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BIO304: Human Physiology

Unit 3: Enzymes, Cellular Respiration, and Cellular Metabolism   Protein enzymes play a significant role in catalyzing (speeding up the rate of) chemical reactions in our body. Protein enzymes are important facilitators in all cellular metabolic processes from digestion to respiration to growth. Enzymes require strict environmental conditions, including pH and temperature requirements and become non-functional or even destroyed if these needs are not met. It is interesting to note that although enzymes bring substances (substrates) together to have a reaction, the enzymes themselves are not changed in this reaction. It is imperative that you understand how enzymes work, because we will see them in all body systems that we cover in this course.

Unit 3 Time Advisory
This unit should take approximately 4.75 hours to complete.

☐    Subunit 3.1: 1.75 hours

☐    Subunit 3.2: 1.5 hours

☐    Subunit 3.3: 1.5 hours

Unit3 Learning Outcomes
Upon successful completion of this unit, the student will be able to: - describe the structure and functions of enzymes; - identify the factors that modulate enzyme activity; - describe the stages of cellular respiration; and - describe the metabolism of biomolecules.

3.1 Enzymes   - Reading: Wikibooks’ Structural Biochemistry: “Enzymes – Overview” Link: Wikibooks’ Structural Biochemistry: “Enzymes – Overview” (HTML)

 Instructions: Click on the link above, read the introductory text,
and click on the table of contents to access and read the “Lock and
Key Model” and “Induced Fit” sections for an introduction to enzymes
and enzymatic action. All cells in the body use enzymes to speed up
the rate of reactions. As you can imagine, we cannot live without
them!  

 Reading these sections should take approximately 30 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Reading: Wikibooks’ Structural Biochemistry: “Active Site” Link: Wikibooks’ Structural Biochemistry: “Active Site” (HTML)

    Instructions: Click on the link above, and read the “Overview” and “Enzyme Inhibitors” sections to learn how enzymatic reactions can be inhibited. It is as important that actions in the body can be stopped as it is that they can start in the first place. Otherwise, control might be lost, and then homeostasis might be lost. This reading will show you how enzyme activity is controlled.

    Reading these sections should take approximately 1 hour.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: YouTube: Neurocirujo’s “Cellular Metabolism, Pathways, and Feedback” Link: YouTube: Neurocirujo’s “Cellular Metabolism, Pathways, and Feedback” (YouTube)

    Instructions: Click on the link above and watch this brief YouTube video about enzyme feedback inhibition through a negative feedback loop. Remember that homeostasis is regulated, in part, by positive and negative feedback loops. As you might imagine, enzyme activity is important for regulating and maintaining homeostasis.

    Watching this video and pausing to take notes should take approximately 5 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

3.2 Cellular Respiration: Glycolysis, Krebs Cycle, and Electron Transport Chain   - Web Media: YouTube: Khan Academy’s “Introduction to Cellular Respiration” Link: YouTube: Khan Academy’s “Introduction to Cellular Respiration” (YouTube)

 Instructions: Click on the link above and watch this video to learn
about cellular respiration, which is the process by which the cell
extracts energy from glucose. This is a very complex process, but
the lecturer does a good job of breaking it down into manageable
segments. Cells within the body use this process to convert
carbohydrate glucose into usable nucleic acid ATP energy. Cellular
Respiration is also described in greater detail in [BIO101A:
Introduction to Molecular and Cellular
Biology](http://www.saylor.org/courses/bio101a/) in “Unit 6:
Cellular Energy.”  

 Watching this video and pausing to take notes should take
approximately 30 minutes.  

 Terms of Use: This video is licensed under a [Creative Commons
Attribution-NonCommercial-NoDerives United States License 3.0](). It
is attributed to the Khan Academy. 
  • Assessment: McGraw Hill Online Learning Center: Stuart Ira Fox’s “Cell Respiration and Metabolism Quiz: Fill in the Blank” Link: McGraw Hill Online Learning Center: Stuart Ira Fox’s “Cell Respiration and Metabolism Quiz: Fill in the Blank” (HTML)

    Instructions: Complete the above quiz and then click the “Submit Answers” button at the bottom of the page for instant grading and feedback. Some of these questions require you to recall what you learned in BIO101A. For any questions that you get incorrect, go back and review the material in the “Unit 6: Cellular Respiration” of BIO101A.

    Completing this assessment should take approximately 1 hour.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

3.3 Cellular Metabolism: Carbohydrates, Proteins, and Fats   - Reading: Wikibooks’ Structural Biochemistry: “Metabolism” Link: Wikibooks’ Structural Biochemistry: “Metabolism” (HTML)

 Instructions: Click on the link above and read the entire webpage,
which will provide you with an overview of the metabolic processes
of an organism. Metabolism includes anabolism (putting things
together) and catabolism (breaking things apart). Catabolism often
provides energy to drive other activities in the body, whereas
anabolism often requires energy. Without metabolism, cells in the
body would not have energy and would eventually die.  

 Reading this webpage should take approximately 1 hour and 30
minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.