|
|
Lecture Learning Tools Hub |
MAIN TOPICS OUTLINE
5.1 ENERGY
5.11 Forms of Energy
5.11.1. Kinetic Energy
5.11.2. Potential Energy
5.12 The Laws of Thermodynamics
5.12.1. First Law of Thermodynamics
5.12.2. Second Law of Thermodynamics
5.2. METABOLIC REACTIONS AND PATHWAYS
5.21 Spontaneous vs. Non-spontaneous reactions
5.22 Major metabolic energy-transforming pathways
5.22.1. Cellular Respiration
5.22.2. Photosynthesis
5.3 ENZYMES
5.31 Enzyme Basics
5.32 Effects of the Chemical and Physical Environment on Enzymes
5.32.1. Effects of Environmental Conditions
5.32.2. Effects of Cofactors
5.32.3. Effects of Enzyme Inhibitors
5.4 ATP
5.41 Cellular Work
5.42 Source of energy for cellular work
5.43 The ATP Cycle
LECTURE OBJECTIVES:
1. Recognize that two laws of thermodynamics guide the nature of energy transformations.
2. Compare the energy transformations / reactions involved in photosynthesis and cellular respiration, showing how these processes are related.
3. Distinguish between exergonic vs. endergonic reactions.
4. Explain the need for enzymes in the maintenance of living things, and describe what happens when an enzyme and substrate combine (recognize that enzymes catalyze biological reactions by lowering the energy of activation needed to break/form chemical bonds).
5. Explain the role of cofactors (e.g., vitamins) in enzyme operation.
6. Describe the effects of enzyme inhibitors and [other] environmental factors, such as temperature, pH and salt, on enzymes.
7. Describe how ATP functions as a universal energy shuttle, carrying energy in usable chunks from large storage molecules to places in cells where work needs to be done.
8. Define selected key terms
Key Terms
def. Active site The specific portion of an enzyme that attaches to the substrate with weak chemical bonds.
def. ATP (Adenosine Triphosphate): An adenine containing molecule with triphosphate chain that releases energy when its phosphate bond is broken.
def. Catalyst: Chemicals that change the rate of a reaction without being consumed by the reaction.
def. Cellular Respiration: The transformation of chemical bond energy from food ("glucose"), into usable form that occurs in all living cells ("glucose" broken down to release energy (ATP) required for life processes).
def. Coenzyme An organic molecule serving as a cofactor, often a vitamin.
def. Cofactor A chemical required for the proper functioning of an enzyme.
def. Endergonic: A non-spontaneous chemical reaction in which energy is absorbed from the surrounding, so that the reaction is showing a net gain in energy, e.g., photosynthesis.
(all reactions of this type requires an input of energy)
def. Energy: the capacity to do work
def. Exergonic: A spontaneous chemical reaction in which energy is released to the surrounding, so that the reaction is showing a net loss in energy, e.g., cellular respiration (products have less energy because we have used some to perform work)
def. Enzyme A class of proteins serving as catalysts.
def. Kinetic Energy: Energy of motion, including heat (molecular movement) and light (wave movement).
def. Potential Energy: Energy stored in some form, chemical form (e.g., gasoline) or physical form (on top of a hill).
def. First law of thermodynamics: Energy is never created nor destroyed.
def. Photosynthesis: The conversion of light energy to chemical energy (stored in the glucose produced by the chemical reaction) from carbon dioxide and water.
def. Second law of thermodynamics: Every energy transfer or transformation increases the entropy of the universe, and at least some form of energy is lost (not destroyed) by being converted to heat (the least ordered form of energy).
def. Substrate The substance on which an enzyme works.
5.1 ENERGY
def. Energy: the capacity to do work
Where is energy coming from?
5.11.1 Kinetic energy ("energy of movement")
-- motion
-- heat
-- light
def. Kinetic Energy: Energy of motion, including heat (molecular movement) and light (wave movement).
-- location energy (something located high up has the potential to move down)
-- chemical energy (structural energy)
def. Potential Energy: Energy stored in some form, chemical form (e.g., gasoline) or physical form (top of hill).
• 5.12 The Laws of Thermodynamics
• Energy can be converted from one form to another. These energy conversions are regulated by
-- thermodynamic laws
def. First law of thermodynamics: Energy is never created nor destroyed.
Example 1: The energy of electricity is transformed to light or heat.
5.12.1 2nd law of thermodynamics
(makes the universe more disordered).
2. Energy is ultimately converted to HEAT (the least orderly form of energy)
5.2 METABOLIC REACTIONS AND PATHWAYS
• 5.21 Spontaneous vs. Non-spontaneous reactions
• Exergonic (spontaneous reaction)
• Endergonic (non-spontaneous reaction)
def. Exergonic: A spontaneous chemical reaction in which energy is released to the surrounding, so that the reaction is showing a net loss in energy, e.g., cellular respiration
(products have less energy because we have used some to perform work)
def. Endergonic: A non-spontaneous chemical reaction in which energy is absorbed from the surrounding, so that the reaction is showing a net gain in energy, e.g., photosynthesis.
(all reactions of this type requires an input of energy)
|
 |
 |
• 5.22 Major metabolic energy-transforming pathways
5.22.1 Photosynthesis
Light energy + Carbon dioxide + Water -> Glucose + Oxygen
Sunlight + 6CO2 + 6H2O 
C6H12O6 + 6O2
5.22.2 Cellular Respiration
Glucose + Oxygen -> Water + Carbon dioxide + Chemical energy
C6H12O6 + 6O2 6H2O + 6CO2 + 36ATP
def. Cellular Respiration: The transformation of chemical bond energy from food ("glucose"), into usable form that occurs in all living cells ("glucose" broken down to release energy (ATP) required for life processes).
def. Photosynthesis: The conversion of light energy to chemical energy (stored in the glucose produced by the chemical reaction) from carbon dioxide and water.
|
 |
 |
 |
 |
 |
 |
5.3 ENZYMES
def. Enzyme A class of proteins serving as catalysts.
def. Catalyst: Chemicals that change the rate of a reaction without being consumed by the reaction.
def. Coenzyme An organic molecule serving as a cofactor, often a vitamin.
def. Cofactor A chemical required for the proper functioning of an enzyme.
def. Active site The specific portion of an enzyme that attaches to the substrate with weak chemical bonds.
def. Substrate The substance on which an enzyme works.
• 5.31 Enzyme Basics
• Enzymes are proteins that function as catalysts
--- Speed up chemical reactions
• Enzymes are NOT used up in the reactions ("recycled", and can be used many times)
Enzyme
SUBSTRATE(S)
PRODUCT(S)Sucrase
SUCROSE + WATER
GLUCOSE + FRUCTOSE • Enzymes are very specific to the substrate (speed up specific reaction)
• Enzymes lower the activation energy needed to start the reaction
-- do not PROVIDE energy
-- change the chemical configuration of the chemicals involved( easier to break/form) |
|
 |
 |
• 5.32 Effects of the Chemical & Physical Environment on Enzymes
5.32.1 EFFECTS ENVIRONMENTAL CONDITIONS
-- Environmental conditions (including the body) must be w/in certain ranges
--- temperature
--- pH
--- salt
-- Nonprotein helper chemicals required by an enzyme to function
--- Inorganic metal irons -- copper, iron, zinc (all trace elements)
--- Organic molecules -- vitamins (coenzymes)
5.32.3 EFFECTS OF ENZYME INHIBITORS
-- chemicals that may enter our body that will inhibit enzymes
--- DDT -- inhibit enzymes in the nervous system
--- Methanol -- inhibit the enzyme breaking down ethanol (toxic product -- cause blindness)
5.4 ATP --- Adenosine Triphosphate
def. ATP (Adenosine Triphosphate): An adenine containing molecule with triphosphate chain that releases energy when its phosphate bond is broken.
• 5.41 Cellular Work
• Mechanical work -- moving structures --- contraction of muscles
• Transport work -- pumping of substances across membranes
--- Active transport -- energy required--- Passive transport -- energy NOT requires (diffusion)• Chemical work -- pushing non-spontaneous chemical reactions
--- put together amino acids to proteins -- energy required--- break down proteins to amino acids -- energy NOT required-- still needs activation energy
• 5.42 Source of energy for cellular work:
ATP (Adenosine triphospate)
• molecule closely related to nucleotides in DNA: Adenosine + triphosphate tail
Adenosine = Adenine + ribose
--- ATP
with a triphosphate tail
-- negative, like charges crowded,
-- REPELLING EFFECT
-- chemical bond is unstable ... can be broken ... energy released
--- ADP
with a diphosphate tail
-- chemical bond is more stable ... not as easy to break
• 5.43 The ATP cycle
ATP is a renewable resource.
|
 |
|
|
|
|
Lecture Learning Tools Hub |
-- Disclaimer: "Dr. Nilsson's CyberOffice", at the time of writing located as a file under the South Texas Community College's (STCC) web server with the general URL http://stcc.cc.tx.us/, is the intellectual property of Dr. Jan A. Nilsson, member of STCC biology faculty. The content of Dr. Nilsson's CyberOffice does not necessarily reflect the opinions and beliefs of the STCC faculty, staff, administration, and Board of Trustees.