Gen.Bio 2

• All plants and animals around the world reproduce as a way of bringing in new generations and slowly initiating changes in the species
• The fertilization process occurs both in plants and in animals
• Reproduction is a distinctive feature of living species
• Asexual reproduction


  Reproduction by a single parent, without the fusion of gametes
• Sexual reproduction


  Reproduction involving two parents of opposite sex, with the fusion of gametes
• Binary fission


  DNA of parent replicates, cell divides into two identical daughter cells
• Budding


  Offspring grows on parent body from a bud-like structure, falls off when large enough
• Fragmentation


  Parent organism splits into several fragments, each evolving into a new organism
• Parthenogenesis

  Female organism generates eggs without fertilization, offspring emerges from the eggs
• Vegetative propagation


  New plants grow from buds on stems, leaves or other plant parts
• Flower

  The sexual reproductive organ in plants
• Parts of a flower


  • Calyx (sepals)
  • Corolla (petals)
  • Androecium (male reproductive part)
  • Gynoecium (female reproductive part)
• Pollination


  Transfer of pollen grains from anther to stigma
• Fertilization


  Fusion of male and female gametes to form a zygote
• Porogamy


  Common type of fertilization in angiosperms, pollen tube enters ovule through micropyle
• Chalazogamy


  Fertilization in Casuarina species, pollen tube enters ovule through chalaza
• Mesogamy


  Fertilization in Cucurbit plants, pollen tube enters ovule through middle or integuments
• Double fertilization


  One sperm fuses with egg, other fuses with polar nuclei to form endosperm
• Human reproduction


  • Sexual reproduction, fertilization occurs within female body (internal fertilization)
• Male reproductive organs


  • Penis
  • Scrotum
  • Testicles
  • Epididymis
  • Vas deferens
  • Seminal vesicles
  • Prostate gland
  • Bulbourethral glands
• Female reproductive organs


  • Uterus
  • Ovaries
  • Vagina
  • Cervix
  • Fallopian tubes
• Uterus


  Hosts the fetus that is developing, produces vaginal and uterine secretions, passes sperm through to the fallopian tubes
• Ovaries


  Produce eggs, produce and secrete progesterone and estrogen
• Internal female reproductive organs


  • Vagina
  • Uterus
  • Fallopian tubes
  • Cervix
  • Ovaries
• External female reproductive organs


  • Mons pubis
  • Pudendal cleft
  • Labia majora
  • Labia minora
  • Bartholin's glands
  • Clitoris
• Fertilization


  Gametes (egg and sperm) fuse to form zygote
• Fertilization


  • One set of chromosomes each in egg and sperm, only one sperm must unite with one egg to ensure child has one full diploid set of chromosomes
• Acrosomal reactions


  Sperm binds to zona pellucida, acrosome produces digestive enzymes that degrade glycoprotein matrix and enable sperm plasma membrane to fuse with egg plasma membrane
• Egg releases proteins in other places until acrosomal reactions occur at one position of egg membrane to prevent other sperm from fusing</b>
• Multiple sperm fusing with egg results in polyspermia, which is not genetically viable and dies within a couple of days
• Cleavage


  Rapid, multiple cell division rounds that form the blastula
• Blastula


  Spherical layer of cells around a fluid-filled or yolk-filled cavity
• Blastocyst


  Mammalian blastula with an inner cell mass different from the surrounding cells
• Gastrulation


  Cells in the blastula are spatially rearranged to create three layers of cells (ectoderm, mesoderm, endoderm)
• Germ layers


  The three cell layers formed during gastrulation (ectoderm, mesoderm, endoderm)
• Organogenesis


  Organs form from the germ layers through the process of differentiation
• Genes unique to skin cells will be expressed by certain cells in the ectoderm, resulting in epidermal cells
• Neural system development


  Epithelial and neural tissues form from the ectoderm, signaling molecules cause cells at the edge to become epidermis and the remaining cells to form the neural plate which rolls up into the neural tube
• If growth factors block the signaling, the entire ectoderm would differentiate into neural tissue
• Mesoderm development


  The mesoderm lying on either side of the neural tube grows into various connective tissues, with a gene expression pattern reorganizing it into somites which further develop into muscles and other structures