A proteins shape depends on four levels of structure The overall three

A proteins shape depends on four levels of structure

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A protein’s shape depends on four levels of structure The overall three-dimensional shape of a protein is called its tertiary structure Tertiary structure generally results from interactions between the R groups of the various amino acids Disulfide bridges are covalent bonds that further strengthen the protein’s shape
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Amino acids Primary structure
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Amino acids Alpha helix Hydrogen bond Secondary structure Pleated sheet
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Polypeptide (single subunit of transthyretin) Tertiary structure
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Transthyretin, with four identical polypeptide subunits Quaternary structure
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Four Levels of Protein Structure Amino acids Primary structure Alpha helix Hydrogen bond Secondary structure Pleated sheet Polypeptide (single subunit of transthyretin) Tertiary structure Transthyretin, with four identical polypeptide subunits Quaternary structure
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NUCLEIC ACIDS
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Nucleic acids are information-rich polymers of nucleotides DNA ( deoxyribonucleic acid ) and RNA ( ribonucleic acid ) are composed of monomers called nucleotides Nucleotides have three parts A five-carbon sugar called ribose in RNA and deoxyribose in DNA A phosphate group A nitrogenous base
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Phosphate group Nitrogenous base (adenine) Sugar
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Nucleic acids are information-rich polymers of nucleotides DNA nitrogenous bases are adenine (A), thymine (T), cytosine (C), and guanine (G) RNA also has A, C, and G, but instead of T, it has uracil (U)
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Nucleic acids are information-rich polymers of nucleotides A nucleic acid polymer, a polynucleotide, forms from the nucleotide monomers when the phosphate of one nucleotide bonds to the sugar of the next nucleotide The result is a repeating sugar-phosphate backbone with protruding nitrogenous bases
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Sugar-phosphate backbone Nucleotide
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Nucleic acids are information-rich polymers of nucleotides Two polynucleotide strands wrap around each other to form a DNA double helix The two strands are associated because particular bases always hydrogen bond to one another A pairs with T, and C pairs with G, producing base pairs RNA is usually a single polynucleotide strand
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Base pair
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Nucleic acids are information-rich polymers of nucleotides A particular nucleotide sequence that can instruct the formation of a polypeptide is called a gene Most DNA molecules consist of millions of base pairs and, consequently, many genes These genes, many of which are unique to the species, determine the structure of proteins and, thus, life’s structures and functions
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EVOLUTION CONNECTION: Lactose tolerance is a recent event in human evolution Mutations are alterations in bases or the sequence of bases in DNA Lactose tolerance is the result of mutations In many people, the gene that dictates lactose utilization is turned off in adulthood Apparently, mutations occurred over time that prevented the gene from turning off This is an excellent example of human evolution Reading on the digital page about lactose tolerance
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  • Winter '15
  • Darcie Ruby
  • DNA

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