Chapter 8 Cell Diversity

Plant Tissues

There are 4 main types of tissue:

Dermal Tissue

Vascular Tissue

Ground Tissue

Meristematic Tissue

Dermal Tissue

A single layer of cells that surround

different parts of the plant

e.g. epidermal cells

2. Vascular Tissue

-Transports materials around

the plant. It consists of two cell

types: xylem and phloem

Xylem

Animal Tissue

There are four main kinds of animal tissue:

Epithelial Tissue

Connective Tissue

Muscular Tissue

Nervous Tissue

e.g. Adipose tissue (which stores fat (under the skin) cartilage, bone and blood.

cord.

Tissue Culture: The growth of cells in or on a sterile nutrient medium (artificial environment) outside an organism.

In vitro means outside the body.

The sample of tissue is removed from the plant/animal and grown in glassware/bath/bioreactor under carefully controlled conditions.

Applications of Tissue Culture

1. Plant Breeding

Micro-propagation is the growth of large numbers of plants

from very small pieces e.g. plant tissue/plant cells.

Steps involved:a) A plant is cut into many small pieces (from one to

a few thousand cells).

b) Cells are grown (cultured) in a lab using a suitable

medium. In time they form a clump of cells (callus).

c) The growing conditions are changed so the callus

continues to grown.

After some time a plant embryo and then a young plant

is formed.

d) When the young plants are sufficiently large they

may be planted out as normal.

2. Cancer Research

Antibodies are special proteins that react with (or join onto) one particular chemical (called an antigen). Antibodies are produced by white blood cells. Cancer cells produce special antigens (chemicals) not present on normal body cells. Monoclonal Antibodies (MABs) have been produced by tissue culture that react with the antigens on cancer cells.

Benefits of Monoclonal Antibodies for Cancer

1. MABs may change colour when they react with cancer antigens. They are used to find out if a sample of cells is cancerous.

2. If toxic drugs are attached to the MABs then the drug is only delivered to the cancer cells.

Skin Grafts

Tissue culture can be used to grow new skin for people.

Previously skin had to be taken from another part of the body e.g. thigh and transplanted onto the damaged area. Stem cells are often used to grow new skin. These are cells that can develop into any body tissue. Stem cells are taken from either embyros, bone marrow and umbilical cord.

Organs

An organ is a structure composed of a numbe3r f tissues that work together to carry out one or more functions.

Plant organs: roots, stems, leaves

Animal organs: stomach, brain, liver

Organ Systems

An organ system consists of a number of

organs working together to carry out one or more

functions. E.g. respiratory system in humans.

Biological Organisation – Organisms are organised in the following

manner.