Cell Diversity - Chp 8

Tissue

a group of cells that work together and are adapted to carry out the same function

2 types of plant tissue

• Dermal tissue
• Vascular tissue

2 types of animal tissue

• Connective tissue
• Nervous tissue

Dermal tissue - description + function + adaptation

• surrounds different parts of the plant, acts like the skin
• protects the plant
• can contain a waxy cuticle to prevent water loss

Vascular tissue - description + function + adaptation

Xylem - transports water and minerals - hollow tubes that run from the roots up to the leaves
Phloem - transports food - series of tube like structures

• xylem and phloem are located in vascular bundles throughout, and reaches all parts of the plant

Connective tissue - description + function + adaptation

• made of a large amount of cells spread out in a matrix
• joins and supports other body structures
• red blood cells have a biconcave shape which increases surface area and allows oxygen to attach

Nervous tissue - description + function + adaptation

• composed of neurons
• neurons carry electrical impulses to and from the brain and spinal cord
• well insulated, allowing the impulse to travel faster

Organ

a structure composed of a number of tissues that work together and carry out one or more functions

Plant organ example

root

Animal organ example

heart

System

consists of a number of organs working together to carry out one or more functions

Plant system example

root system

Animal system example

• circulatory system
• respiratory system

Tissue culture

the growth of tissues in or on an artificial medium outside an organism

Tissue culture process

• tissue sample is removed from a plant or animal and grown in vitro (in glassware) or in a bioreactor under carefully controlled conditions in an artificial environment
• grown by mitosis, producing a cluster of identical offspring

2 applications of tissue culture

• micropropagation of plants
• growing human tissue for organ transplants (skin grafts)

Micropropagation

growth of large numbers of plants from very small pieces

Micropropagation of plants process

• plant cut into very small pieces
• cells grown in lab with suitable medium
• form clump of similar cells called callus
• growing conditions are changes so callus continues growing
• young plant embryo is formed
• when young plants grow large enough they are planted like a normal plant

Micropropagation of plants benefits

• produces exact copies
• quick
• does not require pollinators (which are quite slow generally)

Skin grafts process

• stem cells (either from bone marrow or umbilical cord) often used to grow new skin
• skin graft then transplanted onto the burned area

Skin grafts benefits

• no need to remove skin from other parts of the body
• new skin identical to patient's skin, no risk of rejection