Microbiology, 1,2 - Copy.pdf

Introduction ❖ As we study Biology we need to know the meaning of Biology. ❖ Biology is the study of life & living organisms ❖ The word biology comes from Greek, bios means ‘life’ and logos means ‘the study of’ (‘knowledge’). ❖ It is the study of life and living things (organi...

Introduction ❖ As we study Biology we need to know the meaning of Biology. ❖ Biology is the study of life & living organisms ❖ The word biology comes from Greek, bios means ‘life’ and logos means ‘the study of’ (‘knowledge’). ❖ It is the study of life and living things (organisms). Howdo weknow is something is‘living’? ⚫ All living things are characterised as being able to do seven things ⚫ These are usually remembered by the mnemonic MRS NERG M R Can you guess what these letters stand for? S N E R G  CELLS ⚫ Cells are the structural and functional units of all living organisms. ⚫ All living organism are made of one or more cells. ⚫ These cells are the building block of life. The 7 characteristics of Living Things Movement – Animals move to find food and keep away from predators; plants move to face the light Reproduction – the ability to produce offspring to keep the species in existence Sensitivity – responding and reacting to the environment Growth – Growing larger and stronger → becoming adult size Nutrition – Animals need food for respiration, plants need minerals from the soil Excretion – Getting rid of waste Respiration – Turning food into energy Classifying Organisms Why do Scientists Classify? Imagine a grocery store… How are they organized? What would happen if they were not organized? How is your life organized?  Why do Scientists Classify? Almost 2 million kinds of organisms on Earth Need to keep organized! (Easier to study!) Classification Process of grouping things based on their similarities The science of classifying organisms is known as taxonomy Taxonomy Taxonomy, the science of naming, describing and classifying organisms.  Why do Scientists Classify? Useful because: It is impossible to study every living organism from an individual level. Therefore, classification is necessary to facilitate easy study of organisms. Once classified, scientists will know a lot about an organism Carolus Linnaeus Carolus Linnaeus (1750) – Father of TAXONOMY Devised naming system for organisms: Binomial Nomenclature  Binomial Nomenclature ⚫ Developed by Linnaeus ⚫ Called binomial because two names are used. ⚫ First name is genus, with first name being a capital. ⚫ Second name is species, with no capital. ⚫ Italics are used when the name is printed. ⚫ The name is underlined if it is handwritten. Summary ⚫ Biology is the study of life and living organsium. ⚫ All living organisms are composed of one or more cells. ⚫ Organisms grow by increasing the size and/or number of their cells. ⚫ The number of species of living organisms which have been discovered runs into millions, so a system of classification is essential. Summary ⚫ An organism’s scientific name is composed of the name of the genus followed by the name of the species, e.g Aspergillus niger. This is called the binomial system. ⚫ Scientific names are essential where precise identification is required, e.g. in agriculture and medicine. Levels of Classification -based on contributions of both Aristotle and Linnaeus There are 8 levels of classification. Remember the first letter of this sentence: Dr. King Philip Came Over For Good Spaghetti. Eight classification groups of living things Domain Kingdom Phylum Class Order Family Genus Species Classification  The Old System FIVE KINGDOMS OF ORGANISMS Monera Protista Fungus Plantae Animalia  The New System 6 Kingdom Proposal Archebacteria Eubacteria  Classification of Bacteria Kingdom Monera has been replaced with two kingdoms. Kingdom Archaebacteria – primitive bacteria that live in the harsh environments that resemble the conditions of the early earth when life was first evolving. Kingdom Eubacteria – larger kingdom -- includes heterotrophic & autotrophic organisms; some of the autotrophs are photosynthetic; others are chemosynthetic. Harmful & beneficial forms. Separated because of biochemical differences. Domain ⚫ Based on fundamental molecular differences among the Eubacteria, Archaebacteria, and Eukaryotes, many systematists now use a level of classification above the kingdom, called domain. ⚫ They classify organisms in three domains: Archaea (which corresponds to kingdom Archaebacteria), ⚫ Bacteria (also called Eubacteria) ⚫ Eukarya (eukaryotes) Prokaryotic Eukaryotic ⚫ The Archaea and ⚫ The Eukarya domain Bacteria domains includes eukaryotes, contain prokaryotic or organisms that organisms. These are have a membrane organisms that do not bound nucleus. have a membrane ⚫ This domain is further bound nucleus. subdivided into the kingdoms Protista, Fungi, Plantae, and Animalia. Life’s diversity, which was originally divided into five kingdoms, has been expanded to six when Kingdom Monera was divided into two. http://lesliehorne.tripod.com/sitebuildercontent/sitebuilderpictures/sixkingdoms01.g New methods of comparison such as DNA sequences have led to an ongoing reevaluation of the number & kinds of kingdoms ranging from six to twelve. Most taxonomists now group kingdoms into a higher classification category called a domain.  Archaebacteria ⚫ Microbiologists who study bacteria determined that the DNA of these are much different from other, true bacteria ⚫ Archaebacteria can live in extremely harsh environments ⚫ They do not require oxygen and can live in extremely salty environments as well as extremely hot environments. Domain Eubacteria Formerly a part of the kingdom monera Name means “true bacteria” These are the kind of bacteria likely to make us sick, live in our gut to help us digest food, or be used in the making of cheese  Shapes of Bacteria Bacteria are classified by shape into 3 groups: Spiral: spirilla rod-shaped: bacilli, bacillus Round: cocci Domain Eukarya Contains all of the eukaryotes (organisms with a nucleus in their cells) Protista Fungi Plantae Animalia  Kingdom Protista ⚫ Eukaryotes ⚫ Single-celled or simple multicellular ⚫ Live in damp places of water ⚫ Subdivided into two groups Protozoans and Algae Amoeba Euglena Brown Algae Diatom  Protozoans ⚫ No cell walls or Algae chlorophyll so they are Producers consumers. (chlorophyll) ⚫ Most can move May live as single (locomotion) cells or form long ⚫ Paramecium chains Green Algae  Fungi Kingdom ⚫ Body is made up of a network of threads called hyphae ⚫ The hyphae help to absorb nutrients through their very large surface area. ⚫ Fungi are multicellular, with a cell wall, organelles including a nucleus, but no chloroplasts and heterotrophic. ⚫ Chitin found in their cell walls, ⚫ They are sessile organisms. E.g moulds, mushrooms, yeast How fungi do digests its food? ⚫A fungus digests its food externally by secreting enzymes onto the food and then absorbing the small nutrients that result from digestion. Plant Kingdom ⚫ Multicellular – made up of lots of cells ⚫ Organelles including nucleus, chloroplasts are present, and cell walls are present. ⚫ Their cell walls contain cellulose. ⚫ Make their own food by photosynthesis ⚫ Non-mobile. ⚫ Conifer, ferns, mosses and flowering plants  Plant Kingdom cones ⚫ Seed plants are divided into two groups Gymnosperms and Angiosperms. ⚫ Plants that bear flowers and produce seeds are called flowering plants (Angiosperms). There are two kinds of flowering plants: monocotyledons and dicotyledons. fleshy fruit Why are fungi and plants classified in different kingdoms? ⚫ Based on the presence of the polysaccharide chitin found in their cell walls, rather than the cellulose present in plant cell walls and lack of chlorophyll. Animal Kingdom ⚫ Multicellular – made up of may specialised cells ⚫ Cannot make own food (heterotrophic) ⚫ They have organelles including a nucleus, but no chloroplast or cell walls. ⚫ They have nerves and muscles in their bodies. ⚫ Sponges, corals, birds and mammals ⚫ Can be further classified into vertebrates and invertebrates.  Viruses ⚫ Very small and cannot be seen through a light microscope. ⚫ They can only multiply inside living cells of another organism (host cell). ⚫ They contain nucleic acids such as DNA or RNA and must therefore be considered as being on the border between living and non living. Summary Comparison of Classification Systems Six Kingdom System Kingdoms: Archaebacteria, Eubacteria, Protista, Fungi, Plantae, and Animalia. Three Domain System Archaea Domain Archaebacteria Kingdom (ancient bacteria), Bacteria Domain Eubacteria Kingdom (true bacteria), Eukarya Domain Protista Kingdom Fungi Kingdom Plantae Kingdom Animalia Kingdom Summary The Archaea and Bacteria domains contain prokaryotic organisms. These are organisms that do not have a membrane bound nucleus. Eubacteria are classified under the Bacteria domain and archaebacteria are classified as Archaeans. The Eukarya domain includes eukaryotes, or organisms that have a membrane bound nucleus. This domain is further subdivided into the kingdoms Protista, Fungi, Plantae, and Animalia. Summary ⚫ Bacteria are single cells and microscopic organisms; they have no proper nucleus; they have a cell wall, cytoplasm and a single chromosome. ⚫ Bacteria produce enzymes which digest the surrounding medium ⚫ Bacteria reproduce by cell division. ⚫ Protista are single-celled organisms containing a nucleus Summary ⚫ Viruses are not included in the six kingdom system since many biologists consider them to be non living. ⚫ Viruses are smaller than bacteria and cannot, strictly, be classed as living organisms. ⚫ Each virus particle consists of a DNA or RNA core enclosed in a protein coat. ⚫ Viruses take over the host cell’s physiology and make it produce new virus particles ⚫ The fungus kingdom contains multicellular, eukaryotes which have heterotrophic nutrition. ⚫ Fungi are formed from thread-like hyphae rather than cell ⚫ The branching hyphae produce a network called a mycelium. ⚫ Fungi secrete enzymes into their food and absorb the digested products. ⚫ The plant kingdom contains multicellular, eukaryotes that have autotrophic nutrition by photosynthesis. ⚫ Animals get their food by eating plants or other animals. ⚫ Most animals are invertebrates - animals without backbones. Vertebrates have backbones. ⚫ The animal kingdom contains multicellular, eukaryotes which are usually motile and feed heterotrophic. The End!