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29 Cards in this Set
- Front
- Back
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Petri Dish / Culture Dish |
Used to house cultures (E.g. bacterial and fungal cultures) A culture medium is added to the petri dish to provide nutrients for the growth of the organism |
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Microfuge Tube |
Contains a small amount of substance Has a cap that prevents spillage and evaporation of the content |
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Micropipette |
Measures small volumes accurately Dispenses liquids in microlitres (1 ml = 1000 ul) Set the pipette volume only within the range specified for that pipette and not beyond the maximum or minimum values. Always apply a tip before using the pipette to avoid liquid from being sucked into the nose cone Always keep the micropipette vertical when liquid is in the tip to avoid liquid from running back into the nose cone Control the speed at which the plunger rises and never release it abruptly to prevent air from entering the tip, which would cause the liquid present in the tip to go into the nose cone |
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Autoclave Machine |
Uses high heat and pressure to sterilise equipment or culture mediums before use which would kill harmful organisms to prevent contamination |
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Laminar Flow Cabinet |
Provides a sterile work space since it filters off dust particles, bacterial and fungal spores |
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Ultracentrifuge / Microcentrifuge |
Uses high-speed motor to separate mixtures where the heavier molecules would be spun down and collected into a pellet Tightly close the lid of all microfuge tubes to be placed in the ultracentrifuge Balance out the tubes in the rotor by placing tubes with the same amounts diagonally across from each other |
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Vortex Mixer / Vortexer |
Consists of an electrical motor attached to a cupped rubber piece which would oscillate rapidly when the motor runs, causing a vortex to be created in microfuge tubes that would mix substances and re-suspend pellets or cells |
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Agarose Gel Electrophoresis Chamber |
Separates DNA fragments of different lengths or sizes |
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Bacteria (Monera) |
Belong to the family prokaryotes. Prokaryotes are characterised by absence of a nucleus and other membrane-bound organelles. Unicellular but group together in colonies. Most bacteria absorb food from their environment but some can produce food in the presence of sunlight. |
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Made out of |
Consists of a chromosomal DNA (nucleic acids), plasmids (DNA), ribosomes, cytoplasm, cell membrane and cell wall. Some have capsules or flagella. They do not have membrane-bound organelles. The DNA are instead coiled up to occupy part of the cytoplasm. The cell wall is made of a complex mixture of proteins, sugars and lipids but not cellulose. |
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Random |
Bacteria that need oxygen for their respiration are called aerobic bacteria while those that do not are called anaerobic bacteria. Under favourable conditions bacteria reproduce by binary fission. Bacteria are killed by high heat. Some bacilli bacteria produce endospores under unfavourable conditions. These endospores are resistant to high heat, extreme cold and prolonged dryness. They germinate to produce bacteria which would then go through binary fission to produce bacterial colonies when in favourable temperatures. |
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Differentiating them |
Colour Shape (round / irregular / filamentous / rhizoid / curled) Size (diameter measured in mm) Surface texture (smooth / rough / dull / shiny) Elevation (flat / raised / convex)Edge (smooth / entire / irregular / filamentous) Transparency (transparent / translucent / opaque) Shapes (rodlike / spherical / comma / spiral) - Bacilli / Cocci / Vibrio / Spirilla - Diplo = Pairs / Strepto = Chains / Staphyl = Clusters - Ability to form spores - Reaction to Gram stain (Gram + / Gram -)Gram + are stained purple / Gram - are stained pink or red - Method of energy production (aerobic / anaerobic) |
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Useful Bacteria |
Some species of Lactobacillus are used to produce yoghurt, cheese, kimchi and pickles. Most E. coli strains form part of our natural flora of the gut and produce vitamin K and prevent the establishment of pathogenic bacteria within our intestines. Pseudomonas are decomposers in the soil that break down dead plants and animals to turn them into nutrients and minerals which plants can use. |
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Harmful Bacteria |
Clostridium botulinum produces a neurotoxin that causes botulism, which is the paralysis of muscles. Salmonella typhi causes Typhoid fever, which is characterised by a slowly progressive fever as high as 40 degrees Celsius, profuse sweating and abdominal pain. It is transmitted by the ingestion of contaminated food or water with the faeces of an infected person. Bacillus anthracis produces spores which can be used as a biological weapon since they germinate in our bodies and produce lethal toxins that result in death. |
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Fungi |
They are eukaryotes and more complex than bacteria. They range from small uni-celled to large multi-celled. (Yeast are unicellular while mushrooms are multicellular) |
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Moulds and mushrooms |
Mushrooms and moulds are made of microscopic thread-like tubes called hyphae. The branching hyphae spread through the material in which the fungus is growing and absorb food from it. The network of hyphae that grow over or through the food material is called mycelium. The reproductive structures of moulds are sporangia while mushrooms and toadstools are the reproductive structures. These reproductive structures are known as the ‘fruiting bodies’. |
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Yeast |
Majority of yeast consists of separate, spherical microscopic cells. They live in the nectar of flowers or on the surface of fruits where sugars are available. The cells reproduce by budding where an outgrowth from the cell appears, enlarges and is pinched off as a new yeast cell. |
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Useful Fungi |
Yeast is used in the making of wine and bread. (They feed on sugars and produce ethanol and carbon dioxide during fermentation) There are many edible mushrooms such as shiitake and oysters Soil fungi are decomposers which break down organic waste and return the nutrients back to the soil for plants. Penicillium produces penicillin. |
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Harmful Fungi |
Bread moulds grow on bread which spoils the bread. Ringworm causes skin infection. |
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Viruses |
Can survive outside the host cell but in order for them to reproduce they have to penetrate into a host cell. Once it infects the host cell, it would inject its genetic material into the host cell which would take over the machinery of the cell and make the host cell synthesize their viral DNA / RNA and viral protein coat to produce many viral particles. This may destroy the host cell. |
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Random |
Many viruses cause diseases in plants and animals and can even infect fungi and bacteria. Human diseases caused by viruses include the common cold, poliomyelitis, measles, mumps, rubella, chicken pox, herpes, influenza and AIDs. In gene therapy, viruses are made use of by scientists to deliver a copy of a good gene to replace a defective gene in the host cell. |
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Uses of Microorganisms |
Scientists often use microorganisms in their research as they are small, have small DNA content, and have short life cycles. They occupy less space, are cheap and easy to culture and maintain, single-celled or few cells present. Fewer genes so they are less complicated to analyse. Next generation is obtained quickly so results are seen faster and thus gene inheritance experiments can be conducted in short periods of time. The amount of DNA in bacteria is 500 times less than that of human DNA. Our present knowledge of DNA and gene interactions came from studies of the DNA of microorganisms. Microorganisms are also studied to create vaccines and cures for diseases. |
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Streaking and Gram stain |
Streaking is used to isolate a pure strain of bacteria through a process of isolation dilution. Differences in reaction to Gram staining arises due to differences in structure of the bacteria cell wall. |
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Cells, Chromosomes and DNA |
Cells are the basic units of life. In all of these cells is the set of instructions in the form of genetic material known as Deoxyribonucleic acid (DNA). DNA makes up the chromosomes that are found inside the nucleus. Chromosomes are hereditary, which can be passed down from generation to generation. Chromosomes are found in all cells with the exception of mature red blood cells since the nucleus disappeared to give space for more haemoglobin. The chromosomes in the nucleus contain all the information a cell needs to carry on its life processes. In the cell, DNA is wound up around proteins called histones to form chromatin. The chromatin would wind upon itself to form a more condensed structure called chromosomes. Chromatin are present normally in a cell, while chromosomes are there only when a cell is about to undergo cell division. When the cell is about to divide, the chromatin threads get organised into chromosomes. |
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Structure of DNA |
DNA exists as a double-stranded molecule, with two parallel strands twisted in a helical structure. Each strand is made up of a sugar-phosphate backbone, and a sequence of bases. These bases are located in between the two strands of DNA and are held together by hydrogen bonds. DNA is made up of many repeating units of nucleotides linked together. (A nucleotide is made up of a phosphate, a sugar and a base.) Bases have unique properties where A only pairs with T and C only pairs with G and vice verse. This unique interaction is known as Complementary Base Pairing, which is due to the bases fitting together like jigsaw pieces. |
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Genes |
A length of DNA contains a very long sequence of bases. Segments of the DNA may contain a sequence which codes for a protein. These segments are known as genes or coding DNA. Only 5% of human DNA is coding DNA and the rest are non-coding .Each gene stores information for producing a certain protein. These proteins can either by hormones or enzymes which regulate metabolic activities or proteins which form muscles, hair and skin that give the characteristics or traits to an individual. Hence, a gene stores information about a trait or characteristic.The sequence of DNA bases is of utmost importance as it determines the genetic code. The genetic sequence tells the cell which amino acid to use and in which order, to produce a particular protein. |
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Human Genome |
The human genome is the entire set of DNA within a human cell. The benefits of the Human Genome Project include gene discovery, genetic testing, improved drug design, gene therapy and pharmacogenomics. |
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Karyotyping |
A karyotype is a picture of a complete set of chromosomes in a species. The chromosomes are arranged in pairs and sorted according to type and size from the largest to the smallest. Chromosomes of the same length and type are always paired up and are called homologous chromosomes. In a homologous pair, one chromosome is inherited from each parent and therefore we inherit one set of chromosomes from our mother and one set from our father. |
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Syndromes |
Down syndrome is where each body cell has a total of 47 chromosomes. Body cells have an extra chromosome in chromosome number 21. Usually born to women of older age due to abnormal gamete production. Associated physical characteristics are short stature, broad hands, stubby fingers and toes, a wide round face and a large protruding tongue. Associated disability or disorder are certain degree of cognitive disability, congenital heart defects and susceptibility to respiratory infection. Klinefelter’s syndrome is where an extra X-chromosome is present in a male. Principal effects are development of small testicles and reduced fertility. Associated characteristics are tall stature and sterility. Turner’s syndrome is where one X-chromosome is missing. Females are sterile and are relatively normal. Associated characteristics are short stature, broad chest, low hairline, low-set ears and webbed neck. Jacobs syndrome is where there is an extra Y-chromosome present. No well-defined syndrome and males are somewhat taller than average. |
