cell transport
DESCRIPTION
To study Biology.TRANSCRIPT
BIOLOGYCONCEPTS & CONNECTIONS
Fourth Edition
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
From PowerPoint® Lectures for Biology: Concepts & Connections
CHAPTER 5The Working Cell
Modules 5.1 – 5.4
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Fireflies use light, instead of chemical signals, to send signals to potential mates
• Females can also use light flashes to attract males of other firefly species — as meals, not mates
Cool “Fires” Attract Mates and Meals
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The light comes from a set of chemical reactions, the luciferin-luciferase system• Fireflies make light energy from chemical energy
• Life is dependent on energy conversions
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Living cells are compartmentalized by membranes
• Membranes are sites where chemical reactions can occur in an orderly manner
• Living cells process energy by means of enzyme-controlled chemical reactions
ENERGY AND THE CELL
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Energy is defined as the capacity to do work
• All organisms require energy to stay alive
• Energy makes change possible
5.1 Energy is the capacity to perform work
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Kinetic energy is energy that is actually doing work
• Potential energy is stored energy
Figure 5.1A
Figure 5.1B
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• First law of thermodynamics
• Energy can be changed from one form to another
– However, energy cannot be created or destroyed
5.2 Two laws govern energy conversion
Figure 5.2A
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• Second law of thermodynamics
• Energy changes are not 100% efficient
– Energy conversions increase disorder, or entropy
– Some energy is always lost as heat
Figure 5.2B
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• Cells carry out thousands of chemical reactions
– The sum of these reactions constitutes cellular metabolism
5.3 Chemical reactions either store or release energy
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• There are two types of chemical reactions:– Endergonic reactions absorb energy and
yield products rich in potential energy
Figure 5.3A
Reactants
Po
ten
tia
l en
erg
y o
f m
ole
cule
s Products
Amount of energy INPUT
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
– Exergonic reactions release energy and yield products that contain less potential energy than their reactants
Figure 5.3B
Reactants
Po
ten
tia
l en
erg
y o
f m
ole
cule
s
Products
Amount of energy OUTPUT
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• In cellular respiration, some energy is stored in ATP molecules
• ATP powers nearly all forms of cellular work
• ATP molecules are the key to energy coupling
5.4 ATP shuttles chemical energy within the cell
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• When the bond joining a phosphate group to the rest of an ATP molecule is broken by hydrolysis, the reaction supplies energy for cellular work
Figure 5.4A
Phosphategroups
Adenine
Ribose
Adenosine triphosphate
Hydrolysis
Adenosine diphosphate(ADP)
Energy
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• How ATP powers cellular work
Figure 5.4B
Reactants
Po
ten
tia
l en
erg
y o
f m
ole
cule
s
Products
Protein Work
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
• The ATP cycle
Figure 5.4C
Energy from exergonic reactions
Deh
yd
rati
on
syn
thes
is
Hyd
roly
sis
Energy for endergonic reactions