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gram staing lab experment
gram staining lab answer key
gram staing lab experment
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Bacteria
Bacteria are the most common and ancient microorganisms on earth. Most bacteria are microscopic, measuring 1 micron in length. However, colonies of bacteria grown in a laboratory petri dish can be seen with the unaided eye.
There are many divisions and classifications of bacteria that assist in identifying them. The first two types of bacteria are archaebacteria and eubacteria. Both groups have common ancestors dating to more than 3 billion years ago. Archaebacteria live in environments where, because of the high temperature, no other life can grow. These environments include hot springs and areas of volcanic activity. They contain lipids but lack certain chemicals in their cell wall. Eubacteria are all other bacteria. Most of them are phototrophic, i.e. they use the sun's energy as food through the process of photosynthesis.
Another classification of bacteria is according to their need of oxygen to live. Those who do require oxygen to live are considered aerobes. The bacteria who don't use oxygen to live are known as anaerobes.
The shape of specific bacteria provides for the next step in the identification process. Spherical bacteria are called cocci; the bacteria that have a rodlike shape are known as bacilli; corkscrew shaped bacteria are spirilla; and filamentous is the term for bacteria with a threadlike appearance.
Hans Christian Joachim Gram, a Danish microbiologist, developed a method for distinguishing bacteria by their different reaction to a stain. The process of applying Gram's stain is as follows: the bacteria are stained with a violet dye and treated with Gram's solution (1 part iodine, 2 parts potassium iodide, and 300 parts water). Ethyl alcohol is then applied to the medium; the bacteria will either preserve the blue color of the original dye or they will obtain a red hue. The blue colored bacteria are gram-positive; the red bacteria are identified as gram-negative.
Bacteria contain DNA (deoxyribonucleic acid) just like all cells. However, in bacteria the DNA is arranged in a circular fashion rather than in strands. Bacteria also contain ribosomes which, like in eukaryotic cells, provide for protein synthesis. In order for a bacterium to attach itself to a surface, it requires the aid of pili, or hairlike growths. Bacteria, just like sperm cells, have flagella which assist in movement. But, sperm cells only have one flagellum, whereas bacteria contain flagella at several locations throughout their body surface.
The purpose of this study is to identify an unknown bacterium from a mixed culture, by conducting different biochemical tests. Bacteria are an integral part of our ecosystem. They can be found anywhere and identifying them becomes crucial to understanding their characteristics and their effects on other living things, especially humans. Biochemical testing helps us identify the microorganism present with great accuracy. The tests used in this experiment are rudimentary but are fundamental starting points for tests used in medical labs and helps students attain a better understanding of how tests are conducted in a real lab setting. The first step in this process is to use gram-staining technique to narrow down the unknown bacteria into one of the two big domains; gram-negative and gram-positive. Once the gram type is identified, biochemical tests are conducted to narrow down the specific bacterial species. These biochemical tests are process of elimination that relies on the bacteria’s ability to breakdown certain kinds of food sources, their respiratory abilities and other biochemical conditions found in nature.
What do bacteria need to grow? For bacteria to grow the most typical thing that they like ate a warm and moist environment, but that is not all that they like. Bacteria also like and environment with a PH that is normal or close to a human PH and bacteria also like an oxygen rich environment. The places that could be common to find bacteria in a building are a keyboard, a water fountain, and restrooms. A keyboard is a common place for bacteria because it is being touched constantly with hands when people type and hands are warm, so bacteria like them. The water fountain is another place that is common for bacteria to grow because people's warm hands are touching it and also it has water, which causes it to be moist. The last place that bacteria will we commonly found in buildings are restrooms. The bacteria like restrooms because many people are in then and also there is a lot of water in them.
What are microorganisms? They are organisms that you have to view with a microscope. The three that I will be discussing are bacteria, viruses, and prions. Of the three, a bacterium is the only one that can be helpful to us in many situations, and they are also the most diverse organism on the earth. The structure, reproduction, and the diseases bacteria, viruses, and prion cause are all different. Let’s begin to compare these microorganisms.
Results from Gram staining procedures were provided a week later; hence, a dichotomous (a flowchart that is used to identify bacteria based on its taxonomic classification) was constructed based on a total of 10 possible unknown bacterium. The bacteria were then separated based on its Gram reaction; leading to two subcategories, including Gram positive and Gram negative. Both subcategories were then divided into two separate categories based on bacteria morphology, including rod and cocci shaped. A series of metabolic test were then selected strategically based on metabolic results provided by Dr. McLaughlin (See attached chart for possible results). The metabolic test for Gram positive rod
The purpose of the study was to identify what are unknown bacteria by applying all the methods that we have learn in microbiology for the identification of are unknown. We apply the different test and be able to recognize the different characteristic of are unknown. Each test has its own purpose to help identify the bacteria by the reaction.
A slide was prepared with the unknown bacteria and the Gram stain using crystal violet and safranin as the reagent, iodine as the mordant, and alcohol as the decolorizing agent. This procedure was performed to identify the gram reaction, morphology and the arrangement of the unknown bacteria. A gram negative rod with random arrangement was seen under the light microscope after the gram stain.
Introduction : in this lab we are trying to see what location makes bacteria grow faster and which one has the most . All bacteria reproduce and their DNA floats freely in cell . Eubacteria contains cell wall made of peptidoglycan, but archaebacterias cell wall isn't made of peptidoglycan. Eubacteria is found everywhere but archaebacteria is found in extreme hostile environments.
The background of a gram negative will show layers of the cell wall that hold layers that are peptidoglycan and it also shows that this bacteria has an outer layer that is asymmetrical bilayer (Oliver,2017, p. 33-34). The gram negative rod appeared pink with a thin-long stretched out circular shape. This appeared on the slide once the correct magnitude was place and oil was added. From the results of the gram stain, many of the bacteria were crossed of the chart and it only left two microbes. These two organisms which were Escherichia coli and Enterobacter aerogenes made it difficult to choose from because some of the test matched for both organisms. From the start, it was a difficult choice at first. The result seemed that it could have been E.aerogenes, but with studying the results the choice of E.coli fit all the results more than the first
Biochemical tests are used to identify microbes in the laboratory to aid in pinpointing the different groups of bacteria. The bacteria vary in the cellular morphology and staining properties as well as structural and metabolic properties. Using biochemical testing, it permits a keener study at related organisms. In addition, the use of numerous color changes that occur with the test, allow to for a rapid identification of comparisons and variances of the bacteria that are tested.
Phenotypic methods of classifying microorganisms describe the diversity of bacterial species by naming and grouping organisms based on similarities. The differences between Bacteria, Archaea and Eukaryotes are basic. Bacteria can function and reproduce as single cells but often combine into multicellular colonies. Bacteria are also surrounded by a cell wall. Archaea differ from bacteria in their genetics and biochemistry. Their cell membranes are made with different material than bacteria. Just like bacteria, archaea are also single cell and are surrounded by a cell wall. Eukaryotes, unlike bacteria and archaea, contain a nucleus. And like bacteria and archaea, eukaryotes have a cell wall. The Gram stain is a system used to characterize bacteria based on the structural characteristics of their cell walls. A Gram-positive cell will stain purple if cell walls are thick and a Gram-negative cell wall appears pink. Most bacteria can be classified as belonging to one of four groups (Gram-positive cocci, Gram-positive bacilli, Gram-negative cocci, and Gram-negative bacilli) (Phenotypic analysis. (n.d.).
A Prokaryote is a single cell organisms that does not have a nucleus, which is divided into two major groups: archaeabacteria and bacteria. Prokaryotes are usually found in three common structures, such as bacillus is rod shaped, crocus is spherical-shaped, and spirillum is long shape. Although there are prokaryotes that are responsible for diseases there are also good types of bacteria that we need. Prokaryotes provide essential services to biological systems for instance food and agriculture.
ECOSYSTEMS: Microbes obtain energy from their environment. Like humans, many microbes do this by eating plant and animal material. A typical microbe buffet consists of waste from humans and other animals, dead plants and animals, and food scraps. Bacteria, fungi and algae all take part in decomposing — or breaking down — this waste material. Without them, the world would quickly be overrun with discarded food scraps, raw sewage and dead organisms.
on the composition of their cell wall. These two types are called Gram-positive and Gramnegative.
Bacterial cells, like plant cells, are surrounded by a cell wall. However, bacterial cell walls are made up of polysaccharide chains linked to amino acids, while plant cell walls are made up of cellulose, which contains no amino acids. Many bacteria secrete a slimy capsule around the outside of the cell wall. The capsule provides additional protection for the cell. Many of the bacteria that cause diseases in animals are surrounded by a capsule. The capsule prevents the white blood cells and antibodies from destroying the invading bacterium. Inside the capsule and the cell wall is the cell membrane. In aerobic bacteria, the reactions of cellular respiration take place on fingerlike infoldings of the cell membrane. Ribosomes are scattered throughout the cytoplasm, and the DNA is generally found in the center of the cell. Many bacilli and spirilla have flagella, which are used for locomotion in water. A few types of bacteria that lack flagella move by gliding on a surface. However, the mechanism of this gliding motion is unknown. Most bacteria are aerobic, they require free oxygen to carry on cellular respiration. Some bacteria, called facultatibe anaerobes can live in either the presence or absence of free oxygen. They obtain energy either by aerobic respiration when oxygen is present or by fermentation when oxygen is absent. Still other bacteria cannot live in the presence of oxygen. These are called obligate anaerobes. Such bacteria obtain energy only fermentation. Through fermentation, different groups of bacteria produce a wide variety of organic compounds. Besides ethyl alcohol and lactic acid, bacterial fermentation can produce acetic acid, acetone, butyl alcohol, glycol, butyric acid, propionic acid, and methane, the main component of natural gas. Most bacteria are heterotrophic bacteria are either saprophytes or parasites. Saprophytes feed on the remains of dead plants and animals, and ordinarily do not cause disease. They release digestive enzymes onto the organic matter. The enzymes breakdown the large food molecules into smaller molecules, which are absorbed by the bacterial cells. Parasites live on or in living organisms, and may cause disease. A few types of bacteria are Autotrophic, they can synthesize the organic nutrients they require from inorganic substances. Autotrophic bacteria are either photosynthetic or Chemosynthetic. The photosynthetic bacteria contain chlorophyll that are different from the plant chlorophyll. In bacterial photosynthesis, hydrogen is obtained by the splitting of compounds other than water.
Prokaryotes include several kinds of microorganisms, such as bacteria and cyanobacteria. Eukaryotes include microorganisms as fungi, protozoa, and simple algae. Virus cells often consist of just a nucleic acid either DNA or RNA in a protein capsule. Viruses are considered neither prokaryotes nor eukaryotes because they lack the characteristics of living things, except the ability to replicate (which they accomplish only in living cells).