Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Carbon and organic molecules Carbon and its bonds Polymers and monomers - Carbohydrates - Proteins - Lipids - Nucleic acids
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A carbon atom forms four covalent bonds C can make chains or rings Why is carbon so important to molecules of life? Figure 3.1, top part Structural formula Ball-and-stick model Space-filling model Methane The 4 single bonds of carbon point to the corners of a tetrahedron.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Methane, CH4 Figure 2.8Bx Arrangement of atoms determines molecular shape. Shape determines function of molecules
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Butane, ball and stick model Figure 3.1x3
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings What affects solubility in water? Molecules with +/- charge are usually hydrophilic or “water-loving” Molecules with no charge and non-polar are usually hydrophobic and not soluble in water
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Polymers are long chains of smaller molecular units called monomers A huge number of different polymers can be made from a small number of monomers How do cells make so many different molecules that are needed for life?
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Carbohydrates are a class of molecules –Monosaccharides: glucose, fructose, ribose –Disaccharides: maltose, sucrose, lactose –Polysaccharides: starch, glycogen CARBOHYDRATES
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings are single-unit sugars a multiple of CH 2 O fuels for cellular work Monosaccharides
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Carbohydrates DISACCHARIDES ANIMATION Figure 2.12a–b PRESS TO PLAY
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Molecules, including non-sugars, taste sweet because they bind to “sweet” receptors on the tongue Why is sugar sweet? Table 3.6
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings disaccharides Glucose Maltose Figure 3.5 Sucrose glucosefructose Dehydration synthesis
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Polysaccharides are long chains of sugar units Size: thousands of linked monosaccharides purpose: energy storage, structural
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Starch (plants) and glycogen (animals) Cellulose (plants) and chitin (insects, fungi) Figure 3.7 Starch granules in potato tuber cells Glucose monomer STARCH GLYCOGEN CELLULOSE Glycogen granules in muscle tissue Cellulose fibrils in a plant cell wall Cellulose molecules
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Starch Cellulose Figure 3.7x = fiber Indigestible by animals
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings hydrophobic composed largely of carbon and hydrogen Purposes: - energy storage - insulation, cushioning - membranes - signals Lipids include fats, oils, and steroids.
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Fats are triglycerides –one glycerol molecule linked to three fatty acids –fatty acid chains often differ Fatty acid
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Saturated fats lack double bonds –solid at room temperature (lard) Fatty acids of unsaturated fats contain double bonds –liquid at room temperature (plant oils) Trans fats have “wrong way” double bonds Figure 3.8C
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings both polar and nonpolar portions major component of cell membranes Figure 3.9 Phospholipids
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Waxes form waterproof coatings and can prevent organisms from drying out or getting wet
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Steroids are often hormones testosterone estrogen Anabolic steroids Hormone Replacement Therapy
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cholesterol Membranes Precursor to Vitamin D, bile salts Figure 3.9x1 HDL High Density Lipoprotein LDL Low Density Lipoprotein
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Proteins are involved in –cellular structure –movement –nutrition –defense –transport –communication Enzymes regulate chemical reactions Proteins are essential to the structures and activities of life Figure 3.11
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –Their diversity is based on different arrangements of amino acids Proteins are made from just 20 kinds of amino acids Proteins are the most structurally and functionally diverse of life’s molecules
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Each amino acid contains: –an amino group –a carboxyl group –an R group, which distinguishes each of the 20 different amino acids Amino group Carboxyl (acid) group Figure 3.12A
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Each amino acid has specific properties Leucine (Leu) Figure 3.12B Serine (Ser)Cysteine (Cys) HYDROPHOBICHYDROPHILIC
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cells link amino acids together by dehydration synthesis Peptide bonds Amino acid Dipeptide Dehydration synthesis Carboxyl group Amino group PEPTIDE BOND Figure 3.13
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A protein consists of polypeptide chains folded into a unique shape –shape determines the protein’s function –A protein loses its function when its polypeptides unravel A protein’s specific shape determines its function Figure 3.14AFigure 3.14B
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A protein’s primary structure is its amino acid sequence Secondary structure is polypeptide coiling or folding produced by hydrogen bonding Figure 3.15, 16 Amino acid Hydrogen bond Alpha helix Pleated sheet Primary structure Secondary structure
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Tertiary structure is the overall shape of a polypeptide Quaternary structure is the relationship among multiple polypeptides of a protein Figure 3.17, 18 Polypeptide (single subunit of transthyretin) Transthyretin, with four identical polypeptide subunits Tertiary structure Quaternary structure
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Enzyme (sucrase) Active site Substrate (sucrose) Enzyme available with empty active site Substrate binds to enzyme with induced fit Substrate is converted to products 4 Products are released GlucoseFructose enzyme is unchanged and can repeat the process Figure 5.6 A specific enzyme catalyzes each cellular reaction Enzymes enable chemical reactions
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings What can denature a protein? High temperature pH, low or high High salt concentration
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Nucleic acids such as DNA and RNA serve as the blueprints for proteins They ultimately control the life of a cell DNA sequence is inherited by progeny Nucleic acids are information-rich polymers of nucleotides
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The monomers of nucleic acids are nucleotides Phosphate group Sugar Figure 3.20A –Each nucleotide is composed of a sugar, phosphate, and nitrogenous base Nitrogenous base (A)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The sugar and phosphate form the backbone for the nucleic acid Sugar-phosphate backbone Nucleotide Figure 3.20B
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings DNA consists of two polynucleotides held together by hydrogen bonds Figure 3.20C –The sequence of the four kinds of nitrogenous bases in DNA carries genetic information Nitrogenous base (A) Base pair
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Adenosine triphosphate (ATP) –Chemical energy used by all cells –Energy is released by breaking high energy phosphate bond –ATP is replenished by oxidation of food fuels
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings How ATP Drives Cellular Work Figure 2.20