2.2 Basic components of living systems

Microscopes
1. Magnification how many times larger the image is than the actual size of the object being viewed
2. Resolution how easy it is to distinguish between two separate objects
3. Light microscope
  1. Resolution 200nm
  2. Magnification X1500
  3. In colour but not detailed
4. Transmission electron microscope (TEM)
  1. Resolution 0.1 nm
  2. Magnification X500,000
  3. Image cannot be viewed directly
  4. Black and white not 3D
5. Scanning electron microscope (SEM)
  1. Resolution 0.1 nm
  2. Magnification X100,000
  3. Produces a 3D Black and white image
  4. Picture in black and white and 3D
6. Laser scanning confocal microscope
  1. Resolution 10nm
  2. Magnification X2000
  3. Produces a 3D coloured image
  4. Can be a live specimen
7. I=AM
8. Total magnification= Eyepiece magnification X Objective magnification
9. Staining
  1. Dry mount- place solid specimens onto slide with cover slip
  2. Wet mount- Specimens suspended in a liquid cover slip placed on at angle
  3. Squash slide- wet mount prepared then a lens tissue is pressed down used for soft samples
  4. Smear slides- Edge of slide is used to smear the sample creating a thin even coating
  5. Gram positive crystal violet applied then iodine, it retains the crystal violet staining so appears blue or purple due to the thick cells walls. Gram positive bacteria is susceptible to penicillin which inhibits the formation of cell walls
  6. Gram negative crystal violet and then iodine applied, due to thin cell walls they lose the stain so they are stained again with safranin (counterstain). Due to thinner cell walls they are not susceptible to penicillin
10. Units of measurments
  1. mm X1000 Micrometer um X1000 Nanometer nm
Eukaryotic
1. Nucleus
  1. Largest orgnaelles
  2. Double membrane bound
  3. Histones form complex structures called chromatin, when the chromatin condenses it forms chromosomes
  4. Nuclear envelope
  5. Nuclear pore
  6. Nucleolus
  7. Makes RNA and assembles ribosomes
2. Rough endoplasmic reticulum
  1. Flattened sacs called cisternae
  2. Continuous with the outer membrane
  3. Studded with ribosomes
  4. Ribosomes make proteins which are transported along the cisternae
  5. Some proteins are secreted by the cell some are used
3. Soft endoplasmic reticulum
  1. Flattened sacs known as cisternae
  2. Not studded with ribosomes
  3. Used in the production of lipids which are made here
4. Golgi Apparatus
  1. A sack of membrane bound flattened sacs
  2. Receives proteins packaged into vesicles from the ER.
  3. Modifies proteins and packages them into vesicles for transportation to the cell surface
5. Ribosomes
  1. Small not membrane bound
  2. Two subunits
  3. Site of protein synthesis
  4. mRNA from the nucleus is read and used to assemble amino acids
  5. 80 s size
6. Lysosome
  1. Single membrane
  2. Contains powerful digestive enzymes
  3. Protects the cell from enzymes within
  4. Enzymes are used to break down material, important in the immune system
7. Vesicles
  1. Membrane bound sac
  2. Used to transport substances
8. Plasma membrane
  1. Provides a selective barrier between the cells content and external surroundings
  2. Controls the passage of substances in and out of the cell
  3. Regulates the internal environment of the cell
9. Mitochondria
  1. 2 Membranes inner membrane highly folded- cristae
  2. Fluid interior called matrix
  3. Can form their own DNA and produce their own enzymes and reproduce by themself
  4. Site of aerobic respiration
  5. Produces ATP
10. Chloroplast
  1. 2 Membranes inner membrane is continuous and forms flattened sacs called thylakoids
  2. Site of photosynthesis glucose produced
  3. Contains chlorophyll
11. Cytoskeleton controls cell movement ,movement of organelles and structure
  1. Microfilaments-Formed from the protein actin. Responsible for cell movement and cell contraction
  2. Microtubules- Scaffold like structures which determine the shape of the cell and spindle fibres which physically segregates the chromosomes in cell division
  3. Intermediate fibres- Give mechanical strength
12. Flagella and cillia
  1. Flagella used for movement or used as a sensory organelle detecting chemical changes
  2. Stationary cilia-play an important role in sensory organs
  3. Mobile cilia- Beat in a rhythmic manor creating a current to move objects
  4. In cilia contain two microtubules surrounded by 9 pairs of microtubules 9+2 arrangment
13. Vacuoles
  1. Large membrane bound sac containing water and solutes
  2. Storage of water and solutes
  3. Maintenance of cell turgidity
Orgtanelles
1. Plant cell
  1. Chloroplast
  2. Vacuole
  3. Cellulose cell wall
  4. Linear chromosomes
  5. Endoplasmic reticulum
  6. Golgi body
  7. ATP produced with mitochondria
  8. 9 +2 arrangement of microtubules
  9. Ribosomes
  10. Cell membrane
2. Animal cell
  1. Linear chromosomes
  2. Endoplasmic reticulum
  3. Golgi body
  4. ATP produced in mitochondria
  5. 9 +2 Microtubules
  6. Ribosomes
  7. Cell membrane
3. Prokaryote
  1. Peptidoglycan cell wall
  2. Circular chromosome
  3. Plasmid
  4. DNA free in cytoplasm
  5. ATP produced infolded regions called mesosomes
  6. Flagella
  7. Ribosomes
  8. Cell membrane
Prokaryotic
1. Ribosomes
  1. 70s size
2. Cell wall
  1. Made from peptidoglycan or murein
3. Flagella
  1. Thinner than eukaryote and does not have the 9+2 arrangement
  2. Flagella attached by a basal body
  3. Rotated by a molecular motor

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2.2 Basic components of living systems

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