Reproduction

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Chapter 5

• Reproduction

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Asexual vs Sexual Reproduction

• Asexual Any number of modes of reproduction that
  results in cloned offspring

• Plants

Leaves of the common ornamental plant
Bryophyllum. Mitosis at meristems along the leaf
margins produce tiny plantlets that fall off and
can take up an independent existence.
The horizontal above-ground stems (called
stolons) of the strawberry (shown here) produce
new daughter plants at alternate nodes.
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More Asexual Reproduction

• Animals

New individuals can come from the single limbs in
sea stars a form of budding
Unfertilized eggs in honeybees become male
Parthenogenesis
Some reptiles produce young from unfertilized eggs
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Sexual Reproduction
Involves contributions by two individuals in the
production of offspring
Sexual reproduction requires the formation of
gametes (sex cells) that have ½ the chromosomes
of the parents body cells
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Both asexual and sexual reproduction have
advantages and disadvantages
Asexual Reproduction
Sexual Reproduction
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Sex on the brain
Sexual drive if caused by stimulation of certain
parts of the brain
These areas secrete hormones that target specific
regions and cause them to secrete their own
hormones that stimulate specific reproductive
organs and secondary sexual characteristics
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This chart shows more specifically the results of
brain and sex gland and organs.
You should understand the flow of interactions in
this chart
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FSH (Follicle Stimulating Hormone) is produced in
the anterior pituitary gland (APG) in response to
GNRH (Gonadotropic Releasing Hormone).
Female Mammal Reproductive Cycle

• FSH stumulates a follicle to begin maturing
• As the follicle matures it begin to secrete
  estrogen which causes the endometrium of the
  uterus to enlarge and become more vascular
• Lutenizing hormone (LH) secreted by the APG
  builds and causes the follicle to rupture and
  expel an egg
• Once this happens, the follicle lowers estrogen
  productive and the remnant called the Corpus
  Luteum begins secreting progesterone

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If fertilization of the egg occurs, the corpus
luteum continues to secrete progesterone that
maintains the uterine lining If fertilization
does not occur, the corpus lutem dies and thus
stop producing progesterone causing the mensis of
the lining of the uterus and menstruation will
follow.
What type of feedback loop is being used
throughout this mammalian reproductive cycle?
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