Reproductive Strategies

• Mitosis is the key mechanism for asexual reproduction

• Meiosis involves the production of gametes followed by fertilization.

Reproduction in Prokaryotes• Bacteria and other

prokaryotes have no nucleus, therefore, do not undergo mitosis.

• They reproduce by binary fission.

• The sequence of repeated doubling is called exponential growth. A bacteria can divide in as little as 20 minutes and produce two more cells 20 min. later.

Asexual Reproduction

Budding – a form in which a miniature version of the parent grows outside from the parent’s body.

Vegetative reproduction – strawberry plants have runners that creates a new plant.

Fragmentation – cultivation of potatoes

Parthogenesis – an unfertilized egg develops into an adult.

Alternation of Generations

• The life cycle of plants consists of two generations: a haploid generation and a diploid generation that alternate.

• Alternation of asexual reproduction examples…

The Life Cycle of a fern

The life cycle of moss

The life cycle of a conifer

The life cycle of a cnidarian – ALTERNATION OF SEXUAL CYCLE

Advantages and Disadvantages of Reproduction Strategies

• Sexual reproduction gives an opportunity for genetic variation.

• Three potential advantages:– Offers a population a way to adapt to a

changing environment– Competition among siblings may be reduced

if they are genetically diverse– Pairing of homologous chromosomes and

crossing over offer opportunities to replace or repair damaged chromosomes.

Asexual Reproduction

• Often proceeds more quickly than sexual reproduction

• Usually requires less energy• Helps to maximize the changes that individual

offspring will survive.• ____________________• Each of the new individuals that have been

reproduced, in either way, carries a set of genetic instructions that determines how members of the species will grow and develop.