Strand 1 : Diversity, change & continuity

Strand 1: Diversity, change & continuity

Biodiversity & Classification of micro-organisms

VIRUSES:Basic structure & General characteristics:

•A protein capsule containing DNA or RNA•No organelles present, thus no traditional life functions.

•Viruses that attack bacteria are known as bacteriophages.•That is only one type of virus, there are a number more, e.g. retro-virus; rhinovirus etc.•Viruses attack and complete their life cycle in the same basic stages:

1)Adsorption

2) Entrance

3) Latent phase

4) Lysis

Life cycle:Stuck to surface of host cell

DNA material is pushed into host cell

Virus uses host cell parts to copy DNA and make new ‘bodies’

BurstingHost cell bursts open and releases new viruses.

The general taxonomic structure is as follows:

Order (-virales) Family (-viridae)

Subfamily (-virinae) Genus (-virus) Species (-virus)

As an example of viral classification, the chicken pox virus, varicella zoster (VZV), belongs to the order Herpesvirales, family Herpesviridae, subfamily Alphaherpesvirinae, and genus Varicellovirus.

BACTERIA:Basic structure & General characteristics:

•Prokaryotic, having DNA and RNA but not enclosed in a nuclear membrane.•Can be heterotrophic or autotrophic.•Heterotrophic examples are mainly saprophytic, but some are parasitic.•Autotrophic examples are thought to have been the first life on the planet.

•May live in a variety of temperatures:Very cold = psychrophilicHuman body temp = mesophilicVery hot = thermophilic

•Can be found in presence or absence of oxygen.•Also across the entire pH range .

Reproduction:•Asexual reproduction.•Binary fission:

•Budding:

•Spore formation:

•Conjugation:

Role in Ecosystem:•Assists in nitrogen fixing in plants, thus making atmospheric nitrogen available to plants.•Decomposers, replacing nutrients into the soil.•In human intestines they assist in break down of undigested material in colon as well as synthesizing certain vitamins, specifically vitamin K (E. coli = Escherichia coli).

Types / Shapes:

PROTISTA:Basic structure & General characteristics:•Protists are eukaryotes. •They have a nucleus, large ribosomes, mitochondria, endoplasmic reticulum, and golgi bodies. •Many species have chloroplasts. •Reproduction is by way of mitosis, meiosis, or both.

•The majority of protists are single-celled, but multicellular examples are quite common.•Protists are classified in 3 groups:

1) Heterotrophs

2) Autotrophs

3) Parasitic

Heterotrophic Protista

Autotropic Protista

Autotrophic protista importance:•Food source for animals (flamingoes)•Nutrition source for humans (spirulina)•Source of food poisoning in the form of ‘Red Tide’ = when red algal blooms are experienced.•Source of food for humans (sushi)

Parasitic Protista

Classification:

FUNGI:Basic structure & General characteristics:•Fungi are eukaryotes. •Most are filamentous.•Some are unicellular.•Cellular cross walls may be absent, then referred to as coenocytic (multinuclear / polynucleic).•Uses dead / rotting organic material as food.

Structure:

Classification & uses of Kingdom Mycota:

Phylum Common name

Scientific name

Zygomycota Bread moulds

RhizopusMucor

Ascomycota Yeasts Claviceps (ergot)PenicilliumSaccharomyces

Basidiomycota Mushrooms Agaricus bisporus

Phylum Common name

Scientific name

Deuteromycota Imperfect fungi

Candida