Download Energy Metabolism Notes

Energy and Cellular Metabolism
Dr. Gary Mumaugh – Bethel University
I.
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Properties of Living Organisms
Have a complex structure whose basic unit of organization is the cell.
Acquire, transform, store, and use energy.
Sense and respond to internal and external environments.
Maintain homeostasis through internal and external control systems with feedback.
Store, use, and transmit information.
Reproduce, develop, grow, and die.
Have emergent properties that cannot be predicted from the sum of the parts.
Individuals adapt and species evolve.
II.
Energy in Biological Systems
 All living organisms need a source of energy
o Energy from sunlight in plants
o Energy from chemical bonds in animals
 Energy is defined as the Capacity to Do Work
o Chemical work
 Making and breaking of chemical bonds
o Transport work
 Moving ions, molecules, and larger particles
 Useful for creating concentration gradients
o Mechanical work
 Moving organelles, changing cell shape, beating flagella and cilia
 Contracting muscles
 Energy Comes in Two Forms
o Kinetic energy
 Energy of motion
 Work involves movement
o Potential energy
 Stored energy
 In concentration gradients and chemical bonds
 Must be converted to kinetic energy to perform work
 Transformation efficiency
 Thermodynamic Energy
o First law of thermodynamics
 Total amount of energy in the universe is constant
o Second law of thermodynamics - (Entropy)
 Processes move from state of order to randomness or disorder
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III.
Chemical Reactions
 Bioenergetics is the study of energy flow through biological systems
 Chemical reactions
o Reactants become products
o Reaction rate
 Free energy
 Activation energy
 Net free energy change of the reaction
o Exergonic versus endergonic reactions
o Coupled reactions
 Reversible versus irreversible reactions
IV.
Enzymes: Overview
 Catalyze (initiate or start) biochemical reactions
 Coenzymes (Vitamins and Minerals)
o Helps the enzyme catalyze a reaction.
 Enzyme Inhibitors
o Chemicals that prevent a substrate from attaching to an enzyme
 Examples of Enzyme Inhibitors used in medicine
o Antibiotics inhibit bacterial enzymes
o NSAID, Aspirin and Advil inhibit the enzymes that convert the phospholipids
to prostaglandins >>>>>> inhibiting the inflammation
o Lipitor and other statins inhibit the enzyme that converts the fatty acids into
cholesterol
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V.
Metabolism
 Metabolism is the sum total of all the biochemical reactions of the body
 Catabolism versus anabolism
 Cells Regulate Their Metabolic Pathways
o Controlling enzyme concentrations
o Producing modulators that change reaction rates
o Using different enzymes to catalyze reversible reactions
o Compartmentalizing enzymes within organelles
o Maintaining optimum ratio of ATP to ADP
Metabolism Drawing
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VI.
Two Major Types of Metabolic (Biochemical) Reactions
Anabolic Reactions
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The joining of small molecules to form larger, more complex molecules
Growth processes are made by two types of reactions
o Dehydration synthesis reactions
o The joining together of organic molecules by removing water (dehydration)
o Examples:
Glucose + Glucose + Glucose >>> Disaccharides and Polysaccharides >>> Glycogen
Amino Acid + Amino Acid + Amino Acid >>>> Polypeptides
Nucleotide + Nucleotide + Nucleotide >>>> DNA & RNA >>>> Nucleic Acid
3 Fatty Acids + Glycerol >>>> Triglycerides
What cells of the body does this?
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Growth processes are made by two types of reactions
o Reduction reactions (“RIG” = Reduction It Gains)
o When a molecule gains H atoms + Oxygen (& the gain of energy)
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VII.
Two Major Types of Metabolic (Biochemical) Reactions
Catabolic Reactions
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The splitting of large molecule into smaller molecules
Digestion and energy production
The breaking down processes are made by two types of reactions
o Hydrolysis reactions
o The opposite of dehydration reactions. Water is added to break molecules
down. (Hyd = water / lysis = break apart)
o Examples:
Glycogen >>>> Glucose + Glucose + Glucose
Glcogen >>>> 3 Fatty Acids + Glycerol
Polypeptide >>>> Amino Acid + Amino Acid + Amino Acid
Nucleic Acid >>>> Nucleotide + Nucleotide + Nucleotide
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The breaking down processes are made by two types of reactions
o Oxidation reactions (“OIL” = Oxidation Is Less)
o When a molecule loses H atoms + electrons (and the release of energy)
o Free radicals are chemicals that take H atoms and electrons away from other
molecules.
 Promotes ageing of cells
 Increases cancer risk
o Anti-oxidants give off H atoms and electrons and thus prevent it from
happening.
 Prevents the above risks from happening
OIL RIG = Oxidation Is Less, Reduction is Gain
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VIII.
Maintaining Body Weight, Weight Reduction and
Growth
How do we grow as adults?
How would we get thinner?
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We must break down organic molecules as fast as we make them.
o If you form them faster than you break them down, then you grow … wider,
not taller.
o It is better to increase the amount of proteins in muscle cells instead of
triglycerides in fat cells.
o In either case above you are getter bigger.
 Bulking out in the muscles or increasing the triglycerides in fat
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Getting thinner
o Slow down the growth reactions – Eat Less
o Increase the catabolic reactions – Exercise
 The exercise is using more ATP and sugar, glycogen and triglyceride
stores.
o Example: Teenage boys growth spurt
IX.
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Cellular Respiration
Cellular respiration is the process by which organic molecules (usually
glucose), are broken down and releasing energy that is used to produce ATP
molecules.
Remember “OIL RIG”
The entire purpose is to break apart foods and release energy.
o That energy adds a phosphate group to an ADP to make ATP, which is the fuel
that powers cells.
Coin Laundromat analogy
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IX.
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Cellular Respiration
Overall simplified reaction
o In order to make the fuel of ATP that powers cells we need two things:
 Food - C6H12O6
 Oxygen – O2
o Oxygen acts as a “hydrogen acceptor”
o The majority of energy is given off as heat.
 This is consistent with the Second Law of Thermodynamics
 Law of Entropy says that when you convert one form of energy to
another form of energy, it comes off as heat.
 Example: Light bulbs convert electrical energy to heat energy.
(Class Drawing)
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IX.
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Cellular Respiration
Four statements about cellular respiration
1. In order to make ATP, we need food and water.
2. O2 acts as a hydrogen acceptor and makes H20.
3. We exhale CO2, which is a waste product from the
breaking down of food.
4. These chemical reactions are important because
they all give off heat.
 All the heat is generated when the trillions of
cells of the body break down sugar and
make ATP.
 This is why we are smoking hot … 98.6
What happens with cell respiration in exercise?
How ATP is made
o 1 molecule of glucose can yield some
heat and 38 molecules of ATP.
o Glucose is transferred into ATP
through three separate processes:
 Glycolysis – works in the
cytoplasm
 Yields 2 ATP molecules
 Kreb’s Cycle – works in the
mitochondria membrane
 Yields 2 ATP molecules
 Electron Transport Chain –
works in the mitochondria
 Yeilds 34 ATP
molecules
o Aerobic vs. Anaerobic
 Only 2 molecules of ATP is
made without O2.
 36 molecules are made with
O2.
 This is why we MUST have O2
to survive?
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X.
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Regulating glucose levels in the bloodstream
Since sugar is needed to make ATP to power the cells, understanding how glucose
is regulated in the blood is essential.
Normal glucose levels = 100 mg / mL blood
o Decreased levels = hypoglycemia
o Increased levels = hyperglycemia
Two hormones regulate blood sugar
o Insulin (protein hormone)
 Produced by Beta cells in Pancreatic Islets
 Glucose in bloodstream is transported into liver cells and stored as
glycogen.
 The process of joining together glucose to make a polysaccharide is
glycogenesis.
Glucose in bloodstream >>>>>>>>>>>>>>>>>>>>> stored as Glycogen
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Glycogen (protein hormone)
o Produced by the Alpha cells in Pancreatic Islets
o Glycogen in the liver cells is broken apart into glucose and released
into the bloodstream.
o This process is called glycogenolysis.
Broken Apart
Glycogen in liver >>>>>>>>>>>>>>>>> Glucose delivered into bloodstream
Glucose regulation step-by-step
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Glucose is in the blood
Insulin causes glucose to go to the cells
Glucose is broken apart in CO2 and H20 in most cells
In liver cells, the glucose is joined together to make a polysaccharide called
glycogen
5. When we need sugar, glycogen hormone is released.
6. The glycogen is broken apart and released into the bloodstream.
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(Class Drawing)
XI.
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The Catabolism of Fats and Proteins for Energy
In order to produce ATP for energy, the body breaks down
o Mostly carbohydrates in the body
o Some fats in the body
o Small amounts of proteins in the body
The way fats and proteins make energy in the body is by turning them into sugar.
The Catabolism of Fat
o Fatty acids can be reasonably converted into acetyl sugars, and then broken
down to release energy that is used to make ATP.
o Each gram of fat provides more than twice as much energy as a gram of
carbohydrate or protein.
o Increased catabolism of fat >>>>>>>>>>>>>>>> formation of ketoacids
 Ketone Bodies and Acetone
The Catabolism of Proteins
o Deamination of amino acids – removal of amino acids
Protein
Amino Acids
NH2 (ammonia)
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Ketoacids (Acetone)
Urea (in urine)
Gluconeogenesis
o The formation of new sugars from non carbohydrate sources
Ketoacids (ketone bodies) >>>>>>>>>>>>>>>>>> Acetyl sugar
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The Catabolism of Fats and Proteins – Clinical Considerations
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Ketoacidosis
o Diabetes = deficiency of insulin
 In diabetes, glucose in the blood cannot be transported into the cells
and stored as glycogen for energy.
>>>>>>>>>>>>> ketoacidosis (metabolic acisodis)
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If the carbohydrates are not used for energy, what will the cells in the
body have to break down for energy?
Hypergylcemia >>>>>>>>>>>>>>>>>>>>> glycosuria
Ketonemia (Ketosis) >>>>>>>>>>>>>>>>> ketonuria
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Fasting
o We have stored in our liver a 24-hour supply of glycogen.
o As the liver supply of glycogen is depleted, the body breaks down more fats,
mainly ketoacids (mainly acetone).
o When it is exhaled, the exhaled acetone is very sweet and fruity.
Theory behind Atkins (no carbohydrate) diet
o As the 24-hour supply of glycogen is depleted, the body breaks down fats via
gluconeogenesis.
XII.
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Review of the roles of DNA
There are 46 chromosomes in the nucleus of every single cell in the body
o There are 23 from mom and 23 from dad and they are referred to as
homologous (matching) pairs.
o Every single chromosome has an exact copy of the 23 pairs that were in the
zygote.
 22 of these chromosomes determines genetics and 1 chromosome
determines gender.
XX = female
XY = male
o Every single chromosome contains over 2000 genes
 Genes are simply instructions for making proteins.
o Examples of genes:
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XII.
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Each gene on a chromosome specifies the amino acid sequence of a specific
protein (called a “trait”).
o A gene is simply an instruction manual for building proteins.
Most genetic mutations (defects or change) are harmful because it causes defective
proteins to be produced.
Theses are called genetic or in-born diseases.
o Examples: Cystic Fibrosis, Hemophilia, Albinism, Tay-Sachs
XIII.
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Review of the roles of Proteins
Structural proteins – collagen and keratin
Protein hormones – insulin, glycogen, oxytocin, growth hormone
Contractile proteins – actin and myosin
Antibodies – immunoglobulins and gamaglobulins
Transport proteins – hemoglobin, HDL, LDL
Enzymes – proteins that catalyze biochemical reactions
“Tumor suppressor” genes
XIV.
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Review of the roles of DNA
Catabolism of old nucleic acids
The two main organic waste products that we produce are
o Urea from the breakdown of old proteins
o Uric acid from the breakdown of nucleic acids
The nucleic acids are broken down into nucleotides and the nucleotides are
converted into the waste product uric acid.
Nucleic acids >>>>>>>>>> nucleotides >>>>>>>>>> uric acid (excreted in urine)
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Clinical consideration – Gout
o Gout is a biochemical metabolic disorder in which there is high uric acid levels
in the blood – Hyperurecemia. These high uric acid levels tend to
accumulate in joints.
Clinical question – If patients are prone to hyperurecemia, should
they eat red meat?
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