Plant Reproduction Alternation of Generations Alternation of Generations

Plant Reproduction Alternation of Generations

• Alternation of Generations – the way in which all land plants and many algae undergo sexual reproduction

• First, let’s talk about animals…

Plants are similar • New plants are formed by the union of sex cells • Each sex cell carries half the hereditary material to create a new plant • But, plants can carry both male and female sex cell structures

Plant life cycle • 2 distinct stages, or “generations”, of plants • Adult generation produces spores, and is a sporophyte • Immature “spore” generation are called gametophytes. These produce sex cells, called gametes

Plant Life Cycle • Sporophyte chromosomes exist in its cells in pairs – denoted as “ 2 n” • Full set of chromosomes in a cell is also referred to as being diploid • Gametophyte chromosomes exist in its cells as singles – denoted as “ 1 n” • Half set of chromosomes = haploid Soooooo……….

Plant Life Cycle • Most of a plant’s life cycle is spent with a full set of chromosomes (as a sporophyte) • However, plants live one entire stage, or “generation”, of life with a single set of chromosomes (as a gametophyte) • When the sex cells, or gametes, produced by gametophytes come together, fertilization occurs And the cycle begins again…