"Digestion and Absorption of Food" PPT (Lesson 3)

Description

"Digestion and Absorption of Food" PPT (Lesson 3)

Part One: Learning Objectives

1. Explain the chemical nature and functions of enzymes;

2. Outline the characteristics of high efficiency and specificity of enzyme catalysis;

3. Distinguish various experiments to verify the characteristics of enzymes.

Food digestion and absorption PPT, part 2: catalysis of enzymes

1. What is an enzyme?

Source: Living cells of organisms

Function: catalytic

Essence: Mostly protein

A type of protein with catalytic ability produced by living cells of an organism, also known as biocatalyst.

Such as: saliva - salivary amylase.

Gastric juice - pepsin.

Studying the Catalytic Function of Salivary Amylase

【Experiment preparation】

1. Prepare starch solution.

Weigh 1 gram of soluble starch, put it into a beaker, add 99 ml of distilled water, stir, slowly heat and dissolve to make a 1% starch solution.

2. Collect saliva.

Rinse your mouth with water, then put the tip of your tongue against the root of the maxillary or mandibular teeth, lower your head slightly, put the mouth of the test tube close to the lower lip, let the saliva flow into the test tube, collect about 2 ml, and dilute it with distilled water at a volume ratio of 1:1 saliva.

【Experimental results】

1. Saliva contains salivary amylase, which catalyzes the decomposition of starch.

2. Salivary amylase has no catalytic effect in acidic environment.

What other external factors affect the catalytic effect of enzymes?

2. Functional characteristics of enzymes

(1) The action of enzymes is highly efficient

The catalytic efficiency of enzymes is 107-1013 times that of inorganic catalysts.

(2) The action of enzymes is specific

An enzyme can only catalyze a certain type of chemical reaction.

For example, pepsin only catalyzes proteins.

(3) Enzyme catalysis is affected by external factors

Vulnerable to external factors such as temperature, pH, etc.

For example, enzymes in the human body are most active at a temperature of around 37°C.

Food Digestion and Absorption PPT, Part 3: Class Feedback

1. Enzymes are _______ produced by _______ and have _____ ability. Enzymes in the human body have the strongest catalytic ability when the temperature is _____.

2. Salivary amylase can only digest starch into maltose, which shows that the enzyme has ( )

A. Specificity B. Efficiency

C. Sensitivity D. None of them

3. The following are the main factors that affect enzyme activity ( )

A. Concentration, pH, pressure of reactants

B. Light, temperature, pH

C. Concentration, pH, temperature of reactants

D. pressure, temperature, concentration of reactants

Keywords: Zhejiang Education Edition ninth grade science PPT courseware free download, food digestion and absorption PPT download, .PPT format;

For more information about the "Digestion and Absorption of Food" PPT courseware, please click the "Digestion and Absorption of Food" ppt tab.

"Digestion and Absorption of Food" PPT courseware:

"Digestion and Absorption of Food" PPT Courseware Part One: Digestive System Composition of the Digestive System The human digestive system consists of a digestive tract and some digestive glands that secrete digestive juices. ... ... ... Food Digestion and Absorption PPT, Part 2...

"Digestion and Absorption of Food" PPT (second lesson):

"Digestion and Absorption of Food" PPT (Second Lesson) Part One: Reviewing the Past and Learning the New 1. What does the digestive system consist of? 2. What are the composition and types of teeth? 3. What are the causes of dental caries? What's the harm? Learning Objectives 1. Name protein,...

"Digestion and Absorption of Food" PPT (first lesson):

"Digestion and Absorption of Food" PPT (first lesson) Part One: Situation Introduction 1. Why are people with chronic gastrointestinal diseases thinner? 2. Why do some people eat a lot but never gain weight? Nutrients in food: water, inorganic salts, vitamins...

File Info

Update Time: 2024-07-04

This template belongs to science courseware Zhejiang Education Edition Ninth Grade Science Volume 1 industry PPT template

Preview