Biology 1002B Chapter Notes - Chapter 2.1: Electron Microscope, Yolk, Glycocalyx
29 Apr 2018
School
Department
Course
Professor
2.1 Basic Features of Cell Structure and Function
Cell Theory
1. All organisms are composed of one or more cells
2. Cell is the basic unit of life
3. Cells arise from division of pre-existing cells
2.1a Cells are Small and Can Only Be Seen Using a Microscope
• Cells range in size from bacteria to egg yolk, which is a single cell several cm in
diameter
• Most cells are too small to be seen by unaided eye
o Light microscopes: using light to illuminate specimen
o Electron microscopes: using e- to illuminate specimen
o Electron microscopes have higher resolution than light microscopes, since
the shorter the wavelength the better the resolution
• Cells are small because change in SA to volume ratio as its size increases
o Increase in diameter of cell has larger increase in volume than increase in SA
o Volume determines amount of chemical activity
o SA determines amount of substances that can be exchanged between cell
and outside
o Past a certain point, increase in diameter gives SA that is insufficient to
maintain exchange for its volume
2.1b Cells Have a DNA-Containing Central Region That Is Surrounded by Cytoplasm
• Plasma membrane: bilayer of lipids with embedded proteins
• Central region contains DNA molecules organized in form of genes
• Cytoplasm: all parts of the cell that surround the central nuclear region, consists of
o Organelles: nucleus and other specialized structures of eukaryotic cells
o Cytosol: aqueous solution in cytoplasm
o Cytoskeleton: framework of protein fibres that extends throughout
cytoplasm
2.1c Cells Occur in Prokaryotic and Eukaryotic Form
Prokaryotes
Eukaryotes
• Bacteria and archaea domain
• No nucleus
• Nucleoid as DNA-containing central region
with no membrane
• Eukarya domain
• Has a nucleus
• Membrane bound
compartment for DNA
find more resources at oneclass.com
find more resources at oneclass.com
