Biology Study Guide  -- Biology 100

Chapter 4:   A Tour of the Cell

        Remember that cells are constrained to a small size because of the need to efficiently take in nutrients and discard wastes via the plasma membrane.  As cell size increases, which changes more rapidly, volume or surface area?  Many egg cells are not microscopic, as is true of most cells, but are visible with the unaided eye.  Which cells have a greater surface area relative to their volume, large cells or small cells?

        Vocabulary (be familiar with the correct spelling and formal definition or explanation of each term). 

Become familiar with the functions for each organelle.  For instance the rough endoplasmic reticulum (ER) modifies polypeptides into proteins, synthesizes phospholipids, and transports molecules to the Golgi apparatus for further modification:

(I recommend creating a table and filling in the pertinent information for each cell component.)

prokaryotic       chromosome              chromatin          Golgi apparatus

eukaryotic         nuclear envelope      rough ER            lysosome

organelle           nucleolus                    smooth ER         peroxisome

                                                                                      vacuole

chloroplast:      mitochondrion:

          granum              cristae                  

          stroma                matrix

        I will include an illustration of a plant and animal cell on the exam.  Can you label the various organelles?

        Plant cells and animal cells have important differences.  Remember that plant cells have these structures that are absent from animal cells:  cell wall, large central vacuole, and chloroplasts.

        Internally how do prokaryotic cells and eukaryotic cells differ?  One of the most important ways is the absence of a nucleus within prokaryotic cells.  In

what other ways do they differ?  Consider size in your answer.  Which group of organisms has prokaryotic cells?

        I mentioned four characteristics common to all cells (prokaryotic and eukaryotic).  What are these? (Hint -- One of these is the presence of a plasma membrane.)

        Remember that the cytoskeleton is composed of fibers called microfilaments and microtubules.  What are the functions of these fibers, and which is hollow and which solid?

        Remember that cilia and flagella are both surface structures found on some cells, and both have a 9 + 2 arrangement of microtubules.  What does this say about the arrangement of microtubules?  Which of the two structures (cilia or flagella) is smaller and more abundant on the cells on which they occur?

        Remember that plant cell walls are largely made of cellulose, and adjacent cells share molecules via plasmodesmata.  Animal cells lack a cell wall, and adjacent cells share molecules via cell junctions.  What are plasmodesmata?

Chapter 5:   The Working Cell

        Vocabulary (be familiar with the correct spelling and formal definition or explanation of each term):

kinetic energy                                    endergonic reaction

potential energy                                exergonic reaction

1st law of thermodynamics             metabolism

2nd law of thermodynamics

        What is the ultimate source of energy for nearly all life on Earth?

        Which releases and which stores energy, endergonic or exergonic reactions?  Which results in products that have more energy than the reactants?

        Remember that ATP is the cell's main energy currency and couples endergonic and exergonic reactions.  When ATP is broken down into ADP + Pi, is this an endergonic or exergonic reaction?  Which type of chemical reaction is the break down of ATP, hydrolysis or dehydration synthesis?  When small molecules combine to make large molecules, are these

endergonic or exergonic reactions?  In which organelle is most of a cell's ATP produced?  Remember that ATP is a nucleotide in which the atoms are covalently bonded.  Are the electrons shared or transferred between covalently bonded atoms?

        Be familiar with the more important traits of enzymes.  For instance, they are usually proteins, and they speed up the rate of chemical reactions by reducing the amount of activation energy required.  What other traits are common to enzymes?  How do temperature and pH affect enzyme activity?  What are cofactors?  What is an active site for any enzyme, and what is meant by induced fit? 

        One way to control the amount of substances produced in cells is to control the synthesis of enzymes.  Alternatively, it is possible to control the activity of enzymes.  Be familiar with these means of control:  competitive inhibition, noncompetitive inhibition, and negative feedback.  Which method uses the end product to control enzyme activity?

         Remember that all cell membranes are selectively permeable.  Cell membranes are made of phospholipids, containing hydrophilic (polar) heads (phosphate + glycerol) and hydrophobic (nonpolar) fatty acid tails.  Because of this certain molecules pass freely, others require some input of energy for passage, and others cannot pass at all.  Be familiar with the meanings of these terms as related to movement across cell membranes:

passive transport      hypertonic         facilitated diffusion   endocytosis

diffusion                      hypotonic          active transport         exocytosis

osmosis                       isotonic              phagocytosis              pinocytosis

In which direction is the net flow of water if the cell is 1) hypertonic, 2) hypotonic, or 3) isotonic with regard to the surrounding tissues?  Why is the fluid mosaic model a good concept for cell membranes?

 

Chapter 6:   How Cells Harvest Energy

        Remember that all organisms undergo cellular respiration.  What is the importance of cellular respiration?  It is to generate ATP from food, particularly glucose.  Some organisms undergo aerobic respiration, while others undergo anaerobic respiration.  How do these two types of cellular respiration differ with regard to the requirement for oxygen and the amount of ATP produced?  What is ATP used for?  Aerobic respiration yields much ATP.  However, most of the energy (~60%) of glucose cannot be harvested to yield ATP.  Why?  What happens to this energy?

        Can you memorize the summary equation for aerobic respiration?

Does aerobic respiration (breakdown of glucose) involve largely exergonic or endergonic reactions?  Is the breakdown of glucose a hydrolysis or dehydration synthesis reaction?  Is glucose oxidized or reduced as a result of cellular respiration? (Hint -- see the bulleted statement above)

        Know the difference between oxidation (LEO) and reduction (GER), and know that these reactions are always coupled.

        What are the three stages (e.g., glycolysis) in aerobic respiration, and in which region of the cell do the stages take place?  For each stage, know the net yield of ATP.  The production of ATP is not the most important event for either glycolysis or Krebs cycle.  What is the most important event?  During which stage of aerobic respiration is CO2 released?  What are substrate level phosphorylation and chemiosmotic coupling?  Which yields more ATP?

        Remember that fermentation is a type of anaerobic respiration, and glycolysis is the first stage.  What is the net yield of ATP?  Pyruvic acid is converted to ethanol during alcoholic fermentation, and it is converted to lactic acid during lactic acid fermentation.  Why is it important to convert pyruvic acid?  Which organisms produce the alcoholic beverages sold for human consumption?

        What is the most important source of energy storage in our bodies?  If someone consumes a high protein or high carbohydrate diet, will the diet indeed be fat free?