Biology Topic 13: Prokaryotes, Protists, & Fungi

Biodiversity

The variety of life - in the world, or a habitat, or an ecosystem

Archaea and Bacteria are____ closely related

NOT

Archaea and Bacteria are similar because:

1) both have prokaryotic cells

2) both lack nucleus and other membrane-bound organelles

3) they are all unicellular (entire organism consists of one cell)

About __% of bacteria cause disease - to date there are ____ clear examples of archaea’s that cause disease

10% ; NO

Ecological benefits seen in BACTERIA:

1) plant growth

2) nutrient cycles

3) decomposition

4) oxygen production

5) soil stabilization and fertility

Prochlorococcus

• discovered in 1988

• Most abundant photosynthesizing organism on the planet

• Produces 1/5 of the world’s oxygen

Rhyzobium

-lives in plant roots

-provides nitrogen for plants

E. coli - man varieties

-some varieties normally live in human and other animal digestive tracts

-can keep diseases away and produce vitamin k

-some kinds are harmful!

C. Botulinum

• produces one of the deadliest toxins known

• Minute amounts used in Botox treatment

Antibiotics kill bacteria, but _____ archaea

NOT

Archaea have chemical similarities to cells of ______.

Eukarya

Methanobrevibacter smithii

• most common archaean in the human gut

• Produces methane (a gas)

Prometheoarchaeum

• contains many genes found otherwise only in eukaryotes

• Thought that its ancient ancestor gave rise to eukaryotes including humans

Microbiome

• Community of microorganisms (microbiota) that live on and in our bodies

• Includes both bacteria and archaea

• Outnumber your body cells

• Microbiota protect and help us to: prevent disease organisms from growing, produce vitamins, digestion, healthy weight and immune systems

Characteristics of Eukryotes:

• Cells contain nucleus and membrane-bound organelles

• Cells 10x bigger than prokaryotic cells

• Often multicellular (organism has many cells)

Domain Eukarya contains:

• Plants

• Fungi

• Animals

• “Protists”

Protists

• They all have eukaryotic cells

• All eukaryotes that are NOT plants, animals, or fungi

• The eukaryotic cells that don’t quite fit in

• Some single cell, some multicellular

• May be animal-like, fungus-like, or plant-like

• Most live in water, some in soil / hosts

Algae

Plant-like protists that are producers (i.e green algae, brown algae, and dinoflagellates)

Green algae

• have chlorophyll like plants

• Thought to be like the ancestor of plants

Brown algae

• includes giant kelp

• Hugely important to marine life off the Californian coast

Dinoflagellates

• common in the ocean

• Some highly toxic ‘red tide’

• Some can light up at night

• Includes zooxanthellae in corals

Protozoans

• animal-like protists that are consumers

• Some are parasites such as the malaria organisms

• Some are predators such as paramecium

Fungi are within Domain…

Eukarya

fungus is a …

heterotrophic (consumer) eukaryote that acquires nutrients by absorption

• must obtain energy from other organisms

Fungi are usually…

multicellular – yeast is the exception

fungi body is made of…

hyphae- threadlike flaments

Obtaining food ‘by absorption’ means that…

fungi digests food outside

itself and then absorbs nutrients

• Important characteristic of fungi

Ecological Benefits of Fungi

-Plant growth

• Decomposition

• Unlike bacteria, no fungi produce oxygen

Example of fungi crucial in plant growth

Fungus gives soil minerals and water to plant, plant gives sugar to fungus

Plants can communicate_________________through fungus threads

chemically

Fungi are…

Decomposers

• can break down things no other type of organism can (canvas, wood, some toxic chemicals)

Human Uses of Fungi:

- Mushrooms (reproductive structures)

• Yeast (bread, beer, soy sauce)

• Antibiotics produced by some molds (kill bacteria)

• Cheese

Pathogenic Fungi

About 30% of fungi cause disease, most on plants

• 80% of plant diseases are fungal

– Smuts are common on grains

– Ergot is toxic, can poison grain