Chapter 7 Lecture Outline - Scf

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Oct 27, 2013 (3 years and 1 month ago)

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Energy and Enzymes

Chapter 7

Lecture Outline

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

2

Energy in Living Systems


Metabolism is the sum of all chemical
reactions in the body.


Metabolism transfers energy and follows
the laws of thermodynamics.

Laws of Thermodynamics


1
st

Law: Energy
cannot be either
created or destroyed


2
nd

Law: When
reactions occur, they
become more
disordered

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

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© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

4

The Carbon Cycle and Energy


Living organisms all require energy

to survive


Sun is source of most energy on Earth


Light energy is used by producers

to synthesize sugars


Plants performing photosynthesis

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© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

6


For non
-
photosynthesizing organisms
(mostly consumers), energy is acquired
from food molecules.


Carbon dioxide and food molecules are
involved in this energy transfer.

The Carbon Cycle and Energy

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

7

The Carbon Cycle

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

8

Using Energy from Food


Energy transfer in nonliving systems can be
explosive:



Carbon in wood + O
2


CO
2

+ H
2
O + energy




Energy transfer in cells must be controlled:




Carbon in food + O
2


CO
2

+ H
2
O + energy

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

9

Transfer of Electrons


Capturing energy requires transfer

of electrons


Reactions that transfer electrons are
called redox (oxidation/reduction)
reactions



Oxidation

loss of electrons



Reduction

gain of electrons

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© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

12

Metabolism


All chemical reactions within living cells


Anabolic


Biosynthetic: create complex molecules out of
smaller compounds


Catabolic


Break down

complex molecules

to release energy

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© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

14

Chemical reactions and
thermodynamics


A + B


C + D


Reactants: A + B


Products: C + D


Some chemical
reactions need a “jump
start” to proceed


Activation energy:


Energy needed to
jump
-
start a reaction

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© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

16

Enzymes Speed Up Reactions


Enzymes are biological catalysts


Lower the energy of activation


Increase the speed of reaction

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© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

18

The Structure of Enzymes


Very specific for reactions


Three
-
dimensional shape determines
function


Active site is region where the substrate
binds


Induced fit: active site molds around
substrate

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

19

Enzymes as Molecular Matchmakers

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

20

Enzymes in Metabolism


Metabolic pathways in the body usually
involve several reactions.


There may be several intermediates.


Each intermediate has its own enzyme.

B

A

C

D

Enzyme 1

Enzyme 2

Enzyme 3

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

21

Enzyme Function


Enzymes depend on
random collisions.


Multiple enzymes

may be located close
together.


This maximizes
molecular collisions.

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© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

23

Metabolism and Life Span


Slowing down metabolism increases life span


Higher metabolism results in toxic by products
(free radicals)


Antioxidants help break down free radicals


Some examples of antioxidants


Vitamin E


Vitamin C


Beta
-
carotene

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© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

26

Concept Quiz

Why are high fevers dangerous and

sometimes life
-
threatening?


A.
Molecules move faster at higher temperatures.

B.
Enzymes may change shape at high
temperatures.

C.
Invading microbes survive better and
reproduce faster at high temperatures.

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

27

Concept Quiz

The loss of electrons is called

A.
Oxidation

B.
Reduction

C.
Redox

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

28

Concept Quiz

Where a substrate binds to an enzyme is
known as the

A.
Active site

B.
Activation energy

C.
Energy transfer site

Biology in the News

Doctors Warned about Common Drugs
for Pain; NSAIDs Tied to Risk of Heart
Attack, Stroke


NSAIDs: Non
-
steroid anti
-
inflammatory drugs


Two major categories


COX
-
1 inhibitors


May result in stomach problems


COX
-
2 inhibitors


Long
-
term use associated with heart disease


Removed from the market

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

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Terms

Activation energy

Active site

Anabolic reaction

Biosynthetic reaction

Catabolic reaction

Catalyst

Coupled reaction

Enzyme

First law of
thermodynamics

Induced fit model

Kinetic energy

Metabolic pathway

Metabolism

Oxidation

Potential energy

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

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Terms

Products

Redox reaction

Reactants

Reduction

Second law of
thermodynamics

Substrate

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

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© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

32

Process Animation 7.1a

The Energy of Chemical
Reactions






Macintosh


Windows

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

33

Process Animation 7.1b

Heat and Chemical Reactions






Macintosh


Windows

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

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Process Animation 7.1c

Enzyme Catalysis






Macintosh


Windows

© 2009 W.W. Norton & Company, Inc.
DISCOVER BIOLOGY 4/e

35

Process Animation 7.1d

Enzymes and Activation Energy






Macintosh


Windows

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Discover Biology StudySpace

http://www.wwnorton.com/college/biology/discoverbio4

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Additional Art from Chapter 7

All art files from the book are available
in JPEG and PPT formats on the
Instructor Resource Disc

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