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DNA REPLICATIONGeromil J. Lara, RMT, MSMT
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FUNCTIONS OF DNA Reproduces itselfreplication
Process by which copies of DNA are madeduring cell division
Supplies the information necessary to makeall the proteins in the body
REPLICATION FORK
Point on the DNA where application takesplace
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REPLICATION Bidirectional
Done with the same speed in both
directions 2 daughter strands are synthesized in
different ways
5 to 3 direction LEADING STRAND
3 to 5 direction LAGGING STRAND
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ENZYMES FUNCTION
HELICASE Unwinds the DNA double helix
PRIMASESynthesizes short oligonucleotides(primers)
CLAMP PROTEINAllows the leading strand to bethreaded through
DNA POLYMERASE
Joins the assembled nucleotides
LIGASEJoins Okazaki fragments in thelagging strand
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STEPS IN DNA REPLICATION Opening up the superstructure
Acetylation and deacetylation of histone
Relaxation of higher structures of DNA
Action of topoisomerases (also known asgyrases)
Unwinding the DNA double helix
Action of helicases Primer/Primases
DNA Polymerase
Ligation
Action of DNA ligase
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CENTRAL DOGMA
OF MOLECULAR BIOLOGY Information contained in DNA molecules is
transferred to RNA molecules, and then fromthe RNA molecules the information is
expressed in the structure of proteins
2 Steps in transmission of information:
Transcription
Translation
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CENTRAL DOGMA
OF MOLECULAR BIOLOGY TRANSCRIPTION
Occurs in the nucleus
Information encoded in a DNA molecule iscopied into an mRNA molecule
TRANSLATION
Information encoded in an mRNA molecule isused to assemble a specific protein
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TRANSCRIPTION Starts when the DNA double helix begins to unwind
at a point near the gene that is to be transcribed
Only one strand of DNA molecule is transcribed
3 Kinds of Polymerases (catalyze the transcription)
Polymerase I catalyzes the formation of rRNA
Polymerase II
catalyzes the formation ofmRNA
Polymerase III catalyzes tRNA formation
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2 Major Parts of Eukaryotic Gene Structural Gene
Transcribed into RNA
Made of exons and introns Regulatory Gene
Controls the transcription
Not transcribed but rather has control elements
PROMOTER Contain consensus sequences TATA box
TERMINATION SEQUENCE
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NEXT: Translation