Intro to Microbiology

Microbiology is the study of microscopic organisms. It revolves around 2 things: (1) they use microorganisms to understand basic life processes because microbes are excellent models for understanding cellular processes in unicellular and multicellular organisms.

Advantages of microorganisms

Microorganisms, in terms to their size, they are small that we can work inside the laboratory. In addition, microorganisms can reproduce rapidly compared to other form of organisms. Interestingly, they are the oldest form of life and carry out biogeochemical cycles.

Biogeochemical Cycle

A biogeochemical cycle (or more generally a cycle of matter) is the pathway by which a chemical substance cycles (is turned over or moves through) the biotic and the abiotic compartments of earth. Biogeochemical cycles include water, carbon, nitrogen, phosphorus, and sulfur cycles. Microorganisms living in the tissues of plants produce chemicals so that they couldn’t be eaten by the insects. Nitrogen-fixing bacteria are prokaryotic microorganisms that are capable of transforming nitrogen gas from the atmosphere into “fixed nitrogen” compounds, such as ammonia, that are usable by plants.

Microorganisms

Microorganisms can live in certain places beyond what we can survive. Extremophiles are microorganisms, especially an archaen, that lives in conditions of extreme temperature, acidity, alkalinity, or chemical concentration. Other life forms require microbes to survive. Bacteria and other microbes (like fungi and viruses) in the body make up the human microbiota. The bacteria in our bodies help degrade the food we eat, help make nutrients available to us and neutralize toxins, and defense against infection.

Cells

All cells have the following in common:

• Cell membrane - a barrier that separates the inside and outside of the cell and also act as a “port of entry” for the cell. It is semipermeable and determines what molecules enter and leave the cell.

• Cytoplasm - A place where micromolecules ions and ribosome are found.

• Ribosome - All kinds of cell do have ribosome (for protein synthesis).

• Cell wall - All prokaryotic cells are encased by a cell wall and also the eukaryotic cell of plants.

  Prokaryotic Vs. Eukaryotic Cells

  The most defining characteristic of a prokaryotic cell is that, they don’t exhibit compartmentalization and no membrane bound organelles compared to a eukaryotic cells. Nucleus is for eukaryote (membrane bound) and absent (nucleoloid region) in for prokaryote. Eukaryote are larger (10-100 micrometer) while prokaryotes are smaller ( approx. 1.0 micrometer). Prokaryotes do not have a membrane sorrounding their DNA while eukaryotes have. Examples of prokaryotes are bacteria and archea. On the other hand, eukaryotes are comprised of algae, protozoa, fungi, animals, and plants.

  Genes vs. Genome

  Genes are a segment of DNA, the functional unit of the genome while genomes are the entire genetic complement or material of an organism.

  Eukaryotic DNA vs. Prokaryotic DNA

  A eukaryotic DNA is linear and found inside the nucleus with more the 2. The DNA is associated with proteins that help in the folding/coiled of DNA called histone. In terms in the number of chromosomes, a eukaryotic cell has more than 1. Eukaryotic organisms have 2 copies of each chromosome 23 & 23 equals 46 (from the set of their parents. During a wound, skin cells will constantly replicate themselves through mitosis to make more copies of themselves, ultimately creating more skin to cover our wound.

• DNA is the structure; genome is the entire structure; genes is the specific functional segment of the genome; Chromosome is the coiled DNA.

  Prokaryotic cells have a single circular DNA molecule called chromosome and they are found in nucleoid. The DNA of a prokaryotic cell aggregates to form the nucleoid region of the prokaryotic cells.They have extra amounts of chromosomal DNA called plasmids. The genetic

  information on the plasmids is transferrable between cells, allowing prokaryotes to share such abilities as antibiotic resistance.

Processes of Life

There are 4 four major processes of life: Growth, Reproduction, Developement, and Metabolism (catabolism and anabolism). When a cell is performing metabolism to reproduce, the main goal is to make another copy of the cell. Building of cell membrane is by the process of anabolism. Not all the foods that we break down is for making energy, some are used as raw material to build cell.

Outer structure of a bacterial cell

One of the outer structure of a bacterial cell is glycocalyx. Glycocalyx has 2 forms, the capsule and the slime layer. The first step of invasion is the attachment in the tissue. Another appendage that can be found in bacterial cell is flagellum. Flagellum allow microorganism to move but not all prokaryotic microorganisms have flagella. Flagellum has filament, hook, and basal body. The Filament of a flagellum is composed of a molecule called flagellin it is a protein that composes the filament it is deposited in a helix at the lengthening tip of the flagella. The flagella is able to move 360 degrees and it is also inserted to the cell wall of the bacterium. Flagellum basal body is embedded in the peptidoglycan and cytoplasmic membrane.

Gram positive and negative bacterium

Gram positive bacteria do has 1 (thick) cell wall, 1 cell membrane, and 2 rings. On the other hand, gram negative has 4 rings, 2 cell membrane, 1(thin) peptidoglycan; cell wall is composed of peptidoglycan and outer membrane

Arrangement of flagellum

Only one flagellum at one end is called monotrichus. If there are many in one end, it is called lopotrichus. Flagella on both ends, it is called amphitricus. Flagella is scattered everywhere, it is called peritrichus. A run is a positive taxis in bacterium is counterclockwise. Chemotaxis pertains to stimuli that is chemical for example, sugar or nitrogen.

Fimbrae

There is one pilus that is use for movement called Type IV pili for producing sticky substance on the surface. Nonmotile transactions is true for fimbrea but not for pili. Fimbrae is for adherence. Bacteria is performing horizontal gene transfer typically plasmid called conjugation facilitated by sex pilus.

Prokaryotic Cell Wall

Cell wall of microorganism is the target of antibiotics. Most bacterial cell walls have peptidoglycan but there are also do not have cell wall. Peptidoglycan is composed of sugars called N-acetylglucoseamine (NAG) and N-acetylmuramicacid (NAM) binded by B 1,3 glycosidic acid and peptide bridge for each layer of peptidoglycan. Techoic acid is for gram positive and LPS is for gram negative. In gram positive staining results to purple or blue gram negative is pink. Acid fast staining is another way of determining bacteria without cell wall.

Archea

Archea cell walls do not have peptidoglycan. Cell walls contain a variety of polysaccharides and protein. A cytoplasmic membrane is also called a phospholipid bilayer. Prokaryotic cells don’t have mitochondria but a cell membrane instead.Osmosis is also from higher to lower concentration but through a semi-permeable membrane. The function of rough ER is for synthesis protein. Smooth ER is for lipid synthesis. Golgi body is packaging and modification of large molecules. Lysosome contain catabolic enzymes. Perixomes degrade poisonous wastes. Vacoule is for storage. Mitochondria is the powerhouse. Chloroplast is for photosynthesis.