05 Dna Replication

8/2/2019 05 Dna Replication

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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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05 Dna Replication