Chapter 10 - Nature of the Gene and Genome (Spring 2011)

Opposite directions the sugar phosphate backbone is

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Unformatted text preview: ns The sugar-phosphate backbone is located on the outside of the molecule the bases are inside the helix The DNA is a double helix The 2 DNA strands are held together by hydrogen bonds between each base Pyrimidines are always paired with purines Only A-T and C-G pairs fit within the double helix Molecule has a major groove and a minor groove The double helix makes a turn every 10 residues The 2 chains are complementary to each other To be the genetic material, DNA must fulfill 3 functions: storage of genetic information, replication and inheritance, expression of the genetic message Watson-Crick model suggested a way DNA could store information and replicate itself The Structure of the Genome o o The genome of a cell is its unique content of genetic information The complexity of a genome one important property of DNA is its ability to separate into 2 strands (denaturation) 3 o o o o o o o o o o o o o DNA renaturation: renaturation and reanneling is when single stranded DNA molecules are capable of reassociating Reanneling has led to the development of nucleic acid hybridization where complementary strands of nucleic acids from different sources can form hybrid molecules The rate of renaturation of DNA from bacteria and viruses depends on the size of the genome the larger the genome the greater the time for renaturation Reanneling of eukaryotic genome shows 3 classes of DNA: highly repeated, moderately repeated and nonrepeated Highly repeated DNA sequences represent about 1 to 10% of total DNA Satellite DNA: short sequences that tend to evolve very rapidly Minisatellite DNA: unstable and tend to be variable in population form the basis of fingerprinting Microsatellite DNA: shortest sequences and typically found in small clusters implicated in genetic disorders Fluorescence in situ hybridization and localization of satellite DNA: slide with mitotic chromosome is treated with hot salt solution to denature the DNA, single stranded DNA is incubated with biotinylated DNA probe, then washed to remove any unhybridized DNA, double stranded DNA hybrid is incubated with fluorescently labelled avidin to reveal location of bound labelled DNA probe the satellide DNA was localized in centromeres Moderatly repeated DNA sequences Repeated DNA sequences with Coding Functions: include genes that code for ribosomal RNA and histones Repeated DNA Sequences that Lack Coding: do not include any type of gene product; can be grouped into 2 classes: SINEs and LINEs Non Repeated...
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This document was uploaded on 04/10/2014.

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