GEN BIO 2

• Growth


  A stage of development characterized by an increase in size of an individual
• Development


  Formation of sex cells, span. Development is terminated by death
• Gametogenesis


  1. Biological formation of gametes via a series of cellular division, differentiation, and genetic material reduction to achieve a haploid number of chromosomes

  2. Formation and development of sperm cell via spermatogenesis

  3. Formation and development of egg cell or ovum via oogenesis
• Spermatogenesis


  1. Precursor cell spermatogonium divides and differentiates into two primary spermatocytes via mitosis

  2. Spermatocyte undergoes first meiotic division giving rise to two secondary spermatocytes

  3. Each secondary spermatocyte proceeds to second meiotic division giving rise to four spermatids that mature into sperms having an equal number of genetic material and cytoplasm

  
• Oogenesis


  1. Daughter cells produced from the two meiotic divisions do not receive an equal amount of cytoplasm

  2. High concentration of cytoplasm in an ovum provides enough nourishment to the developing embryo after fertilization

  
• Fertilization


  Sperm cell fuses to an ovum, allowing embryo development to take place

  
• Cleavage


  1. Rapid series of mitotic cell divisions of the developing embryo leading to multicellular ball mass

  2. In mammals, this continuously happens as the embryo transverses the oviduct toward the uterus

  3. Once more than 100 cells are present, the embryo is now a blastocyst, characterized by having a distinct inner cell mass, which eventually forms the fetus

  
• Gastrulation


  Formation of three germ layers: ectoderm, mesoderm and endoderm
• Organogenesis


  1. Phase of embryonic development that starts at the end of gastrulation and continues until birth

  2. The three germ layers formed from gastrulation (the ectoderm, endoderm, and mesoderm) form the internal organs of the organism

  
• Three Germ Layers


  • Ectoderm (Nervous system, epidermis, sense organs)
  • Mesoderm (Muscles, bones, cartilage, circulatory, excretory, and reproductive organs)
  • Endoderm (Digestive and respiratory organs, endocrine glands, germ cells and gametes)
• In many species, the young organism is a larva that may look significantly different from the adult
• In many species, the larval stage is the one that lasts the longest, and the adult is a brief stage solely for reproduction
• General life cycle of plants


  1. Mature, multicellular organism is a diploid sporophyte

  2. Some cells undergo meiosis to produce haploid gametes which are then released

  3. Gametes fuse and form the zygote which develops by mitosis to become the multicellular diploid sporophyte

  4. In some plants, the dominant part of the life cycle is a multicellular, haploid gametophyte

  5. Mitosis releases individual cells that can act like gametes

  
• Haplontic life cycle


  • Dominant stage is a multicellular haploid stage which produces gametes that eventually fuse to form unicellular zygotes
  • Each zygote then undergoes meiosis to become haploid, after which it undergoes mitosis to become the multicellular organism

  
• Haplodiplontic life cycle


  • Organism has a multicellular haploid (gametophyte) stage that produces gametes
  • Gametes fuse to produce a zygote that undergoes mitosis to produce a multicellular sporophyte
  • Within the sporophyte, cells undergo meiosis to produce meiospores
  • These spores germinate by dividing mitotically to become a multicellular gametophyte

  
• Diplontic life cycle


  Organism is in the diploid stage (all cells are diploid in chromosome number) except for mature, haploid sex cells which are called gametes
• Development in Flowering Plants


  Gametophyte - Development through gametogenesis

  • Male gametophyte: Microsporangium contains microsporocytes, each undergoing meiosis to produce four haploid microspores that develop into pollen grains
  • Female gametophyte: Megasporangium contains megasporocytes, one undergoing meiosis to produce four haploid megaspores, three degenerating, remaining megaspore dividing mitotically three times to form the embryo sac

  Pollination - Transfer of pollen grain from anther to stigma

  Double fertilization - Pollen tube discharges sperm cells, one fusing with egg to form zygote, other fusing with polar nuclei to form endosperm

  Embryo development (embryogenesis) - Zygote divides mitotically to produce proembryo and suspensor

  Maturation of ovary and ovule - Ovary matures into fruit, ovule becomes seed which may become dormant

  Seed germination - Transformation of seed to seedling, seed undergoes imbibition to break dormancy, nutrients stored in endosperm or cotyledons

  • Epigeal germination: cotyledon emerges above ground, exposing hypocotyl of plumule
  • Hypogeal germination: cotyledon remains below ground, concealing hypocotyl

  Seedling growth to mature plant - Primary meristems differentiate to become different plant tissues
• Seed germination involves transformation of seed to seedling, seed undergoing imbibition to break dormancy, and nutrients stored in endosperm or cotyledons
• Nutrients


  Compounds in foods essential to life and health, providing us with energy, the building blocks for repair and growth and substances necessary to regulate and manage chemical processes

  
• Six major nutrients


  • Carbohydrates
  • Lipids (fats)
  • Proteins
  • Vitamins
  • Minerals
  • Water
• Monomers


  Smaller units from which larger molecules are made
• Polymers


  Molecules made from a large number of monomers joined together in a chain
• Synthetic polymers


  • nylon
  • polyethylene
  • polyester
  • Teflon
  • epoxy
• Plant Nutrition


  The supply and absorption of chemical compounds for the growth and metabolic processes of plants

  
• Plant nutritional requirements


  • Water
  • Carbon dioxide
  • Essential elements

  
• Water


  • Transports important nutrients, drawn from the soil and utilized by the plant
  • Without proper balance, the plant is malnourished, physically weak, and cannot support its own weight
• Carbon dioxide


  • One of the most important gases on Earth because plants use CO2 to produce carbohydrates in photosynthesis
  • Higher concentrations of carbon dioxide make plants more productive because photosynthesis depends on using the sun's energy to synthesize sugar out of carbon dioxide and water
• Essential elements for plants


  • Carbon
  • Hydrogen
  • Oxygen
  • Boron
  • Calcium
  • Chlorine
  • Copper
  • Iron
  • Magnesium
  • Manganese
  • Molybdenum
  • Nickel
  • Nitrogen
  • Phosphorus
  • Potassium
  • Sulfur
  • Zinc
• Symplast route


  The continuous arrangement of protoplasts of a plant which are interconnected by plasmodesmata
• Apoplast route


  The non-protoplasmic components of a plant, including the cell wall and the intracellular spaces
• Root hairs


  • Slender extensions of specialized epidermal cells that greatly increase the surface area available for absorption
• Root nodules

  • Localized swellings in roots of certain plants where bacterial cells exist symbiotically with the plant
• Mycorrhizae


  • A symbiotic interaction between a young root and a fungus
• Nutritional adaptation by plants


  • Symbiosis of plants and soil microbes
  • Symbiosis of plants and fungi
  • Parasitism
  • Saprophytes
  • Predation

  
• Animal Nutrition


  The dietary nutrients needs of animals, those in agriculture, food production, zoos, aquariums, and wildlife management
• Major classes of nutrients for animals


  • Carbohydrates
  • Fats
  • Fiber
  • Minerals
  • Proteins
  • Vitamins
  • Water
• Carbohydrates


  Energy-giving food that provide energy in the form of calories that the body needs to be able to work, and to support other functions
• Fats


  Triglycerides, made of assorted fatty acid monomers bound to glycerol backbone. Some fatty acids are essential in the diet as they cannot be synthesized in the body
• Major classes of nutrients


  • Carbohydrates
  • Fats
  • Fiber
  • Minerals
  • Proteins
  • Vitamins
  • Water
• Carbohydrates


  Energy-giving food that provide energy in the form of calories the body needs to work and support other functions