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Major Elements in Biological Molecules: Proteins

By: HWC, Views: 7157

Proteins are chains of amino acids linked by peptide bonds. The 20 different amino acids used to make all proteins differ only in their side chains, and the properties of these side chains account for the great diversity of protein structure and function. Collagen is an example of how a prote...

Major Elements in Biological Molecules: Nucleic acids

By: HWC, Views: 7644

DNA and RNA are nucleic acids (polymers of nucleotides). Two polymers with complementary nucleotide sequences can pair with each other. This pairing endows nucleic acids with the ability to store, transmit, and retrieve genetic information. Two strands of DNA pair by hydrogen bonding. A compon...

Major Elements in Biological Molecules: Carbohydrates

By: HWC, Views: 7279

Carbohydrates include simple sugars (monosaccharides) as well as large polymers (polysaccharides). Glucose is a hexose, a sugar composed of six carbon atoms, usually found in ring form. A starch macromolecule is a polysaccharide composed of thousands of glucose units. Glucose molecules can be ...

Major Elements in Biological Molecules: Lipids

By: HWC, Views: 7066

A triglyceride (also called triacylglycerol) is composed of three fatty acid molecules and one glycerol molecule. The fatty acids attach to the glycerol molecule by a covalent ester bond. The long hydrocarbon chain of each fatty acid makes the triglyceride molecule nonpolar and hydrophobic. Pa...

HIV Infection: Viral life cycle

By: HWC, Views: 7094

The series of steps that HIV follows to multiply in the body. The process begins when HIV encounters a CD4 cell. The seven steps in the HIV life cycle are: 1) binding; 2) fusion; 3) reverse transcription; 4) integration; 5) replication; 6) assembly; and 7) budding. Many viruses f...

Properties of macromolecules (Explained with No Audio)

By: HWC, Views: 6693

The term thermoplast refers to a plastic, which when heated is soft and deformable, but which rehardens when cooled. The molecular structure of the macromolecules is comparable to a cotton ball in which the individual fibers of the macromolecules are shown. The fibers of the cotton ball can s...

Cognitive development by Piaget (Preoperational stage or intelligence)

By: HWC, Views: 6949

The next stage of cognitive development proposed by Piaget, is the preoperational stage, roughly between the ages of 2 and 7. At this stage Piaget asserted that a child has what he called preoperational intelligence. hey can mentally representing objects, but do not have a system for organising...

Introduction to Photolithography - WC, BLF, PA, Hard and Soft baking

By: HWC, Views: 7342

Prior to use, wafers are chemically cleaned to remove particulate matter on the surface as well as any traces of organic, ionic, and metallic impurities. Barrier Layer Formation After cleaning, the silicon wafer is covered with the material which will serve as a barrier layer. The most commo...

Double Vacuum Process (Illustration No Audio)

By: HWC, Views: 6946

In this so-called low-pressure process, the wood is first subjected to a short and relatively weak initial vacuum, after which the treatment vessel is flooded with preservative solution and reduced to normal pressure The double vacuum container is loaded with timber. A partial vacuum is draw...