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Elena L [17]
3 years ago
10

Explain how the Meselson-Stahl experiment with "heavy" nitrogen showed that DNA replication is semiconservative.

Biology
1 answer:
Veseljchak [2.6K]3 years ago
3 0

Answer:

1. Bacteria where grow in a medium composed of heavy nitrogen. After several generations the bacteria DNA was composed of heavy nitrogen (heavy nitrogen is an isotope of nitrogen).  

2. After several generations had passed, the bacteria were transferred to a nitrogen light medium.

3. As soon as the bacteria were transferred the bacteria DNA was isolated after the first and second generation through centrifugation.

4. Results: after 2 generations half of the DNA was intermediate and half was light; there was not heavy-only DNA.  The conclusion was that the new DNA is formed by an "old" strand and a "new" strand producing an intermediate weight.

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aalyn [17]

Answer:

<em> e) Ala</em>

Explanation:

Alpha helix is a secondary structure of proteins, it is made of 3.6 aminoacids residues per turn, this structure is possible thanks to local hydrogen bonding between C=O and N-h groups. The result is a cylindrical structure with a hydrogen-bonded backbone and the outside studded with side chains.

Glycin has an -H in its side chain, this makes it a too flexible molecule, therefore it's unusual to find them in alpha-helical structures because their presence could cause the helix to deform. Large R-groups can also affect this stability, phenylalanine has a bulky aromatic side group, this discards it as a stabilizer. Serine has a hydrogen bond donor or acceptor as a side chain, due to the proximity to the main chain it competes with the main chain to form NH and CO bonds. Alanine is the most common amino acid in alpha-helix structures because it has a short and no charged R group (unlike arginine that even when it's short it has a charged R-group), this makes it flexible enough to keep the structure stabilized.

Hope you find this information useful! good luck!

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3 years ago
Asap help! which factor determinants the atomic number of an atom? please explain with full detail
tatiyna
The anatomical number is determined by adding the protons and neutrons which are located in the center of the atom
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Name the two parts of the pectorial muscles.
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Explanation:

Pectoralis muscle, any of the muscles that connect the front walls of the chest with the bones of the upper arm and shoulder.

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A researcher proposes a model of an enzyme-catalyzed reaction in which a reactant is converted to a product. The model is based
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    The transition state is the transition from substrate to product. The molecule is no longer a substrate but also not yet a product.

The enzyme is able to speed up the reaction by stabilizing the transition state. The transition state's energy is also the activation energy in terms of reaction. The activation energy is the minimum energy that is required to break some bonds of the reactants in order to turn them to products.

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