![]() Sed bases of the unzipped parental strand. Free-floating nucleotides form complementary base pairs with the expo.Complementary base paring can occur.Ģ.7.U3 – DNA polymerase links nucleotides together to form a new strand, using the pre-existing strand as a template. We now have two template (parental) strands with bases exposed.Topoisomerase – Enzyme that cuts DNA and reseals it with fewer twists (relieves tension). ![]() As helicase unzips the DNA, strain on the helix increases.Initiator protein binds to an origin of replication and triggers unzipping (several ori.Separated DNA strands form a replication bubble at the origin of replication.Replication bubble – Unwound/open region of a DNA helix where replication occurs.DNA Helicase (an unzipping enzyme) moves along DNA molecule breaking hydrogen bonds between complementary base pairs.But, in order for base pairing to occur, we need to unzip to DNA.ĭNA molecule is split down the middle and forms two, identical copies 2.7.U2 – Helicase unwinds the double helix and separates the two strands by breaking hydrogen bonds.Using the parental DNA strand as a template, two identical strands of DNA are produced.DNA is semi-conservative in terms of replication.In 1957, Meselson and Stahl conducted an experiment providing evidence for semi-conservative replication.Ģ.7.A2 – Analysis of Meselson and Stahl’s results to obtain support for the theory of semi-conservative replication of DNA. 3) Semi -conservative – two parental DNA strands separate and each of those strands then serves as a template for the synthesis of a new DNA strand.įigure 5: The three proposed methods of DNA replication.2) Dispersive – parental DNA double helix is broken into segments that act as templates.1) Conservative – parental strand rejoins after replication.Originally, there were three proposed methods:.How do we know DNA replication is semi-conservative? Figure 3: Semi-conservative DNA replication The parental strand acts as a template and therefore each replicated strand is identical and each daughter cell has the same DNA.ĭue to this, DNA replication is semi-conservative – or each new DNA strand has one parental strand (template) and one newly synthesized strand.Base paring ensures two identical DNA strands are formed after replication is complete.This is due to the molecular structure of the base pairs.Guanine is always matched with Cytosine with three hydrogen bond.Adenine is always matched with Thymine with two hydrogen bonds.Two DNA strands are held together by hydrogen bonding between complementary base pairs. Protein Synthesis slides (Bio 115) DNA Replication – BasicsĢ.7.U1 -The replication of DNA is semi-conservative and depends on complementary base pairing. Transcription and Translation crash course Essential Idea: Genetic information in DNA can be accurately copied and can be translated to make the proteins needed by the cell.ĭNA structure and replication crash course
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