Carbon Chemicals in Cells

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1. Do the following goals related to organic compounds

• Define the term organic chemistry and organic molecule
• Explain why carbon's bonding behavior makes it important for life
• Identify the following polar functional groups: hydroxyl carboxyl, amino, phosphate. See figure 3.6, 3.24 for phosphate
• Distinguish between dehydration synthesis and hydrolysis reactions.
• Define and give examples of the terms monomer and polymer

Comment: A monomer is a small molecule that serves as a building block for making polymers. A polymer is made from many similar monomers joined together by dehydration synthesis. The main types of polymers in cells are polysaccharides, proteins and nucleic acids. Organisms often times need to 'digest' polymers and do that using a series of hydrolysis reactions.

2. Explain and give examples of Carbohydrates

• Define the term carbohydrate
• Distinguish between monosaccharides, oligosaccharides(includes disaccharides), polysaccharides
• What is an isomer and give an example. See fig 3.9
• Compare and contrast the function and structure of starch and cellulose

Comment: Polysaccharides such as starch are examples of what sometimes are called complex sugars.

3. Discuss the chemical and physical composition of Lipids

• Give a general definition of lipids
• Explain why most lipids are hydrophobic- why don't "oil and water" mix?
• Recognize the structure of fatty acids and triglycerides
• Explain the difference between saturated and unsaturated fatty acids
• Recognize the structure of each of the main classes of lipids:
  • Triglycerides
  • Phospholipids. See page 58
  • Sterols and steroids
• List the functions of the main classes of lipids

Comment: Lipids are quite varied in structure and are united by the following: Made up mainly of carbon and hydrogen,and are hydrophobic. Even phospholipids which do have a polar group involving phosphate, are largely hydrophobic. The term oil as applied to lipids is different than the oil that comes out of the ground. Oil in the sense of salad oil refers to unsaturated triglycerides.. Oil out of the ground is made up mainly of hydrocarbons believed to be from the remains of single celled organisms.

Rule of Thumb: Organic compounds consisting of carbon and mainly hydrogen are hydrophobic. The more charged functional groups the compound has, the more hydrophilic the compound is.

4. Discuss the basic structure and function of amino acids and the primary structure of proteins.

• List the main functions of proteins in the organism. See fig 3.18 and p 44
• Recognize the generalized structure of an amino acid
• Diagram how two amino acids are joined in cells to make a peptide bond
• Define the primary structure of a polypeptide. See figure 3.21

5. Define the following levels of protein structure and how they arise.

• Second level(Secondary)
• Third level(Tertiary)
• Fourth level(Quaternary)
• Define denaturation and list two factors that can denature proteins

Comment: Observe that for proteins and other organic molecules, form and function go together.

6. Nucleotides and nucleic acids 3.6

• List and recognize the three subunits that make up a nucleotide
• Define nucleic acid and list the two main types of nucleic acids found in cells
• Diagram the basic structure of DNA

Activities to do:

• Review Questions and Self Quiz p 51
• Process of science questions 1,2 on page 51
• For discussion. Plants typically store energy in the form of starch while animals store their energy in the form of fats. Why do you think this might be? Hint: think about the physical properties of starch vs fats.
• Starch and cellulose are both polymers made from glucose. Animals can digest starch but not cellulose. Why can't animals digest cellulose?

Define the following terms:

pgd 08/25/02 revised 08/30/04