Homework Text p160-1 Green application questions OR Presentation work 1 side a4 on xylem cells and 1 side a4 on root hair cells

Cell Differentiation and organisation Text p.172-3

Objectives What are the advantages of cellular differentiation? How are cells arranged into tissues? How are tissues arranged into organs? How are organs arranged into organ systems?

Specialised cells In a single-celled organism, all the functions necessary for life must be carried out in one cell. In contrast, multicellular organisms can delegate jobs to particular groups of cells. Cells that have adapted to a specific function are known as specialised cells. Specialised cells of one type are grouped into tissues, which combine to make organs and organ systems.

Cell differentiation A d… cell is adapted to perform a specific function. All cells are originally the same after … including the DNA/genes In different types of cell different genes are … So they change (adapt/differentiate) to suit the … it will perform Differences include shape, structure and number of … A differentiated cell often loses the ability to carry out other functions except the one it is … for. It relies on other cells within the organism cell division, organelles, switched on, adapted, differentiated, function

Tissues, organs and organ systems

Plant structure

Tissues An aggregation of similar cells that perform a specific function e.g. Epithelial tissues e.g. Xylem

Organs An aggregation of tissues that are co- ordinated to perform a specific physiological function 1.The stomach is an organ consisting of which tissues? 2.A leaf is an organ consisting of which tissues? 3.Why are arteries and veins organs but capillaries only tissues? (pic p.186)

Organ systems Organs are organised into systems List the organs in the digestive, respiratory and circulatory systems. How many other systems can you name? How many plant systems can you name?

Plus: Endocrine Immune Lymphatic SYSTEMS

Tissue/Organ/System? Heart Muscle Trachea Artery Salivary glands Epithelium Ligament Eye Xylem Root Leaf Phloem Flower Pallisade cells Vein Lower epidermis

Extension – Stem cells Stem cells are the master cells of the human body. They can divide to produce copies of themselves and many other types of cell. They are found in various parts of the human body at every stage of development from embryo to adult. Stem cells taken from embryos that are just a few days old, can turn into (differentiate) any of the 300 different types of cell that make up the adult body.

Stem cells

Stem Cells

Why are stem cells useful? Because stem cells are so versatile, they could potentially be used to repair and replace damaged human tissue. In future it is hoped that stem cells could be used to treat and cure a variety of diseases and injuries including Parkinson's disease, stroke and diabetes.

Where do the embryos come from? Embryonic stem cells can be taken from spare human embryos left over from fertility treatments, or from cloned human embryos developed in the laboratory. Stem cells can be taken from umbilical cord

Rest phase Cells often stop dividing once they are fully differentiated, so where do they fit into the cell cycle? Specialized cells move from G1 into a resting phase known as G0. G0 is also the phase in which stem cells wait until their associated body cells need replacing. A cell may remain in G0 for the rest of its lifetime, or it may just rest in this state temporarily. G0

Cell differentiation