WEEK 1

• Objectives


  • At the end of the lesson, the learners will be able to
  • differentiate asexual from sexual reproduction
  • describe different modes of sexual and asexual reproduction
• Binary fission


  The DNA of the parent bacteria replicates itself and then the cell divides into two halves, each half having its own DNA
• Binary fission


  Bacteria and amoeba typically use this method of reproduction
• Budding


  1. The offspring grows on the parent body from a bud-like structure

  2. The buds fall off the parent body once large enough, and begin their independent life
• Budding


  Usually seen in Echinodermata and hydra
• Fragmentation


  1. The parent organism splits into several fragments or segments

  2. Each of the fragments evolves into a new organism
• Fragmentation


  Starfishes, which exhibit sexual reproduction, also exhibit this type of asexual reproduction
• Parthenogenesis


  1. The female organism generates eggs without fertilization

  2. The offspring emerge from those eggs
• Parthenogenesis


  Seen in lizards, few insects and some fishes
• Vegetative propagation


  New plants grow from buds on the stems, leaves or other plant parts
• Vegetative propagation


  Examples: tuber (potato), bulb (onion), stolon or runner (strawberry), rhizome(ginger), sucker (banana), stem cutting (rose) and leaf (welcome plant)
• Types of asexual reproduction in animals

  • Binary fission
  • Budding
  • Fragmentation
  • Regeneration
  • Parthenogenesis
• Sexual reproduction involves two separate parents that belong to the opposite sex
• Flowering plants undergo sexual reproduction
• Flower


  The sexual reproductive organ in plants
• Parts of a flower

  • Calyx
  • Corolla
  • Gynoecium
  • Androecium
• Calyx


  Green petal-like structures that safeguard the flower while it is still in the bud process
• Corolla


  The collective colorful petals that attract pollinating agents
• Androecium


  The male reproductive section of a flower, made up of stamens with filaments and anthers that produce pollen
• Gynoecium


  The female reproductive organ of the flower, composed of the ovary, style, and stigma
• The ovary is lobed and composed of the female gamete-containing ovules
• Male reproductive organs


  • Testes
  • Urethra
  • Prostate
  • Vas deferens
  • Penis
• Testes


  Produce sperm and testosterone
• Urethra


  Passageway for both urine and semen when exiting the body
• Prostate


  Produces a fluid that mixes with sperm to form semen, nourishing and protecting sperm
• Vas deferens


  Carries sperm from the testes to the urethra during ejaculation
• Penis


  Used for both the elimination of urine from the body and the delivery of sperm for sexual reproduction
• Female reproductive organs


  • Fallopian tube
  • Uterus
  • Vagina
  • Ovary
  • Cervix
• Fallopian tube


  Passageway for eggs from the ovaries to the uterus and provides the site for fertilisation by the sperm
• Uterus


  Where a fertilised egg implants and grows into a fetus during pregnancy
• Vagina


  Receives the penis during sexual reproduction, allows the menstrual blood to exit the body, and lets the baby pass through during childbirth
• Ovary


  Produces eggs (ova) and female sex hormones like estrogen and progesterone
• Cervix


  Allows menstrual blood to flow from the uterus and serves as a pathway for sperm to enter the uterus
• Fertilization occurs in the oviducts, but can occur in the uterus itself
• Acrosomal reaction


  A series of biochemical processes that take place when a sperm binds to the zona pellucida, enabling the sperm plasma membrane to fuse with the egg plasma membrane
• Cleavage and blastula stage

  The fertilized egg undergoes cell division and forms a blastula
• Gastrulation


  Cells in the blastula are spatially rearranged to create three layers of cells (ectoderm, mesoderm, endoderm)
• The ectoderm gives rise to the epidermis and the nervous system, the mesoderm produces the body's muscle cells and connective tissue, and the endoderm gives rise to columnar cells and several internal organs including the digestive system
• Organogenesis


  Organs form from the germ layers through the process of differentiation, as cells express unique sets of genes
• Nutrition


  The mechanism by which food is taken in and converted into energy and other essential nutrients that are needed for life