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Chapter 5 notes

Chapter 5 notes - Chapter 5 notes Basic genetic mechanisms...

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Chapter 5 notes Basic genetic mechanisms – the ways in which cells maintain, replicate, express, and occasionally improve the genetic information carried in its DNA The Structure and Function of DNA Chromosomes contain both DNA and protein Chromosomes become visible as cell prepares to divide Protein components of chromosomes function largely to to package and control the enourmously long DNA molecule DNA is made of 4 nucleotide building blocks A DNA molecule consists of two complementary chains of nucleotides DNA molecule consists of 2 long polynucleotide chains known as DNA chains, or strands Each chain is composed of 4 types of nucleotide subunits Two chains held together by hydrogen bonds between the base portions of the nucleotides Nucleotides composed of a 5-carbon sugar attached to one or more phosphate groups and a nitrogen containing base The nucleotides are covalently linked together in a chain through the sugars and phosphates The way in which the nucleotide subunits are linked together gives a DNA strand a chemical polarity The polarity in a DNA chain is indicated by referring to oe end as the 3’ end and the other as the 5’ end All the bases are on the inside of the helix Sugar-phosphate backbones on the outside A always pairs with T, G always with C The complementary base pairing eneables the base pairs to be pakced I the energetically most favorable arrangement in the interior of the double helix 10 bases per helical turn The members of each base pair can fit together within the double helix only if the two strands of the helix are antiparallel
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A DNA molecule contains a sequence of nucleotides that are exactly complementary to the nucleotide sequence of its partner strand The structure of DNA provides a mechanism for heredity The DNA helix has a major and minor groove The function of a protien is determined by its 3 dimensional stucture Its structure is determined by the sequence of amino acids it is composed of Gene expression – the process by which a cell coverts the nucleotide sequence of a gene into the amino acid sequence of a protein Genome – the complete set of information in an organism’s DNA The structure of Eukaryotic Chromosomes Each human cell contains about 2 meters of DNA, yet the cell nucleus is nonly 5-8 um in diameter The complex task of packaging DNA is accomplished by specialized proteins that bind to and fold the DNA, generating a series of coils and loops that provide increasingly higher
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Chapter 5 notes - Chapter 5 notes Basic genetic mechanisms...

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