Cell Diversity

Tissues

Tissues are a group of structurally similar cells carrying out a particular function.

Plant Tissues: dermal, ground, meristematic, vascular (xylem, phloem).
Animal Tissues: connective, nervous, adipose, muscular.

 

Organs

An organ is formed from a group of different tissues working together performing a specific job.

Plant Organs: root, stem, leaf.
Animal Organs: skin, heart, liver, kidney.

 

Organ System:

Organ systems are a group of different organs operating together carrying out a definite task.

Animal Organ Systems

·         Digestive system: to digest and absorb food.

·         Circulatory system: to transport foods, wastes, etc.

·         Nervous system: to co-ordinate movement and other responses.

·         Skeletal system: to support, protect and for movement.

·         Reproductive systems: to make new individuals.

·         Urinary system: to excrete urine and to osrmoregulate.

·         Respiratory system: to excrete carbon dioxide and to absorb oxygen.

Tissue Culture

This is the growth and multiplication of undifferentiated cells in a sterile nutrient medium in the lab. The medium must be kept at the correct pH and at an optimum temperature.  Hormones and other growth factors may also be present to keep the cell dividing and/or bring about differentiation. Tissue Culture is used in cancer research: culturing specific type of cancer cell for scientific study, plant breeding: culturing of genetically modified plant cells to produce new variety of food plant and in growing human tissues for transplanting.

 

Stem Cells.

Stem cells have two important characteristics that distinguish them from other types of cells. First, they are unspecialised cells that renew themselves for long periods through cell division. The second is that under certain conditions, they can become cells with special functions such as the beating cells of the heart muscle or the insulin-producing cells of the pancreas.

Stem cells are important for living organisms for many reasons. In the 3- to 5-day-old embryo, stem cells in developing tissues give rise to the different cell types that make up the heart, lung, skin, and other tissues. In some adult tissues, such as bone marrow, muscle, and brain, adult stem cells generate replacements for cells that are lost through normal wear and tear, injury, or disease. Stem cells may, at some point in the future, become the basis for treating diseases such as Parkinson's disease, diabetes, and heart disease