The Molecules of Cells

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Chapter 3 The Molecules of Cells
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Got Lactase?
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Who is lactase deficient?

• 75 of African Americans
• 75 of Native Americans
• 90 of Asian Americans
• 15 of European Americans

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Why is this important to this course?

• Lactose sugar
• Lactase protein
• Lactase gene nucleic acid

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Four types of organic molecules

• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids

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Carbon The Organic Backbone
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Carbon The Organic Backbone
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Carbon The Organic Backbone
C4H10
C4H10
Isomers
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Carbon The Organic Backbone
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Carbon The Organic Backbone
Cyclohexane
Benzene
Skeletons may be arranged in rings.
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Molecular Properties

• Two major characteristics that determine the
  chemical properties of organic molecules
• Carbon Skeleton
• of carbons
• Arrangement of carbons
• Functional Groups
• Attached to the skeleton
• Involved in chemical reactions

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Hydroxyl Group
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Carbonyl Group
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Carboxyl Group
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Amino Group
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Phosphate Group
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Steroid Backbone
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Macromolecules

• Many biological molecules are GIGANTIC with
  thousands of atoms
• Polymer large molecule consisting of many
  identical (or nearly) smaller molecules
• Poly many
• Meros part
• Monomer smaller molecules comprising polymer
• Diversity in polymers comes from variation and
  sequence in the arrangement of monomers

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Monomers many have conserved functional groups
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Dehydration Reaction
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Hydrolysis Reaction
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Carbohydrates

• Three categories
• Monosaccharides
• Disaccharides
• Polysaccharides

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Monosaccharides

• Simple sugars
• Have same general molecular formula (CH2O)
• Carbon skeletons vary in length from 3 to 7
  carbons
• Main fuel for cells

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Disaccharides

• Two monosaccharides joined together
• Dehydration reaction
• Examples
• Maltose (glucose glucose)
• Sucrose (glucose fructose)

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Polysaccharides

• Long chains of monosaccharides
• Function in energy storage and/or structure
• Starch energy storage in plants
• Glycogen energy storage in animals
• Cellulose structural in plants

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Lipids

• Three categories
• Fats/Oils (triglycerides)
• Phospholipids
• Waxes

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Fats/Oils (Triglycerides)
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Phospholipids
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Waxes

• One fatty acid connected to a glycerol
• More hydrophobic than fats

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Cholesterol The steroid precursor
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Steroids
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Proteins

• Function determined by 3-D shape (important!)
• Subunit (monomer) is an amino acid
• Several types of proteins
• Enzymes
• Structural
• Contractile
• Defensive
• Signal
• Transport

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Amino Acids are arranged around a central carbon
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LE 3-12b
R groups
Leucine (Leu)
Serine (Ser)
Aspartic acid (Asp)
Hydrophobic
Hydrophilic
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Peptide Bonds
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Proteins can denature (lose shape)

• High temperature
• High/Low pH
• Variation in salt concentration

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Four levels of protein structure

• Primary
• Secondary
• Tertiary
• Quaternary

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Primary Structure
Amino acids
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Secondary Structure
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Tertiary Structure
Amino acids
Hydrogen bond
Alpha helix
Pleated sheet
Polypeptide (single subunit of transthyretin)
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Quaternary Structure
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Nucleic Acids

• Subunit (monomer) is a nucleotide
• Blueprints for proteins
• 2 types
• DNA Deoxyribonucleic Acid
• RNA Ribonucleic Acid

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Nucleotide
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