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Chapter 2 Are We Alone in the Universe? Water, Biochemistry, and Cells Fourth Edition BIOLOGY Science for Life | with Physiology Colleen Belk • Virginia Borden Maier © 2013 Pearson Education, Inc. Copyright © 2009 Pearson Education, Inc. PowerPoint Lecture prepared by Jill Feinstein Richland Community College Requirements for Life: 1. water 2. food 3. oxygen 4. heat 5. pressure © 2013 Pearson Education, Inc. 2.1 What Does Life Require? FOOD the food we ingest as humans is made up of macromolecules Macromolecules: very large compounds made up of smaller molecules joined together in biochemistry – 4 types of macromolecules these macromolecules are found in living organisms many of which we eat © 2013 Pearson Education, Inc. Macromolecules Macromolecules: Carbohydrates Proteins Lipids Nucleic Acids © 2013 Pearson Education, Inc. Structure and Function of Macromolecules Carbohydrates: molecules of carbon, oxygen, and hydrogen Major source of energy for cells Monosaccharides or simple sugars are building blocks for carbohydrates Disaccharides are composed of two monosaccharides joined together Polysaccharides are composed of many monosaccharides joined together © 2013 Pearson Education, Inc. Monosaccharides: - in aqueous solutions –monosaccharides are not linear -they form rings -three ways to represent the ring structure of a monosaccharide 3. Simplest form 1. Molecular ring form © 2013 Pearson Education, Inc. 2. Abbreviated ring structure A. Simple carbohydrates • disaccharide = two monosaccharides bound together -formed by a dehydration synthesis reaction – results in the removal of a water molecule -broken up by a hydrolysis reaction – requires you to put the water back in e.g. glucose + glucose = maltose e.g. glucose + fructose = sucrose e.g. glucose + galactose = lactose © 2013 Pearson Education, Inc. B. Complex carbohydrates or Polysaccharides: •a polysaccharide is an example of a polymer •polymer – compound made of repeating units called monomers •monomer = monosaccharide •some polysaccharides serve as storage materials – hydrolyzed into individual monosaccharides – for energy production -animals = glycogen (highly branched polymer of glucose monomers) -plants = starches (glucose polymers but with different bonds holding them together) •others serve as structural or building materials • plants = cellulose (glucose polymers but with different bonds holding them together) © 2013 Pearson Education, Inc. Amylopectin Amylose Glycogen Complex carbohydrates: High fructose corn syrup (HFCS) First described in 1957 by Richard Marshall and Earl Kooi Required the use of arsenic to make in large quantities Perfected for commercial use in 1961 – Yamanaka HFCS = any corn syrup that has undergone enzymatic processing to convert some of its glucose monomers into fructose HFCS55 – 55% fructose and 42% glucose (similar to honey) HFCS42 – 42% fructose and 53% glucose Cheaper than sucrose due to import tariffs on sugar cane and/or sucrose Used because fructose is sweeter than glucose No difference between HFCS and sucrose in terms of satisfaction and health effects?? Typical American weighs 25 lbs more than 25 yrs ago HFCS entered into the American diet in 1975 © 2013 Pearson Education, Inc. 3. Proteins • nearly every dynamic function of a living organism depends on proteins •Greek – proteios = “first place” •more than 50% of the dry mass of most cells •numerous roles: • structural – support of cells and tissues • storage - energy source • transport across cell membranes • hormones and their receptors – signaling • chemical messengers - signaling • antibodies - defense • metabolic role - enzymes © 2013 Pearson Education, Inc. Structure and Function of Macromolecules Proteins: polymers of amino acids; joined by peptide bonds Side chain (R group) carbon Proteins are made up of carbon, oxygen, hydrogen, and nitrogen. There are 20 different amino acids, with different chemical properties. Different combinations of amino acids give proteins different properties. amino acids are joined by dehydration synthesis reactions © 2013 Pearson Education, Inc. Amino group Carboxyl group • amino acids joined together by a dehydration synthesis reaction forming a peptide bond = between the NH2 of 1 a.a. and the COOH of the next amino acid Side chains Back- bone 2 a.a. dipeptide 3 a.a. tripeptide New peptide bond forming 4 or more a.a. polypeptide Carboxyl end (C-terminus) Amino end (N-terminus) New Peptide bond © 2013 Pearson Education, Inc. Sickle-Cell Disease: A Change in Primary Protein 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 Sickle-cell hemoglobin Normal hemoglobin Primary Structure © 2013 Pearson Education, Inc. 1 2 3 4 5 6 7 Secondary and Tertiary Structures Quaternary Structure subunit Exposed hydrophobic region subunit 10 m Sickle-cell hemoglobin Red Blood Cell Shape Molecules do not associate with one another; each carries oxygen. Normal hemoglobin 1 2 3 4 5 6 7 Function Molecules crystallize into a fiber; capacity to carry oxygen is reduced. 10 m Structure and Function of Macromolecules • proteins have four levels of organization: • 1. Primary – amino acid sequence of the polypeptide chain •sequence is determined by the DNA sequence found within a gene • 2. Secondary – coils and pleats due to interactions among the AAs • 3. Tertiary – 3D structure • 4. Quaternary – more than one polypeptide chain “woven” together © 2013 Pearson Education, Inc. Structure and Function of Macromolecules Lipids: hydrophobic; composed mostly of carbon and hydrogen energy source for cells Three types: 1. Fat is composed of a glycerol molecule joined with 3 fatty acids 2. Steroids are a four carbon ring structure e.g.cholesterol, estrogen and testosterone 3. Phospholipids are composed of a glycerol molecule, 2 fatty acids called “tails” and a phosphate group called a “head group” © 2013 Pearson Education, Inc. 1. Fats • • • • energy supply most plentiful lipids in your body composed of C, H and O “building blocks” = 3 fatty acid chains (hydrocarbons usually from 16 to 18 carbons) PLUS 1 glycerol molecule fatty acid fatty acid fatty acid glycerol portion fatty acid portion © 2013 Pearson Education, Inc. • fatty acids -differ in chain length with each fat -ALSO - differ in the location and number of double bonds within the hydrocarbon chain 1. single C bonds - saturated carboxyl gp • Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds • solids at room temperature – except for palm oil and coconut oil • animal fats and butter © 2013 Pearson Education, Inc. 2. double C bonds - unsaturated monounsaturated: 1 double bond polyunsaturated: 2 or more double bonds • Unsaturated fatty acids have one or more double bonds in the hydrocarbon chains • are liquid at room temperature • oils © 2013 Pearson Education, Inc. 2. double C bonds - unsaturated monounsaturated: 1 double bond polyunsaturated: 2 or more double bonds -Polyunsaturated fatty acids & health -important in regulating cholesterol levels - lower LDL levels in the blood -increase calcium utilization by body –good for bone density - reduce inflammation – role in preventing arthritis? - promote wound healing © 2013 Pearson Education, Inc. (a) Saturated fat (b) Unsaturated fat double bond causes bending in the fatty acid chain. • at room temperature – the molecules of a saturated fat are packed closely together • • • the fatty acid tails are more flexible forms a solid the molecules of an unsaturated fat cannot pack closely together enough to solidify • the C=C bonds produce a “kink” in the fatty acid chain making it difficult to pack them together • if the fat contains one fatty acid that is unsaturated – then the fat is considered unsaturated © 2013 Pearson Education,at Inc.room temperature • liquid 2. Phospholipids •modified fat – replace one fatty acid with a phosphate group (negative electrical charge) • phosphate group hydrophilic “head” • fatty acid groups hydrophobic “tails” • when added to water – self-assemble and form a form a phospholipid bilayer – major component of the plasma membrane © 2013 Pearson Education, Inc. 3. Steroids • backbone is called cholesterol = 4 fused carbon rings • cholesterol is synthesized in the liver • modified in other organs • e.g. testosterone – cholesterol is modified in the testes • diversity through attached functional groups e.g. testosterone, estrogen, aldosterone © 2013 Pearson Education, Inc. Structure and Function of Macromolecules Nucleic acids: polymers of nucleotides Nucleotide: sugar + a phosphate group + a nitrogenous base © 2013 Pearson Education, Inc. Figure 2.15c Nitrogenous bases there are two families of nitrogenous bases: Pyrimidines Cytosine (C) Thymine (T, in DNA) Uracil (U, in RNA) Purines Adenine (A) © 2013 Pearson Education, Inc. Guanine (G) 1. Pyrimidines (cytosine, thymine, and uracil) have a single six-membered ring 2. Purines (adenine and guanine) have a sixmembered ring fused to a five-membered ring • Nucleic acids can be linked together to form a polynucleotide chain - formed by a dehydration synthesis reaction •bond forms between the phosphate of 1 nucleotide and the sugar of the next Sugar-phosphate backbone 5 end 5C 3C phosphodiester bond 5C 3C 3 end (a) Polynucleotide, or nucleic acid © 2013 Pearson Education, Inc. • two major types of polynucleotide chains: 1. RNA 2. DNA Structure and Function of Macromolecules Nucleotides are of two types: RNA and DNA, depending on the sugar in the nucleotide 1. RNA sugar = ribose 2. DNA sugar = deoxyribose HOCH2 O OH H H OH OH ribose © 2013 Pearson Education, Inc. HOCH2 O OH H H OH H deoxyribose A. RNA single polynucleotide chain bases: A, C, G and uracil (U) in place of T numerous types found in cells – the most common is called mRNA or messenger RNA (plays a role in gene expression) B. DNA double polynucleotide chain = double helix 2 chains held together by hydrogen bonds between the bases bases pair up in a complementary fashion A=T C G © 2013 Pearson Education, Inc. Structure and Function of Macromolecules DNA is the hereditary material in nearly all organisms. the structure of a DNA molecule is a double helix. the sugar-phosphate backbone found on the outside of the helix the bases found on the inside the helix is held together by hydrogen bonds between the bases © 2013 Pearson Education, Inc. Structure and Function of Macromolecules Animation: Nucleic Acids Right-click slide / select “Play” © 2013 Pearson Education, Inc. Structure and Function of Macromolecules bonding between bases on opposite strands follows strict base-pairing rules: A with T – double H bonds G with C – triple H bonds so regions of the helix with GC base pairs are held together stronger that regions with AT base pairs © 2013 Pearson Education, Inc. Genomics study of the genome of animals and humans and their relationship to the function of the organism Human Genome Project – June 1990 genome = genetic makeup of an individual (genes + “junk DNA”) humans – 23 chromosome pairs totaling 3.2 billion nucleotides most humans share 99.9% of their genome therefore unique attributes come from only 0.1% of a human’s genome (1 in 100 nucleotides) over 50% of our genome does not code for any protein = junk DNA only about 40,000 active protein-coding genes in our genome (only 1.5% of the human genome!!!) average gene = 3000 base pairs dystrophin – largest human gene = 2.4 million nt’s © 2013 Pearson Education, Inc. c. ATP individual n.t’s can have metabolic functions e.g. adenosine = adenine + ribose -adenine modified by adding three phosphates major source of ATP = breakdown of glucose 1 glucose molecule glycolysis Kreb’s cycle oxidative phosphorylation 36 ATP © 2013 Pearson Education, Inc.