dna replication questions

Best Results From Wikipedia Yahoo Answers Youtube


From Wikipedia

DNA replication

DNA replication, the basis for biological inheritance, is a fundamental process that occurs in all living organisms that copies their DNA. This process is "replication" in that each strand of the original double-stranded DNA molecule serves as template for the reproduction of the complementary strand. Therefore, following DNA replication, two identical DNA molecules have been produced from a single double-stranded DNA molecule. Cellular proofreading and error toe-checking mechanisms ensure near perfect fidelity for DNA replication.

In a cell, DNA replication begins at specific locations in the genome, called "origins". Unwinding of DNA at the origin, and synthesis of new strands, forms a replication fork. In addition to DNA polymerase, the enzyme that synthesizes the new DNA by adding nucleotides matched to the template strand, a number of other proteins are associated with the fork and assist in the initiation and continuation of DNA synthesis.

DNA replication can also be performed in vitro(outside a cell).DNA polymerases, isolated from cells, and artificial DNA primers are used to initiate DNA synthesis at known sequences in a template molecule. The polymerase chain reaction (PCR), a common laboratory technique, employs such artificial synthesis in a cyclic manner to amplify a specific target DNA fragment from a pool of DNA.

DNA structure

DNA usually exists as a double-stranded structure, with both strands coiled together to form the characteristic double-helix. Each single strand of DNA is a chain of four types of nucleotides having the bases: adenine, cytosine, guanine, and thymine. A nucleotide is a mono-, di- or triphosphate deoxyribonucleoside; that is, a deoxyribose sugar is attached to one, two or three phosphates. Chemical interaction of these nucleotides forms phosphodiester linkages, creating the phosphate-deoxyribose backbone of the DNA double helix with the bases pointing inward. Nucleotides (bases) are matched between strands through hydrogen bonds to form base pairs. Adenine pairs with thymine and cytosine pairs with guanine.

DNA strands have a directionality, and the different ends of a single strand are called the "3' (three-prime) end" and the "5' (five-prime) end." These terms refer to the carbon atom in deoxyribose to which the next phosphate in the chain attaches. In addition to being complementary, the two strands of DNA are antiparallel: they are orientated in opposite directions. This directionality has consequences in DNA synthesis, because DNA polymerase can only synthesize DNA in one direction by adding nucleotides to the 3' end of a DNA strand.

The pairing of bases in DNA through hydrogen bonding means that the information contained within each strand is redundant. The nucleotides on a single strand can be used to reconstruct nucleotides on a newly synthesized partner strand.

DNA polymerase

DNA polymerases are a family of enzymes that carry out all forms of DNA replication. A DNA polymerase can only extend an existing DNA strand paired with a template strand; it cannot begin the synthesis of a new strand. To begin synthesis of a new strand, a short fragment of DNA or RNA, called a primer, must be created and paired with the template strand before DNA polymerase can synthesize new DNA.

Once a primer pairs with DNA to be replicated, DNA polymerase synthesizes a new strand of DNA by extending the 3' end of an existing nucleotide chain, adding new nucleotides matched to the template strand one at a time via the creation of phosphodiester bonds. The energy for this process of DNA polymerization comes from two of the three total phosphates attached to each unincorporated base. (Free bases with their attached phosphate groups are called nucleoside triphosphates.) When a nucleotide is being added to a growing DNA strand, two of the phosphates are removed and the energy produced creates a phosphodiester (chemical) bond that attaches the remaining phosphate to the growing chain. The energetics of this process also help explain the directionality of synthesis - if DNA were synthesized in the 3' to 5' direction, the energy for the process would come from the 5' end of the growing strand rather than from free nucleotides.

DNA polymerases are generally extremely accurate, making less than one error for every 107 nucleotides added. Even so, some DNA polymerases also have proofreading ability; they can remove nucleotides from the end of a strand in order to correct mismatched bases. If the 5' nucleotide needs to be removed during proofreading, the triphosphate end is lost. Hence, the energy source that usually provides energy to add a new nucleotide is also lost.

DNA replication within the cell

Origins of replication

For a cell to divide, it must first replicate its DNA. This process is initiated at particular points within the DNA, known as "origins", which are targeted by proteins that separate the two strands and initiate DNA synthesis. Origins contain DNA sequences recognized by replication initiator proteins (e.g. dnaA in E coli' and the Origin Recognition Complex in yeast). These initiator proteins recruit other proteins to separate the two strands and initiate replication forks.

Initiator proteins recruit other proteins to separate t


From Yahoo Answers

Question:Put the following steps of DNA replication in chronological order. 1. Single-stranded binding proteins attach to DNA strands. 2. Hydrogen bonds between base pairs of antiparallel strands are broken. 3. Primase binds to the site of origin. 4. DNA polymerase binds to the template strand. 5. An RNA primer is created. A. 3,2,1,5,4 B. 2,1,3,5,4 C. 1,2,3,4,5 D. 3,1,2,4,5

Answers:I am pretty sure its B......

Question:1.Which of the following would represent the "transformation principal" first proposed by Griffith through his studies on Streptococcus pneumoniae bacterium? protein RNA DNA phage bateriophage 2.Which of the following is the highest (or most complex) level of structure for genetic material? nucleotide double helix DNA gene chromosome 3.Which of the following is FALSE when comparing RNA and DNA? Both are produced by phosphodiester linkages. Both are composed of phosphate groups. Both are composed of sugars. Both are composed of identical nucleotides. 4.A DNA specimen that contains 30% guanine has ________ thymine. 15% 20% 30% 60% The amount of thymine cannot be determined. 5.In producing a strand of DNA the nucleotides combine to form what type of bond? hydrogen peptide phosphodiester purine ionic 6.During DNA replication, all of the following proteins are important for separating the DNA strands and allowing movement of the replication fork EXCEPT DNA polymerase. helicase. topoisomerase. single-stranded binding proteins. both helicase and topoisomerase. 7.Which of the following statements about DNA replication is INCORRECT? It begins at multiple origins of replication sites along eukaryotic chromosomes. It proceeds with the addition of new nucleotides to the 3 end of a growing DNA strand. It is powered by the hydrolysis of ATP. Each strand within the DNA double helix is used as a template for synthesis of a new strand. It requires that each strand in the double helix be separated from the other. 8.Where would one expect to find the most telomerase? male germ cells that give rise to gametes skin cells from a 60-year-old individual skin cells from a 2-year-old individual a nerve cell from a 60-year-old individual a nerve cell from a 2-year-old individual 9.Which of the following statements best describes DNA polymerase? It is an enzyme required to produce a primer needed for DNA replication. It is an enzyme that catalyzes the addition of nucleotides to the 5 end of a growing DNA strand. It is an enzyme that requires the presence of a small double-stranded nucleic acid primer to catalyze the addition of nucleotides to the 3 end of a growing DNA strand. It is an enzyme required to glue pieces of DNA fragments together. It is an enzyme that polymerizes to the DNA and keeps the replication fork open. 10.Which molecule is responsible for separating double-stranded DNA into single strands? DNA primase DNA helicase topoisomerase DNA ligase single-stranded binding proteins Both are composed of a phosphate group, a pentose sugar, and a nitrogenous base.

Answers:1. DNA 2.Chromosome 3. Both are composed of identical nucleotides. 4. 20% 5. phosphodiester 6. DNA polymerase 7. It is powered by the hydrolysis of ATP 8. Telomerase is important in dividing cells, to make sure all the genetic information is retained, so I think this is the germ cell that gives rise to gametes. Could be the 2 year old skin cell, since skin cells have a high turnover rate. 9.It is an enzyme that requires the presence of a small double-stranded nucleic acid primer to catalyze the addition of nucleotides to the 3 end of a growing DNA strand. 10.DNA helicase

Question:I had a paper with 30 questions of DNA replication, but I couldn't get a few answers. I really appreciate your help. 1) how does the nucleotide in one chain of DNA compare with the other chain of DNA? 2) What enzymes help separate the 2 strands of nucleotides on DNA? What bonds do they break? 3) What makes up the "steps" of a DNA molecule? 4) What type of bonds holds the DNA bases together? Are they strong or weak bonds.

Answers:1. The are complementary bases bonded to each other. G with C, A with T. 2. Helicase(s). Hydrogen bonds. 3. Nucleotides (the A, G, T, Cs) 4. Hydrogen bonds...weak. Which is why helicase can break them.

Question:Put the following steps of DNA replication in chronological order: 1) Single-stranded binding proteins attach to DNA strands 2) Hydrogen bonds between base pairs of antiparallel strands are broken 3) Primase binds to the site of origin 4) DNA polymerase binds to the template strand 5) An RNA primer is created. A) 3, 2, 1, 5, 4 B) 1, 2, 3, 4, 5 C) 2, 1, 3, 5, 4 D) 1, 2, 3, 5, 4 thanks guys, much appreciated

Answers:well if it's an easy biology question you should have no trouble answering it, right?

From Youtube

DNA Replication :This clip on DNA Replication may help you in your tests :) lols

DNA Replication :In a replication fork, two DNA polymerases collaborate to copy the leading-strand template and the lagging-strand template DNA. This video shows the process by which DNA replication occurs. This video is from: Essential Cell Biology, 3rd Edition Alberts, Bray, Hopkin, Johnson, Lewis, Raff, Roberts, & Walter ISBN: 978-0-8153-4129-1