BISC 102 Lecture Notes - Lecture 3: Scanning Electron Microscope, Cell Membrane, Cell Theory
Wednesday, September 2, 2015
Bisc 102-3
Ch 3 - Cells
-Cell is the smallest unit that can function independently
-Cell theory: formulated by schlseiden and Schwann.
•3 principles
-All living organisms are made up of one or more cells
-Cell is the most basic unit of life
-All cells come from pre-existing living cells
-Microorganisms - cells are too small to see without microscope
•Light microscopes, generate color images of living cells
•Transmission electron microscope - purpose:visualize internal structures
•Scanning electron microscope - not as big of a range as TEM. only looks at things
on the external surface
-Why are cells so small?
•Smaller cells have more surface area relative to their volume. High surface area
allows the cell to quickly exchange materials with its surroundings.
•Ways to maximize: Surface Area:Volume Ration.
-Want a high surface area: low volume - more efficient
-Like a piece of paper - if its laying flat its taking up too much room but if you fold
it, it takes up less room but still has all of the surface area
-Features cells share:
•DNA, RNA, Ribosomes, Proteins, Cytoplasm, Cell membrane
-Size and structure can change but they all still have these characteristics
-Different Cell Types Characterize Life’s 3 Domains
•Prokaryotes - most ancient forms of life. Lack a nucleus
-Bacteria are prokaryotes
•DNA is free in cytoplasm. Circular.
•Have ribosomes
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Document Summary
Cell is the smallest unit that can function independently. Cell theory: formulated by schlseiden and schwann: 3 principles. All living organisms are made up of one or more cells. Cell is the most basic unit of life. All cells come from pre-existing living cells. Why are cells so small: smaller cells have more surface area relative to their volume. High surface area allows the cell to quickly exchange materials with its surroundings: ways to maximize: surface area:volume ration. Want a high surface area: low volume - more ef cient. Like a piece of paper - if its laying at its taking up too much room but if you fold it, it takes up less room but still has all of the surface area. Features cells share: dna, rna, ribosomes, proteins, cytoplasm, cell membrane. Size and structure can change but they all still have these characteristics. Different cell types characterize life"s 3 domains: prokaryotes - most ancient forms of life.
