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AP Biology Chapter 3: Structure and Function of Macromolecules (Independently brush up on Ch 2 and Ch 3.1)
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Enduring Understandings / IV. A. Interactions within biological systems lead to complex properties. / 1. The subcomponents of biological molecules and their sequence determine the properties of that molecule. / B. Competition and cooperation are important aspects of biological systems. / 1. Interactions between molecules affect their structure and function. / C. Naturally occurring diversity among and between components within biological systems affects interactions with the environment. / 1. Variation in molecular units provides cells with a wider range of functions. / IV. A. Interactions within biological systems lead to complex properties. / 1. The subcomponents of biological molecules and their sequence determine the properties of that molecule. / B. Competition and cooperation are important aspects of biological systems. / 1. Interactions between molecules affect their structure and function. / C. Naturally occurring diversity among and between components within biological systems affects interactions with the environment. / 1. Variation in molecular units provides cells with a wider range of functions.
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Macromolecules Smaller organic molecules join together to form larger molecules macromolecules 4 major classes of macromolecules: carbohydrates lipids proteins nucleic acids
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H2OH2O HO H HH Polymers Long molecules built by linking repeating building blocks in a chain monomers building blocks repeated small units covalent bonds
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H2OH2O HO H HH How to build a polymer Synthesis joins monomers by “taking” H 2 O out one monomer donates OH – other monomer donates H + together these form H 2 O requires energy & enzymes enzyme Dehydration synthesis - Condensation reaction, in which the lost molecule = H 2 O Condensation reaction
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Dehydration Synthesis
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H2OH2O HOH H H How to break down a polymer Digestion use H 2 O to breakdown polymers reverse of dehydration synthesis cleave off one monomer at a time H 2 O is split into H + and OH – H + & OH – attach to ends requires hydrolytic enzymes releases energy Hydrolysis enzyme
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Discussion Under what circumstances would you expect to find a cell conducting a great deal of dehydration synthesis ? In which organs or under what circumstances would you expect to find body cells conducting hydrolysis ?
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Variety of Polymers Every cell has thousands of varieties of macromolecules These molecules are constructed from only 40 to 50 common monomers Analogy: 26 letters of the alphabet can be combined to form millions of words Shortcoming: macromolecules are much longer than the average word and they can be branched or 3D.
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Carbohydrates
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a.k.a. wheeee energy! :D
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Carbohydrates Carbohydrates are composed of C, H, O carbo - hydr - ate CH 2 O) x C 6 H 12 O 6 Function: energy u energy storage raw materials u structural materials Monomer: sugars (monosaccharide) sugar C 6 H 12 O 6 (CH 2 O) x
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Sugars Most names for sugars end in - ose Classified by number of carbons 6C = hexose (glucose) 5C = pentose (ribose) 3C = triose (glyceraldehyde) 653
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Sugar structure 5C & 6C sugars form rings in solution
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Numbered carbons C CC C C C 1' 2'3' 4' 5' 6' O energy stored in bonds You’ll see this come back in our DNA unit…
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Simple & complex sugars Monosaccharides simple 1 monomer sugars Ex: glucose, galactose Disaccharides 2 monomers Ex: sucrose, lactose Polysaccharides 3+ monomers Ex: starch, cellulose, glycogen
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Building sugars Dehydration synthesis to form glycosidic bond | fructose | glucose monosaccharides | sucrose (table sugar) disaccharide H2OH2O
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Polysaccharides Polymers of sugars costs little energy to build easily reversible = release energy Functions: energy storage starch (plants) glycogen (animals) in liver & muscles structure cellulose (plants) chitin (arthropods & fungi)
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Polysaccharide diversity Molecular structure determines function - a major theme! Isomers of glucose Different structure = connect to the next monomer in the chain differently = different 3D structure. Starch - helical. Cellulose - straight, with free OH to bond to neighboring celluloses = rigid structure! in starch in cellulose
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Cellulose Most abundant organic compound on Earth herbivores have evolved a mechanism to digest cellulose most carnivores have not that’s why they eat meat to get their energy & nutrients cellulose = undigestible roughage
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Helpful bacteria How can herbivores digest cellulose so well? BACTERIA live in their digestive systems & help digest cellulose-rich (grass) meals Ruminants
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Discussion In EXACTLY 20 words, summarize the most important point or points to remember about carbohydrates.
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Lipids: Fats & Oils
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Enduring Understandings / IV. A. Interactions within biological systems lead to complex properties. / 1. The subcomponents of biological molecules and their sequence determine the properties of that molecule. / B. Competition and cooperation are important aspects of biological systems. / 1. Interactions between molecules affect their structure and function. / C. Naturally occurring diversity among and between components within biological systems affects interactions with the environment. / 1. Variation in molecular units provides cells with a wider range of functions. / IV. A. Interactions within biological systems lead to complex properties. / 1. The subcomponents of biological molecules and their sequence determine the properties of that molecule. / B. Competition and cooperation are important aspects of biological systems. / 1. Interactions between molecules affect their structure and function. / C. Naturally occurring diversity among and between components within biological systems affects interactions with the environment. / 1. Variation in molecular units provides cells with a wider range of functions.
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Lipid Primary Function: long term energy storage concentrated energy
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Lipids Lipids are composed of C, H, O long hydrocarbon chains (H-C) “Family groups” fats phospholipids steroids Do not form polymers big molecules made of smaller subunits not a continuing chain Same as carbohydrates, but different structure = different function!
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Fats Structure: glycerol (3C alcohol) + fatty acid fatty acid = long HC “tail” with carboxyl (COOH) group “head” dehydration synthesis H2OH2O enzyme
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Building Fats Triglycerol 3 fatty acids linked to glycerol ester linkage between OH & COOH hydroxylcarboxyl
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Dehydration synthesis dehydration synthesis H2OH2OH2OH2OH2OH2OH2OH2O enzyme
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Discussion What kind of molecule would you expect to be hydrophobic - polar or non-polar? Why? Do you think lipids (such as fats, oils, waxes) are probably polar or non-polar? Why?
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Fats store energy Long HC chain polar or non-polar? hydrophilic or hydrophobic? Functions: energy storage 2x carbohydrates cushion organs membranes & waterproofing insulates body think whale blubber!
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Discussion Show me a human who doesn’t want to eat this and I’ll show you a LIAR. LIESSSSSSS Knowing their major functions, hypothesize: what occurred in evolutionary history that led to humans enjoying the tastes of fatty and sugary foods?
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Structure & Function Saturated Fats All C bonded to H No C=C double bonds long, straight chain most animal fats solid at room temp. contributes to cardiovascular disease (atherosclerosis) = plaque deposits
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Structure & Function Unsaturated Fats C=C double bonds in the fatty acids plant & fish fats vegetable oils liquid at room temperature the kinks made by double bonded C prevent the molecules from packing tightly together
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Discussion Unsaturated fats are widely considered to be healthier (sometimes called “good fats” for short) than saturated fats. Why might this be? (Hint: think of their structures, and what they might mean for how easily the body would use them for energy vs. storing them in fat cells)
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Phospholipids Structure: glycerol + 2 fatty acids + PO 4 PO 4 = negatively charged
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Phospholipids Hydrophobic or hydrophilic? fatty acid tails = PO 4 head = split “personality” interaction with H 2 O is complex & very important! “repelled by water” “attracted to water” hydrophobic hydrophillic
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Phospholipids in water Hydrophilic heads “attracted” to H 2 O Hydrophobic tails “hide” from H 2 O can self-assemble into “bubbles” called micelles can also form a phospholipid bilayer Early Earth history - a cell part that self-assembles! bilayer water
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Why is this important? Phospholipids create a barrier in water define outside vs. inside they make cell membranes !
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Steroids Structure: 4 fused C rings + ?? different steroids created by attaching different functional groups to rings different structure creates different function examples: cholesterol, sex hormones cholesterol
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Cholesterol Important cell component animal cell membranes precursor of all other steroids including vertebrate sex hormones high levels in blood contribute to cardiovascular disease
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Cholesterol helps keep cell membranes fluid & flexible Important component of cell membrane
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From Cholesterol Sex Hormones What a big difference a few atoms can make!
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Discussion In EXACTLY 20 words, summarize the most important point or points to remember about lipids.
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Nucleic Acids Information storage
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Enduring Understandings / IV. A. Interactions within biological systems lead to complex properties. / 1. The subcomponents of biological molecules and their sequence determine the properties of that molecule. / B. Competition and cooperation are important aspects of biological systems. / 1. Interactions between molecules affect their structure and function. / C. Naturally occurring diversity among and between components within biological systems affects interactions with the environment. / 1. Variation in molecular units provides cells with a wider range of functions. / IV. A. Interactions within biological systems lead to complex properties. / 1. The subcomponents of biological molecules and their sequence determine the properties of that molecule. / B. Competition and cooperation are important aspects of biological systems. / 1. Interactions between molecules affect their structure and function. / C. Naturally occurring diversity among and between components within biological systems affects interactions with the environment. / 1. Variation in molecular units provides cells with a wider range of functions.
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proteins DNA Nucleic Acids Function: genetic material stores information genes blueprint for building proteins DNA RNA proteins transfers information blueprint for new cells blueprint for next generation
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Nucleic Acids Examples: RNA (ribonucleic acid) single helix DNA (deoxyribonucleic acid) double helix Structure: monomers = nucleotides RNA DNA
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Nucleotides 3 parts nitrogen base (C-N ring) pentose sugar (5C) ribose in RNA deoxyribose in DNA phosphate (PO 4 ) group Nitrogen base I’m the A,T,C,G or U part!
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Types of nucleotides 2 types of nucleotides different nitrogen bases purines double ring N base adenine (A) guanine (G) pyrimidines single ring N base cytosine (C) thymine (T) uracil (U) Purine = AG “Pure silver!”
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Nucleic polymer Backbone sugar to PO 4 bond phosphodiester bond new base added to sugar of previous base dehydration synthesis again! polymer grows in one direction N bases hang off the sugar-phosphate backbone Dangling bases? Why is this important?
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Pairing of nucleotides Nucleotides bond between DNA strands H bonds purine :: pyrimidine A :: T 2 H bonds G :: C 3 H bonds Matching bases? Why is this important?
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DNA molecule Double helix H bonds between bases join the 2 strands A :: T C :: G Like carbohydrates, strands have direction that matters to structure The end with a dangling phosphate (5’) can’t have any more bases added to it, unlike the other end (3’) H bonds? Why is this important?
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Copying DNA Replication 2 strands of DNA helix are complementary have one, can build other have one, can rebuild the whole Matching halves? Why is this a good system?
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Interesting note… Ratio of A-T::G-C affects stability of DNA molecule 2 H bonds vs. 3 H bonds biotech procedures more G-C = need higher T° to separate strands high T° organisms many G-C parasites many A-T (don’t know why)
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Another interesting note… ATP Adenosine triphosphate ++ modified nucleotide adenine (AMP) + P i + P i
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Discussion In EXACTLY 20 words, summarize the most important point or points to remember about nucleic acids.
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Proteins Multipurpose molecules
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Enduring Understandings / IV. A. Interactions within biological systems lead to complex properties. / 1. The subcomponents of biological molecules and their sequence determine the properties of that molecule. / B. Competition and cooperation are important aspects of biological systems. / 1. Interactions between molecules affect their structure and function. / C. Naturally occurring diversity among and between components within biological systems affects interactions with the environment. / 1. Variation in molecular units provides cells with a wider range of functions. / IV. A. Interactions within biological systems lead to complex properties. / 1. The subcomponents of biological molecules and their sequence determine the properties of that molecule. / B. Competition and cooperation are important aspects of biological systems. / 1. Interactions between molecules affect their structure and function. / C. Naturally occurring diversity among and between components within biological systems affects interactions with the environment. / 1. Variation in molecular units provides cells with a wider range of functions.
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Proteins Most structurally & functionally diverse group Function: involved in almost everything enzymes (pepsin, DNA polymerase) structure (keratin, collagen) carriers & transport (hemoglobin, aquaporin) cell communication signals (insulin & other hormones) receptors defense (antibodies) movement (actin & myosin) storage (bean seed proteins)
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Proteins Structure monomer = amino acids 20 different amino acids polymer = polypeptide protein can be one or more polypeptide chains folded & bonded together large & complex molecules complex 3-D shape Rubisco hemoglobin growth hormones H2OH2O
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Amino acids Structure central carbon amino group carboxyl group (acid) R group (side chain) variable group different for each amino acid confers unique chemical properties to each amino acid like 20 different letters of an alphabet can make many words (proteins) —N——N— H H C—OH || O R | —C— | H
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Effect of different R groups: Nonpolar amino acids nonpolar & hydrophobic
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Effect of different R groups: Polar amino acids polar or charged & hydrophilic
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Ionizing in cellular waters H+ donors
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Ionizing in cellular waters H+ acceptors
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Sulfur containing amino acids Form disulfide bridges covalent cross links betweens sulfhydryls stabilizes 3-D structure H-S – S-H
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Building proteins Peptide bonds covalent bond between NH 2 (amine) of one amino acid & COOH (carboxyl) of another C–N bond peptide bond dehydration synthesis H2OH2O
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Building proteins Like carbs & nucleic acids, polypeptides have direction that matters! N-terminus = NH 2 end C-terminus = COOH end repeated sequence (N-C-C) is the polypeptide backbone can only grow in one direction, N -> C
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Protein structure & function hemoglobin Function depends on structure 3-D structure twisted, folded, coiled into unique shape collagen pepsin
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Primary (1°) structure Order of amino acids in chain amino acid sequence determined by gene (DNA) slight change in amino acid sequence can affect protein’s structure & its function even just one amino acid change can make all the difference! Remember sickle-cell anemia? lysozyme: enzyme in tears & mucus that kills bacteria
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Sickle cell anemia I’m hydrophilic! I’m hydrophobic! Just 1 out of 146 amino acids! Non- polar valine “tries to hide” from water of cell by sticking to another hemoglobin molecule
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Secondary (2°) structure “Local folding” folding along short sections of polypeptide interactions between adjacent amino acids H bonds weak bonds between R groups forms sections of 3-D structure -helix -pleated sheet
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Secondary (2°) structure
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Tertiary (3°) structure “ Whole molecule folding ” interactions between distant amino acids hydrophobic interactions cytoplasm is water-based nonpolar amino acids cluster away from water H bonds & ionic bonds disulfide bridges covalent bonds between sulfurs in sulfhydryls (S – H) anchors 3-D shape
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Quaternary (4°) structure More than one polypeptide chain bonded together only then does polypeptide become functional protein Collagen = skin & tendon structure Hemoglobin = holds O 2
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Sequence -> Structure Structure -> Function amino acid sequence peptide bonds 1° determined by DNA R groups H bonds R groups hydrophobic interactions disulfide bridges (H & ionic bonds) 3° multiple polypeptides hydrophobic interactions 4° 2°
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Protein denaturation Unfolding a protein conditions that disrupt H bonds, ionic bonds, disulfide bridges temperature pH salinity alter 2° & 3° structure alter 3-D shape destroys functionality some proteins can return to their functional shape after denaturation, many cannot
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Discussion In EXACTLY 20 words, summarize the most important point or points to remember about proteins.
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Macromolecule Review
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Carbohydrates Structure / monomer monosaccharide Function energy raw materials energy storage structural compounds Examples glucose, starch, cellulose, glycogen glycosidic bond
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Lipids Structure / building block glycerol, fatty acid, cholesterol, H-C chains Function energy storage membranes hormones Examples fat, phospholipids, steroids
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Nucleic acids Structure / monomer nucleotide Function information storage & transfer Examples DNA, RNA phosphodiester bond
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Proteins Structure / monomer amino acids levels of structure Function enzymes u defense transport u structure signals u receptors Examples digestive enzymes, membrane channels, insulin hormone, actin peptide bond
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Discussion In EXACTLY 20 words, summarize the major theme/s in studying biomacromolecules. (And no, wise guy, I don’t mean “they’re hard.”)
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