialised & distinct from one another

Question 2

What causes cells to differentiate?

Answer 2

Activation of different instructions (genes) within a given cell by chemical signals

Question 3

Why are cells specialised in multicellular organisms?

Answer 3

To carry out specific functions

Question 4

Differentiation

Answer 4

Where unspecialised cells develop into cells with a more distinct structure & function

Question 5

Advantages of specialisation

Answer 5

Increased efficiency in carrying out specific functions by specialised cells in multicellular organisms

Question 6

Stem cell

Answer 6

An undifferentiated cell of a multicellular organism that can form more cells of the same type for an unspecified period

Question 7

What is self renewal in stem cells?

Answer 7

Continuous division & replication

Question 8

What is potency in stem cells?

Answer 8

Where they have the capacity to differentiate into specialised cell types

Question 9

What are the 4 types of stem cells

Answer 9

Totipotent
Pluripotent
Multipotent
Unipotent

Question 10

Explanation of totipotent

Answer 10

differentiate into any type of cell, including a whole organism

Question 11

Explanation of pluripotent

Answer 11

Differentiate into all body cells but cannot rise whole organism

Question 12

Explanation of multipotent

Answer 12

Differentiate into a few closely related body cells

Question 13

Explanation of unipotent

Answer 13

Only differentiate into associated cell type

Question 14

Formation of stem cells

Answer 14

1. Diploid single cell (zygote) begins dividing
2. It becomes a solid ball of about 16-32 cells (morula)
3. Another 6 more days, morula becomes a hollow ball (blastocyst)
4. Outer cell (trophoblast) will become the placenta
5. Inner cell mass (ICM) will become the embryo

Question 15

Morphogens

Answer 15

Give the cells ‘form’

Question 16

How does concentration affect morphogens?

Answer 16

Higher concentration of morphogens near secreting cells, lower concentration further away

Concentration gradient is detetcted by receptors on the embryo cells & respond accordingly

Question 17

How does the microenvironment influence how the cell differentiates?

Answer 17

Stem cells interact with extracellular matrix with signaling molecules in the matrix either telling cells to remain dormant or to active gene expression

Can lead to creation of more stem cells OR existing cells to differentiate

Question 18

What is the largest organ in the body

Answer 18

The Skin

Question 19

What regenerates new hair follicles?

Answer 19

stem cells

Question 20

How do stem cells work in the treatment of leukaemia?

Answer 20

1. Harvest hematopoietic stem cells (HSC’s) - can be taken from bone marrow, peripheral blood or umbilical cord blood
2. Patient undergoes chemotherapy & radiotherapy to get rid of diseased white blood cells
3. HSC’s transplanted back into bone marrow, where they differentiate to form new healthy white blood cells

Question 21

Leukaemia results in… blood cells

Answer 21

An abnormal number of white

Question 22

Factors that influence cell size

Answer 22

SA:V ratio

As size or volume of a cell increases = SA:V ratio reduces

Question 23

Example of a single celled organism with a large surface area to volume ratio

Answer 23

Amoeba

Question 24

What happens is a cell continues to grow

Answer 24

Not enough of the necessary molecules can get in & not enough waste can get out

Question 25

When a cell continues to grow what happens & why

Answer 25

Divides Large SA:V ratio is restored

Question 26

What is the biggest cell in humans?

Answer 26

Egg (ovum)

Question 27

What is the smallest cell in humans?

Answer 27

Sperm