Chapter 2 Chapter 2 - The Cell - Structure and Function.docx - Chapter 2 The Cell Structure and Function 2.1 Biomolecules Biomolecules Carbon has four

Chapter 2 Chapter 2 - The Cell - Structure and...

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Chapter 2 - The Cell - Structure and Function 2.1 Biomolecules Biomolecules Carbon has four electrons in its outer shell and forms covalent bonds by sharing these electrons with other atoms, including other carbon atoms o Other atoms common to biomolecules include oxygen, hydrogen, and nitrogen o Ability of carbon to share four electrons and to form covalent bonds with other carbon atoms enables carbon-containing molecules to be large and complex Four basic types of biomolecules are carbohydrates, lipids, proteins, and nucleotides Carbohydrates Carbohydrates are composed of carbon, hydrogen, and oxygen in a ratio of 1:2:1, with the general chemical formula (CH 2 O) n . The carbons actually bond to hydroxyl groups (-OH) and hydrogens (-H) o Presence of several hydroxyl groups makes carbohydrates polar molecules so they readily dissolve in water Monosaccharides, Disaccharides, and Polysaccharides Carbohydrates can be classified further into 3 major groups: Monosaccharides, Disaccharides, and Polysaccharides Monosaccharides are simple sugars composed of a single unit o Most common is glucose, an important source of energy for our cells o General formula is C 6 H 12 O 6 o Two other common: Fructose and galactose Share the same general formula as glucose Atoms are arranged differently, given each its own chemical properties o Ribose and deoxyribose – important component of nucleotides Disaccharides are carbohydrates formed by the covalent bonding of two monosaccharides o Common examples: Sucrose: composed of a glucose subunit and a fructose subunit joined together Table sugar Lactose: composed of a glucose subunit and a galactose subunit joined together Carbohydrate found in milk Polysaccharides are carbohydrates formed by the covalent bonding of several monosaccharides Glycogen is a polymer of glucose subunits o Found in animal cells
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o Several types of cells in the body can store glucose as glycogen and later break it down when they need glucose for energy o Glycogen is needed for that reason: if cells store energy in the form of monosaccharides, they would exert an osmotic force that would draw water into the cells, making them swell and possibly burst Starch is a polysaccharide found in plants o Humans consume starch in various plant food products The digestion process makes the glucose subunits of starch available as energy sources Cellulose is another polysaccharide found in plants and consumed by humans but we’re unable to digest and absorb it o Known as dietary fiber Passes through our GI tract Synthesis and Breakdown of Saccharides To synthesize disaccharides and polysaccharides, monosaccharides must be linked together by covalent bonds.
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