Chapter 7 DNA

A is equal to T, G is equal to C. Pyrimidines are equal to purines.

Watson and Crick

S cells were virulent, R cells were nonvirulent. Virulent = kills mice. Griffith injected dead S cells into mice and the mice would not die. Griffith then injected live R cells and dead S cells into the mice which resulted in the mice dying and the R cells becoming S cells. The R cells took some chemical components from the S cells which made them virulent. This is called Transformation. The 3 goobers simply purified the substance involved down to only DNA, when DNA is present the transformative principle can be seen.

GATC, there are 18 repeats

Demonstrated that the genetic material of phages is DNA and not protein. Used radioactive isotopes of phosphorus for DNA and Sulfur for Protein. Phosphorus was found inside the cell.

Determined DNA was Semiconservative. Used Isotope density.

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Through X-ray crystallography, she purified DNA and crystallized it. An X-ray emitter hit the crystal, producing a shadow on the X-ray film. This experiment produced a circle with a uniform diameter. Purine matches with pyrimadine

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1379

Topoisomerase type 1 will break bonds to allow swivel and relieve torsional strain. Topoiosomerase will introduce supercoiling to relieve helical stress.

Deoxyribose sugar, Nitrogenous bases, Phosphate group

An early name for DNA, concieved from nonvirulent bacteria becoming virulent bacteria.

Forms a phosphodiester bond. Phosphate groups and 3 end hydroxyl group.

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Histone Octamers and Nucleosomes

Histone octamers are eight protein complexes found at the center of a nucleosome core. Has C terminal tails that are post-transformationally modifications.

Nucleosomes are a chain of DNA coiled around a core of histones.

Chemical reaction where methyl group gets added to DNA or other molecules. Turns off expression. Methylated by DAM methylase enzyme. The A sequence of GATC.

When the DNA molecule coils itself to help with strain caused by helical stress. Caused by type 2 Topoisomerase. Can convert a positive supercoil into a negative supercoil.

Positive supercoils are introduced by opening DNA, Negative supercoils store free energy for opening.

Regulates gene expression and turns on expression. Opens or closes chromatin structure.

Cistron is a section of DNA/RNA that encodes a polypeptide product.

Polycistronic mRNAs, Monocistronic mRNAs.

After replication the double stranded DNA helix will be hybrid and contain half of old original strand.

Hemimethylated DNA, once the DNA is open Seq A will prevent replication from continuing further until the prokaryote (Ecoli) has enough resources to begin.

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Opening the DNA at the origin and initiating the process of DNA replication as biphasic replication forks.

DNAA binds to oriC, DNAB is helicase, DNAC loads DNAB.

Origin of replication in E Coli, Has 3 13bp repeats, 5 9bp repeats. 245bp in total.

DNAA binds cooperatively to the 9mer repeats first and bends DNA back to the 13mer repeats to achieve initial melting.

Loads DNAB onto the lagging strand template

Primes the leading strand 1st with RNA primer, RNA primase. (transiently associates with DNA B)

Pyrophosphate

Cuts out the RNA its only substrate. Nuclease activity.

MutS scans for distortion of DBL helix. MutH has endonuclease activity to remove the DNA around the mistmatch.

A lesion such as thymine dimer prevents polymerase 3 from working as intended. Polymerase 5 ignores this lesion and continues work then poly 3 can join again.

Because pyrophosphate is easily reversible and can take back the nucleotides. Pyrophosphatase cleaves pyrophosphate into 2.

B subunit and T subunit

Slides in a 5 to 3 direction, and unzips the helix at the replication fork. Homohexamer that forms a ring around the lagging strand template. Helicase.

Sliding clamp, leash for DNA pol 3, wraps around the double stranded DNA.

Holds everything together like scaffolding

Breaks bonds between nucleotides of nucleic acid.

Endonuclease cuts within the nucleic acid chain. Exonuclease removes nucleotides from an end of nucleic acid chain.

It can go 5 to 3 and 3 to 5 direction.

Removes RNA nucleotides and replace with DNA. Exonuclease activity.

Exonuclease activity, DNA polymerase 1 adds DNA to 3 end and ligase seals it

The tedency of a polymerase to stay at Primer Template Junction

How well polymerase can make the complementary strand and fix any errors.

UVRA UVRB UVRC UVRD, XP genes (Xeroderma Pigmentosa).

XP genes (Xeroderma Pigmentosa)

NHEJ and Recombination repair