|MadSci Network: Genetics|
Hello Katherine, Your question does not have a simple answer! The number of seeds in a mandarin orange depends on the number of ovules in the flower that are fertilized. An ovule is the part of the plant that contains the egg cell. The number of ovules in the flower depends on the tree variety. There are a cluster of several genes which determine the number of ovules that the flower would produce. A note about genes- just like in humans (and in all other living things), all of the cells that make up a tree would have the same genes. These genes are the same ones from the pollen and the egg cell (also called an ovum). When the ovum is fertilized by the pollen, the ovum then begins to develop into a seed. The fertilized ovum is the cell which contains a complete set of genes that will guide the development of a new plant. This cell will make a copy of the set of genes, split into two cells, each with the same set of genes. Then these two cells will each make a copy of the set of genes, split into two cells, again, each with the same genes. This copying and splitting of the cell is already being directed by the genes! Even when the cells differentiate, as in when the cells start to take on the different shapes of the plant cells, each cell still contains the same set of genes. ***What I have just written is a very simplified idea of how cells and genes are made in plants. This is much much MUCH more complicated with polyploidy and haploidy rampant in the plant world.*** There are plant cells that differentiated into the flower cells, and other cells that differentiated into the ovule and ovum cells. The genes that guided the development of the cells into the flower, ovule and ovum are from the same set of genes that came from that original fertilized ovum! As for the number of fruits to be produced on a mandarin tree, that is not the same as what happens with a human female. A baby girl is born with all of the egg cells already formed. Her hormones will guide each egg cell to develop into an ovum every month once her body is mature enough. A tree does not have all of the egg cells already formed. These occur every season, when the tree produces flowers. I hope that I have ironed out some of your questions! Keep asking! Evelyn References: *These are references that I used to answer your question. You can link onto them, but I do not know if they will be easy to read!* Link to a detailed description of several varieties of mandarin orange: http://www.hort.purdue.edu/newcrop/morton/mandarin_orange.html#Des cription Link to a detailed description of cell division and differentiation http:// web.ukonline.co.uk/webwise/spinneret/life/celdiv.htm Link to university-level descriptions of plant growth and flowering: http://www.biologie.uni-hamburg.de/b- online/e28/28c.htm http://gears. tucson.ars.ag.gov/book/chap5/citrus.html Link to definition of polyploidy: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Polyploidy. html Link to definition of haploidy: http://www.fact- index.com/h/ha/haploid.html
Try the links in the MadSci Library for more information on Genetics.