Week 3 & Week 4

Week 3 & Week 4 - Chapter 3: Cells 04/02/2008 14:05:00...

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Chapter 3: Cells 04/02/2008 14:05:00 Cell Theory     Cell is the smallest unit of life All living organisms are composed of cells Cells come from pre-existing cells Characteristics of All Cells Cells are very small o Lower limit Bacteria Cells What a cell needs to have in order to be a cell o Upper limit Cannot exceed the volume that can be nourished by materials  passing through the membrane Surface area-to-volume ratio Volume – everything inside of the cell Small cells have a very high surface area-to-volume ratio Cells must obtain energy and nutrients o ATP Cells contain DNA o The genetic material o Organized into chromosomes
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Cells contain cytoplasm o Cytosol: Semi-fluid substance inside cell o Cytoplasm: Cytosol + all suspended materials Cells contain ribosomes o The site of protein synthesis o Particles composed of proteins and RNA Cells are bound by plasma membrane o Outer boundary of cell Q: Which of the following is most likely to occur at a ribosome? Answer: Amino acids joined together to form proteins Studio Daily: Inner workings of a Cell Video Plasma Membrane: Outer boundary of cell Structure: o Phospholipid bilayer o Embedded and attached proteins o Embedded cholesterol
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o Attached carbohydrates on outer surface o Fluid mosaic Functions o Structure o Cell-cell recognition o Cell-cell communication o Cell-cell adhesion o Regulates movement of substances in and out Movement across plasma membrane     Plasma membrane is selectively permeable o Allows some substances through, but not others o Due to structure Passive transport o Diffusion of a substance across a membrane with no energy  investment Simple diffusion Facilitated diffusion Osmosis Active transport Bulk transport
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Passive Transport     Diffusion of a substance across a membrane with no energy investment o Diffusion : Movement of substance from region of higher concentration  to region of lower concentration Movement down concentration gradient 3 Types of Diffusion:     o Simple Diffusion Movement of substances down concentration gradient through  lipid bilayer Small and non-polar substances o Facilitated Diffusion Movement of substances down concentration gradient through 
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This note was uploaded on 04/22/2009 for the course BIO 309D taught by Professor Jessicawandelt during the Spring '08 term at University of Texas.

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Week 3 & Week 4 - Chapter 3: Cells 04/02/2008 14:05:00...

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