Classification_ppt

Fungi
• Mushrooms, toadstools, moulds, yeasts
• Mushrooms, toadstools and moulds are multicellular, yeasts are unicellular • No chloroplasts • Cell walls are made of chitin
• Viruses affect plant, animal, fungi and bacterial cells • In humans, the body’s immune system usually destroys the virus • In the case of HIV this particular virus destroys the immune system, so another virus can invade and will not be killed
Classification
• There are many different habitats on earth • Mutations have produced variety in organisms leading to the evolution of approximately 5 million different species
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Viruses
• Many types (not species – they are not classified this way)
• All are parasites • Can only reproduce inside living cells (called the host) • Much smaller than bacteria (0.01 – 0.1 m) • Not made of cells • No nucleus or cytoplasm • Only made of genetic material (DNA or simpler RNA) surrounded by a protein coat • Sometimes there is an envelope around this, which is taken from the membrane of the host cell
• Natural systems classify organisms according to what characteristics they have in common
– This method gives information about evolution – organisms that are classified together probably evolved from the same type of ancestor
• Do not feed, respire, excrete, move, grow or respond to surroundings • Only reproduce • They enter and take over the genetic machinery of the host cell, using it to make more viruses • When many viruses are made, the cell bursts open, releasing the viruses (and killing the cell)
– This is called saprotrophic nutrition
Yeasts
• Tiny • Single celled
• They absorb soluble substances over their whole surface • There are many different species • Useful for making bread and wine
• In order to be able to identify and compare different species we have developed a way of classifying them into groups • this process is called taxonomy
– (sucrose is also stored in fruits)
Animals
• Very wide variety • Includes vertebrates and invertebrates • 60% are insects
• Multicellular • No chloroplasts • Feed on other animals or plants to get nutrition • No cell walls, so cells can change shape • Body often coordinated by a nervous system • Carbohydrate stored as glycogen
– Small, circular rings of DNA – Very useful in genetic engineering
• • • •
Some have chlorophyll Most feed of other organisms Many are decomposers Some are useful, eg Lactobacillus bulgaricus is used to make yoghurt from milk • Some are pathogens (disease causing)
Methods of classification
• Artificial systems use a single characteristic
– Eg plants that are medicines and plants that are poisonous – Eg can fly, cant fly
Multicelluar fungi
• Reproduction is by fruiting bodies which release spores
• Cells join up to make hypae (hi-fee) • These make a network called a mycelium • Digestion is extracellular – they secrete enzymes onto material (often dead matter) and once the enzymes have digested it into soluble substances they absorb the products
Bacteria
• 3 basic shapes: spheres, rods and spirals
• Very, very small (10-50 m)
– (1 m = 0.001 mm)
• All have a similar structure
• All have a cell wall (different to plants and fungi) and a cell membrane • May have a capsule or slime layer, for protection from drying out and from other invading bacteria or viruses • No nucleus • DNA is a single, circular chromosome, loose in the cytoplasm • Some can swim with their flagellum • Some have plasmids
• This process began at the time of Aristotle in Ancient Greece and has developed to the system that we use today
– This type of system was first developed in the 17th century by John Ray and was improved soon after by Carl Linnaeus – who also came up with the binomial system for naming organisms
Features of different groups of animals
Plants
• Includes flowering plants, mosses and ferns
• Muticelluar • Cells contain chloroplasts • Make their own nutrition (through photosynthesis) • Cells have cell walls made of cellulose (a carbohydrate) • They store energy as starch • They transport energy as sucrose