1. Lab 12 Digestive System Enzymes:
Biology 102
Lab 12 Digestive System Enzymes:
Activity, Purpose, and Optimal Conditions
100 min, 52 slides

2. Objectives for Today
Become more familiar with some of the enzymes used for chemical digestion
For each enzyme used in today’s experiment, you should know:
Their major action, i.e., the type(s) of substrates on which they act
Their primary site of action in the body
The optimal pH at which they work
Additional factors, if any, they need to work efficiently

3. Enzymes and Metabolic Reactions
Enzymes are Biological catalysts
control rates of metabolic reactions
lower activation energy needed to start reactions
globular proteins with specific shapes
not consumed in chemical reactions
*substrate specific
shape of active site (3D) determines which substrate(s) the enzyme can act on
Figure From: Marieb & Hoehn, Human Anatomy & Physiology, 9th ed., Pearson
Enzymes work optimally under specific conditions of temperature and pH

4. Enzymes as Proteins – 3D Structure
Specific folding and bending of a polypeptide or protein.
**It is the 3-D structure of a protein that allows it to perform its specific function.
Secondary structure
Secondary structure
Figure from: Hole’s Human A&P, 12th edition, 2010
What would happen if an enzyme is exposed to extreme heat? pH?

5. Enzymes used in today’s experiment
1. Salivary amylase
Starch (polysaccharide) → Maltose (disaccharide)
Salivary glands
What do you predict is its optimum temp/pH?
How would we know if this reaction has occurred?
IKI – Potassium Iodide
Benedict’s Reagent
What is an experimental control? What kinds of controls are there?

6. Enzymes used in today’s experiment
2. Pepsin
Proteins → Peptides, amino acids
Where is pepsin active in the body? What does it do?
What do you predict is its optimum temp/pH?
How would we know if this reaction has occurred?
BAPNA - Nα-Benzoyl-DL-arginine 4-nitroanilide hydrochloride
(the amino acid, arginine)
Causes solution to turn yellow when cleaved from BAPA by a peptidase
Yellow dye produced by the reaction changes the solution’s optical density; this can be measured by a spectrophotometer. Colorless solutions have an optical density of zero.

7. Enzymes used in today’s experiment
3. Lipase
Triglycerides → Monoglyceride + 2 Fatty acids
Where do lipases come from in the body?
What do you predict is their optimum temp/pH?
Is there anything else lipases need to function efficiently in the body, e.g., in the intestine?
How would we know if this reaction has occurred?
Example of using phenol red as a pH change indicator
Is there anything else we can use in the lab to detect pH changes?
Acidic
(below 6.8)
Basic
(above 8.2)

8. Using PhysioEx 9.1
PhysioEX 9.1 is current

9. Using PhysioEx 9.1
Note: PhysioEx 9.1 is most current version

10. Using PhysioEx 9.1

11. Using PhysioEx 9.1

12. Using PhysioEx 9.1

13. Using PhysioEx 9.1

14. Using PhysioEx 9.1

15. Using PhysioEx 9.1
Note: Save this to the desktop and name the file: Lab12_<Day>_Group<#>.pdf
me the file and be sure to one to yourself and the other members of your group if you want a copy for studying.
Put the names of your group members in the subject line of the followed by ‘Lab 12’.

16. What You Should Do in Lab Today…
Using the DVD version or online version of the software, access PhysioEx 9.1 in Mastering A&P and do Exercise 8:
Salivary amylase (Activities 1 and 2)
Pepsin (Activity 3)
Lipase (Activity 4)
For each experiment,
Be sure to do the pretest
Answer the ‘Prediction’ questions as you go
Generate a PDF file to submit as your lab report (so, you will be submitting 4 PDF files)
Also submit a Summary Table Lab Report (hard copy) from your group.

17. For next lab… Gross/microscopic anatomy of the urinary system
Human models
Cats
Gross anatomy of the reproductive system
Human models (no, not live ones!)

18. Amylase activity on Starch

19. Amylase activity on cellulose

20. Pepsin activity on BAPNA (protein)

21. Lipase activity on triglycerides

22. Review of Subjects for Lab Exam 2
Lab Exam 1 will consist of 25 stations and 52 fill-in-the-blank questions. (plus bonus questions)  You will be expected to be able to recognize all structures listed in your Laboratory Guide and know the items listed on this study guide.
Remember that SPLLEING COUTNS!!  You will lose 1 point for every 2 spelling errors you make.
For help in studying the following items and getting practice, be sure to look at the following items in the Laboratory Section of the gserianne.com Web site
1. The online PowerPoint Quizzes and 'Links to Explore' (if available)
2. Mastering A&P Web site (PAL, PhysioEx)

23. Review of Subjects for Lab Exam 2
Respiratory System (Labs 9 and 10) – 14 questions
Be able to calculate minute volume given tidal volume and breathing rate
Define respiratory volumes and capacities in words and relate the numeric formulas to their definitions.
Solve for vital capacity, inspiratory capacity, functional residual capacity, using known (given) volumes and/or capacities.
Define tidal volume and recall the normal, average tidal volume in adults (if it's not given to you).
Name and correctly spell the equipment used to assess lung volumes and capacities.
Predict the effect of blood CO2 levels and various experimental conditions on breathing.
Recognize the anatomical structures listed in your study guide on the human models/photographs and in the dissected cat (larynx, trachea, L/R bronchi, R/L lung, and diaphragm - and the thyroid gland)
Identify microscopically, in photomicrographs: a) the type of epithelium lining the respiratory tract b) mucus glands/goblet cells and c) respiratory cilia