Cell structure

• Vacuoles maintain internal PH, isolate harmful substances, contains waste products and keeps the cell rigid
• ultrastructure- fine structure in a cell only seen with and high magnification and electron microscope
• Cell wall in prokaryotes is made from peptidoglycan or murein- made from amino acids and sugars
• TEM- Pass high energy beam of electrons through thin specimen
• TEM- more dense structures appear darker, the absorb more electrons
• SEM- 3D, beam of electron move back and forth and produces black and white image
• TEM- 2D, higher resolution than sem, electron beam penetrates cell, only views dead specimen, colour
• Electron microscope- vacuum, artefact more likely, 0.2nm resolution
• SEM- uses electromagnetic lenses to focus beam on specimen
• Squash slide- use wet mount and lens tissue to press coverslip
• Smear slides- edge of slide used to create thin coating, add coverslip
• Dry mount- solid specimen cut in slices, place on slide with cover slip
• Wet mount- suspend in water and at cover slip at an angle
• Microfilaments- made of actin which works with myosin. important for cellular events requiring motion eg cell division
• Intermediate filaments- bear tension, maintain shape of cell, anchor organelles in place
• Cytoskeleton- scaffolding, movement of cilia, mechanical strength changing shape of cell, forms centrioles
• Laser scanning confocal microscope- focus laser beam on specimen with objective lens, fluorophores emit photons, photomultiplier amplifies signal into detector, image produced
• Staining allows you to see contrast and identify compounds
• Prokaryotes have thinner flagella with no 9+2 arrangement
• electron microscopes can only view dead tissues because beams of electrons kill specimens
• Cis face- receiving end of Golgi body
• Trans face- sending end of golgi body
• Rough ER has ribosomes attached to it
• Golgi apparatus is involved in protein modification and packaging
• Ribosomes are the site of protein synthesis
• Light microscopes have longer wavelengths so have a lower resolution
• Cytoplasm isn’t an organelle
• Mitochondria, chloroplasts and nuclei have a double envelope
• Mitochondria and chloroplasts have their own DNA
• Genes in prokaryotes are grouped in operon so number of genes can be switched on/off
• Centrioles are only found in animal cells
• Ultrastructure- fine structure in a cell, only see with a high magnification microscope
• Histones- DNA wrap around histones to for nucleosome which as a chain makes chromatin
• Prokaryotes don’t have lysosomes or ERs or mitochondria