Answer/Explanation:
DNA polymerase is the enzyme responsible for replicating DNA. It is hugely important that is performs its functions accurately, as if incorrect bases are incorporated this can lead to mutations that disrupt the structure and function of genes. It adds nucleotides in a 5' - 3' direction only.
DNA polymerase III also has high processivity, which means that for every time it binds DNA, it is able to add many bases before it becomes dissociated.
A. DNA polymerase avoids the incorporation of improperly paired nucleotides in two ways:
- The first way depends on the structure of the enzyme. If the nucleotide that the enzyme is in the process of adding is not complementary to the template, then the nucleotide will not align with the template, and thus it is more inefficient to add. This inefficiency means the nucleotide is more likely to leave the active site before it is added, and DNA polymerase can replace it with the correct nucleotide.
- It also has proofreading capabilities. This means, when an incorrect base is added, it recognises the error and can fix this. It can do this because it possesses 3'-5' exonuclease activity. That means, it can chop out incorrectly added bases.
B. Ribonucleotides are the nucleotides that are incorporated into a growing RNA molecule. They are different from deoxyribonucleotides because of the differences in the sugar backbone (ribose vs deoxyribose). Their incorporation would disrupt the structure and function of the DNA, leading to problems with transcription and replication.
DNA polymerase avoids incorporating these nucleotides primarily because of the structure of the enzyme. Ribonucleotides cannot fit into the active site of DNA polymerase due to what is called a "steric filter" or "steric gate". This gate/filter function is performed by specific amino acid residues which usually have a bulky side chain and thus block the incorporation of the 2'OH of the ribose sugar (which is lacking in the deoxyribose sugar)
The answer to your question is A. Higher latitudes receive less radiation due to the curvature of the Earth.
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Answer:
Humans have breached this cycle by digging up fossil fuels and burning them, leading to carbon dioxide building up in the atmosphere faster than natural systems can soak it up. This has led to a net increase in greenhouse gases in the atmosphere, causing the planet to heat up.
Explanation:
Answer:
Explanation:
Can you think of a solid that can flow?
You use one twice a day! Toothpaste is a solid that can flow. Is the asthenosphere made of toothpaste? Only if the
toothpaste is ultramafic in composition, and then it would only be able to flow if it were really, really hot. Still the
toothpaste analogy gives you a good image of how the asthenosphere might behave if you squeezed it!
Lithosphere
The lithosphere is composed of both the crust and the portion of the upper mantle that behaves as a brittle, rigid
solid. The lithosphere is the outermost mechanical layer, which behaves as a brittle, rigid solid. The lithosphere is
about 100 kilometers thick. How are crust and lithosphere different from each other?