Cell As A Unit Of Life

CELL AS A UNIT OF LIFE

 

ANIMAL CELL

PLANT CELL

FUNCTION OF CELL STRUCTURES

COMPARISON OF ANIMAL AND PLANT CELL

What are microorganisms?

There are many small organisms in the world that we call micro-organisms or microbes. Some are harmful - they may cause illness. Bacteria and viruses may carry diseases. Keeping clean can help prevent these diseases. Keeping our food carefully can help prevent them, too. Micro-organisms live and reproduce on food. Eating poorly-kept or decaying food can cause food poisoning.

But other micro-organisms do a great deal of good. Without them, nothing would decay, and so materials from dead plants and animals would not return to the soil to be used again. Rubbish would pile up forever.

Other micro-organisms help in the production of food. Yeast is a micro-organism - a kind of fungus that produces bubbles of gas that makes bread rise. Bacteria are essential to making yoghurt and cheese

BACTERIA

Bacteria are micro-organisms.

Some bacteria are harmful to the human body.  Given the right conditions, bacteria will grow and multiply.

Bacteria grow most rapidly:

·    in certain foods;

·    at body temperature (37⁰C)

They are killed at high temperatures.

They are dormant at low temperatures (below O⁰C). 

3 groups of bacteria:-

• spirilla (with a spiral body shape);
• cocci (with a spherical body shape);
• bacillus ( with a rod (stick) shaped body.

CYANOBACTERIA

Cyanobacteria are aquatic, photosynthetic organisms

sometimes called blue-green algae

they make their energy through photosynthesis

cyanobacteria live in water, damp soil and rocks

PROTOZOA

Sometimes they are also called protists

neither plants nor animals

Some protozoans, like Euglena, have chloroplasts like plants and make their own food

can be free-living or parasitic

unicellular or colonial

Protozoans move around using their flagella or pseudopodia - cytoplasmic temporary 'feet'

FUNGI

Fungi are saprophytic (feed on decaying organic matter) and parasitic organisms

include moulds, rusts, mildews, smuts, mushrooms and yeast

All fungi are made of eukaryotic cells

can be single-celled or with cells arranged in filaments

All fungi are heterotrophic

None of the fungi are photosynthetic

Some fungi are parasites and can cause diseases in humans, animals and plants

VIRUSES

Viruses are much smaller than common microbes

They are made of a DNA molecule covered with a protein shell called a capsid

Viruses cannot reproduce outside the host cell

often cause diseases in organisms

Try out these cool activities :

Make your own microbes!