Ch. 8 Cell Diversity

cell – tissue – organ - system Defn: A cell is the smallest basic unit of living things Defn: A tissue is a group of similar cells that are modified (or adapted) to carry out the same functions Simple Tissue = 1 cell type Complex Tissue = > 1 cell type

Plant Tissue (need to know 2) Main types 1.Dermal 2. Vascular 3. Ground 4. Meristematic Dermal Tissue A single layer of cells that surrounds different parts of a plant. E.g. The Epidermis

E.g. The Epidermis Location An outer covering on leaves, stems & roots Description Living, rectangular shaped cells Slightly thickened cell wall Can have a waterproof layer called the Cuticle on outer surface Function Protection Waterproofing if Cuticle is present

(2) Vascular Tissue Transportation of minerals around plant A complex tissue – 2 types of cells i.e. xylem & phloem

Xylem Description Hollow tubes running from root, through stem & into leaves Function Transport water & dissolved minerals Support in woody plants

Phloem Description Tube like structures Found in leaves, stems & roots Function - Transport food from leaves to other parts of plant

Animal Tissue 4 main types: Epithelial, Connective, Muscular (can contract) & Nervous Tissue **need to know 2 in detail

Connective Tissue connects/binds other tissues together E.g.'s Adipose tissue (stores fat), Cartilage, Bone Blood

Blood Tissue Consists of: - red cells (carry oxygen), - white cells (defence) platelets (clot blood) All suspended in a liquid called plasma

Nervous tissue Description Compound of nerve cells called Neurons Function Neurons carry electrical impulses to & from brain & spinal cord

Learning Check Can you name 3 types of cell? What is a tissue? Can you recall 2 types of animal tissue? Can you recall 2 types of plant tissue?

Tissue culture Defn: Tissue culture is the growth of cells in or on a sterile nutrient medium outside an organism How it works? A tissue sample is removed from a plant or animal & grown in glassware (in vitro – outside the body) in a bath of sterile nutritive fluid which often contains hormones and growth substances

Growth is by mitosis and produces a cluster of identical offspring - a clone Main conditions necessary for Tissue culture Absence of contaminating microorganisms Food, vitamins & minerals Substances to stimulate growth (e.g hormones) Oxygen Correct pH

Q. Suggest a reason why sterile conditions are needed in tissue culture? A. to prevent bacterial growth or contamination

Stages in Tissue Culture Example of tissue culture is Organ transplants Skin cells obtained Enzymes added Individual Cells isolated Controlled culture medium Sheets of cells grown

Applications of Tissue Culture Plant breeding = Micropropagation Cancer research Skin grafts **need to know 2

Applications of tissue cultures Virus reproduction Hela cells used to grow and investigate viruses **Micropropagation of plants Produces exact copies Quickly produces mature plants Doesn’t need pollinators or seeds Producing plants that are disease resistant and virus free

Applications of tissue cultures **Growing human tissue for organ transplants Skin cells Liver cell Pancreas cells Producing biotechnology products Insulin Interferon Pregnancy testing kits Drug testing kits Cancer testing kits

(2) Skin Grafts New skin can be grown from cells (usually stem cells)

Learning Check What is Tissue Culture? What kind of conditions do cells in tissue culture need? What are the stages of tissue culture? Can you name two uses for tissue culture?

Organs Defn: An organ is a structure composed of a number of tissues that work together to carry out one or more functions Examples of Plant Organs: root, stem, leaves, flowers, stems & fruit Examples of Animal Organs: stomach, brain, liver, kidney & heart

Need to know 1 E.g. of a Plant Organ Organ: Leaf Tissues it contains: Dermal (found in Epidermis) Vascular ( found in Vascular bundle as Xylem & Phloem tissue) Ground ( found as Palisade & Mesophyll Cells)

Highlight Tissue types in the diagram in your book

E.g. of An Animal Organ Organ: Heart Tissues it Contains: Muscle tissue called Cardiac Muscle Enclosed in Pericardium (a membrane - contains epithelial tissue) Connective Tissue ( blood & vessels) Controlled by Nervous Tissue

An Organ System: consists of a number of organs working together to carry out one or more functions All organ systems combine to make the organism

Numerous organ systems in human The Circulatory System: heart, blood vessels, blood & lymph Function: transport materials & fight infection The Digestive System: mouth, oesophagus, stomach, small intestine, large intestine & Anus Function: Take in food, break it down, & transfer it to the circulatory system.

Learning Check What is an organ? Can you name 2 plant organs? Can you name 2 animal organs? What is an organ system? Can you recall 2 animal organ systems?