DNA TrackStar Questions

TrackStar Questions

1) The statement that DNA bases pair up in a complimentary way means that adenine will only and always bond to thymine, and cytosine will only and always bond to guanine. The type of bonds that are found between complimentary bases are hydrogen bonds.

2) DNA ensures that its copies are identical to the original because the original strand is divided into two strands and, from these strands, two new DNA molecules are formed. In other words, to copy itself, DNA splits itself into two pieces, and re-produces the removed bases to form two copies, each with half of the original strand.

3) One strand of DNA is copied continuously while the other lags because the DNA polymerase can only read DNA in a specific direction. Therefore, the lagging strand must be looped back around and re-fed into the DNA polymerase, and thus is not copied as quickly as the leading strand.

Helicase - splits strands of DNA
Single-stranded DNA binding proteins - prevent split DNA from re-bonding together.
DNA polymerase III - creates a corresponding strand for a split DNA strand
Polymerase I - replaces RNA primers with DNA
DNA Ligase - links Okazaki fragments

4) DNA polymerase can only read DNA in the 5' direction of a specific strand. This informs my previous entry because there is now the knowledge that, since DNA can only be read in a specific direction, the 3' strand must be the lagging strand and the 5' strand must be the leading strand.

5) DNA is transcribed into RNA beginning with a process known as initiation, which consists of RNA polymerase, the RNA transcription enzyme, binding to a specific “start transcribing” nucleotide sequence on the DNA, known as a promoter. Once the polymerase is bonded, synthesis of a RNA strand begins in a process known as elongation, during which the RNA strand gradually peels away from the DNA. Once the RNA polymerase reaches a specific “ending point,” or terminator, the RNA polymerase detaches from the DNA strand and the RNA molecule has been completed.

6) Translation of a mRNA molecule into a polypeptide begins with the process of initiation, in which a mRNA molecule binds onto a ribosomal subunit and has an initiator tRNA molecule bonded to it on the start codon, or the nucleotide sequence AUG. Following the bonding of the tRNA, a larger ribosomal subunit bonds to the smaller ribosomal subunit, creating a functional ribosome, which has two tRNA binding sites. The P binding site is filled with the initiator tRNA and the A site awaits another tRNA bearing an amino acid. In elongation, another tRNA that bears an anticodon that matches the codon of the A site bonds to the A site. The P site tRNA's amino acid or polypeptide jumps from the P site to the A site's tRNA, bonding to that tRNA's specific amino acid. After this, the P site tRNA unbonds and drifts away, and the A site tRNA is moved to the P site, with both the tRNA and mRNA moving together. This process is repeated until a codon known as a stop codon, specifically UAA, UAG and UGA, is reached. At this point, termination begins: the polypeptide unbonds from the tRNA and the ribosome splits into its subunits.

7) RNA polymerase binds to a specific spot on the DNA and begins producing RNA while traveling down the DNA molecule. Once it reaches the specific ending spot, the mRNA is removed from the RNA polymerase and bonds to a small ribosomal subunit. Then, a initiator tRNA molecule bonds to the start codon of the mRNA, the large ribosomal subunit bonds to the small subunit, and more tRNA molecules begin to bond, donate amino acids, and unbond from the designated sites on the ribosome. Finally, when the polypeptide is completed, the ribosome separates and the polypeptide is released into the cell.

mRNA contains genetic instructions as to how to create the polypeptide(s)
tRNA holds the amino acids needed by the mRNA to synthesize the polypeptide(s)
rRNA creates the ribosomes necessary to the utilization of mRNA and tRNA and thus polypeptide creation

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