Science (Q4)

• Carbohydrates - are molecules that are composed of carbon, hydrogen, and oxygen. They have the general formula CnH2nOn.
• Carbohydrates basically contain an aldehyde or a ketone unit, with multiple hydroxyl groups at almost all carbon atoms.
• Carbohydrates also called saccharides, derived from the Latin word saccharum, which means sugar.
• Classification of Carbohydrates

  1. Monosaccharides
  2. Disaccharides
  3. Polysaccharides
• Monosaccharides are the simplest form of carbohydrates. The prefix mono suggests that these carbohydrates are composed of only one basic molecule. 
• Disaccharides are two monosaccharides bonded to each other. Disaccharides are formed when two monosaccharides combine.
• In a disaccharide, the monosaccharides are linked via a condensation reaction producing an ether (C−O−C) group called glycosidic bond.
• Polysaccharides are long chains of monosaccharide units. They are also called complex carbohydrates.
• Carbohydrates can either be homopolysaccharides, which are composed of one type of monosaccharide, or heteropolysaccharides with multiple types. 
• chitin is a polysaccharide that forms the exoskeleton of arthropods and the cell walls of fungal cells.
• Cellulose chains make up the microfibrils, which in turn are organized into fibrils that make up the cell wall of plant cells. 
• Lipids are large, nonpolar biomolecules.
• Classification of Lipids

  1. Complex Lipids (Triglycerides)
  2. Waxes
  3. Phospholipids
  4. Simple Lipids (Steroids)
• Fatty Acids consists of a straight chain of an even number of carbon atoms.
• Trans-fatty acids, are a form of unsaturated fat.
• Triglycerides are lipids composed of fatty acids and glycerol.
• Waxes are lipids that are produced by both plants and animals.
• Phospholipids are lipids that contain phosphate groups, and are biologically very important molecules.
• A phospholipid is composed of a phosphate “head” which is hydrophilic, and a fatty acid “tail” which is hydrophobic.
• Steroids are lipids without fatty acid chains. It came from the Greek word stereos meaning solid.
• Proteins are biomolecules composed of amino acid units.
• Fibrous Proteins - collagen, actin, and keratin; soluble in water and are the main structural components of the body.
• Globular Proteins - albumin, hemoglobin, and immunoglobin are soluble in water and are mainly used for nonstructural purposes.
• Amino acids are organic compounds that combine to form proteins. 
• Amino acids and proteins are the building blocks of life.
• Levels of Protein Structure

  • A dipeptide is a protein molecule made of two amino acids.
  • A tripeptide is a protein molecule made of three amino acids.
  • A polypeptide is a protein molecule made of more than 10 amino acids.
• Nucleic acids are large biomolecules that include the deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
• Rosalind Franklin, an English scientist, used a method known as X-ray crystallography to produce the first-ever photographs of the structure of DNA.
• Nucleotides are units with three components: a phosphate group, a 5-carbon sugar, and a nitrogen-containing base.
• There are two kinds of nucleic acid: the ribonucleic acid (RNA) and the deoxyribonucleic acid (DNA).
• Ribonucleic acid has ribose as its sugar part. Deoxyribonucleic acid has deoxyribose as its sugar part.
• Purine bases are ones with two rings, and pyrimidines have one.
• A rule known as Chargaff’s rule states that purines and pyrimidines should be found in equal ratios within a cell
• Combined reaction - In a combination reaction, two or more elements can combine to form a new compound.
• Decomposition reaction - The reaction in which a compound is broken down into its elements into simpler compounds.
• Single Replacement Reaction - A reaction in which a more active free element replaces a less active one in a compound.
• Double Replacement Reaction - The reaction in which two compounds exchange metallic and non metallic ions to form two new compounds.
• Precipitation - The reaction that produces a solid compound called precipitate: mixing of two compounds.
• Neutralization - A reaction in which acids and bases react to produce salt and water.