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• Digestive system


  Includes the digestive tract and its accessory organs, which process food into molecules that can be absorbed and utilized by the cells of the body
• Digestion


  Food is broken down, bit by bit, until the molecules are small enough to be absorbed and the waste products are eliminated
• Digestive tract


  Also called the alimentary canal or gastrointestinal (GI) tract, consists of a long continuous tube that extends from mouth to anus
• Parts of the digestive system

  • Mouth
  • Salivary glands
  • Pharynx
  • Esophagus
  • Liver
  • Stomach
  • Gallbladder
  • Pancreas
  • Small intestine
  • Appendix
  • Large intestine
  • Rectum
  • Anus
• Mouth


  Where food enters the alimentary canal & digestion begins
• Salivary glands


  Produces saliva containing amylase
• Pharynx


  Known as throat that gets food from mouth to esophagus
• Esophagus


  Brings food to stomach by peristalsis (wave-like contractions)
• Liver


  Produces & holds bile
• Stomach


  Partially digests the food (chyme)
• Gallbladder


  Stores bile
• Pancreas


  Produces 3 digestive enzymes
• Small intestine


  Produces digestive enzymes & absorbs food that has been digested
• Large intestine


  Stores undigested food & water
• Rectum


  Holds undigested food until elimination
• Anus


  Opening through which undigested food is eliminated
• Enzyme


  Protein that speeds up chemical reactions in a body
• Digestive enzymes


  Speeds up chemical reactions that break down large food molecules into small molecules
• Digestive enzymes make it much easier and quicker for chemical reactions to take place
• Digestive enzymes can be used over and over again
• Digestive enzymes


  • Amylase
  • Pepsin
  • Trypsin
  • Pancreatic lipase
  • Deoxyribonuclease
  • Ribonuclease
• Amylase


  Produced in the mouth, breaks down large starch molecules into smaller sugar molecules
• Pepsin


  Produced in the stomach, breaks down proteins into amino acids
• Trypsin


  Produced in the pancreas, breaks down proteins
• Pancreatic lipase


  Produced in the pancreas, breaks apart fats
• Deoxyribonuclease & ribonuclease


  Produced in the pancreas, breaks the bonds in nucleic acids like DNA & RNA
• Bile acids


  When you eat a meal, bile is secreted into the intestine, where it breaks down fat
• Bile salts


  Bile acids that help to break down fat
• Digestion process


  1. Ingestion (intake of food which happens in the mouth)

  2. Digestion (breaking down food so that it can be absorbed by the body)

  3. Absorption (the process of absorbing food in the form of nutrients into the bloodstream of the body (Small Intestine))

  4. Assimilation (the process of nutrients being absorbed by each cell of the body in the form of energy)

  5. Egestion (secretion of waste, unwanted and excess substances from the body after food has been digested (Anus))
• Mechanical digestion


  Large pieces of food that are ingested have to be broken into smaller particles that can be acted upon by various enzymes, this begins in the mouth with chewing or mastication and continues with churning and mixing actions in the stomach
• Chemical digestion


  The complex molecules of carbohydrates, proteins, and fats are transformed by chemical digestion into smaller molecules that can be absorbed and utilized by the cells, through a process called hydrolysis, using water and digestive enzymes to break down the complex molecules, this happens in the stomach and small intestine
• Cell cycle


  • G1 Phase: Cell Grows
  • S Phase: Cell makes copies of its chromosomes
  • G Phase: The cell checks the duplicated chromosomes & gets ready to divide

  
• Mitosis


  One cell gives rise to two genetically identical daughter cells, resulting in cell duplication and reproduction, the number of chromosomes is preserved in both the daughter cells, a short period of chromosome condensation, segregation, and cytoplasmic division, occurs in the somatic cells, meant for the multiplication of cell numbers during embryogenesis and blastogenesis of plants and animals, remarkably similar in all animals and plants as a process, replaces dead cells, damaged cells/cells that have short life spans, lasts for 1-2 hours

  
• Mitosis stages


  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
  • Cytokinesis

  
• Meiosis


  Process in eukaryotic, sexually-reproducing animals that reduces the number of chromosomes in a cell before reproduction, many organisms package these cells into gametes, such as egg and sperm, the combination of two gametes will yield a zygote with the same number of alleles as the parents due to the number of alleles being reduced

  
• Meiosis stages


  • Prophase I
  • Metaphase I
  • Anaphase I
  • Telophase I
  • Cytokinesis

  
• Meiosis II is the same as mitosis, but with 2 cells

  
• Johann Gregor Mendel


  Father of Genetics, worked and lived in a monastery with large gardens planted with different kinds of peas, got interested in peas and noted several of their distinguishing character traits

  
• Mendel used pea plants because they are easily noticeable & easy to breed & grow, which makes it easy to reproduce new generations of peas in a short period of time & in large numbers
• Monohybrid cross


  Involves a cross using a single factor or character traits