DNA REPLICATION Animation gone Crazy DNA Replicates and

DNA REPLICATION

Animation gone Crazy • DNA Replicates and Replicates

DNA is anti-parallel • Two strands run parallel to each other but with opposite alignments (directions) • Mc. Graw-Hill DNA • Why is being antiparallel an advantage to the DNA molecule?

DNA REPLICATION • Semi-conservative = each one of the parent DNA strands is passed to the daugher DNA + one new strand for each • Semi-conservative DNA (30 secs) SNEAK PREVIEW: DNA REPLICATION PLAYERS (enzyme review)

Fill out DNA Replication Enzymes CHART • Lots of enzymes are needed to start each step

Topoisomerase • Topoisomerase Youtube I and II (1: 45) • Topoisomerase Animation (2: 16)

Enzyme Helicase: Helicase separates (breaking Hbonds) double helix at the replication fork DNA-RNA-Protein (see ani) YOU TUBE DNA replication (1: 05)

DNA Helicase • The enzyme is unwinding the chain and breaking the H-bonds between the complementary base pairs (A-T, G-C).

RNA Primer • Nucleotides for the starting point for DNA replication • Short strands of RNA

DNA replication is initiated at many points in eukaryotic chromosomes. • Called Replication Bubbles • They will eventually all meet to form whole replicated strand

DNA Replication Bubble: DNA duplicates in both directions

SSB’s single strand binding proteins • Stabilize the DNA strands as they are being replicated • Prevents rejoining of DNA strands

DNA Polymerases • DNA Polymerase I • Cuts off RNA primers and fills in with DNA (between Okazaki fragments) – lagging strand • Can proofread • DNA Polymerase III • Elongates the strand by adding DNA nucleotides on leading strand • Also proofreads and corrects the DNA strand

Anti-parallel strand builds in the opposite direction (but always in 5’ to 3’ direction)

Leading Strand Lagging Strand • Template strand of • Other DNA strand DNA • Forms short strands • Continuous addition of of Okazaki fragments nitrogenous bases (that will be joined later) • in 5’ to 3’ direction • Mc. Graw-Hill Replication Fork • in the 5’ to 3’ direction • DNA Replication You Tube (1: 35)

• OKAZAKI FRAGMENTS • The short strands of newly made DNA fragments on the lagging strand are called Okazaki fragments after the Japanese Biochemist Reiji Okazaki. •

DNA LIGASE is the enzyme that joins the Okazaki fragments (sugar phosphate backbone) with covalent bonds DNA REPLICATION (look for ligase) 2: 00

SUMMARY DNA Replication (5: 45) – shows all the enzymes • Summary Youtube of DNA replication (4: 11) • Good explanation of the 5’ to 3’ strands and leading and lagging strands

Includes all your friendly enzymes • DNA Replication (3: 56) Great animation

How Fast? • Prokaryotic DNA polymerase can work at about 1000 bases per second. • Eukaryotic DNA polymerase can work at about 50 bases per second.

Animation: DNA Replication • DNA makes DNA • *DNA with enzymes cartoons

• Mc. Graw Hill Replication Fork animation

DNA Replication Easy Version (3: 11) • DNA Replication Youtube (7: 48) • Good CLICK and REVIEW

What if there is a mistake?

DNA Replication Activity Work in Lab Groups • Card stock papers are original DNA strands • Colored paper are new DNA strands • MAKE OWN ENZYMESconstruction paper

Telomeres • At the ends of each chromosome is a protective cap called a telomere. • Each time a cell divides, the telomeres are snipped shorter,

Telomerase • enzyme which adds DNA sequence repeats ("TTAGGG" in all vertebrates) to the 3' end of DNA strands (an overhang) • Mc. Graw Hill Telomeres Animation

Telomeres Added to ends of chromosomes Rutgers Telomere Animation

QUIZ • Activity (choose your enzymes and proteins)

MOVIE • Media Showcase (cool animation) • Replication Overview Movie

QUESTION • In this diagram of the process of DNA replication at a replication fork, the strand labeled B is the: • A template strand • B lagging strand • C leading strand • D Okazaki fragment • E RNA primer

QUESTION • In this diagram of the process of DNA replication at a replication fork, the newly synthesized DNA strand labeled C is the: A coding strand • B parental DNA • C leading strand • D lagging strand

ANSWER • C lagging strand • The lagging strand is the newly synthesized DNA where addition of nucleotides is on the end opposite or away from the replication fork.

QUESTION • In this diagram of the process of DNA replication at a replication fork, the black boxes labeled D and E are: • A RNA primers • B DNA template strands • C Okazaki fragments • D DNA polymerase • E Newly synthesized DNA strand

ANSWER • A. RNA primers • The initiation of replication always starts with a short RNA piece. The DNA replicating enzymes will only add nucleotides to the 3' end of DNA.

QUESTION • For the DNA strand 5'-TACGATCATAT-3' the correct complementary DNA strand is: A 3'-TACGATCATAT-5 • 'B 3'-ATGCTAGTATA-5‘ • C 3'-AUGCUAGUAUA-5‘ • D 3'-GCATATACGCG-5‘ • E 3'-TATACTAGCAT-5'

ANSWER • B 3'-ATGCTAGTATA-5'