Answer: It is an amino acid that cannot be made by the body. It must be obtained from eating certain foods.
Explanation:
Answer;
DNA replication is semi-conservative.
The meselson-stahl experiment supported the hypothesis that DNA replication is semi-conservative.
Explanation;
The Meselson-Stahl experiment was an experiment by Meselson and Stahl that proved that the semi-conservative model by Watson and Crick was correct.
DNA replication is semi-conservative in the sense that the new helices formed after replication contain, one new DNA strand and one old strand from the parent DNA molecule.
Answer:
1. Sympathetic
2. Parasympathetic
Explanation:
The sympathetic nervous system is activated when the person experiences any stress conditions. This nervous system stimulates the release of stress hormones from the adrenal gland and generates flight or fight response. There are an increased heart rate and breathing rate to increase the oxygen supply to skeletal muscles.
Once the person comes out of the stress conditions, the parasympathetic nervous system is activated which slows down the physiological responses generated by the sympathetic system. The activated parasympathetic nervous system stimulates the digestion and absorption of nutrients.
Answer:
A and F are phosphate groups.
B and E are sugars.
C and D are nitrogenous bases.
Explanation:
Nucleotides are the molecules responsible for composing DNA and RNA. They are formed by three units: a phosphate group, a sugar molecule and a nitrogenous base.
The sugar molecule is a pentose, which means that it is a molecule formed by 5 carbons. These collections are represented by geometrical figures such as the letters "B" and "E" shown in the figure above, where each tip represents a carbon.
The nitrogenous bases are molecules that are named adenine (A) and guanine (G) and the pyrimidine bases cytosine (C), uracil (U) and thymine (T).
The phosphate group, in turn, is a molecule derived from phosphoric acid and is the only one that does not vary in each nucleotide.