Bio Short Answers

  1. The endomembrane transport system consists of the rough ER, smooth ER, and the Golgi body. Explain the function of each of these organelles and how macromolecules move through this system.
    The rough ER has internal membranes studded with ribosomes that carry out protein synthesis. The smooth ER has a system of internal membranes that aid in the manufacturing of carbohydrates and lipids. As new molecules are made on the surface of the ER, they are passed from the ER to flattened stacks of membranes called golgi bodies. Golgi bodies function in the collection, packaging and distribution of molecules manufactured in the cell. Macromolecules are manufactured on the ER membranes, transported through the ER channels, and are packaged into transport vesicles that bud off from the Er. The vesicles fuse with the membrane of the Golgi body, dumping their contents.
  2. 2. The theory of endosymbiosis proposes that chloroplast and mitochondria were derived from bacterial prokaryotic species. Explain how this could have occurred through symbiosis. Also, describe 3 pieces of evidence that supports this theory from the several we discussed in class
    The theory of endosymbiosis proposes that some of today’s eukaryotic organelles evolved by a symbiosis in which one cell of a prokaryotic species was engulfed by and lived inside the cell of another species of prokaryote that was a precursor to eukaryotes. Evidence is that both mitochondria and chloroplast are surrounded by two membranes. Both contain circular DNA similar to those in bacteria. Mitochondria are about the same size as bacterial cells.
  3. Molecules, ions, and other substances can cross the plasma membrane either by passive transport or active transport. Describe the 3 types of passive transport and the 1 type of active transport discussed in lecture. How do they occur? What proteins are used if any? Is energy required? Use drawings if needed.
    The three types of passive transport are simple diffusion which is a process whereby a substance passes through a membrane without the aid of an intermediary such as a integral membrane protein, selective diffusion which is a mechanism of transport where molecules move towards the side in which they are scarcest, and facilitated diffusion which is a mechanism of transport of molecules down it concentration gradient using carrier proteins. For passive transport no energy is needed, and proteins used are a particular sugar, aminol acid, or ion. For active transport sodium-potassium pump, expends metabolic energy (ATP) to actively pump sodium out of the cells and potassium ions into the cell.  Requires energy, a transport protein is used.
  4. . Explain how some enzymes act as activators and others as repressors. What is feedback inhibition? Describe the two ways in which it can occur.
    Enzymes must have a precise shape to work correctly, and many enzymes can have its shape altered by the binding of signal molecules to their surface. Feedback inhibition is a mechanism where the product of the reaction acts a repressor to regulate enzymes. It can occur in two ways: competitive inhibitor- a molecule which blocks the active site so that substrates cannot bind and by noncompetitive inhibitor
  5. Describe how the two photosystems are used and describe the differences between C3 photosynthesis, C4 photosynthesis, and CAM photosynthesis.
    Photosystem II captures energy that is used to produce the ATP needed to build sugar molecules. Photosystem I powers production of hydrogen atoms needed to build sugars and other organic molecules from CO. C3 is the calvin cycle and is the main cycle of the dark reaction of photosynthesis, in which CO2 binds to ribulose 1, 5-biosphosphate (RuBP) to form two 3-carbon phosphoglycerate (PGA) molecules. Does not need light to occur. C4 and CAM occur to decrease photorespiration, C4 photosynthesis occurs in some plants and the plants are able to fix carbon using different types of cells and chemical reactions within their leaves. CAM has stromata open during the night and close during the day.
  6. Describe how glucose is broken down into 2 pyruvate molecules in glycolysis. Is any energy made? Are there any special enzymes, any waste products, or any molecules oxidized/reduced?
    Glucose is broken down in ten steps to two molecules of pyruvate, which then enters the mitochondria where it is oxidized through the tricarboxylic acid cycle to carbon dioxide and water. No special enzymes, The two 3-carbon sugar phosphates are then converted to pyruvate. NAD+ harvests energy rich H+ and forms NADH. Also picks up 2 electrons. NAD+ is made up of carbon, hydrogen, nitrogen, oxygen and phosphorus atoms . very electronegative. When the NAD+ bonds with a hydrogen, the electrons are hogged by the very negative atoms. Two ATP molecules are formed from each pyruvate. 2 ATP’s to start the reaction, 4 ATP’s were released. Net ATP= 2 created
  7. Aerobic respiration consists of glycolysis, the Krebs cycle, and the electron transport chain. State where these processes occur and how many ATPs are produced in each. Be specific about the locations.
    Glycolysis occurs in the cytoplasm and two ATPs are produced. Krebs cycle takes place inside the matrix of the mitochondria and two ATPS are produced. The electron transport chain occurs across the inner membrane of the mitochondria and two ATPs are produced.
Author
karlaesc1
ID
338507
Card Set
Bio Short Answers
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short answers
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