BIOLOGY SEMESTER ONE
UNIT 8
Checklist unit 8:An introduction to Metabolism and Cellular Respiration
In this module you will explore how an organism transforms matter and energy to perform cellular work. The collection of chemical reactions that occur within an organism is referred to as metabolism, and includes catabolic (breaking down molecules, releasing energy) and anabolic (building molecules, absorbing energy) reactions. These reactions are often aided by enzymes.
All energy transformation within biological systems follows the laws of physics. Spontaneous, or exergonic, reactions are those that require no energy input, while those that require additional energy are non-spontaneous or endergonic. The additional energy for non-spontaneous reactions in cellular metabolism comes from the hydrolysis, or breakdown, of ATP (adenosine triphosphate) to ADP (adenosine diphosphate).
Enzymes significantly increase reaction time by lowering the amount of extra energy a reaction may require to proceed. Enzymes are substrate-specific: when bound to their specific reactant, their shape changes slightly. Some catalyze reactions by aiding in the orientation of reactants. Each enzyme has optimal conditions for reaction (pH and temperature) and may be repressed by unfavourable conditions or other inhibitor molecules.
Learning objectives
At the end of this module you should be able to:
- Explain the role of catabolic and anabolic pathways in cellular metabolism.
- Distinguish between kinetic and potential energy.
- Distinguish between an isolated and an open system. Explain why an organism is considered an open system.
- Explain the first and second laws of thermodynamics, and explain why highly ordered living organisms do not violate the second law of thermodynamics.
- Distinguish between exergonic and endergonic reactions in terms of free energy change.
- Explain why metabolic disequilibrium is one of the defining features of life.
- List the three main kinds of cellular work. Explain in general terms how cells obtain the energy to do cellular work.
- Describe the structure of ATP, and explain how ATP performs cellular work.
- Describe the function of enzymes in biological systems, and describemechanisms by which enzymes lower activation energy.
- Explain how substrate concentration affects the rate of an enzyme-catalyzed reaction, and how temperature, pH, cofactors, and enzyme inhibitors can affect enzyme activity.
Check List
Read Chapter 8: An Introduction to Metabolismof Campbell and Reece’s Biology, 9th Ed.
As you are reading, address each of the learning objectives listed above.
It is recommended that you make flash cards for the terminology list provided. This will be beneficial for studying for the midterm and final exams later in the semester.
You may be able to review the PowerPoint Lecture and other resources for this unit. Refer to your instructor’s notes for more details.
For extra practice try the Self Quiz or Practice Test on the Mastering Biology Website. To log onto the website, use the access code provided in your textbook. You will also find other resources, such as downloadable MP3 tutorials for each chapter, a glossary, and an electronic copy of your text—you can catch up on your reading anywhere!
Key Terms
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BIOLOGY SEMESTER ONE
UNIT 8
activation energy
active site
adenosine triphosphate (ATP)
allosteric regulation
anabolic pathway
bioenergetics
catabolic pathway
catalyst
chemical energy
coenzyme
cofactor
competitive inhibitor
cooperativity
endergonic reaction
energy
energy coupling
entropy
enzyme
enzyme-substrate complex
exergonic reaction
feedback inhibition
first law of thermodynamics
free energy
heat
hemoglobin
induced fit
kinetic energy
metabolic pathway
metabolism
noncompetitive inhibitor
order
phosphorylated
potential energy
ribose
second law of thermodynamics
substrate
thermal energy
thermodynamics
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BIOLOGY SEMESTER ONE
UNIT 8
Root Words to Know
allo- = different (allosteric site: a specific receptor site on some part of an enzyme molecule remote from the active site)
ana- = up (anabolic pathway: a metabolic pathway that consumes energy to build complex molecules from simpler ones)
bio-= life (bioenergetics: the study of how organisms manage their energy resources)
cata- = down (catabolic pathway: a metabolic pathway that releases energy by breaking down complex molecules into simpler ones)
endo- = within (endergonic reaction: a reaction that absorbs free energy from its surroundings)
ex- = out (exergonic reaction: a reaction that proceeds with a net release of free energy)
kinet- = movement (kinetic energy: the energy of motion)
therm- = heat (thermodynamics: the study of the energy transformations that occur in a collection of matter)
sources
Campbell, N. A. (2008). Biology, Eighth Edition. San Francisco: Pearson, Benjamin Cummings.
Krogh, D. (2000). Biology, A Guide to the Natural World. Upper Saddle River: Prentice Hall.
Pearson Education. (2010). Retrieved 2010, from Mastering Biology :
NANSLO Biology Core Units and Laboratory Experiments
by the North American Network of Science Labs Online,
a collaboration between WICHE, CCCS, and BCcampus
is licensed under a Creative Commons Attribution 3.0UnportedLicense;
based on a work at rwsl.nic.bc.ca.
Funded by a grant from EDUCAUSEthrough the Next Generation Learning Challenges.
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