sex vs asex rep.notebook
February 15, 2012
Asexual Vs. Sexual Reproduction
Asexual Reproduction
• the production of a new individual from just one parent
• each offspring contains genetic information that is identical to that of the parent, unless there is a mutation • Genetic continuity is the transmission of hereditary information from one generation to the next
• maintains genetic continuity, but limits variability (differences in individuals in a population
• used predominantly by unicellular organisms like bacteria
• methods of asexual reproduction include: budding, binary fission, fragmentation, sporulation (spore formation), and vegetative propagation
sex vs asex rep.notebook
February 15, 2012
Methods of Asexual Reproduction
Method Organism Description Diagram of Method
• bacteria lack organelles for mitosis
bacteria
Binary
• bacterial chromosome remains attached to cell amoeba
membrane
Fission
paramecium
• parent cell divides into two new individuals
• nuclear material undergoes mitotic division
• cytoplasm divides but smaller cell (bud) remains attached
• bud eventually separates from parent
Budding
yeast
hydra
Fragment­
ation
flatworms
sea stars
moulds
Vegetative
Propagation
plants
• new plant is formed from piece of root stem or leaf from parent plant
ferns
bread moulds
mushrooms
• specialized spore cells contain genetic info in a tough outer case
• spores may be stored in spore cases (sporangia) until released
• if the spore land where conditions are favourable the spore will grow into a new organism
Spores
• body of parent breaks into pieces
• each piece regenerates missing parts to create whole new organism
sex vs asex rep.notebook
February 15, 2012
Sexual Reproduction
• involves the union of gametes (haploid sex cells) from two parents
• each offspring contains genetic information that is unique because of the random assortment and genetic recombination that occurs during meiosis
• each individual will contain characteristics from each parent, but will not be exactly the same as either one (variation)
• plants and animals use sexual reproduction
sex vs asex rep.notebook
February 15, 2012
Comparing Asexual and Sexual Reproduction
Asexual
Sexual
Genetic characteristics of offspring
When is this method useful
Benefits
• identical to
parent
• unique, but has some
characterisitics of each parent
• when organisms are well
• when the environment is
adapted to their environment, changing and adaptation is
and the environment is stable required - survival of the fittest
(unchanging)
• easy method of reproduction • allows adaptation of a species to
a changing environment
• genetic continuity
• genetic variability
• doesn't require a mate
Disadvantages • organisms may be
susceptible to a changing
environment - extinction
• requires time, energy
• requires finding a mate