Differentiation Higher Human Biology Differentiation unspecialised cells become
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 Smooth muscle Hyaline cartilage
Somatic cells neutrophil Ciliated epithelial cell platelets Red blood cell
Somatic cells Cardiac muscle Squamous epithelial cells Nerve 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 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.
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