Notes

-Antibiotics are drugs that kill or disable infectious forms of bacteria. Because of this, they are considered marvels of modern medicine, due to their healing properties.

- The primary goal of the use of antibiotic treatment is to harm invasive bacteria while doing no damage to the human host.

- The most common form of microscope used in biology today is known as the LIGHT MICROSCOPE. Visible light is projected through the observable specimen such as a single-celled protist. Glass lenses then adjust and enlarge the image and project it into a human eye or camera.

- The most important two factors in microscopy are MAGNIFICATION and RESOLVING POWER.

-MAGNIFICATION is an increase in the object's image size, compared with the object's actual size. The clarity of said enlarged image is dependent on its RESOLVING POWER: the ability of an optical instrument to show two objects as SEPARATE.

- CELL THEORY: States that all living things are composed of cells and that all cells are created from other cells.

- ELECTRON MICROSCOPE: A microscope that uses a beam of electrons to resolve and display objects. This gives electron microscopes a distinctive advantage over regular light microscopes, as electron microscopes have 100 fold, or a hundred times the resolution of regular light microscopes.

- Two types of electron microscopes include the SCANNING ELECTRON MICROSCOPE (SEM): used to study the detailed architecture of the cell's surface and the TRANSMISSION ELECTRON MICROSCOPE (TEM), used to study the internal structure of a cell. The most powerful electron microscopes can distinguish objects as small as 0.2 Nanometer (nm).

- The endless amount of cells that exist on Earth fall into two categories, Prokaryotic Cells and Eukaryotic Cells. PROKARYOTIC CELLS are found in organisms of the domains Bacteria and Archea, known as prokaryotes. Organisms of the domain known as Eukarya- protists, plants, fungi and animals are composed of EUKARYOTIC CELLS and are called eukaryotes.

- All cells have several features that are similar to each other. All of them are bounded by a barrier called the PLASMA MEMBRANE which regulates the traffic of molecules between a cell and its surroundings.

-Inside all cells is a thick jelly-like fluid known as CYTOSOL, in which cellular components are suspended.

- All cells have one or more CHROMOSONES carrying genes made of DNA. And finally all cells have RIBOSOMES which build proteins according to instructions from the genes.

- Prokaryotes are much older than Eukaryotes, as they are the first known form of life on Earth.

- Only Eukaryotic cells have ORGANELLES, which are also called "little organs" that are membrane enclosed structures that preform specific functions.

- NUCLEUS: The most important organelle because it houses most of an Eukaryotic cell's DNA.

- A prokaryotic cell lacks a nucleus, instead its DNA is coiled in a nucleus-like region known as the NUCLEOID.

- The entire region of the cell, between the nucleus and the plasma membrane is called the CYTOPLASM.

- The Cytoplasm of a Eukaryotic cell consists of various organelles suspended in the liquid cytosol.

- The Plasma membrane and other membranes of the cell, are composed of mostly lipids and proteins. Most of the lipids belong to a special category, known as PHOSPHOLIPIDS that are related to dietary fats but have only two fatty acid tails instead of three. Replacing the third fatty acid is a phosphate group that combined phosphorous and oxygen.

- By forming a two layered membrane, or PHOSOPHOLIPID BILAYER the hydrophobic fatty acid tails of the molecules stay in the membrane interior away from water, while the hydrophilic phospholipid heads remain surrounded by water on the inside or the outside of the cell.

- A membrane is a FLUID MOSAIC, fluid because the molecules can move freely past one another and a mosaic because of the diversity of proteins that float like icebergs in the phospholipid sea.

- Although animal cells lack a cell wall, most of them secrete a sticky coat called the extra-cellular matrix. In addition, the cells of animals contain cell junctions, structures that connect cells together into tissues, allowing them to function in a coordinated way.

- The nucleus is separated from the cytoplasm by a double membrane called the NUCLEAR ENVELOPE. Each membrane of the nuclear envelope is similar in structure to the plasma membrane. Within the nucleus, long DNA molecules and associated proteins form fibers called CHROMATIN, where each long chromatin fiber contains one chromosome.

- The NUCLEOSIS is a prominent structure within the nucleus, the site where the components of ribosomes are made.