keyconceptstopic7

keyconceptstopic7 - T opic 7 Cells the basic unit of life 1...

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Topic 7: Cells, the basic unit of life. 1.) All cells come from pre-existing cells (= Cell Theory), and therefore have in common many processes, molecules, and structures. 2.) What is a cell, and what is thought to be the adaptive advantage of this? Cells are reactions enclosed in a membrane. (Membrane defines the limits). 3.) Why are cells limited in size by their surface area-to-volume ratio? Because the surface area to volume ratio drops when surface area increases. Diffusion would occur at an ineffective rate. 4.) What is the function of the plasma membrane, and what is it about phospholipids that allow this? It allows cells to regulate their contents, acts as a selectively permeable barrier, is the surface across which cells send out and receive signals to and from other cells, and is studded with molecules that allow cells to bind to one another. 5.) What are the functions of the cell wall (for those cells that have them)? Acts as a rigid supporting structure located outside of the plasma membrane and usually composed of polysaccharides. Found in algae, plants, bacteria, fungi, and some other groups. 6.) How do prokaryotes differ from eukaryotes in size and structure? Prokaryotes can vary from being 1 /10 to 1 /100 the size of a eukaryote. They have a simple structure. They lack a nucleus. They have a nucleoid where chromosomes exist. A selectively permeable plasma membrane. A capsule, which is a fibrous carbohydrate coat and acts as a defense and also prevents cells from drying out. They also have a cell wall and specialized features such as membranes and flagella. Eukaryotes have compartmentalization which is key to their function. The Nucleus contains, stores, protects the DNA. This is where genetic control takes place. DNA replication takes place. Way bigger than prokaryotes and they have an actual nucleus. 7.) Are some prokaryotes able to perform photosynthesis and respiration, even though they have no chloroplasts or mitochondria? Explain. No. The function of mitochondria is to catalyze oxidation-reduction reactions and ATP synthesis. Their function is for ATP production. Chloroplasts are the enzyme that also catalyze oxidation-reduction reactions. They are responsible for the production of ATP and
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sugars via photosynthesis. No other cell components can achieve photosynthesis and respiration. 8.) What are the main differences between prokaryotes and eukaryotes? Prokaryotes are much smaller than an eukaryote and also lacks a true nucleus. It has a
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This note was uploaded on 11/08/2010 for the course BIO 12334343 taught by Professor Jony during the Fall '09 term at Arizona.

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keyconceptstopic7 - T opic 7 Cells the basic unit of life 1...

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