Introduction and Perspective A Understand and be able to define the terms selective breeding phenotype and genes a For thousands of years man has recognized that traits tend to be passed from parents to offspring and the best way to obtain a plant or animal with desirable traits is to start with parents with desirable traits This is the simple premise behind selective breeding Selective breeding is the way humans have developed all of our modern breeds of dogs from wild wolves and a number of our present day vegetables from the wild mustard plant b Phenotype is defined as the observable properties of an organism It is a description of the characteristics that we can observe or measure in an individual ex With respect to hair color brown hair In humans phenotype includes the individual s health as it might be affected by the presence of any of a number of minor or life threatening genetically based diseases c Genes the basic units of heredity that are made of DNA and are located on chromosomes Each gene typically codes for one functional product wither a protein or a functional RNA such as rRNA or tRNA B Know why it s important that all members of society have a rudimentary knowledge of genetics a Deciding how to use our knowledge of genetics will require input from scientists ethicists policy makers and society at large As we move in the 21st century it is increasingly important for each of us to have some knowledge of genetics Chapter 1 Protein s the Basis of Cell and Organismal Function A Know that proteins are linear chains of amnio acids Know the basic structure of an amnio acid how amnio acids are joined by peptide bonds to form a protein and how the sequence of amnio acids in a protein determines the three dimensional structure of the protein Finally understand how structure relates to function in a protein using collagen and hemoglobin as specific examples a Proteins are linear chains of amnio acids b All amnio acids are similar to each other in that they have the same core of carbon oxygen nitrogen and hydrogen atoms but they differ in that each group has its own characteristic side group or R group c Proteins are linear unbranched chains of hundreds or even thousands of amnio acids Because of their common core any two adjacent amnio acids are always linked the same way with a peptide bond The differences in proteins are in the sequence and identity of the amnio acids and their R groups along the length of the chain d Protein folding the shape of the protein is dictated by the chemical interactions between different regions of the chain frequently in the form of interactions between positive and negative charges in different R groups the sequence of amnio acids in a protein determines the three dimensional structure of that protein e The structure of a protein determines its function i Collagen ii Hemoglobin 1 Three collagen molecules interact to form a rigid triple helix Bundles of these triple helices then interact to form sense fibers said to have the tensile strength of steel The interactions between collagen molecules to form triple helices and the interaction between triple helices to form tensile fibers involve interactions between the R groups of amnio acids that are precisely positioned along the length of the collagen protein chain the sequence of amnio acids in collagen is responsible for the formation of the structurally important collagen fibers 1 The sequence of its amnio acids causes the hemoglobin to fold into a three dimensional structure which has a pocket within the molecule that has the right shape and chemical environment to bind a molecule of oxygen In red blood cells four of these hemoglobin molecules join to form a complex Each complex of this type in red blood cells carry four molecules of oxygen from the lungs to other tissues of the body where the oxygen is used to fuel the process of respiration The sequence of amnio acids in a protein determines its structure which in turn gives the protein a very specific and unique function B Understand the relationship between protein variation and phenotypic variation and how sickle cell anemia results from a variant form of hemoglobin a Many of our proteins occur in variant forms that result in variant phenotypes ex Skin or eye color b Some people make a variant form of hemoglobin that differs from the normal form by just one amnio acid This small difference causes the hemoglobin molecules to aggregate with each other and the red blood cells carrying the aggregated hemoglobin instead of having the usual disk like appearance become sickle shaped The result is a disease called sickle cell anemia that is characterized by the reduced ability to transport oxygen through the blood stream The sickle shaped blood cells become stuck in smaller blood vessels resulting in serious problems such as liver damage kidney damage stroke and early death Chapter 2 Gene s DNA Replication and A Know the chemical components of DNA how these components are combined to make a strand of DNA and how two strands of DNA join to form a double helix as first modeled by Watson and Crick a In DNA the subunits are components called nucleotides Every nucleotide consists of a sugar group deoxyribose a phosphate group and a nitrogenous base Four different nitrogenous bases are found in DNA adenine A guanine G thymine T and cytosine C b The sugar of one nucleotide is linked to the phosphate of the next nucleotide which in turn is linked to the next nucleotide by the same sugar to phosphate bond All DNA molecules have identical sugar phosphate backbones they differ only in the sequence of nitrogenous bases that protrude from the backbone c Watson and Crick found that each DNA molecule actually consists of two chains or strands of nucleotides wrapped around each other in the form of a double helix The two strands are held together by weak chemical interactions called hydrogen bonds between the nitrogenous bases in the two strands B Understand the complementary nature of the two strands of DNA in a double helix and how DNA is replicated using the rules of complementarity a Each nitrogenous base in one strand is paired with a base in the other strand Strict rules govern the type of base pairing interactions that can form T A G C Two DNA strands with nitrogenous base sequences that will form with proper base pairing interactions are said to be complementary to each other b The mechanism for duplicating genes is called replication and is based on
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