The nucleus of plant cells and animal cells contains chromosomes. During interphase of the cell cycle, chromosomes are present individually but cannot be seen. The chromosome material is called chromatin. Alterations take place in interphase, producing a difference between the chromatin in the G1 phase and the chromatin in the G2 phase. State and explain the difference in chromatin in the G1 phase compared with chromatin in the G2 phase.
Describe the features of a nucleus, apart from chromatin. You may use the space below the lines to add a diagram.
Starch, cellulose and pectins are polysaccharides present in plant cells but absent from animal cells. Pectins are complex polysaccharides located in the cell wall. Describe the structural features of starch that are different from the structural features of cellulose.
Cell wall pectins can differ in different plant cell types and at different stages of plant cell development. Pectin molecules are secreted from cells as basic structures and then altered within the cell wall by adding side chains. RG-I is a pectin molecule with a variable structure. Its basic structure is a repeated disaccharide made from two different monosaccharides. RG-I has three different side chains that can be added in different positions. Monoclonal antibodies (mAbs) are used to investigate the structure, location and role of cell wall pectins. Suggest and explain why scientists need to use a number of different monoclonal antibodies when investigating a pectin such as RG-I.