As food travels through the digestive system it is exposed to a variety of ph levels

Presentation on theme: "As food travels through the digestive system, it is exposed to a variety of pH levels. The stomach has a pH of 2 due to the presence of hydrochloric acid."— Presentation transcript:

1 As food travels through the digestive system, it is exposed to a variety of pH levels. The stomach has a pH of 2 due to the presence of hydrochloric acid (HCl), and the small intestine has a pH ranging from 7 to 9. HCl converts pepsinogen into pepsin, an enzyme that digests proteins in the stomach. Which of the following most likely happens to pepsin as it enters the small intestine? A. It becomes inactive. B. It begins to replicate. C. Its shape changes to engulf large proteins. D. Its activity increases to digest more proteins.

2 Interactive Journal Entry “Enzymes SC.912.L.18.11”
Left Side Right Side Concept Map Guided Notes (Note: when copying reduce size to 67% to fit in composition books; students can staple/tape it in landscape format) Enzyme Graphical Analysis Questions

3 Enzymes Slides 3-7 can be gone through very quickly (overview). Slides 8-12 should cover the first portion of the benchmark – do a “check for understanding” at slide 12. Slides should cover the second part of the benchmark. SC.912.L Explain the role of enzymes as catalysts. Identify factors, such as pH and temperature, and their effect on enzyme activity.

4 Introduction on Enzymes
Enzymes have extremely interesting properties that make them little chemical-reaction machines.

5 Introduction on Enzymes
The purpose of an enzyme in a cell is to allow the cell to carry out chemical reactions very quickly.

6 Introduction on Enzymes
These reactions allow the cell to build things or take things apart as needed. This is how a cell grows and reproduces.

7 Introduction on Enzymes
At the most basic level, a cell is really a little bag full of chemical reactions that are made possible by enzymes!

8 Enzymes Serves as a catalyst (speeds up rate of chemical reactions).

9 Enzymes – What are they made of?
A protein molecule; Review - What is the monomer of a protein? Reduce the amount of activation energy needed in a chemical reaction. Enzymes – How do they work?

10 Chemical Reaction with an Enzyme

11 Why are Enzymes Important?
The purpose of an enzyme in a cell is to 1) allow the cell to carry out chemical reactions very quickly. These chemical reactions allow 2) the cell to build things or take things apart as needed. This is how 3) a cell grows and reproduces. At the most basic level, a cell is really a little bag full of chemical reactions that are made possible by enzymes!

12 Enzymes SC.912.L Explain the role of enzymes as catalysts. Identify factors, such as pH and temperature, and their effect on enzyme activity. You should now be able to explain the role of enzymes as catalysts

13 Enzymes SC.912.L Explain the role of enzymes as catalysts. Identify factors, such as pH and temperature, and their effect on enzyme activity.

14 What affects enzyme activity?
The environment it is in: Temperature Too hot and it will cook the protein. Too cold and it will freeze the protein. It will denature the structure of the protein and the enzyme will no longer be able to catalyze a reaction. pH Too acidic or basic and it will denature the structure of the protein and the enzyme will no longer be able to catalyze a reaction.

15 What affects enzyme activity?
- Concentration Increasing the concentration of enzymes increases the rate of reaction because of an increased rate of interactions with substrate molecules. Why does the rate of reaction flatten out an not continue getting higher?

16 As food travels through the digestive system, it is exposed to a variety of pH levels. The stomach has a pH of 2 due to the presence of hydrochloric acid (HCl), and the small intestine has a pH ranging from 7 to 9. HCl converts pepsinogen into pepsin, an enzyme that digests proteins in the stomach. Which of the following most likely happens to pepsin as it enters the small intestine? A. It becomes inactive. B. It begins to replicate. C. Its shape changes to engulf large proteins. D. Its activity increases to digest more proteins. Give students a chance to change their answer – the next slide will show the answer. Engage in a “Why?” conversation.

17 As food travels through the digestive system, it is exposed to a variety of pH levels. The stomach has a pH of 2 due to the presence of hydrochloric acid (HCl), and the small intestine has a pH ranging from 7 to 9. HCl converts pepsinogen into pepsin, an enzyme that digests proteins in the stomach. Which of the following most likely happens to pepsin as it enters the small intestine? A. It becomes inactive. Why? B. It begins to replicate. C. Its shape changes to engulf large proteins. D. Its activity increases to digest more proteins.

18 You Do Questions The following questions can be projected when an instructor reaches the “You Do” or an instructor can use the handout.

19 A. Enzymes aid in oxygen acquisition for respiration.
Many factors can affect the rate of reaction in which an enzyme can catalyze. Enzyme X is placed in an environment at an optimal pH and temperature. This optimal area is marked by point A in the graph below. Which of the following actions would alter the rate of Enzyme X from point A to point B? A. Increase the pH B. Increase the temperature C. Increase the concentration of enzyme D. Increase the concentration of activation energy Enzymes are critical macromolecules which are needed by all life forms. In what way are enzymes necessary to maintain homeostasis within the cell? A. Enzymes aid in oxygen acquisition for respiration. B. Enzymes aid in carbon dioxide and toxin release during respiration. C. The vital chemical reactions take up too much space in the cell if enzymes are not present. D. The vital chemical reactions are too slow to meet the needs of the cell if enzymes are not present. These questions can be projected, or the handout can be given.

20 Measured amount of glucose
Many people worldwide eat beans as a source of cheap protein, but they are also a complex gassy carbohydrate. An experiment was conducted to determine the conditions in which “Beano” – an enzyme which metabolizes gassy carbohydrate molecules into glucose – works best. In the experiment, refried beans, water, and one Beano tablet were all placed in three separate test tubes. The test tubes were placed in different environmental conditions. After 10 minutes, strips were placed in the test tube and the amount of glucose was measured. The table below shows the results of the experiments. Contents of Test Tube Environmental Change Measured amount of glucose Test Tube #1 5 mL Refried Beans, 5 mL of Water and 1 Beano tablet 42.0 degrees Fahrenheit 0.30 ug/ mL Test Tube #2 78.0 degrees Fahrenheit 0.55 ug/mL Test Tube #3 120.0 degrees Fahrenheit 0.09 ug/mL Which response best predicts how much glucose you would expect to find if you conducted this experiment at 98.0 degrees Fahrenheit, the enzyme’s optimum temperature? Between 0.09 ug/mL and 0.55 ug/mL of glucose Between 0.30 ug/ mL and 0.55 ug/ mL of glucose More than 0.55 ug/mL of glucose because Beano works best at body temperature. Less than 0.09 ug/mL of glucose because Beano does not optimally work at body temperature.

What substance gives the stomach its pH of 1 2?

When the pH or temperature is changed an enzyme becomes denatured by changing the?

What happens to the activity of pepsin when it enters the small intestine where the pH is 8?

What will happen to the reaction rate if the appropriate enzyme is added to a chemical reaction?