Answer:
The correct answer is b. He determined that DNA contains four nitrogenous bases.
Explanation:
Levene was an American biochemist who studied the structure of DNA in the early 1900s and in 1920 he found that DNA consists of four nitrogenous bases that are Adenine, Guanine, Thymine, Cytosine.
He also found deoxyribose sugar and phosphate group and said that nucleotide is the basic unit of DNA which contains a ribose sugar with attached nitrogenous base and phosphate group.
He also concludes that an equal amount of adenine, guanine, thymine, and cytosine makes the DNA which is now known as tetranucleotide hypothesis. So the correct answer is b. He determined that DNA contains four nitrogenous bases.
Throughout the history of nursing research, most studies have focused on clinical problems. TRUE
Answer:
I think it's A: Sodium is needed to generate an action potential
Answer:
See the answer below
Explanation:
The phenomenon is best explained by the fact that the <u>genetic codes are degenerates</u>. In other words, more than one codon can specify for the same amino acid being carried by the tRNA.
<em>The base-pairing rule between the third nucleotide of a codon and that of the anticodon on the tRNAs loosens off. For example, GUU, GUC, and GUA all specify for the amino acid valine while GCU, GCC, and GCA all specify for alanine. </em>
