GED Science : DNA and DNA Repair
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Example Questions
Example Question #1 : Dna, Rna, And Proteins
Which of the following is NOT common to both DNA and RNA?
Both use thymine as a nitrogenous base
Both use adenine as a nitrogenous base
Both are composed of nucleotides
Both have a sugar phosphate backbone
Both use thymine as a nitrogenous base
RNA and DNA have many similarities in structure. They are both nucleic acids, meaning they are polymers of nucleotides; the structure of both DNA and RNA is made by bonding many nucleotide units into a long polymer chain. These chains are created by bonding in the sugar phosphate backbone. Each nucleotide contains a sugar, a phosphate, and a nitrogenous base. When the sugars and phosphates bind, nucleotides are strung together to create the nucleic acid chain.
There are two key structural differences between DNA and RNA. The first is the identity of the sugar used in the sugar phosphate backbone. DNA uses deoxyribose, while RNA uses ribose. Both are pentose sugars, meaning they have five carbons, but the 2' carbon in RNA has a hydroxyl group that is absent in DNA. The second major difference is the identity of the nitrogenous bases used to code genetic information. DNA uses cytosine, guanine, adenine, and thymine. RNA uses cytosine, guanine, adenine, and uracil. Thymine will not be found in RNA and uracil will not be found in DNA.
Example Question #2 : Dna, Rna, And Proteins
What does it mean to say that DNA replication is semiconservative?
Only one DNA strand is replicated at a time
DNA replication occurs spontaneously in aqueous solutions
Daughter DNA molecules have one old strand from the parent molecule and one newly synthesized strand
DNA replication has a leading strand, which is synthesized continuously, and a lagging strand, which is synthesized in fragments
Daughter DNA molecules have one old strand from the parent molecule and one newly synthesized strand
DNA replication is defined as being semiconservative. This statement means that when a DNA molecule undergoes replication, the DNA helix unwinds and each strand serves as a template for the new strand to be created. Once a new DNA molecule has been created, it is composed of both an old strand (template), and the newly created strand, thus making a new double helix.
While the answer choice about leading and lagging strands is a true statement with regard to DNA replication, it is unrelated to the semiconservative nature of the process.
Example Question #53 : Biology And Life Sciences
During DNA replication, primase creates a(n) __________ which serves as a site for __________ to attach and begin strand synthesis.
RNA primer . . . DNA polymerase I
DNA primer . . . DNA polymerase III
RNA primer . . . DNA polymerase III
DNA primer . . . RNA polymerase
RNA primer . . . DNA polymerase III
During DNA replication, DNA polymerase III needs a site of attachment in order to begin DNA strand synthesis. This template is provided by primase, which lays down an RNA primer for DNA polymerase III to attach.
RNA polymerase is not involved in DNA replication (it is involved in translation), and DNA polymerase I is used to replace the RNA primers with DNA nucleotides.
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