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In 1869, DNA was found to be acidic & rich in __ (element)
phosphorus
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From the experiment with virulent, avirulent, & heat-killed virulent bacteria, they discovered that __. This is called the __
by adding heat-killed bacteria to avirulent bacteria, genetic material was passed on from a virulent to an avirulent bacteria. The presence of that gene (in this case, the thick capsule) causes the mouse to die;
transforming principle
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How was DNA discovered to be the genetic material of bacteria and not RNA or protein?
- Deoxyribonuclease treatment (digesting DNA) of the heat-killed virulent bacteria prevented transformation of an avirulent bacteria to a virulent bacteria while digestion of protein (protease) & RNA (ribonuclease) did not affect the transformation.
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evidence that DNA is the genetic material when pure DNA was isolated from the capsulated bacteria
- CapS (from isolated DNA) was found to be the gene responsible for generation of a capsule (makes it pathogenic). When CapS was entered into a non-pathogenic (non-capsulated) cell, recombination & cell division produces pathogenic, capsulated cells.
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How were virus genes proven to be made of DNA & not protein?
- If the DNA of the virus enters the bacteria, then DNA is the genetic material, if the capsid (protein part) of the virus does, then the protein component is the genetic material. DNA was labeled with 32P (phosphorus) & protein was labeled with 35S (methionine). After centrifuging, they found that infected bacteria mainly contained phage DNA (70% 32P). New phages are made in the infected bacterium from the presence of this DNA.
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DNA is a long polymer containing __
- phosphates, sugar molecules (deoxyribose), & 4 nitrogenous organic bases
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Each base is attached to __ of a deoxyribose (glycosidic bond), phosphate(s) bound to __ of deoxyribose
carbon 1; carbon 5
(In RNA, each base is attached to carbon 1 of a ribose.)
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Subunits of DNA are linked by 3' to 5' __ bonds
phosphodiester
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Watson & Crick identified DNA structure to have a __. The strands are held together by __ bonds.
- double helix;
- hydrogen
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A pairs with T and C pairs with G because __
There is a same ratio of A to T, and C to G. (In RNA, A is complementary to U.)
Base pairing is due to the formation of hydrogen bonds between A & T, and between G & C nucleotides in the 2 strands of DNA. The order of nucleotides in the parental DNA can determine the order of nucleotides in the daughter DNA. (opening up the 2 strands can create new strands with complementary base pairs)
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DNA polymerization requires __
- the building blocks of DNA in the form of high energy molecules containing 3 phosphates, dATP, dTTO,dGTP, dCTP.
- the presence of DNA template to determine the order of nucleotides in the newly synthesizing DNA strand
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DNA polymerase attaches the __ of the 5' end of the new nucleotide to the 3' __ of the previous nucleotide in the chain.
- phosphate; OH-
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The DNA polymerase synthesized the new DNA directly from the __
parental DNA
(DNA is the direct template for DNA, no other intermediate molecules such as protein was needed.)
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DNA replication is __, meaning the daughter DNA consists of __. From the Meselson-Stahl experiment, after another generation, there are __ bands.
- semiconservative; 1 strand being a parent DNA, the other strand being the new DNA; 2 (1 slightly heavier, 1 lighter)
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Genes are transcribed into __. The enzymes that perform transcription are called __.
- RNA; RNA polymerases
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__ are the building blocks of RNA
Nucleotides
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Crick referred to the pathway of info flow from DNA to RNA to protein as the __
- Central Dogma
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For protein synthesis, __ are needed that can specifically bind to each amino acid & have specific binding to RNA.
adaptor molecules
(tRNA molecules are the adaptor molecules needed for the flow of info from RNA to protein.)
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More than 85% of cellular RNA is in __. This RNA is referred to as __
ribosomes; rRNA (ribosomal RNA)
(rRNA are very conserved among organisms with similar GC ratios).
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This type of RNA is coded by DNA (sequence similar to DNA) & interacts with ribosomes for protein synthesis
- mRNA (messenger RNA)
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Amino acids before incorporation into proteins, bind to small RNA molecules called __
tRNA (transfer RNA)
- (On one side of a tRNA, there is a specific sequence for interaction with mRNA & on the other side of a tRNA molecule an amino acid is bound).
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In the Pulse Chase assay experiment, RNA was found to be synthesized in the __ & moves to the __
- nucleus; cytoplasm
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All amino acids can be coded with __ nucleotides called __
- 3; codons
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A polypeptide is a __
- polymer of amino acids (more than a few) linked one by one by peptide bonds. has an amine end (N terminal) & carboxyl end (C terminus)
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Ribosomes recruit __ (contains the info) and __ that translate the __ into amino acids & polymerize the amino acids into specific proteins (polypeptides)
- mRNA; aminoacyl-tRNAs; codons
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gene expression
transcription of a gene to RNA & translation of a mRNA to a protein
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Proteins are synthesized from the __ terminal to __ terminal
N; C
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DNA polymerization requires __
the building blocks of DNA in the form of high energy molecules containing 3 phosphase, dATP, dTTP, dGTP, dCTP
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DNA polymerase polymerizes the DNA strand by attaching __. Addition of each nucleotide releases __
- the phosphate of the 5' end of the new nucleotide to the 3'-OH of the previous nucleotide in the chain (making phosphodiester bonds);
- pyrophosphate (PPi)
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Polymerization also requires the presence of __ to determine the order of nucleotides in the newly synthesizing DNA strand
DNA template
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The DNA polymerase synthesized the new DNA __
directly from the parental DNA
(DNA is the direct template for DNA, no other intermediate molecules such as protein was needed.)
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