Transcript Colorado AgriScience Plant Science

Colorado AgriScience
Plant Science
Unit 4: Plant Reproduction & Genetics
Lesson 2: Sexual Reproduction in Plants
Sexual Reproduction
• Involves flowers, fruit, & seed
• Sperm from male flower fuses w/the
ovum of the female plant
• Results in recombination of DNA
– Results in genetically unique individual
– Allows plants to adapt & evolve to
environmental change
Pollination
• Transfer of pollen from the male to the
female part of the plant(s)
• How pollination occurs
– Self-Pollination
• Pollen from a plant pollinates a flower on the
same plant
– Cross-Pollination
• Pollen from a plant pollinates a flower on a
different plant
Fertilization
• Necessary in flowering plants in order for a
seed to develop
• Double Fertilization
– Unique to plants
– Two sperm nuclei involved in fertilization
– 1st fertilization occurs when one sperm fuses with
the egg creating a zygote
– 2nd fertilization occurs when the 2nd sperm nucleolus
fuses with the two nuclei in the embryo sac
• Results in the formation of the endosperm
Fertilization
• Hybrid
– Fertilization occurring from parents that
are genetically different
– Advantages
• Best traits of each parent is expressed
• Results in Hybrid Vigor
– Increased growth, drought resistance, or insect
resistance is possible
Fertilization & Genetics
• Genetic information is stored in
every cell of the plant in DNA
• Segments of DNA, called genes,
establish the code for plant
appearance and traits
• Genes are arranged into a set of
chromosomes
Fertilization & Genetics
• Diploid
– Normal sets of cells containing two
chromosomes
• Haploid
– Sex cells contain one chromosome
• When fertilization occurs, the single sets of
chromosomes are combined into the double
set, one from each parent
• Results in traits from each parent to be
passed on to offspring.