Sci

• Ingestion


  Taking in of food
• Absorption


  Uptaking of nutrients/materials
• Assimilation


  Using of nutrients by the body
• Excretion


  Removing of undigested materials
• Digestion


  Breaking down of food into absorbable forms
• Digestive system

  • Mouth
  • Esophagus
  • Stomach
  • Small intestine
  • Large intestine
  • Liver
  • Pancreas
  • Gallbladder

  
• Mechanical digestion


  Physically breaking the food into tiny bits and pieces
• Chemical digestion


  Breaking down of food into simpler forms that can be used and assimilated by the body
• Enzymes help the digestive system with chemical changes
• Mouth


  Beginning of the digestive tract where digestion starts, food is ingested and broken down by chewing and saliva

  
• Esophagus


  Muscular tube that transports food from the mouth to the stomach
• Stomach


  Thick-walled organ that holds and breaks down food into usable form, mixes food with gastric juices
• Small intestine


  Where most of the food is chemically digested, digestive juices from liver and pancreas help complete digestion

  
• Liver


  Largest organ in the digestive system, produces bile to help digest fats
• Pancreas


  Elongated organ that produces enzymes to aid digestion of all three organic compounds

  
• Gallbladder


  Small sac that stores bile until needed by the small intestine for fat emulsification
• Large intestine


  Removes useful liquids from undigested food, solidifies feces for excretion
• Digestive juices


  Aid in the digestion of all three organic compounds
• Gall Bladder


  • A small pear-shaped sac that stores the bile until it is needed by the small intestine for the emulsification of fats
  • When food moves into the small intestine, the gall bladder releases bile
• Large Intestine


  • Also known as colon
  • The organ in the digestive system which is next to the small intestine
  • Removal of useful liquids from the undigested food is the job of the large intestine
  • The feces or undigested food is solidified and is pushed out into the anus
  • The reabsorption of salt for further use by the body is performed by this organ
• Mitosis


  Cell division that is responsible for making new body cells (somatic cells)

  
• Meiosis


  A process where a single cell divides twice to produce four cells containing half the original amount of genetic information (sex cells - sperm and eggs)

  
• Cell cycle

  1. Interphase

  2. Cell division phase (mitotic phase)

  
• Interphase


  • Period that follows one cell division and leads to another, where the cell does not divide but just grows
  • Chromosomes replicate and each DNA molecule produces an exact duplicate

  
• Stages of interphase


  • G1 (First Gap Period)
  • S (Synthesis)
  • G2 (Second Gap)
• Mitosis

  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase

  
• Meiosis

  1. Prophase 1

  2. Metaphase 1

  3. Anaphase 1

  4. Telophase 1

  5. Prophase 2

  6. Metaphase 2

  7. Anaphase 2

  8. Telophase 2

  
• Chromosomes


  • Genetic material that serves as the sets of instructions that direct the activities and functions of the cells
  • In eukaryotic cells, the DNA is bound with proteins and organized as beads on strings to form chromosomes

  
• Chromosomes change form as the cell transitions from one stage to another in the cell cycle
• Tumor is an uncontrollable cell division in a specific area or organ in the body
• Synthesis or replication


  G2 (second Gap) – period of fast cell growth to prepare for the cell division; this period falls between S period to the next cell division phase

  
• Interphase

  1. DNA is copied resulting in two identical full sets of chromosomes

  2. Microtubules extend from the centrosomes

  
• Prophase


  • Chromosomes are thicker and shorter because of repeated coiling
  • Chromosomes are double-stranded
  • Each strand is called a chromatid
  • Two chromatids produced from one chromosome are still attached at the centromere
  • Nuclear membrane and nucleoli may still be present

  
• Metaphase


  • Spindle is at the center of the cell where the nucleus used to be
  • Nucleus membrane has disappeared
  • Chromatids are almost at the middle of the spindle
  • Each centromere of the sister chromatids is attached to a single spindle fiber

  
• Anaphase


  • Centromere divides and the two new single-stranded chromosomes move away from each other, toward opposite poles of the spindle
  • New chromosomes come from chromatids of double-stranded chromosomes formed in the S phase of the interphase

  
• Telophase


  • Chromosomes are now at opposite poles of the spindle
  • They start to uncoil and become indistinct under the light microscope
  • A new nuclear membrane forms around them
  • Spindle fibers disappear

  
• Cytokinesis


  Division into two daughter cells is completed - diploid (2n = 4 double stranded chromosomes)

  
• Meiosis


  • A process where a single cell divides twice to form four cells which contains half the original amount of genetic information
  • These are our sex cells – sperm cells in males, egg cells in females

  
• Meiosis I

  1. Interphase: DNA is copied resulting in two identical full sets of chromosomes

  2. Microtubules extend from the centrosomes

  3. Prophase I: Chromosomes condense into X-shaped structures

  4. Chromosome pairs may exchange bits of DNA in recombination or crossing over

  5. Nuclear membrane dissolves

  6. Meiotic spindle extends across the cell

  7. Metaphase I: Chromosome pairs line up at the equator

  8. Anaphase I: Pairs of chromosomes pulled to opposite poles

  9. Telophase I and cytokinesis: Chromosomes gather at opposite poles, new nuclei form, cell divides into two daughter cells

  
• Meiosis II


  1. Prophase II: Chromosomes condense again, nuclear membrane dissolves, centrioles duplicate, meiotic spindle forms

  2. Metaphase II: Chromosomes line up end-to-end at equator, spindle fibers attach to sister chromatids

  3. Anaphase II: Sister chromatids pulled to opposite poles

  4. Telophase II and cytokinesis: Chromosomes gather at poles, new nuclei form, cell divides into four granddaughter cells