Differentiation Higher Human Biology
Jan 04, 2016
Differentiation
Higher Human Biology
Differentiation
• unspecialised cells become altered and adapted
• perform a specialised function• permanent tissue• Division of labour • Multicellular organisms
Differentiation in Human Cells
• Fertilised egg (zygote)• Divides rapidly by
mitosis and cell division to form an embryo
• Many different specialised cells created – each adapted to suit its function.
• Each embryonic cell contains all the genes for constructing the whole organism
• Unlike adult cells these genes are either switched on/ have the potential to be switched on.
• As embryological development proceeds embryonic cells become differentiated and specialised in;– Structure– Biochemical properties
• Perfectly adapted to carry out particular functions.
Somatic cells
B Lymphocyte
Hyaline cartilage
Smooth muscle
Somatic cells
Ciliated epithelial cell
Red blood cellplatelets
neutrophil
Somatic cells
Cardiac muscle
Nerve cells
Squamous epithelial cells
T lymphocyte
Selective Gene Expression
• Differentiated cells only express the genes that code for the proteins specific to the workings of that particular cell.
Nerve cells - genes that code for formation of neurotransmitter substances switched on - genes for production of mucus switched off.
Goblet cells – genes that code for mucus production switched on- Genes that code for neurotransmitters switched off.
• Only a fraction of genes in a specialised cell are expressed.
• Approx 3 – 5 % in a typical human cell.