bio paper 1

• Eukaryotic cells


  Cells that contain a true nucleus
• Components of eukaryotic cells

  • Cell membrane
  • Cytoplasm
  • Nucleus
  • Ribosomes
  • Mitochondria
  • Cell wall (plant cells)
  • Chloroplasts (plant cells)
  • Permanent vacuole (plant cells)
• Nucleus


  Contains the DNA or genetic material and controls the actions of the cell
• Cytoplasm


  The liquid jelly where most of the chemical reactions in the cell take place
• Cell membrane


  Responsible for controlling what can go into and out of the cell
• Ribosomes


  Used to synthesize protein
• Mitochondria


  The site for aerobic respiration which is used to release energy
• Cell wall (plant cells)

  Made of cellulose and strengthens and gives the cell support
• Chloroplasts (plant cells)


  Absorb light and are where photosynthesis takes place
• Permanent vacuole (plant cells)


  A storage of cell sap used to keep the cell rigid to support the plant
• Prokaryotes (e.g. bacteria)


  Lack a true nucleus and membrane-bound subcellular structures
• Bacterial DNA


  Exists as a single circular chromosome, and some may also have small circles of DNA called plasmids
• Bacterial ribosomes


  Significantly smaller than eukaryotic ribosomes
• Binary fission


  The process by which bacteria reproduce, a form of mitosis in bacteria
• Bacteria can rapidly increase in numbers with division times often as short as 20 minutes, provided they have sufficient nutrients and a suitable temperature</b>
• Bacteria can be cultured or grown as colonies in a petri dish filled with a mixture of agar jelly and LB nutrient broth, or in a tube of the same broth
• Preparing a streak plate

  Sterilize the petri dish, culture media, and inoculating loop, then use the loop to put a small amount of the bacterial sample onto the agar plate and spread it in a zigzag pattern
• It's important to tape down the lid of the petri dish with small pieces of adhesive tape, not sealing it completely, to allow oxygen to get in
• Bacteria are incubated at 25 degrees in school to avoid growing human pathogens, while still allowing the desired bacteria to grow
• Calculating the area of a bacterial colony

  Measure the radius of the circular colony and use the formula pi*r^2 to calculate the area
• Performing a zone of inhibition test


  Cover an agar plate in a bacterial culture, then place paper discs soaked in different antiseptics on the plate and measure the area around each disc where no bacteria are growing (the zone of inhibition)
• The bigger the zone of inhibition, the more effective the antiseptic
• Cell specialization


  Cells are adapted structurally to suit their function, involving changes in shape and the presence of subcellular structures
• Specialized cells


  • Sperm cells (tail and many mitochondria)
  • Nerve cells (branched shape)
  • Muscle cells (many mitochondria and ribosomes)
  • Palisade cells in leaves (many chloroplasts)
  • Root hair cells (extended shape, no chloroplasts)
• Xylem


  Transport water and mineral ions from roots to leaves, made of dead cells reinforced with lignin
• Phloem


  Transport sucrose from leaves to other parts of the plant, made of living cells with companion cells
• Good conditions for transpiration are hot, dry, light, and windy weather
• Stem cells


  Unspecialized cells that can differentiate into various specialized cell types
• Adult human stem cells are limited in the cell types they can become, while embryonic stem cells can become almost any cell type
• In therapeutic cloning, an embryo is made with the same genes as the patient to produce stem cells that won't be rejected
• Meristems


  Plant tissues containing stem cells that can become any cell type
• Resolution


  The smallest measurement that can be made
• Magnification


  How much bigger the image looks than the actual object
• Light microscopes


  • Magnification up to 1500x, resolution down to 0.2 micrometers
  • Can't see structures smaller than the resolution limit, like ribosomes
• Electron microscopes


  • Magnification up to 500,000x, resolution down to 1 nanometer
  • Can visualize subcellular structures and nanoparticles
• Calculating magnification


  Divide the size of the image by the size of the object, ensuring the units are the same
• Hierarchy in a eukaryotic cell

  Nucleus contains chromosomes made of DNA, which contain genes
• Mitosis


  Cell division used by body cells for growth and repair
• Chromosomes


  23 pairs in a human body cell, each containing about a thousand different genes made of DNA
• Mitosis


  One of the two types of cell division, used by body cells for growth and repair