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BREAKDOWN OF MOLECULES: METABOLISM AND CELLULAR RESPIRATION (CELLULAR…
BREAKDOWN OF MOLECULES: METABOLISM AND CELLULAR RESPIRATION
Metabolism
All of the reactions taking place within an organism
Metabolic reactions: a sequence of steps, each controlled by an enzyme
Catabolic reactions: release energy stored in complex molecules
Anabolic reactions: biosynthetic pathways; require energy to remake complex molecules
Bioenergetics: study of energy transformations in organisms
Forms of Energy
Energy: the capacity to cause change
Kinetic: the energy of motion; matter that is moving
Thermal: the randomly moving atoms or molecules
Heat: thermal energy transferring from one body of matter to another
Potential: capacity of matter to cause change due to location/arrangement
Chemical: form of potential energy available to release in chemical reactions
Laws of Energy Transformation
Thermodynamics:
First Law of Thermodynamics:
Principle of conservation of energy; energy can be transferred and transformed
One kind to another; total energy of universe stays the same.
Example was the circles with pieces cut inside and moved around.
Energy can be neither created or destroyed
Second Law of Thermodynamics:
Every energy transfer or transformation; increased disorder within the universe
Entropy: used as a measure of disorder or randomness
Some energy is converted to thermal energy
A disordered form of energy; released as heat
study of energy transformation in a collection of matter
Open system: energy and matter may be exchanged between the system and its surroundings
Organisms are known as open systems
Isolated system: exchange does not occur
Exergonic Reaction
Spontaneous Process:
without an input of energy
an increase in entropy
energetically favorable
Negative triangle -(G)
Net release of free energy
Spontaneous
Energetically favorable
Magnitude of (G)- maximum amount of work an exergonic reaction can perform
Break bonds
Catabolic- the root word (cata- means down)
Endergonic Reaction
Nonspontaneous Process:
Leads to a decrease in entropy
Only if energy is supplied
Considered on its own
Positive triangle +(G)
Absorb free energy from its surrounding
Nonspontaneous
Energy required to perform
Needs energy from an exergonic reaction
Form bonds
Anabolic- the root word (ana- means up)
Free Energy
Symbolized by triangle-G
Entropy (S) measure of disorder
Enthalpy (H) energy of a system
Absolute temperature (T)
Equilibrium: chemical reaction; forward and backward reactions occur at same rate
What is left form an exergonic reaction
Energy Coupling
Use of exergonic processes to drive endergonic ones
Cells use ATP as immediate source of energy for it works (3 kinds)
Chemical: endergonic and exergonic reactions
Transport: moving proteins as an example
Mechanical: moving with the use of ATP
ATP
Adenosine triphosphate
Nitrogenous base adenine bonded to the sugar ribose
Connected to a chain of three phosphate groups (triphosphate)
Ability to be hydrolyzed to ADP (adenosine diphosphate)
Phosphate likely to break with hydrolysis.
Free energy released used to transfer the broken phosphate group to a reactant molecule
Produces a phosphorylated intermediate
Phosphorylation when phosphate is added and helps drive reaction.
Enzymes
Biological catalysts: agents that speed the rate of a reaction but are unchanged by the reaction
Activation energy
Free energy of activation ( Ea)
Energy absorbed by reactants to reach the unstable transition rate
Bonds are likely to break
Reaction can proceed
Catalysis:
enzymes are able to lower (Ea: activation energy)
Reactions can proceed with cellular temperatures
(G) for a reaction does not change with enzymes
Substrate Specificity
Protein enzymes: macromolecules with characteristic 3-D shapes, with a particular substrate.
Active site: substrate attaches within the enzyme; a pocket or groove
Active site: found on surface of enzyme has compatible shape to substate
Enzyme-substrate complex: substrate is temporarily bound to enzyme
Enzyme changes shape slightly to create an induced fit.
Induced fit: enhances the ability of the enzyme to catalyze the chemical reaction
Enzymes Active Site
Substrate held within the active site by hydrogen/ionic bonds
Side chains of surrounding amino acids facilitate; substrate into product
Product leave the active site and the catalytic cycle repeats, astonishing speeds
Effect on Enzyme Activities
The speed of an enzyme-catalyzed reaction may increase with rising temperatures
Temp. changes may disrupt the weak bonds and interactions that stabilize protein shape.
Optimal conditions: a temperature and pH that enzymes favor its most active shape.
Cofactors: small molecules that bind either permanently or reversibly with enzymes
Enzymes need cofactors for necessary enzyme functions.
Coenzymes: most vitamins; precursors of coenzymes (cofactors)
Inhibitors: disrupt the action of enzymes
Reversibly by binding the enzyme with weak bonds
Irreversibly by attaching with covalent bonds
Competitive: compete with the substrate for the active site of the enzyme
Increasing the substrate concentration helps prevent this type of inhibition
Noncompetitive: bind to a part of the enzyme separate from the active site
Enzyme action impeded by changing the shape of the enzyme
Allosteric Regulation
Molecules may inhibit or activate enzymes activity when they bind to a site separate from the active site.
Activator: stabilizes the catalytically active shape
Inhibitor: stabilizes the inactive form of the enzyme
Allosteric enzymes: may be critical regulators of both catabolic and anabolic enzymes.
Cooperativity: substrate molecule binding to one active site in a multisubunit enzyme changes the shape of all subunits
Active sites are stabilized in the active form.
Feedback Inhibition: metabolic pathways are commonly regulated by this.
End products act as an allosteric inhibitor of an enzyme early in the pathway.
Root Words
(all- =different)
(ana- =up)
(bi- =life)
(cata- =down)
(endo- =within)
(ex- =out)
(kinet- =movement)
(therm- = heat)
(aero- =air)
(an- =not)
(chem- =chemical)
(glyc- =sweet)
CELLULAR RESPIRATION
Respiration- gas exchange between organism and its environment
Breathing- the alternation of inhalation and exhalation
ATP- energy for the cell
Glucose- energy storage molecule (C6H12O6)
Anaerobic means without oxygen
Oxygen and hydrogen converted to water
Maximum of 36 to 38 ATP produced by cell
Glucose broken down into carbon dioxide which is released from mitochondria.
Aerobic Respiration
Aerobic means with oxygen
C6H12O6 + 6O2 6CO2 + 6H2O + energy
Glycolysis, Krebs, E.T.S/E.T.C
One glucose molecule 36 or 38 ATP
Glycolysis:
Occurs in cytoplasm of cell near mitochondria
Reactants:
1 Glucose
2 NAD+ from ETS
2 ADP + 2P
Products:
2 ATP
2 Pyruvic Acids
2 NADH go to the ETS/ETC
2 H+
Does not require oxygen
Substrate-Level Phosphorylation:
Enzyme transfers phosphate groups from a substrate molecule to ADP to form ATP
Transition Reaction:
Location is from the Cytoplasm to the Mitochondria
No Oxygen required
Uses CoA to make Acetyl CoA
Reactants:
2 Pyruvic Acids
2 NAD+ from ETS/ETC
2 Coenzyme A
Products:
2 CO2
2NADH go to ETS/ETC
2 Acetyl CoA
Krebs Cycle:
Also known as the Citric Acid Cycle
Located in the Mitochondrial Matric
No Oxygen required
Occurs two times per glucose molecule since glucose is split into two.
Reactants
2 Acetyl CoA
6 NAD+ from ETS/ETC
2 ADP + 2P
2 FAD from ETS/ETC
Products
4 CO2
6 NADH go to ETS/ETC
2 FADH2 go to ETS/ETC
2 ATP
Electron Transport System:
Sometimes know as the Electron Transport Chain
Location is in the inner mitochondrial membrane
It is aerobic which means oxygen is required.
Chemiosmosis: the use of an H+ gradient across a membrane to drive cellular work
Intermembrane space is in-between the inner membrane and outer membrane
Inner mitochondrial membrane built from a phospholipid bilayer.
Reactants:
10 NADH
2 FADH2
O2
H+
ADP + P
Products:
H20
32/34 ATP
NAD+
FAD
Fermentation
Anaerobic reaction
Breakdown of glucose into (2) 3-carbon molecules called pyruvic acid
Pyruvic acid converts into carbon dioxide and either alcohol or lactic acid
2 types: alcoholic or lactic acid
Both keep glycolysis working with recycled NAD+
Ethyl alcohol fermentation
Yeast INTO wine
Yeast INTO bread
NAD+ and NADH 2 times – recycled
Anaerobic small burst of energy
Lactic acid fermentation
Produces muscle fatigue
Bacteria INTO cheese
Bacteria INTO yogurt
NAD+ and NADH 2 times – recycled
2 H+
2 Lactic acid
2 ADP + 2 P = 2 ATP
Oxidative Phosphorylation:
Occurs in the Cristae of Mitochondria
Cristae: infoldings in the inner membrane
Responsible for greatest production of ATP
Oxidative- use of oxygen as terminal electron acceptor
Phosphorylation- comes from a molecule ATP being Phosphorylated to ATP
Aerobic means needs oxygen
Electron carriers bring the electrons to a group of coenzymes (electron transport chain)
Electron are transported down the chain, energy is released
Energy changes ADP + P into ATP.
Final acceptor of electrons is oxygen
Oxygen removes hydrogen and electrons to create H2O (water)