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CH. 6-7 (Types of microscopes (Electron Microscope (EM)- focuses a beam of…
CH. 6-7
Types of microscopes
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Scanning Electron Mircroscope (SEM)- is useful for detailed study of the tropography of a specimen. The end result is that the image of the specimens surface appears three- dimensional.
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Transmission Electron Microscope (TEM) - is used to study the internal structure of cells. It uses an electromagnet as a lenses to bend the paths of the electrons. TEM aims an electron beam through a very thin section of the specimen.
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Plasma Membrane- functions as a selective barrier that allows passage of enough oxygen, nutrients, and waste to service an entire cell
Membrane Protein functions- do signaling , involved in diffusion,
-Transport protein
-Receptor
-identitiy marker
-enzyme
-anchoring site
-cell adhesion
Prokaryotes Structure- their DNA is concentrated in the Nucleiod
-usuallly smaller that eukaryotes
-membrane bound organelles are usually absent in prokaryotes
Eukaryote Structure- most of its DNA is located in the Nucleus
-Are generally bigger that prokaryotes
-within the cytoplasm are a variety of organelles of specialized form and function.
Active Transport-the movement of ions or molecules across a cell membrane into a region of higher concentration assisted by enzymes and requiring energy.
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Secondary Active Transport -Pumps are powered by energy harnessed as a second substance moves through a channel down a concentration gradient
Symport - two substances are moved in the same direction
Antiport - Two substances are moved in opposite directions.
Cell Fractionation- is a technique for studying cell structure and function by taking cells apart and separating major organelles and other sub cellular structures from each other.
Surface Area- volume ratio- i.e. the amount of surface area per unit volume of an object or collection of objects
Diffusion- The moment of particles of any substance so that they spend out into the available space .
Simple Diffusion- small and non polar substances move between phospholipid molecules of the plasma membrane
Facilitated Diffusion- small, charged, or polar substances move assisted by a transport protein
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