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Ch 2 Notes

Ch 2 Notes. Molecules of Life. Four categories of molecules are unique to cells (called macromolecules ) Carbohydrates Lipids Proteins Nucleic acids Synthesis of macromolecules involves a dehydration reaction Breakdown of macromolecules involves a hydrolysis reaction. Carbohydrates.

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Ch 2 Notes

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  1. Ch 2 Notes

  2. Molecules of Life • Four categories of molecules are unique to cells (called macromolecules) • Carbohydrates • Lipids • Proteins • Nucleic acids • Synthesis of macromolecules involves a dehydration reaction • Breakdown of macromolecules involves a hydrolysis reaction

  3. Carbohydrates • The ratio of hydrogen (H) atoms to oxygen (O) atoms is approximately 2:1 • Function for quick, short-term cellular energy

  4. Carbohydrates • Simple carbohydrates • Low number of carbon atoms (3-7) • Monosaccharides • Glucose • Fructose – found in fruits • Galactose – found in milk • Disaccharides • Two monosaccharides joined together • Sucrose (table sugar) – formed when glucose joins with fructose • Lactose – formed when glucose joins with galactose

  5. Carbohydrates • Complex carbohydrates • Contain many glucose (monosaccharide) units • Starch – storage form of glucose in plants • Glycogen – storage form of glucose in animals • Cellulose • Found in plant cell walls • Humans are unable to digest (passes through digestive tract as fiber)

  6. Lipids • Contain more energy per gram than other biological molecules • Some function as long-term energy storage in organisms • Do not dissolve in water • Consist mostly of carbon and hydrogen atoms; contain few oxygen atoms

  7. Lipids • Fats and Oils • Formed when one glycerol molecule reacts with three fatty acid molecules • Fats • Usually of animal origin • Solid at room temperature • Used for long-term energy storage, insulation, and cushioning • Oils • Usually of plant origin • Liquid at room temperature

  8. Lipids • Emulsification – cause fats to mix with water • Saturated and Unsaturated Fatty Acids • Fatty acid (carbon-hydrogen chain ending with an acidic group –COOH • Saturated fatty acids have only single covalent bonds; lard and butter are examples • Unsaturated fatty acids have double bonds between carbon atoms wherever fewer than two hydrogens are bonded to a carbon atom; vegetable oils

  9. Lipids • Steroids • Structure consists of four fused carbon rings with attached functional groups • Cholesterol • Structural component of animal cell membrane • Precursor of several other steroids

  10. Proteins • Function of proteins • Fibrous structural proteins • Hormones • Muscle contraction • Transport • Protection • Enzymes

  11. Proteins • Structure of proteins • Made of amino acid subunits • Amino group • Acid group • R (Remainder) group – differentiates amino acids • Dipeptide – two amino acids joined together • Polypeptide – three or more amino acids joined together

  12. Nucleic Acids • Huge macromolecules composed of nucleotides • Nucleotides composed of 3 subunit molecules: • A phosphate • A pentose sugar • A nitrogen-containing base • Two classes of nucleic acids • DNA • RNA

  13. Nucleic Acids • Two classes of nucleic acids • DNA • Make up genes • Contain pentose sugar deoxyribose • Nitrogen-containing bases • Adenine (A) • Thymine (T) • Guanine (G) • Cytosine (C) • Usually double stranded

  14. Nucleic Acids • RNA • Intermediary in process of protein synthesis • Contain pentose sugar ribose • The nitrogen-containing base uracil (U) replaces thymine • Usually single stranded

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