prophase I : homologous chromosomes are paired 
metaphase I : the centrosome replicates 
anaphase I: homologous chromosomes are separated 
telophase I : nuclear envelopes form around separated chromosomes 
 
        
             
        
        
        
Remember the cell theory by Virchow that states that all cells come from pre existing cells, if a single cell dies, it can be replaced unless it's a brain cell.
        
             
        
        
        
If p = frequency of A and q = frequency of a, then assuming H-W equilibrium we have
p + q = 1   ⇒   q = 1 - p = 1 - 0.55 = 0.45
Then the expected frequency of the heterozygous genotype Aa is 2pq = 2 • 0.55 • 0.45 = 0.495.
 
        
             
        
        
        
There are three types of RNA involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribisomal RNA (rRNA). All three of these nucleic acids work together to produce a protein. The mRNA takes the genetic instructions from the nucleus to the cytoplasm, where the ribosomes are located.