Sci 1&2

• Cell cycle


  Mechanism by which cells multiply and make new cells
• Stages of the cell cycle


  • Interphase
  • Cell division or mitotic phase

  
• Interphase


  Period between mitotic divisions - G1, S, and G2

  
• G1


  Cell prepares to divide
• S phase


  Cell synthesizes DNA
• G2


  Cell organizes and condenses genetic material, prepares to divide
• M phase


  Cell divides and partitions genetic material into two daughter cells
• Cell division in the body helps to expand and fix worn-out tissues, and can lead to an increased number of cells growing
• Mitosis


  Cell division that produces two daughter cells having the same genetic material as the parent
• Digestive system


  • Breaks down food particles into organic compounds that can be used by the cells in the body
  • Has two ways of breaking down food: mechanical digestion and chemical digestion
• Stages of mitosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase
• Parts of the digestive system

  • Gastrointestinal tract (mouth, esophagus, stomach, intestine)
  • Organs that store, release and make up chemicals that aid digestion (pancreas, liver, gall bladder, salivary glands)
• Meiosis


  Cell division that produces haploid sex cells or gametes from diploid cells
• Digestion


  1. Food enters mouth

  2. Passes through a long tube

  3. Exits as feces/stool in the anus
• Stages of meiosis I


  1. Prophase I

  2. Metaphase I

  3. Anaphase I

  4. Telophase I
• Ingestion


  Food is ingested or taken in into the mouth
• Stages of meiosis II


  1. Prophase II

  2. Metaphase II

  3. Anaphase II

  4. Telophase II
• Mechanical digestion


  Food is broken down into smaller pieces through chewing, grinding, squeezing and tearing
• During fertilization, gametes such as eggs and sperm unite, forming a diploid zygote
• In male animals, sperm cells are produced in the testes through meiosis
• Chemical digestion


  Food is broken down with the help of chemicals and other substances to liquefy
• In female animals, egg cells are produced in the ovary through meiosis
• Digestion in the mouth


  1. Food is broken down mechanically

  2. Salivary glands produce a chemical to start breaking down carbohydrates

  3. Food is swallowed and propelled down to the esophagus
• Zygote


  Diploid cell formed when egg and sperm unite
• Gametogenesis


  Production of gametes from haploid precursor cells
• Pharynx


  Hollow tube inside the neck that propels food down to the esophagus
• One set of chromosomes from the male parent and another set from the female parent are required for the zygote
• Esophagus


  Tube that creates a connection from the mouth to the stomach and where peristalsis begins
• In humans, through their gametes, both father and mother contribute 23 chromosomes each. The zygote, therefore, has 46 chromosomes
• Zygote formation


  1. Zygote breaks several times

  2. New diploid multicellular organism is created
• Peristalsis


  Involuntary movement that involves alternating waves of contraction to move food from the esophagus to the stomach
• Sperm cells


  Produced in the testes through meiosis, which develops four very small but equally sized cells that become sperm or spermatozoa
• Stomach


  Bag-like organ that grinds and mixes food with digestive juices/enzymes, producing chyme
• Sperm cell structure


  • Nucleus in the head
  • Mitochondria in the middle section that provide energy for the tail to move
• Egg cells


  Produced in the ovary, where meiosis creates one large cell and one or two small cells, with the large cell becoming the egg cell
• Small intestine


  Where chemical digestion mostly happens, containing several digestive juices
• The egg cell contains a lot of stored food that is used by the developing embryo, while the sperm cell contributes only its genetic material contained in the head during fertilization
• Liver

  Largest solid internal organ that secretes bile to break up fats
• Meiosis

  1. One parent cell forms four daughter cells, each receiving half the number of chromosomes from the parent cell

  2. Daughter cells are genetically distinct due to crossing-over
• Gall bladder


  Stores and concentrates bile