Biology 3

Cell Structure 

Number of mitochondria depends on activity of cell, respiration occurs in mitochondira. Liver and muscle cells have large numbers of mitochondria.

DNA and the  genetic code

Nucleaus contains genes. Each gene - Is a section of a chromosome made of DNA. Codes for a perticular protein.

DNA is made of two strands coiled to form a double helix, each strand contains chemicals called bases. There are 4 bases: A,T,C and G.    The cross…