Answer:
Semi-conservative replication
Explanation:
After the double-helix discovery of Watson and Crick, there were three possible models about the DNI replication:
- The Conservative model stated that the two strands of DNI together were the template of another new molecule. The final product was the original double-stranded molecule and the new molecule.
- The semi-conservative model stated that the original DNI molecule separated into two strands, and each of them served as a template for the synthesis of a new complementary strand. The replication product would be two double-stranded DNA molecules, each carrying an original strand a new one.
- The Dispersive moles stated that the replication product would be two molecules made by a mixture of segments of the original and the new molecules.
Meselson and Stahl joined to discover which of the models was the correct one. To do it they used E. coli and Nitrogen isotopes.
- First, they extracted DNI from bacteria grown in a medium with N¹⁴ and got its density band by centrifugation.
- Then they grew bacteria in a medium with N¹⁵, extracted their DNI molecules, centrifugated them, and got the density band, which was heavier than the firsts ones.
- The researchers then transferred bacteria grown in medium with N¹⁵ to a medium with N¹⁴, and they allowed only one replication process to occur. DNI was extracted and centrifugated again, and a new band appeared. This band was an intermediate form between bands of DNI-N¹⁵ and DNI-N¹⁴.
This event <em>eliminated the conservative model</em>. If this model were correct, the expected result would be to get two bands: one corresponding to the density DNI-N¹⁵ and the other corresponding to the density DNI-N¹⁴.
- Bacteria grown in a medium with N¹⁵ and then transferred to a medium with N¹⁴ were finally allowed to replicate twice. Their DNI was extracted and centrifugated. The result was two bands: one of them coincided with the intermediate band, and the other one with the DNI-N¹⁴.
<u>This result was conclusive</u> because if the dispersal model were correct, these two bands should not appear, as all the DNI strands would have part of the original molecule.
With this experiment, Meselson and Stahl proved that the correct replication model was the semi-conservative one.
Eukaryotic cells and prokaryotic cells contain a cytoplasm and ribosomes. Eukaryotic cells have organelles and a nucleus.
Prokaryotic cells were most likely to evolve first because of the simple structure.
the flagellum helps the cell to move through water. Scientists think that the flagellum and the light-sensitive spot work together to increase photosynthesis. Light sensitive spot detects light.
I researched this! Hope it helps!
The year in which the deer population closest to ZPG is in 1971
That year the population of deer closest to Zero population
<h3>Living organisms </h3>
Living organisms; be it plants or animals are any organic or living system composed of cells and function as an individual entity.
- All living organisms share a number of key characteristics or functions such as movement, respiration, homeostasis, reproduction, growth, evolution, competition and others.
- Animals and plants also posess systems such as the digestive, skeletal, transport, nervous, excretory, respiratory and reproductive system.
- Living organisms are also taxonomically classified as either unicellular microorganisms or multicellular plants and animals
So therefore, the year in which the deer population closest to ZPG is in 1971
Complete question:
Zero population growth occurs when a population has the same number of individuals entering the population (births) as those leaving the population (deaths). In which year, was the deer population closest to ZPG?
Learn more about living organisms:
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Answer AND Explanation:
Respiration by both plants and animals as well as by microorganisms converts some of the organic compounds into carbon dioxide. The latter is released back to the atmosphere and reused by green plants.
