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Chapter 8

MMG 141 Chapter 8: Ch. 8.6-7 DNA Replication and Chromosomes

2 pages32 viewsSpring 2019

Department
Microbiology and Molecular Genetics
Course Code
MMG 141
Professor
Jennifer Neal
Chapter
8

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Human Heredity
MMG 141
Ch. 8.6-7
DNA Replication
DNA has two major functions in cell
Replicate itself
Carry genetic information for proteins and RNA molecules necessary for
life
Before cell divides, DNA must be copied
Semiconservative replication
One old strand of DNA conserved in each new molecule, one new
strand synthesized
Stages of DNA Replication
Complex, multistep process
Begins at sites along chromosome called origins of replication
Double helix unwound by breaking H bonds
Enzyme DNA polymerase reads nucleotide sequence and links
nucleotides together in complementary, anti parallel format
Enzyme checks strand, removing and replacing incorrect strands
Formed in short stretches and combined with different enzyme to form
continuous strand
Proteins then wind strands into double helix
Organization of DNA in Chromosomes
Chromatin: the DNA and protein components of chromosomes, visible as
clumps or thread in nuclei
Histones: DNA-binding proteins that help compact and fold DNA into
chromosomes
Nucleosomes: bead-like structure composed of histone wrapped with DNA
DNA must fit in nucleus, compacted by histones to fit initially
Must be further compacted to account for mitotic chromosomes
Chromosomal Regions
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