Biology 2201Unit 2- Biodiversity

Classifying Living ThingsCh. 5 – Mostly Micro-organisms

Ms. K. Morris – 2010-2011

Section 5.1

• Kingdom Bacteria• Kingdom Archaea

–p. 132 - 139

Kingdom BacteriaGeneral Characteristics:

• Cell Type: all are prokaryotic.• Body Form: most are unicellular, some are

colonial. – Three main shapes are:• cocci which are round• bacilli which are rod shaped• spirilli which are spiral shaped

– Also grow in patterns:• diplo are in pairs• staphylo are in clusters• strepto are in chains

• Cell Wall: most bacteria have one, often contains peptidoglycan.

• The cell wall structure and thickness is determined by using a Gram Stain which was developed by Hans Gram.– Gram-positive bacteria have thick walls and

peptidoglycan, which is carbohydrates and proteins. These stain purple.

– Gram-negative bacteria have two cell walls. These stain pink. This type is more common.

• Locomotion: Many are motile, some are non-motile. The ones that are motile move by means of cilia or flagella.

• Nutrition: They can be autotrophs (photosynthetic or chemosynthetic) and they can be heterotrophs.

• There are four groupings based on nutrition:– photoautotrophs– photoheterotrophs– chemoautotrophs– chemoheterotrophs• Refer to page 133

• Reproduction: • Asexual Reproduction by Binary Fission:

– One parent– Genetic material replicates.– Cell elongates.– Septum forms to make two distinct cells.– Daughter cells are formed; they are exact copies of parent cell.– This can occur every 20 minutes.

• Sexual Reproduction by Conjugation:– Two parents (or more in the case of bacteria)– cells become linked and exchange chromosomes.

– Other possible types of bacteria reproduction:• Gene transfer through plasmids. This is used in genetic

engineering.• Spore formation. Involves the production of endospores which

are composed of DNA and a small amount of cytoplasm. They can resist extreme heat or cold, dryness and chemicals.

• Bacteria play vital roles in ecosystems. They are needed for the survival of ecosystems because are important in the nutrient cycles; such as the carbon and nitrogen cycles.

• They are classified by their shape, the structure of their cell walls, and their sources of food and energy.

• Bacteria are found in the air, in the soil, in the water, and on and inside you. They make up the greatest number of organisms.

• They can cause infection inside humans if they build up to a large number. Antibiotics are used to stop the growth of bacteria. Sometimes, bacteria can create a resistance to the antibiotics and then their usefulness declines.

• Examples:

• Bacteria • Cyanobacteria• Blue-green algae • E. Coli

Kingdom ArchaeaGeneral Characteristics:

• Cell Type: all are prokaryotic.• Body Form: most are unicellular, some are

colonial. – There is considerable variation in size; from the

microscopic unicellular arrangements to the very long (over 200m long filaments).

– They can be cocci (round), bacilli (rod-shaped), and spirilli (spiral) shapes (some are triangular and square shape).

• Cell Wall: Archaea have a different cell wall structure than bacteria - No peptidoglycan.

• Archaea have unusual lipids (fats) that remain stable at very high temperatures or very low temperatures.

• Locomotion: Some archaea, like bacteria, do not have movement. Others that can move, do so through 1 or more flagella (same as bacteria). So, many are motile, some are non-motile.

Nutrition: Archaea are chemosynthetic (chemotrophic) bacteria species which can make their own food by converting inorganic substances such as methane and sulphur into organic food.They can be autotrophs:

• Photosynthetic• Chemosynthetic

They can be heterotrophs

• Reproduction:Asexual (binary fission)—most commonSexual (conjugation)– See bacteria notes on this

Many members of this kingdom are extremeophiles that is they live in extreme environments, including water whose temperature exceeds that of boiling water (such as hot spring geysers and sub sea (sea floor) vents). They are also found in acidic or alkaline environments, saline (salty) environments, inside volcanoes, as well as deep below the earth surface.

They are very diverse, both in form and function. These organisms are used in biotechnology

–Archaea differ from the Bacteria in many important respects, as well as from the eukaryotes.

– These differences include: • The wall structure and chemistry • The lipids that make up their membrane • Their metabolism• They look like members of kingdom Bacteria

but their genetic material is very different.

• There is also something special about members of this kingdom because some are able to do cellular respiration without the presence of a certain chemical: Oxygen.

• So, Archaea can be Aerobic or Anaerobic.– Aerobic: use oxygen to carry out life’s processes.– Anaerobic: do not need oxygen to carry out life’s processes.

• Instead they use:– Methane ( CH4)

– Carbon Dioxide (CO2)

– Nitrogen Gas (N2)

– Hydrogen Sulfide (H2S)

• Examples:

• Some are methanogens - organisms which can use methane for food. These live in the guts of animals, such as cows.

• Others are thermophiles - organisms which live under extreme temperatures in hot springs. They often can convert the sulphur in hot water springs into food.

• Halophiles live in salt lakes.

Life Cycle of E. ColiA bacteria representing the Kingdoms Bacteria & Archaea.

• Reproduce asexually using method called binary fission. Can also reproduce sexually using a method called conjugation .

Binary Fission (Asexual) (see diagram in text p. 134, fig. 5.4)• Each bacteria has a single chromosome. Before fission, the

bacteria makes a copy of this chromosome, so it has 2 chromosomes.

• Binary fission has 4 stages:– A. Elongation - when ready to divide , the bacteria gets longer.– B. A septum begins to form - an extension of the cell wall.

Chromosomes separate to opposite sides of the cell.– C. The septum fully forms, separating the bacteria into 2 cells.– D. the bacterium splits into 2 genetically identical bacteria.

• Binary fission takes about 20 min in good conditions. This leads to exponential growth of their populations.

• Binary fission rate is limited by: – (1) predation – (2) unfavorable conditions – ( 3) food

• Has a huge reproductive capacity ( 1 bacterium dividing can result in 1,000,000 offspring being produced in 10 - 12 hours)

• Waste products from some types of disease - causing bacteria produce toxins that lead to food poisoning or infections in humans. Many bacteria are beneficial to us.

• We use bacteria to treat sewage, decompose compost, make cheese and yogurt. Their ability to rapidly multiply is useful for such processes.

Conjugation (Sexual) (see diagram on p. 135, fig. 5.5)• Happens during less favorable conditions• Produces genetic variation in offspring - mixes up the genes for

better chances of survival.

• Conjugation has 4 stages:– A. A pilus forms (Pilus - bridging structures made up of hair-like

tubes that allow microscopic organisms to exchange genetic material during a form of sexual reproduction, such as conjugation)

– B. Two bacteria become connected via the pilus– C. one bacteria transfers all or part of its chromosome to the

other bacteria– D. the recipient bacteria uses the received chromosome material

and later starts to divide by using asexual binary fission. In this way , all of the offspring are now genetically different than either parent.

Section 5.2

• Kingdom Protista–p. 140 - 151

Kingdom ProtistaGeneral Characteristics:

• Cell Type: all are eukaryotic.

• Body Form: most are unicellular, some are colonial, some are simple multi-cellular. –There are a few forms that are multi-cellular,

for example the brown and red algae. –Most though are single-celled organisms,

and are typically only 0.01-0.5 mm in size, too small to be seen without a microscope.

• Cell Wall: some have cell walls, some do not. Composition will vary.

• Locomotion: many are motile (flagella or cilia), some are non-motile.

• Nutrition: some are autotropths, some are heterotrophs (ingestion and absorption) and some both.

• Reproduction: asexual reproduction and/or sexual reproduction.

• The Kingdom Protista is one of the commonly recognized biological kingdoms. They include all the eukaryotes except for the plants, fungi, animals, and sometimes other groups which are treated in separate kingdoms.

• They are most easily defined by what they are not; they are not bacteria, plants, animals or fungi. This is the garbage bucket kingdom where some organisms are placed that cannot fit into the other kingdoms.

• Protists are widespread throughout wet environments and the soil. They are able to survive dry periods by forming cysts; a few others are significant parasites.

– There are 3 groups of Protista, based upon how they get their nutrition:

1. Protozoa (animal-like protists)

2. Algae (plant-like protists that contain chloroplasts)

3. Slime & Water Molds (fungus-like protists)

Protozoa (animal-like)• Feeding on and engulfing other organisms or dead

matter. They can be scavengers, predators, or parasites (that can live inside humans).

• They lack cell walls• Four groups based on their method of movement:– Flagellates one flagella‑– Sarcodines form limb like extensions of cytoplasm ‑ ‑

called pseudopodia (false feet) (amoeba)– Ciliates hundreds of cilia (paramecium)‑– Sporozoans parasites which form spores (plasmodium ‑

vivax)

Algae (plant-like)• Simple and aquatic (live in water)• Contain chlorophyll and carry out photosynthesis

(make their own food)• Once classified as plants• Six types based on types of pigments:– Green algae chlorophyll and cellulose cell walls‑– Brown algae seaweeds with cell walls of cellulose and ‑

pectin– Red Algae seaweeds with cell walls containing agar‑– Diatoms most abundant unicellular algae with rigid cell ‑

walls (plankton)– Dinoflagellates unicellular and cellulose protective coats‑– Euglenoids can be autotrophic or heterotrophic‑

Slime Molds & Water Molds (fungus-like)• Produce spores at some point in their life cycle (which is what

makes them be similar to fungi).• Ingest food like protozoa• They are heterotrophs that obtain their food by:

• Feeding off others• They can be saprotrophs (that feed off dead matter) • Parasites (that feed of living things)

• Cellulose cell walls like plants• Three types:– Water Moulds live on dead organic matter (saprotroph) but ‑

some are parasites– Slime Moulds plasmodium crawl on plants and ingest small ‑

particles of food– Cellular Slime Moulds individual cells with one nucleus which ‑

ingest tiny bacteria or yeast cells

• Examples:

– Protozoa• Amoeba • Paramecium

– Algae – Slime & Water Molds • Plasmodium

Life Cycle of Plasmodium (Slime Mold) (p. 150 - 151)A representative of Kingdom Protista

• Slime mold is very unusual and is difficult to classify because it has characteristics similar to protists, fungi and plants.

• Visible to naked eye as tiny slug - like blob , called a plasmodium. Plasmodia creep over the soil surface, living off decaying material. They take in food particles by using endocytosis.

• Plasmodium - part of the life cycle of a slime mold. It resembles a slimy mass and contains many nuclei.

• Reproduce via sexual reproduction:• Sporangia - spore-bearing structures developing from a plasmodium (slime mold)

during its sexual reproduction process.– 1. plasmodium develops sporangia (sporangium - singular).– 2. Sporangia produce spores.– 3. Spores are released– 4. Spores produce two types of cells:

• amoeboid cells (move like an amoeba)• flagellated cells (move using flagella)

– 5. Each Amoeboid cell fuses with a flagellated cell– 6. A zygote forms– 7. zygote grows into a new plasmodium.

Section 5.3

• Kingdom Fungi–p. 152 - 158

Kingdom FungiGeneral Characteristics:

• Cell Type: all are eukaryotic.

• Body Form: some are unicellular (yeasts), many are multi-cellular. Many are plant-like in their appearance.

• Most fungi have vegetative bodies (called a thallus or soma) that is made up of single cell-thick filaments called hyphae.

• Generally they do not merge into a visible object, but instead form a microscopic network within the substrate, called the mycelium, through which food is absorbed.

• Cell Wall: Exists. Usually composed of chitin.

• Nutrition: all are heterotrophic (unlike plants). They get their food from other organisms. They digest food outside of their body by secreting enzymes and then absorb it. (parasites and saprophytes). The fungi are absorptive heterotrophs.

• Locomotion: they are non-motile (do not move). • Reproduction: Asexual and Sexual. The more

conspicuous parts of fungi like mushrooms are fruiting bodies, reproductive structures that produce spores.

• Fungi live in symbiotic relationships with plants or animals.

• There are four groups of fungi: – Zygospore Fungi bread moulds which reproduce both ‑

asexually and sexually by conjugation– Club Fungi mushrooms‑– Sac Fungi truffles and single celled yeasts‑ ‑– Imperfect Fungi penicillin which reproduce only ‑

asexually

• The Fungi (singular: fungus) are a large group of organisms. They include important decomposers and many parasites. Parasitic fungi infect animals, including us, other mammals, birds, and insects, with results varying from mild itching to death.

• Other parasitic fungi infect plants, causing disease such as Potato Blight. Many vascular plants are associated with mutualistic fungi, called mycorrhizae, which help with the absorption of nutrients and water. Some fungi are used as food, such as mushrooms and truffles; others are very poisonous and can cause death if eaten.

• Examples:

• Mushrooms• Yeasts• Mold• Bread Mold (Rhizopus)

• Life cycle of a sample organism from the Kingdom Fungi: “Rhizopus” (common bread mold - see p. 154)

• Hyphae - a network of fine filaments found in a fungus.• Mycelium - loose, branching network of hyphae under the

substrate that makes up the main bulk of a fungus.• Rhizoid - downward growing hyphae present in the mycelium of a

bread mold, which penetrates the bread and anchors the mycelium.• Stolon - horizontal hyphae present in the mycelium of a bread

mold.• Sporangiophore - form of hyphae that projects upwards above the

mycelium of a bread mold. Used during asexual reproduction.• Zygospore - diploid structures that develop after two haploid bread

mold hyphae of opposite types (called + and -) combine and fuse their nuclei together.

• Sexual Reproduction in Rhizopus: (involves the stolons)

• The stolons are either plus (+) or minus (-) strains. Each one is haploid. If environmental conditions are unfavorable, (+) and (-) strains of stolons fuse at their tips to produce a diploid structure called a zygospore (see diagram p. 154).

• The zygospore can survive long periods of time and bad environmental conditions and stays dormant until conditions become good again (e.g. warm and damp).

• When conditions improve, it becomes active by growing producing a sporangia. The sporangia produces haploid spores. Each spore blows away on air currents. Each spore can produce a new fungus mycelium.

• Sporangia- hyphae structure that grows out of a zygospore; produces haploid spores.