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35 Cards in this Set
- Front
- Back
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Where is DNA found?
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In the nucleus and chromosomes.
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What did Fred Griffith do and what was learned?
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He discovered the transforming pricinciple (DNA) probably carried heritalbe information. He discovered this while working with virulent and non virulent strains.
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What did Hershey and Chase find?
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Found that DNA was the cell's genetic material. Used radioactive tracers.
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What did Roslaind Frankling learn and how did he learhn this?
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He learned about the structure of DNA. He did this by taking deffraction X-rays of DNA.
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What are the two purines of DNA? What are the two pyrimidines of DNA?
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Adenine and Guanine. Cytosine and Thymine.
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What did Erwin Chargaff do?
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He proved the amounts in the four bases of DNA. The amnt of Adenine =amnt of Thymine. Amnt of guanin=amnt of cytosine.
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What is Chargaff's rule?
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The pairing of the bases equal each other, even though the actual proportion of those bases differ amoung species.
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What did Watson & Crcick do?
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They described the double helix based off of Franklin's x-ray.
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What are the four features that summarize the molecular structure of DNA?
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(1) The DNA molecule is a double-standed helix of uniform diameter. (2) The twist in DNA is right-handed (3) The two stands run in different directions, antiparallel. (4) The outer edges of the nitrogenous bases are exposed in the major and minor grooves.
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What are three things associated with DNA?
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(!1)Two strains colid together are called the double helix. (2) Sides of the pentose sugar Deoxyribose bonded to phosphate groups by phosphodiester bonds (3) Center made of nitrogen bases bonded together by weak hydrogen bonds.
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What is the structure of most of the DNA helix?
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Most DNA has right hand twist with 10 base pairs in a complete turn.
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What is Z-DNA or Southpaw DNA?
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It is left twisted helix DNA?
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What happens when right handed and left handed twisted DNA meet?
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Mutations occur.
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What are some characteristics of the nucleotide?
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(1) 1 Phophate group (2) 5 carbon sugar (3) A nitrogenous base
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What are antiparallel strands?
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They are polynucleotides that are defined by the linkakges between adjacent nucleotides.
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Which nitrogenous bases are double pringed purines?
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Adenine and Guanine
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Which nitrogenouse bases are single rind pyrimidines??
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Thymine and Cytosine.
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How many hydrogen bonds are required to bond the nitrogenous bases Guanine & Cytosine?
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Three hydrogen bonds
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How many hydrogen bonds are required to bind the nitrogenous bases of Adenine and Thymine?
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Two Hydrogen Bonds.
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What are three facts about DNA replication
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(1) DNA has to be copied before it divides (2) DNA is copied during the S (or synthesis) phase of the interphase (3) New cells will need identical DNA strands
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What is the first step in the DNA replication?
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The replications begins at the origin of the replication?
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What is the second step in the DNA replication process?
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Two strands open, forming the "Replication Forks"
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What is the third step in the DNA replication process?
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New strands from at the "repcliation forks"
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What is the fourth step in the DNA replication process?
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As the DNA strands open at the origin, replication bubbles form.
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What is the difference between prokaryotes and eukaryotic replication bubbles?
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Prokaryotes have a single bubble and Eukaryotic chromosomes have many bubbles.
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What does the Enzyme Helicase do?
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It unwinds & seperates the 2 DNA strands, breaking the weak hydrogen bonds.
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What keeps 2 DNA seperated during the DNA replication process?
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Single-strand binding proteins that attach to the srtands.
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What is the function to DNA topoisomerase?
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It attaches to the 2 forks to relieve stress on the DNA molecule as it seperates.
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What is needed for DNA to start?
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A primer, RNA, which starts the addition of the new nucleotides (by primase)
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What is needed for the DNA polymearse to add new neuclotides?
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A primer has to take place.
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During synthesis of DNA, what happens to the leading strand?
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The leading strand, from the point of origin toward the opening of the replication fork is synthesized.
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What happens to the lagging strand during DNA sysnthesis?
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It is synthesized discountinously agains overall direction of the replication.
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What are Okazaki framgents?
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Lagging strands which must grow in relatively small, discontinuous pieces
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What is required in a Okazaki Fragment?
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A RNA primer.
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What are the three DNA repair mechanisms?
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(1) proofreading mechanism corrects errors during the replication process (2) mismatch repair mechanism scans and repairs errors in DNA shortly after replication (3) excision repair mechanism operates over the life of the cell to repair errors that result from chemical or radiation damage
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