Bacteria and Protists

Bacteria and Protists Chapters 3 and 4 Red Book

Characteristics of Bacteria • Bacteria are living cells that carry on all the processes of life. • Bacteria live everywhere • On food and in drinks • In the air • On the surfaces of everything you touch • 1000’s of meters underground • On your skin • In your body

Structure of Bacteria • 3 basic shapes • Cocci – round spheres • Bacilli – rod shaped • Spirilla – spiral shaped • Contains cytoplasm surrounded by a cell membrane and a cell wall • Genetic material in the cytoplasm • Circular piece of DNA called “Plasmid” • Ribosomes in the cytoplasm

Obtaining Food and Energy • Producers - Some bacteria with chlorophyll make their own food. Other bacteria use energy from chemical reactions to make food. • Consumers – Do not make their own food. Can break down dead organisms to obtain energy or live as parasites and get energy from their hosts.

Classification of Bacteria • Two kingdoms • Eubacteria – the larger of the 2 kingdoms, diverse organisms. Grouped according to cell shape and structure, the way they obtain food, type of food they eat and the wastes they produce. • Archaebacteria – contains bacteria that often is found in extreme conditions.

Beneficial Bacteria • Most bacteria is helpful, only a few cause illness • Bacteria in your intestines produce Vit. K, some produce antibiotics • Some bacteria decompose dead material and help recycle nutrients • Some change nitrogen in the air into nitrogen that plants can use. • Some help clean up the environment • Some are in food – cheese, yogurt, vinegar, pickles

Harmful Bacteria • Some bacteria are known as pathogens • A pathogen is any organism that causes disease • Enter body through cut in skin, inhaled, or various other ways • Once inside the body, they multiply, damage normal cells, and cause illness and disease • They may produce toxins as well

Pasteurization • The process of heating food to a temperature that kills most harmful bacteria but causes little change to the taste of the food.

Treating Bacterial Diseases • Antibiotics – destroy bacteria in various ways • Vaccines – prevent bacterial diseases

Protists • What exactly is a protist? • It’s a one- or many-celled organism that lives in moist or wet surroundings. They are all made of eukaryotic cells. • They are divided into 3 groups: plant-like, animal-like, and fungus-like.

Plant-Like Protists • These protists contain chlorophyll in chloroplasts and can make their own food. • Many have cell walls like plants. • Some have structures that hold them in place. • Also known as Algae. Maybe one or many celled. • Not all are green!

Types of Plant-Like Protists • Diatoms – found in water, look yellow-brown, their cell walls contain silica. They are used in road paint. • Dinoflagellates – have 2 flagella which cause the cell to spin. Almost all live in salt water. Most have chlorophyll and make their own food, however some don’t and must feed on other organisms.

More Types of Plant-Like Protists • Euglenoids – Have characteristics of both plants and animals. Many have chloroplasts, many move by whipping their flagella. • Green algae – about 7,000 species. The most plant-like of all the algae. Most live in water although others can survive in moist environments.

…And Even More Types of Plant-Like Protists • Brown Algae – usually found in cool, salt-water environments. Many-celled and vary in size. Giant kelp is the largest organism in the protist kingdom and can grow to be 100m in length. • Red algae – sometimes called seaweed, it contains both chlorophyll and lots of red pigment. It lives up to 200 m deep in the ocean.

Importance of Algae • Most animals that live in the ocean either eat algae themselves, or they eat an animal that eats algae. Algae is an important source of food. • They produce oxygen • Used in foods and products – cosmetics, toothpastes, puddings, salad dressings, ice cream and marshmallows, rubber tires and hand lotion.

Animal-Like Protists • Also known as protozoans • Different types – ciliates, flagellates, pseudopods, and non-movers • They are classified by how they move

Ciliates • Protists with cilia, or short threadlike structures that extend from the cell membrane • These cilia beat in a coordinated way, causing the organism to swiftly move. • They usually eat bacteria that’s swept into the oral groove; wastes are removed through the anal pore

Flagellates • Move through their environment by whipping their long flagella (tail). • Many live in fresh water, some are parasites that harm their hosts.

Pseudopods • Pseudopod = “false foot” • Move through their environment by extending their cytoplasm in temporary extensions called pseudopods • They also use their pseudopods to capture their prey.

Importance of Protozoans • Important source of food for larger organisms • Some cause diseases in humans

Fungus-like Protists • Slime molds – help dead things decay • Water molds, downy mildews – live in water or moist environments. Most are parasites that feed on plants and animals and kill them, some feed on dead organisms

Importance of Fungus-like Protists • Help break down dead organisms • Cause diseases in plants and animals • Downy mildews can have huge effect on economics – cause the Irish potato famine, still affects crops today

Bacteria and Protists