Cell Differentiation and Organisation

Success Criteria Describe the term differentiation with reference to the erythrocytes and neutrophils and the production of xylem and phloem from cambium. Describe and explain how cells of multicellular organisms are specialised for particular functions. Explain the terms tissue, organ and organ system. Explain how cells are organised into tissues – epithelial cells, xylem and phloem. Discuss the importance of cooperation between cells, tissues, organs and organ systems

Cell Differentiation Cell differentiation – the process by which cells become specialised for different functions. HOW? All cells contain the same genes, so why do they look and act differently? Different genes are switched on and off in each of the specialised cells.

How do cells differ? They differ in shape They differ in the number of each organelle - Examples? Contents of the cell Sperm cell – many mitochondria / White blood cell – many lysosomes / Muscle cells – many mitochondria

Tissues Tissue – a collection of cells (not necessarily identical ones) that perform a specific function. Examples: Epithelial Tissues Xylem Tissues http://en.wikipedia.org/wiki/Tissue_%28biology%29

Organs Organ – a combination of tissues that are coordinated to perform a variety of functions. Examples: Stomach – What tissues is it made from? Leaf – What tissues is it made from? Stomach – made from muscle (to churn), epithelium (to protect and produce secretions) and connective (to hold together the other tissues) Leaf – palisade (photosynthesis), mesophyll (gas exchange), phloem (sucrose), xylem (water)

Organs Organ – a combination of tissues that are coordinated to perform a variety of functions. Examples: Stomach – made from muscle (to churn), epithelium (to protect and produce secretions) and connective (to hold together the other tissues) Leaf – palisade (photosynthesis), mesophyll (gas exchange), phloem (sucrose), xylem (water) Stomach – made from muscle (to churn), epithelium (to protect and produce secretions) and connective (to hold together the other tissues) Leaf – palisade (photosynthesis), mesophyll (gas exchange), phloem (sucrose), xylem (water)

Organ Systems Organ Systems – organs work together as a single unit. Examples: Digestive System – What organs is it made from? Respiratory System – What organs is it made from? Circulatory System – What organs is it made from? Digestive System – salivary glands, oesophagus, stomach, duodenum, ileum, pancreas, liver Respiratory System – trachea, bronchi, lungs Circulatory – heart, arteries, veins, NOT capillaries (these are a tissue)

Task Example 1 Example 2 Organ System Organ Tissue Cell CELL- myocardiocyteal muscle cells TISSUE- Cardiac Muscle Tissue ORGAN- Heart ORGAN SYSTEM- Cardiovascular System

Describe, using examples, the difference between cells, organs and organ systems. (6)

Specific Cells – case 1 Blood Cells Blood cells all have the same DNA but all do different jobs. Blood cells are all produced from undifferentiated stem cells in bone marrow.

Copy and complete the following table using page 34-35 Type of cell Role Structure of cell Erythrocyte Neutrophil Sperm Cell Root Hair Cells Learn these examples

Types of Tissue Xylem – transport water around plant and provide support. Thickened walls with perforated pits Parenchyma cells fill gaps between vessels

Types of Tissue Phloem –moves sugars around the plant. Sieve cells, tubes and companion cells Sieve plate allows sap to move through easily. Companion cell assists cells with living functions. Sieve cells have sieve plates at the ends.

Cambium contain stem cells. These make the xylem and phloem cells. The vascular cambium forms a ring inside roots and shoots Cells grow out from the ring as the differentiate.  Rings on trees.

Animal Tissues Epithelial Cells – layers and linings e.g. in the lungs. Connective tissues – hold structures together and provide suport e.g. bone and cartilage. Muscle tissue – cells specialised to contract. Nervous tissue – cells that convert stimuli into impulses.

Epithelial tissue

Squamous Epithelial Cells These are thing flattened cells. They provide a thin, smooth, flat surface. They are used for lining tubes where fluids can pass over them easily. They are found in the alveoli – short diffusion pathway. These are held in place by the basement membrane which is secreted by the epithelial cells. It is made of collagen and glycoproteins. This attaches the epithelial cells to the connective tissue.

Ciliated Epithelial Cells Column shaped cells Inner surface of tubes e.g. trachea, bronchi, bronchioles, uterus, oviducts. Cilia cover the surface and some produce mucus. What do they do!?

Complete the worksheet using pages 36-37 This will form your notes.

Organs - Leaves What is the job of a leaf? What is needed for photosynthesis? What has to happen to maintain the rate of photosynthesis?

Roles of cells in plants Feature Function Transparent surface layer Layer of cylindrical palisade cells under epidermis Loosly packed spongy mesophyll layer Lower epidermis – stomata and guard cells Veins

Opening and closing stomata