biology paper 2

• Eukaryotic cells


  Cells found in organisms such as animals, plants and fungi
• Cytoplasm


  Jelly-like liquid that makes up the bulk of the cell and contains the organelles
• Nucleus


  Organelle containing the nucleic acids DNA (the genetic material) and RNA, as well as protein, surrounded by a double nuclear membrane with pores
• Protoplasm


  The cytoplasm and nucleus combined
• Ultrastructure


  The detailed organization of the cell, only visible using the electron microscope
• Intracellular


  Inside the cell
• Chromatin


  The granular combination of DNA bonded to protein found in the nucleus when the cell is not actively dividing
• Nucleolus


  An extra-dense region of almost pure DNA and protein found in the nucleus; it is involved in the production of ribosomes and control of growth and division
• Mitochondria


  Rod-like structures with inner and outer membranes that are the site of aerobic respiration
• Cristae


  The infoldings of the inner membrane of the mitochondria which provide a large surface area for the reactions of aerobic respiration
• Eubacteria


  True bacteria (prokaryotic organisms)
• Centrioles


  Bundles of tubules found near the nucleus and involved in cell division by the production of a spindle of microtubules that move the chromosomes to the ends of the cell

  
• Spindle


  A set of overlapping protein microtubules running the length of the cell, formed as the centrioles pull apart in mitosis and meiosis

  
• 80S ribosomes


  The main type of ribosome found in eukaryotic cells, consisting of ribosomal RNA and protein, made up of a 60S and 40S subunit; they are the site of protein synthesis
• 70S ribosomes


  The ribosomes found in the mitochondria and chloroplasts of eukaryotic cells and in prokaryotic organisms
• Endosymbiotic theory


  A theory that suggests mitochondria and chloroplasts originated as independent prokaryotic organisms that began living symbiotically inside other cells as endosymbionts
• Lysosomes


  Organelles full of digestive enzymes used to break down worn-out cells or organelles or digest food in simple organisms
• Apoptosis (Programmed Cell Death)

  The breakdown of worn-out, damaged or diseased cells by the lysosomes
• Rough Endoplasmic Reticulum (RER)


  A system of membranes trapping a fluid-filled space and the surfaces are covered with ribosomes, it folds and processes proteins coming from the ribosome
• Smooth Endoplasmic Reticulum


  The same as the RER but with no ribosomes, they synthesize and process lipids and steroids, they are found a lot in the testes and the liver
• Golgi Apparatus


  A group of fluid-filled, membrane-bound, flattened sacs. Vesicles are often seen at the edges of the sacs. It processes and packages new lipids and proteins. It also makes lysosomes
• Protein Production


  1. Proteins are made at the ribosomes

  2. The ribosomes on the rough endoplasmic reticulum (ER) make proteins that are excreted or attached to the cell membrane. The free ribosomes in the cytoplasm make proteins that stay in the cytoplasm

  3. New proteins produced at the rough ER are folded and processed (e.g. sugar chains are added) in the rough ER

  4. Then they're transported from the ER to the Golgi apparatus in vesicles

  5. At the Golgi apparatus, the proteins may undergo further processing (e.g. sugar chains are trimmed or more are added)

  6. The proteins enter more vesicles to be transported around the cell. e.g. extracellular enzymes (like digestive enzymes) move to the cell surface and are secreted

  
• Prokaryotic cells


  Cells found in bacteria, cyanobacteria and archaebacteria

  
• Bacterial Cell Walls


  All bacteria cells have walls, the content of the cell is usually hypertonic to the medium so water moves inside the cell by osmosis and cells prevent the cell from bursting. It also maintains the shape of bacteria, and gives support and protection to the contents of the cell
• Peptidoglycan


  A large, net-like molecule found in all bacterial cell walls made up of many parallel polysaccharide chains with short peptide cross-linkages
• Capsule


  A layer formed from starch, gelatin, protein or glycolipid, found around the outside of some bacteria
• Pili


  Thread-like protein projections found on the surface of some bacteria

  
• Bacteriophage


  Virus that attacks bacteria
• Flagella


  Many-stranded helixes of the contractile protein flagellin found on some bacteria; they move the bacteria by rapid rotations
• Nucleoid


  The area in a bacterium containing the single circular loop of coiled DNA
• Plasmids


  Small, circular pieces of DNA that code for specific aspects of the bacterial phenotype

  
• Gram Staining


  A staining technique used to distinguish types of bacteria by their cell wall

  
• Gram-positive Bacteria


  Bacteria that contain teichoic acid in their cell walls and stain purple/blue with Gram staining
• Teichoic Acid


  A chemical substance found in the cell walls of Gram-positive bacteria
• Gram-negative Bacteria


  Bacteria that have no teichoic acid in their cell walls; they stain red with Gram staining

  
• Bacterial Cell Shapes


  • Cocci (spherical)
  • Bacilli (rod-shaped)
  • Spirilla (twisted or spiral)
  • Vibrio's (comma-shaped)
• Obligate Aerobes


  Organisms that need oxygen for respiration
• Facultative Anaerobes


  Organisms that use oxygen if it is available, but can respire and survive without it
• Obligate Anaerobes


  Organisms that can only respire in the absence of oxygen and are killed by oxygen
• Cells


  The building blocks of life, they make up every single organ and part of the body we have, are present everywhere, and cannot be seen by the human eye