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Brums [2.3K]
3 years ago
6

In the classic Meselson and Stahl experiment, Coli are first grown in 15N-enriched media (0th generation) and subsequently switc

hed to 14N media. A DNA sample isolated during the first generation of E. Coli grown in 14N media is subjected to a centrifugation step in a dense CsCl gradient. Assuming that replication occurs in a semiconservative fashion, the DNA sample will _______.
Biology
1 answer:
AfilCa [17]3 years ago
8 0

Options are not provided inthe question. Th ecomplete question is as following:

In the classic Meselson and Stahl experiment, Coli are first grown in 15N-enriched media (0th generation) and subsequently switched to 14N media. A DNA sample isolated during the first generation of E. Coli grown in 14N media is subjected to a centrifugation step in a dense CsCl gradient. Assuming that replication occurs in a semiconservative fashion, the DNA sample will _______.

1) run as two bands (of equal intensity), one at the same position as a uniformly 15N-labeled DNA, and one at the same position as a uniformly 14N-labeled DNA.

2) run as one band, at the same position as a uniformly 15N-labeled DNA.

3) run as one band, at the same position as a uniformly 14N-labeled DNA. run as one band, at a position expected for a DNA containing a 14N:15N ratio equal to 7.

4) run as one band, at a position expected for a DNA containing a 14N:15N ratio equal to 1.

Answer:

1)

Explanation:

In 1957, Meselson and Stahl gave an experimental evidence for semi-conservative replication  of DNA, means that each DNA strand act as template for synthesis of new DNA.

For the experiment, they use  E. coli grown in heavy isotope of 15N nitrogen and switch to 14N nitrogen undergoing one, two, or three generations and the DNA samples are collected. The DNA samples are then mix with cesium chloride and separated as light and heavy DNA.

As the replication occurs in a semiconservative fashion, the double DNA sample will run as two bands with intermediate density, having mixtures of 15N and 14N DNA, either of which would have appeared as DNA.

Hence, the correct option is (1).

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Explanation:

Fermentation has a comparatively low efficiency as it produces the same amount of energy, whereas aerobic  respiration produces up to 38 molecules of ATP .

Aerobic respiration in the mitochondria utilizes oxygen for the production of ATP in the Krebs’ or Citric acid cycle via the oxidization of pyruvate( through the process of glycolysis in the cytoplasm).

Within cells, aerobic respiration may not occur due to several factors:

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Thus, they utilize other means for the generation of energy in the form of ATP and to replenish NAD+ an oxidized form of NADH, the main electron carrier in glycolysis. Pyruvate is produced in the cytoplasm via glycolysis- it is also used as an electron acceptor in a process called fermentation.

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Further Explanation:

overall in aerobic respiration: C6H12O6 (glucose) + 6 O2 → 6 CO2 + 6 H2O + ≈38 ATP

In all eukaryotic cells mitochondria are small cellular organelles bound by membranes, these make most of the chemical energy required for powering the biochemical reactions within the cell. This chemical energy is stored within the molecule ATP which is produced. Respiration in the mitochondria utilizes oxygen for the production of ATP in the Krebs’ or Citric acid cycle via the oxidization of pyruvate( through the process of glycolysis in the cytoplasm).

Oxidative phosphorylation describes a process in which the NADH and FADH2 made in previous steps of respiration process give up electrons in the electron transport chain these are converted it to their previous forms, NADH+ and FAD. Electrons continue to move down the chain the energy they release is used in pumping protons out of the matrix of the mitochondria.

This forms a gradient where there is a differential in the number of protons on either side of the membrane the protons flow or re-enter the matrix through the enzyme ATP synthase, which makes the energy storage molecules of ATP from the reduction of ADP. At the end of the electron transport, three molecules of oxygen accept electrons and protons to form molecules of water...

  • Glycolysis: occurs in the cytoplasm 2 molecules of ATP are used to cleave glucose into 2 pyruvates, 4 ATP and 2 electron carrying NADH molecules. (2 ATP are utilized for a net ATP of 2)
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Learn more about cellular life at brainly.com/question/11259903

Learn more about cellular respiration at brainly.com/question/11203046

#LearnWithBrainly

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