1.3 Aspects of Biology

1. 1.3 Aspects of Biology Micro-Organisms SJ Gaze

2. Key Concepts • Structure and function of parts of bacteria, fungi and viruses • Extra-cellular digestion by bacteria and fungi • Aerobic and anaerobic respiration • Bacterial reproduction by binary fission • Viral reproduction • Excretion of toxins • Other life processes for bacteria, fungi and viruses • Culturing micro-organisms • Conditions for growth of micro-organisms – temperature, food, moisture, pH, oxygen. • Disinfectants, antiseptics and antibiotics • Disease • Nutrient cycles – carbon and nitrogen • Food production SJ Gaze

3. Living, Non-living or Dead? • Biology is the study of living things • A living object is an object that caries out life functions • A non-living object is an object that has not been alive • A dead object is an object that was once alive Revision SJ Gaze

4. Functions of Living organisms Biologists have decided that an object is living if it carries out the following 8 functions: Movement: all or part of the living object can move Respiration: living things obtain energy from food during respiration Sense the environment: living things respond to changes in their environment Circulation: living things circulate gases and other chemicals Growth: living things grow Reproduction: living things produce new offspring Excretion: living things are able to get rid of waste products from their bodies Nutrition: living things can make their own food or obtain it by eating other living or once-living (dead) things. Mrs C. Gren. Revision SJ Gaze

5. Living or Non-Living? SJ Gaze

6. The three domains of Life All living organisms are divided into three domains based on their similarity. The Archaea were the first type of living organism found on Earth. They are all unicellular, (single cell) prokaryote (simple cells without a nucleus) organisms. The Bacteria are also unicellular and prokaryote. The Eukaryotes are both unicellular and multicellular. Their cells contain a nucleus plus mitochondria. This domain contains fungi, protisa, plants and animals. SJ Gaze

7. The Five Kingdoms of Life The traditional division of living organisms. There is much more variety between the Monera Kingdom (divided into the Bacteria and ArchaeaDomains) than there is between the remaining 4 kingdoms that make up the Eukaryote Domain. SJ Gaze

8. Plant Classification Scientists universally use a classification system developed from Linnaeus (1753) to catergorise every species of living organism so far discovered. SJ Gaze

9. Animal Classification Current classification systems have developed from Linnaeus' original work. However, modern classification systems are much more complicated having many levels of hierarchical organization. These systems are also taxonomic(structural and physiological connections between organisms), phylogenic (classification based on genetic connections between organisms), and are structurally based on Darwin's theory of evolution. SJ Gaze

10. Micro-organisms Living Non-living Fungi - Eukaryote Viruses Bacteria - Prokaryote SJ Gaze

11. Cell Types SJ Gaze

12. Cell Structure - Prokaryotes Absence of nucleus No organelles in cytoplasm (except ribosomes) SJ Gaze

13. Prokaryotes and Eukaryotes SJ Gaze

14. Unicellular and Multicellular Human - Animal Paramecium - Protist Gaze

15. Micro-organisms Micro-organisms (or microbes) are very small organisms, which are usually only visible with the aid of a microscope. Sometimes a colony of micro-organisms can be seen with the naked eye. Micro-organisms which have single cells are unicellular. Those made of many cells are multicellular. Some have no cells at all – viruses. SJ Gaze

16. Relative size of Micro-organisms SJ Gaze

17. Scale of size DNA Cell membrane Ribosome Mitochondria Nucleus Animal cell Plant Cell Leaf cross-section Leaf 0.1nm 1nm 10nm 100nm 1µm 10µm 100µm 1mm 10mm SJ Gaze

18. Microscopes Most cells are to small to be clearly seen by eye and require a microscope to view. Magnification: the number of times the image is enlarged Resolution: the clarity and ability to see detail in the image The branch of biology relating to preparation and viewing tissue under a microscope is known as Histology. SJ Gaze

19. Microscopes arm - this attaches the eyepiece and body tube to the base.base - this supports the microscope.body tube - the tube that supports the eyepiece.coarse focus adjustment - a knob that makes large adjustments to the focus.diaphragm - an adjustable opening under the stage, allowing different amounts of light onto the stage.eyepiece - where you place your eye.fine focus adjustment - a knob that makes small adjustments to the focus (it is often smaller than the coarse focus knob).high-power objective - a large lens with high magnifying power.inclination joint - an adjustable joint that lets the arm tilt at various angles.low-power objective - a small lens with low magnifying power.mirror (or light source) - this directs light upwards onto the slide.revolving nosepiece - the rotating device that holds the objectives (lenses).stage - the platform on which a slide is placed.stage clips - metal clips that hold a slide securely onto the stage. SJ Gaze

20. RULES FOR ABiological drawing 1. Use unlined paper. 2. Draw in pencil. 3. Always print. 4. Leave at least a 5mm margin on all four sides of the paper. 5. Center the title and print it in capital letters. 6. Center the drawing on the page. 7. Never cross lines. 8. Never use the plural form of a work when pointing to a single object or part. 9. Do little or no erasing. 10. When using the scientific name of an organism in places other than the title, remember that the genus or first part of a scientific name is always capitalized. The species or second part of a scientific name is not. FOR EXAMPLE:      Canis familiaris is the genus and species name for a dog. In a title it would be CANIS FAMILIARIS 11. Print your name and other information as specified by your teacher. SJ Gaze

21. Virus Viruses are not plants, animals, or bacteria. Viruses are not living organisms because they are unable to carry out all of the characteristics of living organisms without invading a living cell and ‘hijacking’ it’s processes. Viruses do not posses cells or cell components of their own. They cannot synthesise proteins, because they lack ribosomes. Viruses cannot generate or store energy. Because viruses can not survive without cells, scientists predict that they originated from rogue pieces of DNA/RNA strand. SJ Gaze

22. Examples of viruses Rabies virus Influenza virus Bacteriophage virus Viruses can take numerous forms SJ Gaze

23. Virus Structure Spikes Protein Coat Lipid layer RNA/DNA strands Example – HIV Virus SJ Gaze

24. Virus Structure • All viruses contain: • >Nucleic acid, either DNA or RNA (but not both), • >a protein coat (capsid), which encases the nucleic acid. • Some viruses are also enclosed by an envelope of fat and protein molecules. SJ Gaze

25. Function of Virus Components • Capsid - The capsid is the protein shell that encloses the nucleic acid; The capsid has three functions: • it protects the nucleic acid from digestion by enzymes, • 2) contains special sites on its surface that allow the virus to attach to a host cell, and • 3) provides proteins that enable the virus to penetrate the host cell membrane and, in some cases, to inject the infectious nucleic acid into the cell's cytoplasm. SJ Gaze

26. Function of Virus Components Nucleic Acid - Just as in cells, the nucleic acid (DNA or RNA) of each virus encodes the genetic information for the synthesis (creation) of all proteins. While the double-stranded DNA is responsible for this in prokaryotic and eukaryotic cells, only a few groups of viruses use DNA. Most viruses have single-stranded RNA. The genetic material can only make protein when it is slotted into the DNA of a host cell. SJ Gaze

27. Culturing Virus Viruses will not grow on agar (jelly made from seaweed with nutrients) because they cannot feed. They need living cells to reproduce in and are often grown in fertile hen’s eggs. The introduction of micro-organisms onto agar or into living cells is known as inoculation. It is to dangerous to grow viruses in the school laboratory as all viruses are Pathogens (harmful to living organisms). SJ Gaze

28. Reproduction of viruses Absorption Viruses can enter an organism through any cavity or broken surface of an organism. Once inside, they find a host cell to infect. Entry The Virus attaches to a specific cell type and ‘injects’ its genetic material. Replication The viruses genetic material joins into the cell DNA and viral protein is made. Assembly Various pieces of viral protein are constructed into individual viral particles (or virions). Release The newly created virions break through the cell wall (killing it) and proceed to infect other cells.

29. Lysogenic Cycle Extra Once inside the host cell, some viruses, such as herpes and HIV, do not reproduce right away. Instead, they mix their genetic instructions into the host cell's genetic instructions. When the host cell reproduces, the viral genetic instructions get copied into the host cell's offspring. The host cells may undergo many rounds of reproduction, and then some environmental or predetermined genetic signal will stir the "sleeping" viral instructions. The viral genetic instructions will then take over the host's machinery and make new viruses as described above. This cycle, called the lysogenic cycle, is shown in the figure above. SJ Gaze

30. Targeted cells The virus attaches to the target cell, usually through specific protein-protein interactions between capsid and cell surface receptors. Only then can the genetic material be taken into the host cell. • There are three requirements that must be met to ensure successful infection of a virus: • sufficient virus must be present • the cells must be susceptible and permissive (matching) to the virus, • and local defenses (immune system) must be absent. SJ Gaze

31. Fungi • FUNGI ARE: • Made of tangled threads called HYPHAE • Parasites or decomposers • Spread by spores • Fuzzy- looking!

32. Fungi Fungi can either be multicellular such as mushrooms and mould or unicellular such as yeast. The Fungi have their own Kingdom but share similarties with both plants – do not move around, and animals – can not make their own food. Fungi are either parasitic – feeding off live hosts or saprophytic – feeding off dead organisms. Fungi make up an important part of the food chain as decomposers – breaking down dead organic mater and returning the nutrients so they are availible to other organisms. SJ Gaze

33. Fungi Structure Spores Sporangium Stalk hyphae SJ Gaze

34. Fungi Structure (Multicellular) >Spores, haploid (only half the chromosomes) used for reproduction – both asexual (growing into an exact copy) or sexual (when combining with a spore from another fungus) >Sporangium or fruiting body. The visible part of the fungi that produces and distributes the spores. > Hyphae, the feeding threads. A mat of hyphae is called a mycelium.The hyphae can also be involved in sexual reproduction when they come in contact with hyphae from another fungus. SJ Gaze

35. Fungus Reproduction • Can be ASEXUAL – by spreading spores • Can be SEXUAL – where two hyphae touch

36. Fungi Reproduction

37. Fungi Asexual Reproduction 1.Special spore capsules or cases called sporangia develop and produce the spores. These spores are haploid – they have only half the number of chromosomes. They can be either + or – strains. (rather than male or female). 2. Millions of spores are released to float in the air 3. When spores land on tissue they germinate, sending out hyphae that rapidly branch and invade the new host. SJ Gaze

38. Fungi Sexual Reproduction 1. Fungi form a gamete producing area called a Gametangia. 2. Gametangia from a + strain and a – strain join – but still from the same species of fungi. 3. The 2 gametes (haploid) fuse to form a diploid zygote with a full set of chromosomes. 4. The zygote grows to produce spores (haploid) 5. This process allows the fungi to produce variation amongst the offspring SJ Gaze

39. Fungi Nutrition Multicellular fungi are made up of a mass of very fine threads called hyphae, which invade the tissue of the host organism or dead matter. Fungi feed like bacteria by releasing digestive enzymes onto food, then reabsorbing the nutrients. This is called extra-cellular digestion. SJ Gaze

40. Fungi Extra-cellular Digestion • Steps to feeding; • Enzymes are released from the hyphae. • The food material outside the hyphae is digested. • The food molecules are small enough to diffuse into the hyphae. Fungal hypha Smaller food particles absorbed Enzymes secreted to break up large particles Large food particle SJ Gaze

41. Fungi Respiration This can be aerobic (with oxygen) or anaerobic (without oxygen). Bread and wine yeasts respire anaerobically, producing carbon dioxide and alcohol. This is important in wine making, brewing of beer and rising of bread. The process is called fermentation. Sugar alcohol + carbon dioxide C6H12O6 CH3CH2-OH+2CO2 (+ 2ATP) SJ Gaze

42. Fungi Excretion Carbon dioxide and alcohol (ethanol) are waste products of yeasts. Other fungi may produce different waste products including toxins. Toxins excreted by fungi that kill or stop the growth of bacteria are known as antibiotics. Humans have made use of the antibiotics produced by fungi to fight harmful bacteria in their bodies. The most commonly used antibiotic is produced by the penicillin sp. of fungi. SJ Gaze

43. Helpful vs. Unhelpful Fungi • UNHELPFUL: • Mould is a fungus that is unhelpful when it gets on food like bread and spoils it • Yeast is a fungus that is unhelpful to humans when it causes infections like “Thrush” • Penicillin is a fungus that looks really bad for you • HELPFUL: • However, humans eat some moulds like the “blue” in blue cheese! • However, yeast is useful in fermentation to make beer, wine and ginger beer and for making bread rise • However, Penicillin is an important antibiotic medicine

44. HOW TO MAKE A CULTURE… • Collect a “swab” and petri dish • Wash your hands - to avoid contamination of plate • Swab area you have been asked to investigate • Lift up side of petri dish lid without taking it off - to avoid contamination • Swab agar hard enough to leave microbes on - take care not to tear agar • Close lid and tape sides of the petri dish - so you can still see your cultures • Write your name and place you swabbed in small writing on bottom of dish - so you can still see your cultures NOW, LEAVE FOR A COUPLE OF DAYS IN A WARM PLACE...

45. IDENTIFYING MICROBES • Name:M. luteus (type of bacteria) • How you identify it: bright yellow, shiny, & smooth • Name:Staphylococcus aureus (type of bacteria) • How you identify it: large & cream-colored • Name:Streptococcus pyogenes (type of bacteria) • How you identify it: smaller than staphylococcus & white • Name:Corynebacteria (type of bacteria) • How you can identify it: dry and crinkly • Name:Fungi • How you can identify it: fuzzy

46. Bacteria • BACTERIA: • Are microscopic • Are made up of one cell • Are round, long & thin, or spiral shaped • Need food and warmth to grow • Use enzymes to digest food

47. Unique features of Bacteria • Bacteria are sufficiently different to be classified within their own domain, separate from the plants, fungi, protists and animals. Bacteria have a vast variety of different lifestyles and survival methods. • They have no mitochondria, the cell membrane is the site of energy release. • The DNA is in a single loop rather than chromosomes • Outside the cell membrane is a cell wall and often a slime capsule for protection • There may be a flagellum to help the bacterium move. • size – they are much smaller • All bacteria are prokaryotes – they have no nucleus membrane, just an area that the DNA occupies

48. Bacteria cell SJ Gaze

49. Examples of Bacteria Streptococcus pyogenes These spherical bacteria are common inhabitants of the throat. Sometimes they can cause strep throat or even more serious disease like necrotizing fasciitis (commonly called flesh-eating bacteria)

50. Bacteria Structure Cell wall Cell membrane flagellum Slime capsule RNA/ DNA cytoplasm SJ Gaze