Chapter 24: Metabolism, Appetite Control, and
Thermoregulation
Objectives
Describe metabolism and enzymes
Explain factors which regulate enzyme function
Describe the major steps of cellular respiration
Define the regulatory mechanisms of appetite and
temperature control
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Metabolism
Metabolism
Anabolism
Glycogenesis
Protein Synthesis
Transcription
Translation
Lipogenesis
DNA Synthesis
Mitosis
Meiosis
Catabolism
Glycogenolysis
Glycolysis
Proteolysis
Lipolysis
Interconversion
Gluconeogenesis
Liponeogenesis
Enzymes
2
Enzymes
Activation energy
Heat as activation energy
Heat increases kinetic
energy of molecules
Critical thinking: Why is heat
not a suitable form of activation
energy in living systems?
Enzymes
Biological catalysts
Speed up chemical
reactions by lowering the
activation energy
3
Enzymes: Structure
Enzymes
Proteins
End in –ase
Sucrase
Substrate
Active site
Allosteric site
Specificity
4
Mechanism of Enzyme Action
5
Cofactors and Coenzymes
Holoenzyme
Apoenzyme
Non protein portion
Non protein portion
Cofactors
Ex. Calcium ions
Coenzymes
Ex. Vitamin K
6
Environmental Effects on Enzymes
Enzyme Activity
Turnover rate=rate at which an
enzyme catalyzes a chemical
reaction
Temperature
pH
Regulators
7
Temperature and pH
Temperature
Optimal Temperature
Human body=
Denature Enzymes
pH
Optima pH
Human body=
Denature Enzymes
Exceptions
Pepsin
8
Regulators
Promoters
Hemoglobin
Inhibitors
Competitive Inhibitors
Active site
Noncompetitive
Inhibitors
Allosteric site
Antibiotics
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Stop and Practice
Statement
Answer
Define the general function of
enzymes
Differentiate between active and
allosteric site on an enzyme
Define general function of cofactors
and coenzymes
Enzyme which loses its structure is
said to be
Inhibitors which bind to allosteric site
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Cellular Respiration
Cellular Respiration
Anaerobic
Aerobic
Critical thinking: Why do cells need
energy?
Skeletal muscle cells
Cardiac muscle cells
Nerve cells
Critical thinking: Why do we need to
convert glucose into ATP?
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Mitochondrion
Mitochondrion
Outer membrane
Inner membrane
Cristae
Proteins
Matrix
Enzymes
mDNA
12
Aerobic Respiration: Steps
Cellular Respiration
Reactants
Glucose
Oxygen
Products
Water
Carbon Dioxide
34 ATP-Energy Currency
Basic Steps
Glycolysis
Citric acid cycle
Electron-transport system
13
Glycolysis
Glycolysis
Location: Cytosol
Reactants:
Glucose (1)
ATP (2)
Products:
Pyruvate (2)
NADH (2)
ATP (4)
14
Citric Acid Cycle
Citric Acid Cycle
Location:
Mitochondrial Matrix
Reactants:
Acetyl-CoA (modified
pyruvate)
Products:
FADH2 (1)
NADH (4)
ATP (1)
CO2 (3)
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Electron-transport System
Electron-transport
system
Location:
Mitochondrial cristae
Cytochrome
enzymes
Proton pump
ATP synthase
In:
1
NADH
FADH2
O2 (Final Electron
Acceptor) (6)
Out:
ATP (30)
H2O (4)
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2
3
Anaerobic Respiration
Anaerobic Respiration
Location: Cytoplasm
Pyruvate (Final electron acceptor)
Alcohol Fermentation
Pyruvate converted to Ethanol
Lactic Acid Fermentation
Pyruvate converted into lactic acid
Skeletal Muscle
During exercise?
During common cold?
17
Stop and Practice
Statement
Answer
Starting materials and end products
of cellular respiration include
Glycolysis yields a net of how many
ATPs
CO2 is generated during this step of
cellular respiration
Cellular respiration which takes place
in absence of oxygen
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Regulation of Appetite
Short Term Regulation
Ghrelin
PYY
Insulin
Long Term Regulation
Leptin
Thyroid hormone
Cortisol
Lipotropins
19
States of Energy
Potential energy
Chemical energy
Kinetic energy
Electrical energy
Mechanical energy
Sound energy
Radiant energy
Heat
20
Laws of Thermodynamics
Laws of
Thermodynamics
First law of
thermodynamics
Second law of
thermodynamics
21
Thermoregulation
Thermoregulation
Maintenance of body
core temperature close
to 37 ºC.
Critical thinking: Why is it
important to maintain
temperature at 37 degrees
C?
Hypothalamus
Thermoregulatory
centers
Peripheral
thermoreceptors
Central
thermoreceptors
22
Thermoregulation: Heat Exchange
Heat exchange
Heat always flows from an
area of higher temperature to
an area of lower temperature
until the two areas achieve an
equilibrium with respect to
temperature.
Conduction
Convection
Radiation
Evaporation
23
High Environmental Temperature
Increase in body
temperature
Maximize heat loss
Vasodilation of cutaneous
blood vessels
Increased sweating
Behavioral responses
Use of fans
Immersion in cool water
Staying out of sun
Minimize heat production
Diminish food intake
Behavioral responses
Decreased physical
activity
Decrease in contraction
of skeletal muscles
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Low Environmental Temperature
Decrease in body temperature
Minimize heat loss
Vasoconstriction of cutaneous
blood vessels
Contraction of arrector pili
muscle
Behavioral responses
Adding layers of clothing
Curling up
Standing near heat source
Maximize heat production
Shivering thermogenesis
Contraction of skeletal
muscles
Nonshivering thermogenesis
Mitochondrial uncoupling in
adipocytes of brown fat
Behavioral responses
Increased voluntary activity
Increased contraction of
skeletal muscles
25
Stop and Practice
Statement
Answer
Hormone which stimulates appetite
centers
Hormone produce by adipose tissue
Define the term conduction
Receptors which detect external
temperature
Define shivering thermogenesis
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