Cell and macromolecules
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Enzymes are catalytic proteins that speed up biochemical reactions without being consumed themselves. They lower the activation energy needed for reactions to occur. Structural 69 Structural proteins Keratin Example: Keratin in hair and nails provides strength and rigidity. Function: Structure
Cell and macromolecules
- 1. The Cell The basic unit of life 1sanjukaladharan
- 2. Engage: Cell History • Cytology- study of cells • 1665 English Scientist Robert Hooke • Used a microscope to examine cork (plant) • Hooke called what he saw "Cells" 2sanjukaladharan
- 3. Cell History • Robert Brown – discovered the nucleus in 1833. • Matthias Schleiden – German Botanist Matthias Schleiden – 1838 – ALL PLANTS "ARE COMPOSED OF CELLS". • Theodor Schwann – Also in 1838, – discovered that animals were made of cells 3sanjukaladharan
- 4. Cell History • Rudolf Virchow – 1855, German Physician – " THAT CELLS ONLY COME FROM OTHER CELLS". • His statement debunked "Theory of Spontaneous Generation" 4sanjukaladharan
- 5. Cell Theory • The COMBINED work of Schleiden, Schwann, and Virchow make up the modern CELL THEORY. 5sanjukaladharan
- 6. 1. All living things are composed of a cell or cells. 2. Cells are the basic unit of life. 3. All cells come from preexisting cells. The Cell Theory states that: 6sanjukaladharan
- 7. Prokaryotic Cell Cell membrane Cell membrane Cytoplasm Cytoplasm Nucleus Organelles Eukaryotic Cell Internal Organization 7sanjukaladharan
- 8. Prokaryotes Eukaryotes Cell membrane Contain DNA Ribosomes Cytoplasm Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cytoskeleton Compare and Contrast 8sanjukaladharan
- 10. EUKARYOTIC CELLS Two Kinds: Plant and Animal 10sanjukaladharan
- 12. Plant Cell Nuclear envelope Ribosome (attached) Ribosome (free) Smooth endoplasmic reticulum Nucleus Rough endoplasmic reticulum Nucleolus Golgi apparatus Mitochondrion Cell wall Cell Membrane Chloroplast Vacuole Section 7-2 12sanjukaladharan
- 13. Animal Cells Plant Cells Centrioles Cell membrane Ribosomes Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cytoskeleton Cell Wall Chloroplasts Compare and Contrast Venn Diagrams 13sanjukaladharan
- 15. Internal Organization • Cells contain ORGANELLES. • Cell Components that PERFORMS SPECIFIC FUNCTIONS FOR THE CELL. 15sanjukaladharan
- 16. Cellular Organelles • The Plasma membrane – The boundary of the cell. – Composed of three distinct layers. – Two layers of fat and one layer of protein. 16sanjukaladharan
- 17. • it is composed mainly of a lipid bilayer of phospholipid molecules, but with large numbers of protein molecules protruding through the layer. • Two types of proteins occur: integral proteins that protrude all the way through the membrane, and peripheral proteins that are attached only to one surface of the membrane and do not penetrate all the way through. • Also, carbohydrate moieties are attached to the protein molecules on the outside of the membrane and to additional protein molecules on the inside. 17sanjukaladharan
- 18. The Nucleus • Brain of Cell • Bordered by a porous membrane - nuclear envelope. • Contains thin fibers of DNA and protein called Chromatin. • Rod Shaped Chromosomes • Contains a small round nucleolus – produces ribosomal RNA which makes ribosomes. 18sanjukaladharan
- 19. Nucleoli • The nuclei of most cells contain one or more highly staining structures called nucleoli. • it is simply an accumulation of large amounts of RNA and proteins of the types found in ribosomes. • The nucleolus becomes considerably enlarged when the cell is actively synthesizing proteins. 19sanjukaladharan
- 20. Ribosomes • Small non-membrane bound organelles. • Contain two sub units • Site of protein synthesis. • Protein factory of the cell • Either free floating or attached to the Endoplasmic Reticulum. 20sanjukaladharan
- 22. Endoplasmic Reticulum • Complex network of transport channels. • Two types: 1. Smooth- ribosome free and functions in poison detoxification. 2. Rough - contains ribosomes and releases newly made protein from the cell. 22sanjukaladharan
- 24. Golgi Apparatus • A series of flattened sacs that modifies, packages, stores, and transports materials out of the cell. • Works with the ribosomes and Endoplasmic Reticulum. 24sanjukaladharan
- 26. Lysosomes • Recycling Center – Recycle cellular debris • Membrane bound organelle containing a variety of enzymes. • Internal pH is 5. • Help digest food particles inside or out side the cell. 26sanjukaladharan
- 27. Centrioles • Found only in animal cells • Paired organelles found together near the nucleus, at right angles to each other. • Role in building cilia and flagella • Play a role in cellular reproduction 27sanjukaladharan
- 29. Cytoskeleton • Framework of the cell • Contains small microfilaments and larger microtubules. • They support the cell, giving it its shape and help with the movement of its organelles. • The fibrillar proteins of the cell are usually organized into filaments or tubules. • These originate as precursor protein molecules synthesized by ribosomes in the cytoplasm. • The precursor molecules then polymerize to form filaments. • Eg microtubules 29sanjukaladharan
- 30. Mitochondrion • Double Membranous • It’s the size of a bacterium • Contains its own DNA; mDNA • Produces high energy compound ATP 30sanjukaladharan
- 32. The Vacuole • Sacs that help in food digestion or helping the cell maintain its water balance. • Found mostly in plants and protists. • Smaller one in animal cell 32sanjukaladharan
- 34. The FOUR Classes of Large Biomolecules • All living things are made up of four classes of large biological molecules: • Carbohydrates • Lipids • Protein • Nucleic Acids • Macromolecules are large molecules composed of thousands of covalently bonded atoms • Molecular structure and function are inseparable 34sanjukaladharan
- 38. The central dogma of molecular biology. 38sanjukaladharan
- 39. sanjukaladharan 39 28.11 Nucleic Acids and Heredity • Processes in the transfer of genetic information: • Replication: identical copies of DNA are made • Transcription: genetic messages are read and carried out of the cell nucleus to the ribosomes, where protein synthesis occurs. • Translation: genetic messages are decoded to make proteins.
- 40. Definitions Nucleic acids are polymers of nucleotides In eukaryotic cells nucleic acids are either: Deoxyribose nucleic acids (DNA) Ribose nucleic acids (RNA) Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (tRNA) Nucleotides are carbon ring structures containing nitrogen linked to a 5-carbon sugar (a ribose) 5-carbon sugar is either a ribose or a deoxy-ribose making the nucleotide either a ribonucleotide or a deoxyribonucleotide 40sanjukaladharan
- 41. Nucleic Acid Function DNA Genetic material - sequence of nucleotides encodes different amino acid RNA Involved in the transcription/translation of genetic material (DNA) Genetic material of some viruses 41sanjukaladharan
- 42. Nucleotide Structure Despite the complexity and diversity of life the structure of DNA is dependent on only 4 different nucleotides Diversity is dependent on the nucleotide sequence All nucleotides are 2 ring structures composed of: 5-carbon sugar : β-D-ribose (RNA) β-D-deoxyribose (DNA) Base Purine Pyrimidine Phosphate group A nucleotide WITHOUT a phosphate group is a NUCLEOSIDE 42sanjukaladharan
- 44. Names of Nucleosides and Nucleotides 44sanjukaladharan
- 45. base （ purine 、 pyrimdine ） +ribose （ deoxyribos N-glycosyl linkage nucleoside+phosphate phosphoester linkage nucleotide phosphodiester linkage 45sanjukaladharan
- 46. Functions of Nucleotides and Nucleic Acids • Nucleotide Functions: – Energy for metabolism (ATP) – Enzyme cofactors (NAD+ ) – Signal transduction (cAMP) • Nucleic Acid Functions: – Storage of genetic info (DNA) – Transmission of genetic info (mRNA) – Processing of genetic information (ribozymes) – Protein synthesis (tRNA and rRNA) 46sanjukaladharan
- 47. sanjukaladharan 47 28.10 Base Pairing in DNA: The Watson–Crick Model • In 1953 Watson and Crick noted that DNA consists of two polynucleotide strands, running in opposite directions and coiled around each other in a double helix • Strands are held together by hydrogen bonds between specific pairs of bases • Adenine (A) and thymine (T) form strong hydrogen bonds to each other but not to C or G • (G) and cytosine (C) form strong hydrogen bonds to each other but not to A or T
- 48. sanjukaladharan 48 The Difference in the Strands • The strands of DNA are complementary because of H- bonding • Whenever a G occurs in one strand, a C occurs opposite it in the other strand • When an A occurs in one strand, a T occurs in the other
- 50. Primary Structure of Nucleic Acids • The primary structure of a nucleic acid is the nucleotide sequence • The nucleotides in nucleic acids are joined by phosphodiester bonds • The 3’-OH group of the sugar in one nucleotide forms an ester bond to the phosphate group on the 5’-carbon of the sugar of the next nucleotide 50sanjukaladharan
- 51. sanjukaladharan 51 Generalized Structure of DNA
- 52. Reading Primary Structure • A nucleic acid polymer has a free 5’- phosphate group at one end and a free 3’-OH group at the other end • The sequence is read from the free 5’-end using the letters of the bases • This example reads 5’—A—C—G—T—3’ 52sanjukaladharan
- 53. The strands of DNA are antiparallel The strands are complimentary There are Hydrogen bond forces There are base stacking interactions There are 10 base pairs per turn Properties of a DNA double helix 53sanjukaladharan
- 54. Untwisted it looks like this: • The sides of the ladder are: P = phosphate S = sugar molecule • The steps of the ladder are C, G, T, A = nitrogenous bases (Nitrogenous means containing the element nitrogen.) A = Adenine T = Thymine A always pairs with T in DNA C = Cytosine G = Guanine C always pairs with G in DNANucleotide (Apples are Tasty) (Cookies are Good) 54sanjukaladharan
- 55. Secondary Structure: DNA Double Helix • In DNA there are two strands of nucleotides that wind together in a double helix - the strands run in opposite directions - the bases are are arranged in step-like pairs - the base pairs are held together by hydrogen bonding • The pairing of the bases from the two strands is very specific • The complimentary base pairs are A-T and G-C - two hydrogen bonds form between A and T - three hydrogen bonds form between G and C • Each pair consists of a purine and a pyrimidine, so they are the same width, keeping the two strands at equal distances from each other 55sanjukaladharan
- 59. Ribonucleic Acid (RNA) • RNA is much more abundant than DNA • There are several important differences between RNA and DNA: - the pentose sugar in RNA is ribose, in DNA it’s deoxyribose - in RNA, uracil replaces the base thymine (U pairs with A) - RNA is single stranded while DNA is double stranded - RNA molecules are much smaller than DNA molecules • There are three main types of RNA: - ribosomal (rRNA), messenger (mRNA) and transfer (tRNA) 59sanjukaladharan
- 61. sanjukaladharan 61 Messenger RNA (mRNA) • Its sequence is copied from genetic DNA • It travels to ribsosomes, small granular particles in the cytoplasm of a cell where protein synthesis takes place
- 62. sanjukaladharan 62 Ribosomal RNA (rRNA) • Ribosomes are a complex of proteins and rRNA • The synthesis of proteins from amino acids and ATP occurs in the ribosome • The rRNA provides both structure and catalysis
- 63. sanjukaladharan 63 Transfer RNA (tRNA) • Transports amino acids to the ribosomes where they are joined together to make proteins • There is a specific tRNA for each amino acid • Recognition of the tRNA at the anti- codon communicates which amino acid is attached
- 64. Transfer RNA • Transfer RNA translates the genetic code from the messenger RNA and brings specific amino acids to the ribosome for protein synthesis • Each amino acid is recognized by one or more specific tRNA • tRNA has a tertiary structure that is L-shaped - one end attaches to the amino acid and the other binds to the mRNA by a 3-base complimentary sequence 64sanjukaladharan
- 65. Ribosomal RNA and Messenger RNA • Ribosomes are the sites of protein synthesis - they consist of ribosomal DNA (65%) and proteins (35%) - they have two subunits, a large one and a small one • Messenger RNA carries the genetic code to the ribosomes - they are strands of RNA that are complementary to the DNA of the gene for the protein to be synthesized 65sanjukaladharan
- 67. Proteins Come In Many Varieties! • Proteins include a diversity of structures, resulting in a wide range of functions • Proteins account for more than 50% of the dry mass of most cells • Protein functions include structural support, storage, transport, cellular communications, movement, and defense against foreign substances 67sanjukaladharan
- 68. Enzymatic 68 Enzymatic proteins Enzyme Example: Digestive enzymes catalyze the hydrolysis of bonds in food molecules. Function: Selective acceleration of chemical reactions sanjukaladharan
- 69. Storage 69 Storage proteins Ovalbumin Amino acids for embryo Function: Storage of amino acids Examples: Casein, the protein of milk, is the major source of amino acids for baby mammals. Plants have storage proteins in their seeds. Ovalbumin is the protein of egg white, used as an amino acid source for the developing embryo. sanjukaladharan
- 70. Defensive 70 Defensive proteins Virus Antibodies Bacterium Function: Protection against disease Example: Antibodies inactivate and help destroy viruses and bacteria. sanjukaladharan
- 71. Transport 71 Transport proteins Transport protein Cell membrane Function: Transport of substances Examples: Hemoglobin, the iron-containing protein of vertebrate blood, transports oxygen from the lungs to other parts of the body. Other proteins transport molecules across cell membranes. sanjukaladharan
- 72. Hormonal proteins Contractile and motor proteins Receptor proteins Structural proteins Example: Insulin, a hormone secreted by the pancreas, causes other tissues to take up glucose, thus regulating blood sugar concentration. Function: Coordination of an organism’s activities Normal blood sugar High blood sugar Insulin secreted Examples: Motor proteins are responsible for the undulations of cilia and flagella. Actin and myosin proteins are responsible for the contraction of muscles. Function: Movement Muscle tissue Actin Myosin 30 µm Connective tissue 60 µm Collagen Examples: Keratin is the protein of hair, horns, feathers, and other skin appendages. Insects and spiders use silk fibers to make their cocoons and webs, respectively. Collagen and elastin proteins provide a fibrous framework in animal connective tissues. Function: Support Signaling molecules Receptor protein Example: Receptors built into the membrane of a nerve cell detect signaling molecules released by other nerve cells. Function: Response of cell to chemical stimuli 72sanjukaladharan
- 73. More About Enzymes 73 • Enzymes are a type of protein that acts as a catalyst to speed up chemical reactions • Enzymes can perform their functions repeatedly, functioning as workhorses that carry out the processes of life sanjukaladharan
- 74. Amino Acids: Yet Another Monomer • Amino acids are organic molecules with carboxyl and amino groups • Amino acids differ in their properties due to differing side chains, called R groups 74 Side chain (R group) Amino group Carboxyl group α carbon sanjukaladharan
- 76. Polypeptides • Polypeptides are unbranched polymers built from the same set of 20 amino acids • A protein is a biologically functional molecule that consists of one or more polypeptides 76sanjukaladharan
- 77. npolar side chains; hydrophobic Side chain Glycine (Gly or G) Alanine (Ala or A) Valine (Val or V) Leucine (Leu or L) Isoleucine (Ile or I) Methionine (Met or M) Phenylalanine (Phe or F) Tryptophan (Trp or W) Proline (Pro or P) Hydrophobic: Therefore retreat from water! 77sanjukaladharan
- 78. 78 Hydrophilic: Therefore Are Attracted to Water sanjukaladharan
- 79. 79 Hydrophilic: But Electrically Charged! sanjukaladharan
- 80. Peptide Bonds • Amino acids are linked by peptide bonds • A polypeptide is a polymer of amino acids • Polypeptides range in length from a few to more than a thousand monomers (Yikes!) • Each polypeptide has a unique linear sequence of amino acids, with a carboxyl end (C-terminus) and an amino end (N-terminus) 80sanjukaladharan
- 83. Protein Structure & Function • At first, all we have is a string of AA’s bound with peptide bonds. • Once the string of AA’s interacts with itself and its environment (often aqueous), then we have a functional protein that consists of one or more polypeptides precisely twisted, folded, and coiled into a unique shape • The sequence of amino acids determines a protein’s three-dimensional structure • A protein’s structure determines its function 83sanjukaladharan
- 84. Protein Structure: 4 Levels • Primary structure consists of its unique sequence of amino acids • Secondary structure, found in most proteins, consists of coils and folds in the polypeptide chain • Tertiary structure is determined by interactions among various side chains (R groups) • Quaternary structure results when a protein consists of multiple polypeptide chains 84sanjukaladharan
- 85. Primary Structure • Primary structure, the sequence of amino acids in a protein, is like the order of letters in a long word • Primary structure is determined by inherited genetic information 85sanjukaladharan
- 86. Secondary Structure • The coils and folds of secondary structure result from hydrogen bonds between repeating constituents of the polypeptide backbone • Typical secondary structures are a coil called an α helix and a folded structure called a β pleated sheet 86sanjukaladharan
- 88. Tertiary Structure • Tertiary structure is determined by interactions between R groups, rather than interactions between backbone constituents • These interactions between R groups include actual ionic bonds and strong covalent bonds called disulfide bridges which may reinforce the protein’s structure. • IMFs such as London dispersion forces (LDFs a.k.a. and van der Waals interactions), hydrogen bonds (IMFs), and hydrophobic interactions (IMFs) may affect the protein’s structure 88sanjukaladharan
- 90. Quaternary Structure • Quaternary structure results when two or more polypeptide chains form one macromolecule • Collagen is a fibrous protein consisting of three polypeptides coiled like a rope 90sanjukaladharan
- 91. Quaternary Structure • Hemoglobin is a globular protein consisting of four polypeptides: two alpha and two beta chains 91sanjukaladharan
- 92. Four Levels of Protein Structure Revisited 92sanjukaladharan
- 93. Sickle-Cell Disease: A change in Primary Structure • A slight change in primary structure can affect a protein’s structure and ability to function • Sickle-cell disease, an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin 93 “Normal” Red Blood Cells sanjukaladharan
- 94. Sickle-Cell Disease: A change in Primary Structure • A slight change in primary structure can affect a protein’s structure and ability to function • Sickle-cell disease, an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin 94sanjukaladharan
- 95. What Determines Protein Structure? • In addition to primary structure, physical and chemical conditions can affect structure • Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to unravel • This loss of a protein’s native structure is called denaturation • A denatured protein is biologically inactive 95sanjukaladharan
- 96. Denature: Break Bonds or Disrupt IMFs 96sanjukaladharan
- 98. Carbohydrates serve as fuel and building material • Carbohydrates include sugars and the polymers of sugars • The simplest carbohydrates are monosaccharides, or single sugars • Carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks © 2011 Pearson Education, Inc. 98sanjukaladharan
- 99. Sugars • Monosaccharides have molecular formulas that are usually multiples of CH2O • Glucose (C6H12O6) is the most common monosaccharide • Monosaccharides are classified by – The location of the carbonyl group (as aldose or ketose) – The number of carbons in the carbon skeleton © 2011 Pearson Education, Inc. 99sanjukaladharan
- 100. Figure 5.3 Aldoses (Aldehyde Sugars) Ketoses (Ketone Sugars) Glyceraldehyde Trioses: 3-carbon sugars (C3H6O3) Dihydroxyacetone Pentoses: 5-carbon sugars (C5H10O5) Hexoses: 6-carbon sugars (C6H12O6) Ribose Ribulose Glucose Galactose Fructose 100sanjukaladharan
- 101. Figure 5.3a Aldose (Aldehyde Sugar) Ketose (Ketone Sugar) Glyceraldehyde Trioses: 3-carbon sugars (C3H6O3) Dihydroxyacetone 101sanjukaladharan
- 102. Figure 5.3b Pentoses: 5-carbon sugars (C5H10O5) Ribose Ribulose Aldose (Aldehyde Sugar) Ketose (Ketone Sugar) 102sanjukaladharan
- 103. Figure 5.3c Aldose (Aldehyde Sugar) Ketose (Ketone Sugar) Hexoses: 6-carbon sugars (C6H12O6) Glucose Galactose Fructose 103sanjukaladharan
- 104. • Though often drawn as linear skeletons, in aqueous solutions many sugars form rings • Monosaccharides serve as a major fuel for cells and as raw material for building molecules © 2011 Pearson Education, Inc. 104sanjukaladharan
- 105. Figure 5.4 (a) Linear and ring forms (b) Abbreviated ring structure 1 2 3 4 5 6 6 5 4 3 2 1 1 2 3 4 5 6 1 23 4 5 6 105sanjukaladharan
- 106. • A disaccharide is formed when a dehydration reaction joins two monosaccharides • This covalent bond is called a glycosidic linkage © 2011 Pearson Education, Inc. 106sanjukaladharan
- 107. Figure 5.5 (a) Dehydration reaction in the synthesis of maltose (b) Dehydration reaction in the synthesis of sucrose Glucose Glucose Glucose Maltose Fructose Sucrose 1–4 glycosidic linkage 1–2 glycosidic linkage 1 4 1 2 107sanjukaladharan
- 108. Polysaccharides • Polysaccharides, the polymers of sugars, have storage and structural roles • The structure and function of a polysaccharide are determined by its sugar monomers and the positions of glycosidic linkages © 2011 Pearson Education, Inc. 108sanjukaladharan
- 109. Storage Polysaccharides • Starch, a storage polysaccharide of plants, consists entirely of glucose monomers • Plants store surplus starch as granules within chloroplasts and other plastids • The simplest form of starch is amylose © 2011 Pearson Education, Inc. 109sanjukaladharan
- 110. Figure 5.6 (a) Starch: a plant polysaccharide (b) Glycogen: an animal polysaccharide Chloroplast Starch granules Mitochondria Glycogen granules Amylopectin Amylose Glycogen 1 µm 0.5 µm 110sanjukaladharan
- 111. Figure 5.6a Chloroplast Starch granules 1 µm 111sanjukaladharan
- 112. • Glycogen is a storage polysaccharide in animals • Humans and other vertebrates store glycogen mainly in liver and muscle cells © 2011 Pearson Education, Inc. 112sanjukaladharan
- 113. Figure 5.6b Mitochondria Glycogen granules 0.5 µm 113sanjukaladharan
- 114. Structural Polysaccharides • The polysaccharide cellulose is a major component of the tough wall of plant cells • Like starch, cellulose is a polymer of glucose, but the glycosidic linkages differ • The difference is based on two ring forms for glucose: alpha (α) and beta (β) © 2011 Pearson Education, Inc. 114sanjukaladharan
- 115. Figure 5.7 (a) α and β glucose ring structures (b) Starch: 1–4 linkage of α glucose monomers (c) Cellulose: 1–4 linkage of β glucose monomers α Glucose β Glucose 4 1 4 1 41 41 115sanjukaladharan
- 116. Figure 5.7a (a) α and β glucose ring structures α Glucose β Glucose 4 1 4 1 116sanjukaladharan
- 117. Figure 5.7b (b) Starch: 1–4 linkage of α glucose monomers (c) Cellulose: 1–4 linkage of β glucose monomers 41 41 117sanjukaladharan
- 118. © 2011 Pearson Education, Inc. • Polymers with α glucose are helical • Polymers with β glucose are straight • In straight structures, H atoms on one strand can bond with OH groups on other strands • Parallel cellulose molecules held together this way are grouped into microfibrils, which form strong building materials for plants 118sanjukaladharan
- 119. Cell wall Microfibril Cellulose microfibrils in a plant cell wall Cellulose molecules β Glucose monomer 10 µm 0.5 µm Figure 5.8 119sanjukaladharan
- 120. • Enzymes that digest starch by hydrolyzing α linkages can’t hydrolyze β linkages in cellulose • Cellulose in human food passes through the digestive tract as insoluble fiber • Some microbes use enzymes to digest cellulose • Many herbivores, from cows to termites, have symbiotic relationships with these microbes © 2011 Pearson Education, Inc. 120sanjukaladharan
- 121. • Chitin, another structural polysaccharide, is found in the exoskeleton of arthropods • Chitin also provides structural support for the cell walls of many fungi © 2011 Pearson Education, Inc. 121sanjukaladharan
- 123. sanjukaladharan 123
- 124. Lipids are a diverse group of hydrophobic molecules • Lipids are the one class of large biological molecules that do not form polymers • The unifying feature of lipids is having little or no affinity for water • Lipids are hydrophobic because they consist mostly of hydrocarbons, which form nonpolar covalent bonds • The most biologically important lipids are fats, phospholipids, and steroids © 2011 Pearson Education, Inc. 124sanjukaladharan
- 125. Fats • Fats are constructed from two types of smaller molecules: glycerol and fatty acids • Glycerol is a three-carbon alcohol with a hydroxyl group attached to each carbon • A fatty acid consists of a carboxyl group attached to a long carbon skeleton © 2011 Pearson Education, Inc. 125sanjukaladharan
- 126. Figure 5.10 (a) One of three dehydration reactions in the synthesis of a fat (b) Fat molecule (triacylglycerol) Fatty acid (in this case, palmitic acid) Glycerol Ester linkage 126sanjukaladharan
- 127. Figure 5.10a (a) One of three dehydration reactions in the synthesis of a fat Fatty acid (in this case, palmitic acid) Glycerol 127sanjukaladharan
- 128. © 2011 Pearson Education, Inc. • Fats separate from water because water molecules form hydrogen bonds with each other and exclude the fats • In a fat, three fatty acids are joined to glycerol by an ester linkage, creating a triacylglycerol, or triglyceride 128sanjukaladharan
- 129. Figure 5.10b (b) Fat molecule (triacylglycerol) Ester linkage 129sanjukaladharan
- 130. • Fatty acids vary in length (number of carbons) and in the number and locations of double bonds • Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds • Unsaturated fatty acids have one or more double bonds © 2011 Pearson Education, Inc. 130sanjukaladharan
- 131. © 2011 Pearson Education, Inc. Animation: Fats Right-click slide / select “Play” 131sanjukaladharan
- 132. Figure 5.11 (a) Saturated fat (b) Unsaturated fat Structural formula of a saturated fat molecule Space-filling model of stearic acid, a saturated fatty acid Structural formula of an unsaturated fat molecule Space-filling model of oleic acid, an unsaturated fatty acid Cis double bond causes bending. 132sanjukaladharan
- 133. (a) Saturated fat Structural formula of a saturated fat molecule Space-filling model of stearic acid, a saturated fatty acid Figure 5.11a 133sanjukaladharan
- 134. Figure 5.11b (b) Unsaturated fat Structural formula of an unsaturated fat molecule Space-filling model of oleic acid, an unsaturated fatty acid Cis double bond causes bending. 134sanjukaladharan
- 135. • Fats made from saturated fatty acids are called saturated fats, and are solid at room temperature • Most animal fats are saturated • Fats made from unsaturated fatty acids are called unsaturated fats or oils, and are liquid at room temperature • Plant fats and fish fats are usually unsaturated © 2011 Pearson Education, Inc. 135sanjukaladharan
- 136. • A diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits • Hydrogenation is the process of converting unsaturated fats to saturated fats by adding hydrogen • Hydrogenating vegetable oils also creates unsaturated fats with trans double bonds • These trans fats may contribute more than saturated fats to cardiovascular disease © 2011 Pearson Education, Inc. 136sanjukaladharan
- 137. • Certain unsaturated fatty acids are not synthesized in the human body • These must be supplied in the diet • These essential fatty acids include the omega-3 fatty acids, required for normal growth, and thought to provide protection against cardiovascular disease © 2011 Pearson Education, Inc. 137sanjukaladharan
- 138. • The major function of fats is energy storage • Humans and other mammals store their fat in adipose cells • Adipose tissue also cushions vital organs and insulates the body © 2011 Pearson Education, Inc. 138sanjukaladharan
- 139. Phospholipids • In a phospholipid, two fatty acids and a phosphate group are attached to glycerol • The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head © 2011 Pearson Education, Inc. 139sanjukaladharan
- 140. Figure 5.12 Choline Phosphate Glycerol Fatty acids Hydrophilic head Hydrophobic tails (c) Phospholipid symbo(b) Space-filling modela) Structural formula HydrophilicheadHydrophobictails 140sanjukaladharan
- 141. Choline Phosphate Glycerol Fatty acids (b) Space-filling model(a) Structural formula HydrophilicheadHydrophobictails Figure 5.12a 141sanjukaladharan
- 142. • When phospholipids are added to water, they self- assemble into a bilayer, with the hydrophobic tails pointing toward the interior • The structure of phospholipids results in a bilayer arrangement found in cell membranes • Phospholipids are the major component of all cell membranes © 2011 Pearson Education, Inc. 142sanjukaladharan
- 144. Steroids • Steroids are lipids characterized by a carbon skeleton consisting of four fused rings • Cholesterol, an important steroid, is a component in animal cell membranes • Although cholesterol is essential in animals, high levels in the blood may contribute to cardiovascular disease © 2011 Pearson Education, Inc. 144sanjukaladharan
- 146. Macromolecular assembly (MA) • The term macromolecular assembly (MA) refers to massive chemical structures such as viruses and non-biologicnanoparticles cellular organelles and membranes and ribosomes, etc. that are complex mixtures of polypeptide, polynucleotide, polysaccharide or other polymeric molecules. • They are generally of more than one of these types, and the mixtures are defined spatially (i.e., with regard to their chemical shape), and with regard to their underlying chemical composition and structure. 146sanjukaladharan
- 147. Figure 13.13 Note: S or Svedberg units are not additive A ribosome is composed of structures called the large and small subunits Each subunit is formed from the assembly of Proteins + rRNA Bacterial Ribosomes (and mitochondrial/chloroplast) 147sanjukaladharan
- 148. Figure 13.13 The 40S and 60S subunits are assembled in the nucleolus Then exported to the cytoplasm Formed in the cytoplasm during translation Eukaryotic Ribosomes 148sanjukaladharan
- 149. Ribosomes contain three discrete sites: Peptidyl site (P site) Aminoacyl site (A site) Exit site (E site) 149sanjukaladharan
- 150. Release factors Initiator tRNA Three Stages: Initiation Elongation Termination 150sanjukaladharan
Editor's Notes
- #35: This lesson will deal with protein and nucleic acids. Emphasize yet again that within the molecule, the intramolecular forces are covalent bonds, but the intermolecular forces (IMFs) between molecules will vary due to the polarity of the molecule as a whole.
- #68: Ask students what they already know about proteins and protein synthesis. Hopefully, they remember a few things from Biology I.
- #69: Emphasize the specificity of enzymes. Also emphasize the catalytic nature of enzymes and that they function best in a unique set of pH and temperature conditions. Why is that? It is due to the shape of the enzyme molecule. That shape is held in place by IMFs and/or covalent or ionic bonding. Changes in pH or temperature often disrupt the electrostatic forces that are responsible for an enzyme’s specific shape.
- #70: Ask students to identify other food sources that are proteins. One of my favorite quotes ever is from Bob Harper, a personal trainer from The Biggest Loser. Simply put, “If the food in question had a mother, then it’s a protein!”
- #71: Ask students which body system utilizes these types of proteins.
- #72: Ask which body system utilizes hemoglobin.
- #73: Figure 3.16b An overview of protein functions (part 7)
- #74: This is a perfect time to bring out the “water noodle” enzyme models. You can extend this portion of the lesson to include competitive inhibition, etc.
- #75: There are 23 amino acids (aa’s) but only 20 are biologically active.
- #77: Ask, how many peptide bonds are formed. Ask how many amino acids are in this polypeptide. Additionally, emphasize the arrangement of the aa’s in this diagram. If one of the aa’s is “flipped” along the horizontal axis, it’s amine group no longer aligns with the neighboring aa’s carboxylic acid group, thus no dehydration reaction can occur.
- #78: Absolutely no need to memorize these, but there is a need to recognize WHY these retreat from water. Point out that these “R” groups are very nonpolar as evidenced by the “hydrocarbonish” or CHX nature of the elements involved in the R groups.
- #79: Absolutely no need to memorize these, but emphasize that while these R groups also look “hydrocarbonish”, that there are unpaired electrons left off this diagram. Each N, O or S atom has unshared electron pairs that make them polar and water soluble.
- #80: Again, no need to memorize these but students should know that ammonia (NH3) is a weak base from Chemistry I. Remove an H from ammonia and you have its “cousin” the amine group which is also basic.
- #81: Emphasize that the peptide bond forms as a consequence of a dehydration synthesis reaction.
- #85: Now is the time to explain that a string of aa’s is a polypeptide and NOT yet a protein. The protein forms once the secondary, tertiary and quaternary structures are established and that is usually facilitated in an aqueous environment. Also emphasize that “conformation” is the “big people” word for shape and that if the conformation changes, the function of the protein is affected.
- #86: Keep it simple. Explain to students that when they were about 3 years old, they would sing the alphabet song to anyone that would listen! They had no idea that one day they’d use that to spell or that they would use it to read, or write sentences, or paragraphs or research papers! Also, remind them yet again that they have some prior knowledge regarding DNA and the process of protein synthesis.
- #87: Emphasize yet again that a H-bond is NOT a bonded H! It’s an IMF, not a covalent bond, but rather an electrostatic force. H-bonds are fragile and easily interrupted by pH or temperature changes.
- #88: Linus Pauling is my favorite scientist, so I’d have to share that he won his first Nobel Prize in Chemistry in 1954 "for his research into the nature of the chemical bond and its application to the elucidation of the structure of complex substances". Those complex substances are proteins and he figured out the helix and a folded structure called a pleated sheet! Students may know that the electronegativity scale they learned in Chemistry I is the “Pauling Electronegativity Scale”. But, they may not know that he was hot on the heels of beating Watson & Crick to the “discovery” of the structure of DNA OR that he also won a Nobel Prize for Peace. Whew!
- #89: Here we go again, the second bullet refers to actual chemical bonds—the sharing of a pair of electrons. The third bullet refers to intermolecular forces (IMFs) with LDFs that the biology books often refer to as van der Waals forces or interactions. H-bonds are a special case of dipole-dipole interactions. While none of these distinctions will be asked on the AP Biology exam, they certainly will on the AP Chemistry exam and should be taught in Chem I as well. It’s not surprising that students are confused since the vocabulary is so different from book to book! Ugh!
- #90: Revisit the “curly hair” example for disulfide bridges. Folks with curly hair have more disulfide bridges and we often use heat to alter them 1.Use a hair dryer-brush-mechanically pull on the hair while applying heat to disrupt the S-S bridges. 2. Flat irons on dry hair 3. “Perms”—A basic solution that reeks of ammonia (a base, thus a pH rather than thermal approach) is applied to hair that has been wound onto skinny curlers and left to sit for about 20 minutes to allow S-S to form.
- #91: Emphasize that Quaternary structure involves a collection of polypeptides brought together into a new conformation.
- #92: The classic example!
- #93: A nice visual summary!
- #94: A perfect practical example of how a change in protein structure affects function. Be sensitive to the fact that you may have a student that suffers from sickle-cell disease.
- #95: The sickled cells cannot move the blood vessels as effectively and can obstruct capillaries and restrict blood flow to an organ, resulting in pain, necrosis and often organ damage. Ask if students studied the connection between sickle-cell trait and malaria in Biology I.
- #96: Ask how EACH of the items mentioned could disrupt protein structure.
- #97: This concept is an energy concept as well. If thermal energy is added, the molecules vibrate more vigorously. At some point the electrostatic attractions (H-bonds) are overcome and “let go”. When students write free-responses, make sure they define terms they use within their writing. “A change in temperature denatures a protein since the H-bonds (or IMFs) are disrupted (or overcome, or altered, or anything else that implies the structure is broken down).” Lots of ways to wordsmith the response correctly!
- #101: Figure 5.3 The structure and classification of some monosaccharides.
- #102: Figure 5.3 The structure and classification of some monosaccharides.
- #103: Figure 5.3 The structure and classification of some monosaccharides.
- #104: Figure 5.3 The structure and classification of some monosaccharides.
- #106: Figure 5.4 Linear and ring forms of glucose.
- #108: Figure 5.5 Examples of disaccharide synthesis.
- #111: Figure 5.6 Storage polysaccharides of plants and animals.
- #112: Figure 5.6 Storage polysaccharides of plants and animals.
- #114: Figure 5.6 Storage polysaccharides of plants and animals.
- #116: Figure 5.7 Starch and cellulose structures.
- #117: Figure 5.7 Starch and cellulose structures.
- #118: Figure 5.7 Starch and cellulose structures.
- #120: Figure 5.8 The arrangement of cellulose in plant cell walls.
- #127: Figure 5.10 The synthesis and structure of a fat, or triacylglycerol.
- #128: Figure 5.10 The synthesis and structure of a fat, or triacylglycerol.
- #130: Figure 5.10 The synthesis and structure of a fat, or triacylglycerol.
- #133: Figure 5.11 Saturated and unsaturated fats and fatty acids.
- #134: Figure 5.11 Saturated and unsaturated fats and fatty acids.
- #135: Figure 5.11 Saturated and unsaturated fats and fatty acids.
- #141: Figure 5.12 The structure of a phospholipid.
- #142: Figure 5.12 The structure of a phospholipid.
- #144: Figure 5.13 Bilayer structure formed by self-assembly of phospholipids in an aqueous environment.
- #145: For the Cell Biology Video Space Filling Model of Cholesterol, go to Animation and Video Files. For the Cell Biology Video Stick Model of Cholesterol, go to Animation and Video Files.
- #146: Figure 5.14 Cholesterol, a steroid.