Nas Enzymes Lesson 2

Lesson ReviewDefinition of Enzymes

Properties of Enzymes

• Speeds up chemical reaction• Required in small amounts• Highly specific in action• Work best at their optimum temperature and pH• May need co-enzymes for activity

1. Review Enzyme Definition & Enzyme Action

3. Factors affecting Enzyme Activity

Lesson Objectives

2. Properties of Enzymes

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1. Review Enzyme Definition & Enzyme Action


Lesson Objectives


Definition of Enzymes

Enzymes are biological catalysts that alters/speed up the rate of a chemical reaction and remains chemically unchanged at the end of reaction.

Definition of Enzymes

Enzymes are biological catalysts that alters/speed up the rate of a chemical reaction and remains chemically unchanged at the end of reaction.

^

made of proteins

Enzyme in action

+Active sites

Substrates Enzyme+ Enzyme-substrate complex

products

1. Review Enzyme Definition


Lesson Objectives




Lesson Objectives


Properties of an enzyme

• Speeds up chemical reaction• Required in small amounts• Highly specific in action• Work best at their optimum temperature

and pH• May need co-enzymes for activity



and pH• May need co-enzymes for activity

Enzymes are Highly Specific In Action

• Each chemical reaction in a cell is catalyzed by unique enzyme(s).

Sucrose SucraseLipid Lipase

Why are enzymes highly specific in action?

We explain enzyme specificity via the Lock & Key Hypothesis

Lock & Key Hypothesis• Presence of Active sites (depressions)• Substrates fit into active site of enzyme• Enzyme = lock; Substrate = key• shape of substrate complementary to

shape of enzyme.



(practical) and pH• May need co-enzymes for activity (FYIO)

Both properties and factors affecting enzymes



Lesson Objectives




Lesson Objectives


What are the factors affecting enzyme activity?

Factors Affecting Enzyme Activity

• Temperature• pH• Enzyme Concentration• Substrate Concentration• Inhibitors (FYIO)

How is enzyme activity affected by temperature?

• http://www.kscience.co.uk/animations/model.swf

http://www.kscience.co.uk/animations/model.swf




How is enzyme activity affected by pH?

How is enzyme activity affected by pH?

• http://www.kscience.co.uk/animations/model.swf





Toothpickase activity

Directions:1. Get into pairs.2. Each pair will receive 70 toothpicks and a

stopwatch. 3. Use 35 toothpicks for part I and 35 toothpicks

for part II.4. 1 person will be the ‘breaker’ the other the

timer. 5. Do only pg 1 & 2 in class…

What can you deduce from the ‘Toothpickase’ activity?

If enzyme concentration increases, number of products form increases.

Questions to think about

1. What if you only had 10 toothpicks for the activity?

2. What happens to the rate of enzymatic reactions at very cold and very high temperatures?

3. What are some of the properties of the enzymes that are found in the human stomach?

Enzyme definition

Summary

Enzymes are biological catalysts made of protein that alters/speed up the rate of a chemical reaction and

remains chemically unchanged at the end of reaction. Properties of EnzymesSpeeds up Small/minute amountsHighly specific in actionWork best at their optimum temperature and pHMay need co-enzymes for activity

Factors affecting Enzyme Activity -Temperature - pH - Substrate Concentration - Enzyme Concentration

Homework

1. Complete ‘Toothpickase’ WS2. 3. Do workbook Ex 3.2 ‘Enzymes’ pg 29-32 by

tomorrow (fri 12th Mar 10). 3. Explore ‘Factors affecting enzyme rate of

reaction’ website http://www.kscience.co.uk/animations/model.swf

4. Read up textbook pg 77-85 to prepare for short quiz next lesson to prepare for quiz when school re-opens.


Next Lesson

Tips for experiment on“Effects of temperature on amylase (enzyme) activity”

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Nas Enzymes Lesson 2