Cell specialisation

Question 1

What is fertilisation?

Answer 1

Fertilisation is a multi-step process in which a sperm and egg cell fuse to form a single cell called a zygote.

Question 2

In what does fertilisation occur?

Answer 2

Fertilisation cours in sexually reproducing organisms that produce haploid gametes (e.g. in plants and animals).

Question 3

What happens when the zygote is divided by mitosis?

Answer 3

The zygote is divided by mitosis to form an embryo composed of genetically identical cells.

Question 4

What are the cells in the zygote and embryo?

Answer 4

The cells in the zygote and embryo are unspecialised stem cells.

Question 5

What happens to the zygote and embryo (unspecialised stem cells) as the cells of the embryo continues to divide?

Answer 5

As the cells of the embryo continue to divide, they begin to specialise in structure and function.

Question 6

What does cell specialisation allow cells to do?

Answer 6

Cell specialisation allows cells to perform a function with increased efficiency.

Question 7

What is differentiation?

Answer 7

Differentiation is the development of specialised structures and functions in cells.

Question 8

When does differentiation occur?

Answer 8

Differentiation occurs when different cell types express different genes.

Question 9

What is gene expression?

Answer 9

Gene expression is the process by which the information encoded in a gene is turned into a function.

Question 10

How does the position of a cell within the embryo determine how it differentiates?

Answer 10

The position of a cell in an embryo impacts how it differentiates by exposing the cell to specific signalling molecules and physical cues from neighbouring cells.

Question 11

What do the positional cues (of a cell in an embryo) create?

Answer 11

They create gradients of molecules called morphogens which establishes a spatial pattern in the embryo. Cells interpret these gradients and other environmental signals to “decide” which genes to express, leading to specialized cell types.

Question 12

Explain the morphogen gradient?

Answer 12

Cells near the source of a morphogen (a signaling molecule that diffuses from one location) receive higher concentrations than those farther away. The concentration of a morphogen at a cell’s position signals which genes to turn on or off, guiding the cell toward a particular fate.

Question 13

What is retinoid acid and what important roles does it have?

Answer 13

Retinoid acid is a morphogen that plays important roles in cell growth, differentiation and organ development.

Question 14

What does retinoid acid do?

Answer 14

It diffuses throughout the embryo switching genes on and off and imparting different cell fates depending on its concentration.

Question 15

What is a stem cell?

Answer 15

A stem cell is a cell that can be divided by mitosis an unlimited number of times.

Question 16

What is a stem cell niche?

Answer 16

A stem cell niche is a specific location where stem cells remain in the human body.

Question 17

Explain how bone marrow is a stem cell niche.

Answer 17

-Bone marrow provides a niche for stem cells which are used to replace red blood cells, white blood cells and platelets
-This is important for continual production of these cells which are required indefinitely

Question 18

Explain how a hair follicle is a stem cell.

Answer 18

-This niche is located at the root of the hair where the hair is anchored into the skin
-Stem cells here promote continual hair growth

Question 19

What are the requirements of the environment of a stem cell niche?

Answer 19

The environment provided by the niche must have
-The ability to maintain an inactive state of the stem cells
-The ability to stimulate stem cell proliferation and differentiation

Question 20

What is potency?

Answer 20

The ability of stem cells to differentiate into more specialised cell types is known as potency.

Question 21

What is totipotency?

Answer 21

Totipotent stem cells are stem cells that can differentiate into any cell type found in an embryo, as well as extra-embryonic cells (the cells that make up the placenta).

Question 22

What are pluripotent cells?

Answer 22

Pluripotent stem cells are embryonic stem cells that can differentiate into any cell type found in an embryo but are not able to differentiate into extra-embryonic cells (the cells that make up the placenta)

Question 23

what are multipoint cells?

Answer 23

Multipotent stem cells are adult stem cells that can differentiate into closely related cell types.

Question 24

What are unipotent cells?

Answer 24

Unipotent stem cells are adult cells that can only differentiate into their own lineage.

Question 25

In what do eukaryotic cells become specialised for specific functions (division of labour)?

Answer 25

In complex multicellular organisms.

Question 26

How does specialisation enable the cells in these tissues to function more perfectly?

Answer 26

They develop specific adaptations for their role. The development of these distinct specialised cells occurs by differentiation

Question 27

How is the structure of a cell adapted?

Answer 27

the structure of a cell is adapted to help it carry out its function (this is why specialised eukaryotic cells can look extremely different from each other)

Question 28

What do structural adaptations include?

Answer 28

Structural adaptations include:
The shape of the cell
The organelles the cell contains (or doesn’t contain)
For example: Cells that make large amounts of proteins will be adapted for this function by containing many ribosomes (the organelle responsible for protein production)

Question 29

What do cells that have differentiated come in?

Answer 29

They come in different shapes and sizes.

Question 30

Give examples of the cells that have differentiated that come in