Saturated fatty acids in phospholipids makes them more solid. Example animal fat. Think about how his might relate to plants or animals that must experience a wide range of temperatures. Made of amino acids joined by peptide bonds. There are 20 R groups that define each amino acid.
R groups can be polar, non polar, acidic or basic.
Cells are the fundamental units of life. With big cells, diffusion rates are too slow to move molecules fast enough for biochemical reactions to occur at rates required for living processes. Nuclear pores allow transport between nucleus and cytosol. Chromosomes contained in the nucleus. Nucleolus, within the nucleus, is where ribosomes are made.