module 2: biology

• organelles in eukaryotic cells:

  nucleus, cell membrane, RER, SER, golgi apparatus, lysosomes, mitochondria, ribosomes, vacuole, chloroplasts, cell wall
• function of lysosomes

  vesicle of digestive enzymes that hydrolyses phagocytotic cells
• function of golgi apparatus

  processes and packages proteins for export
• function of RER

  provides a large surface area for protein synthesis
• function of SER

  synthesises and stores lipids + carbohydrates
• function of cell membrane

  controls what enters & exits the cell
• organelles in prokaryotic cells:

  cell wall (murein), plasmid, capsule, flagella
• 5 differences between eukaryotic and prokaryotic

  eukaryotic: 

  • has a nucleus
  • has 80S ribosomes
  • cell wall consists of chitin/cellulose
  • has multiple membrane-bound organelles
  • larger cell

  prokaryotic:

  • has no nucleus
  • has 70S ribosomes
  • cell wall consists of murein
  • has no membrane-bound organelles
  • smaller cell
• structure of a virus particle

  attachment protein, capsid, genetic material
• define magnification

  refers to how many times larger the image is compared to the object
• define resolution

  minimum distance between 2 objects that can be viewed separately
• 3 types of microscopes

  optical microscope, transmission electron microscope, scanning electron microscope
• pros of optical microscope

  colour images

  living specimens can be used
• cons of optical microscope

  poor resolution

  lower magnification
• process of TEM

  specimens are stained and put into a vacuum

  penetrates through

  parts of the specimen absorbs the electrons (would appear darker)
• pros of TEM

  shows internal structures

  high resolution + magnification
• cons of TEM

  non-living specimen required

  2D image

  thin specimen

  black & white image
• process of SEM

  beam of electrons scan the surface of the specimen rather than penetrate
• pros of SEM

  3D image

  high resolution + magnification
• cons of SEM

  non-living specimen required

  black & white image
• equation for magnification

  image size / actual size
• conversion of nanometre to micrometre

  divide by 1000
• conversion of millimetre to micrometre

  multiply by 1000
• condition for solution for cell fractionation

  ice isotonic buffered solution
• why should the solution be cold

  reduces enzyme activity 
• why should the solution be buffered

  prevents damage to organelles
• why should the solution be isotonic

  same water potential needed to prevent osmosis from occurring
• stages of cell fractionation

  homogenisation & ultracentrifugation
• homogenisation

  cells are homogenised in a homogeniser

  homogenate (solution from blender) is filtered to remove large debris
• ultracentrifugation

  filtered homogenate is spun at a centrifuge

  spun at various speeds and separates organelles according to density

  pellet would be formed = isolated organelle

  supernatant would be spun again
• how do prokaryotic cells replicate

  binary fission:

  replication of circular dna & plasmids

  division of cytoplasm
• how do viruses replicate

  replicate inside of host cells
• cell cycle:

  interphase,mitosis, cytokinesis
• interphase:

  G1, S, G2
• what is G1

  growth + preparation of the cell
• what is S

  DNA synthesis/ replication
• 4 stages of mitosis

  prophase,metaphase,anaphase,telophase
• what occurs in prophase

  chromosome condense

  nuclear envelope disintegrates

  centrioles separate to either side of cells
• what occurs in metaphase

  chromosomes align at the equator

  spindle fibres released for centrioles and attach to centromere
• what occurs in anaphase

  spindle fibres pull, causing tension for chromatids to break apart 

  pulled towards opposite poles