Differentiation in Somatic Cells Higher Human Biology Unit 1 – Sub-Topic 1 (b)

Learning Intention To discuss what somatic cells are and cells that arise from the differentiation of somatic cells.

Somatic cells – What is a somatic cell? B Lymphocyte Smooth muscle Hyaline cartilage

Somatic cells - examples Ciliated epithelial cell neutrophil Red blood cell platelets

Somatic cells - examples Cardiac muscle Squamous epithelial cells T lymphocyte Nerve cells

Somatic cells divide by mitosis to form more somatic cells Somatic cells are the differentiated cells that form the different types of body tissue that exist. Somatic cells divide by mitosis to form more somatic cells Somatic cells are produced by cellular differentiation where a cell develops more specialised functions by expressing the specific genes needed for each cell type. Please see comments in Teacher notes regarding protein expression

Tissues and organs Body organs are formed from a variety of tissues made from somatic cells. E.g. Epithelial cells which cover the body surface and line body cavities (E.g bladder, respiratory etc) Connective tissue includes blood, bone and cartilage cells Muscle cells form muscle tissue Nerve cells form nervous tissue

proteins characteristic for that type of cell. Once a cell becomes differentiated it only expresses the genes that produce the proteins characteristic for that type of cell. DON’T MEMORISE. Remember that specialised blood cells are produced by cell division ( mitosis) and gradually become different as they specialise by:- Differentiation specialised genes being switched on for each cell type only making specialised proteins to help them perform their function

Think………… Can you name a specialised protein in each of the somatic cells below? Red Blood Cell Phagocyte Lymphocyte Thrombocycte

Give an account, with examples, of the different body tissue types and their functions. (8 marks) Body tissue cells derive from somatic stem cells … by repeated mitosis. Epithelial tissue - covers the organ surfaces. Protection - skin / secretion - intestinal glands / absorption - villi. Connective tissue - gives shape to organs and supports them. Protection - skull bones / structural framework - ribs / storage of energy - adipose tissue / connecting body organs - blood / connecting epithelial to muscle tissue - cartilage (in tendons) Muscle tissue - which causes locomotion or movement within organs. Skeletal muscle - locomotion / smooth muscle - in arterioles control of access to capillary bed / cardiac muscle - contraction of the heart. Nervous tissue - which transmits messages between the central nervous system and the rest of the body (and within the central nervous system). Neurons - conduct impulses / glial cells - maintain a constant environment for neurons.

Learning Outcomes Somatic cells divide by mitosis to form more somatic cells. (b) Cellular differentiation is the process by which a cell develops more specialised functions by expressing the genes characteristic for that type of cell. (c) Once a cell becomes differentiated it only expresses the genes that produce the proteins characteristic for that type of cell.