Marshall Nirenberg and Heinrich Mattaeis contributed to out current understanding of the genetic code by discovering genetic codons. Their experiment deciphered the first of the 64 triplet codons in the genetic code by using nucleic acid homopolymer to translate specific amino acids. Their experiment cracked the first codon of the genetic code and showed that RNA controlled the production of certain types of proteins.<span />
Answer:
a) During metaphase, each of the 46 chromosomes line up along the center of the cell at the metaphase plate.
Pollination occurs when pollen grains from the anther land on a stigma. After pollen grains land on the stigma, a pollen tube grows from the pollen grain, through the style, and into the ovary. Sperm cells inside the pollen grain travel down the pollen tube and into the ovary which contains the ovules.