DNA Replication
- There are two antiparallel strands, comprised of nucleotides. A nucleotide is comprised of a phosphate, a 5-carbon sugar called deoxyribose, and 1 of the 4 nitrogen containing bases: Adenine, Thymine, Cytosine, Guanine. They are held together via covalent bonds. The nitrogen bases each have a pair: Adenine and Thymine, and Cytosine pairs with Guanine. They are paired together via hydrogen bonds. The strands are strands are antiparallel because the deoxyribose sugar faces the opposite way. The deoxyribose is connected to the phosphate via carbon 5’.
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2. DNA replication occurs when a cell needs to divide. A cell needs DNA to make proteins to work. So, DNA needs to replicate so the new daughter cell can work too.
3. First the DNA gets unzipped by DNA Helicase by the origin point. The Helicase breaks the H-bonds between the base pairings. The from the origin point one strand is carbon 3’, the leading strand, the other is carbon 5’, the lagging strand. From there, the DNA polymerase begins pairing the bases with their complementary base pair, which are in the nucleuses. DNA polymerase works from 3’ to 5’. It can work continuously on the leading strand; it needs to work in sections on the lagging strands. The DNA ligase fixes the bonds in the lagging strands.
4. During the complementary base pairing stage, we separated the 2 strands completely that got new based and matched them. Then, we got the deoxyribose and phosphate, added those on and drew the bonds. During the joining of adjacent nucleotides step, we made gaps the back bone on the lagging strand, then showed the ligase crating those bonds. This activing is well suited to show theses steps because you get to manipulate pieces of paper and put what you know into practice. It is inaccurate in the sense of scale.
RNA Transcription
5. mRNA had only a single back bone instead of 2 like in DNA. mRNA has Ribose instead of Deoxyribose. Instead of the Adenine, thymine, Cytosine and Guanine, like in DNA, mRNA has Adenine Uracil, Cytosine, and Guanine.
6. First a single gene gets unwound and unzipped. One side of the gene is the nonsense stand, the other is called the sense strand. the sense and nonsense strand will switch sides on DNA depending on the gene. The mRNA will get sequenced matched on the sense strand. the nitrogen bases on the sense strand get paired with nucleotides for mRNA. The bond between the DNA and the mRNA is broken by RNA ligase. The RNA is modified and leaves the cell nucleus as the DNA rezips and recoils.
7. I think it was accurate in showing how mRNA is different visually than DNA. I don’t think it was accurate in showing the process.
Protein synthesis
8. Initiation: mRNA has a 3 letter language. Every 3 letters (triplet) on mRNA (codon) codes or a nucleic acid. The process begins with the codon AUG. in order to read the mRNA a ribosome holds onto the strand and reads the triplets, after it hit AUG the process starts. Elongation: For every mRNA codon, a tRNA has a matching anticodon. The ribosome has two sites that act like docking bays. A tRNA attaches to the P site and another tRNA attaches to the A site. The attachment of a second tRNA in the A site causes the tRNA in the P site to let go of it’s amino acid. The amino acid binds to the neighboring amino acid. The empty tRNA gets lets let go off the ribosome. The A site can’t be occupied with a tRNA without a tRNA in the p site, the tRNA in the a site shifts over to the p site leaving the a site open. The mRNA would shift with the tRNA. Termination: the elongation process continues until the ribosome reaches the end codon. No new amino acid is added to the chain and it disassociates from the ribosome. A new polypeptide is made.
9. I think that it is accurate in helping to understand the process behind protein synthesis. It was not accurate because it is easy to make a mistake in creating the mRNA.