B2.3 Cell Specialisation

___ organisms have many types of ___ ___ (specific ___ and ___ —> a ___ as ex. gametes)

multicellular organisms have many types of specialised cells (specific structure and function —> a purpose as ex. gametes)

Outline the start of life from fertilisation to beginning differentiation

1. fertilisation: fusion of gametes into one cell, a zygote

2. the zygote undergoes mitosis repeatedly into a solid ball of cells, a morula

3. after 5-6 dyas, the morula differentiates into a blastocyst (trophoblast and ICM), which has begun differentiations. specific layers have received signals about which organ, tissue, ccell type they’ll become

the trophoblast and ICM will each differentiate into

a placenta and an embryo, respectively

___ cells contain the same ___, but not all ___ are ___ at the same time. it is controlled by ___.

ICM cells contain the same genome, but not all genes are expressed at the same time. it is controlled by morphogen.

outline the effect of a morphogen CG

• morphogen is released from a source cell

• the early embryo closer to it experience a higher conc, the farther a lower conc

• affect gene expression differently, causing differentiation along specific pathway (fates)

Outline eachfo the 4 potencies indicate

1. Totipotent: nto any type of cell. Gives rise to complete organism. E.g. early stage animal embryo, morula

2. Pluiripotent: into any body cells. Can’t give rise to a whole organism. E.g. embryonic stem cells of the blastocyst

3. Multipotent: into closely related body cell types. Aka adult stem cells. E.g. umbilical cord stem cells

4. Unipotent: into their associated cell type. E.g. liver stem cells make liver cells

what is the potency of an early-stage animal emrbyo?

totipotent, but soon pluripotent

what is the potency of stem cells in adult tissue?

multipotent

what are the interactions between adult stem cells and their niche and their purposes (2)?

• interactions include:

  • cell-cell interactions

  • interaction with extracellular matrix

  • signal molecules affecting gene expression

• purpose is to:

  • maintain stem cells (self renewal)

  • promote proliferation and differentiation into specialised cells

outline 2 examples of a stem cell niche

• hair follicles have cycles of degenration, growth and rest

• a multipotent stem cell niche at the bulge, is involved in the cycle of follicle regeneration

• also invovled in the production of sebaceous glands and epidermal skin cells

• bone marrow have blood stem cells that

  • create more stem cells

  • OR create a variety of blood cells (multipotency)

List 3 adaptations to higher SA:V ratios with examples

1. flattening (e.g. type 1 pneumocytes)

2. invagination (e.g. erthocytes)

3. microvilli (e.g. proximal convoluted tubule cells in the nephron of the kidney)

Cell SA corresponds to its ___ ___ and its ability to ___ ___

cell V corresponds to its need for ___ of ___ for ___

Cell SA corresponds to its plasma membrane and its ability to exchange materials

cell V corresponds to its need for exchange of materials for metabolism

order from largest to smallest

• WBC

• fat cell

• RBC

• egg cell

• sperm cell

• Neuron

• skeletal muscle cell

1. Neuron

2. skeletal muscle cell

3. WBC

4. RBC

5. fat cell

6. egg cell

7. sperm cell