Metabolism

Thermodynamics

Thermodynamics

Deals with the transformation of energy in all forms

First Law of Thermodynamics

The total amount of energy in any closed system is constant. Energy cannot be created or destroyed; it can only be converted from one form to another. If a physical system gains an amount of energy, another physical system must experience a loss of energy of the same amount.

Bond Energy

A measure of the stability of the covalent bond between atoms and is measured in kJ or is the amount of energy required to break one mole of bonds between two atoms and is also equal to the amount of energy released when that bond is formed

Energy

Absorbed when the reactant bonds break and released when the product bonds form

Activation Energy

Equal to the difference between the potential energy level of the transition state and the potential energy of the reactions

Exothermic

Releases more heat than it uses

Endothermic

More heats enters the system than is actually released at the end of the reaction

Enthalpy

The overall change in energy that occurs in a chemical reaction

Second Law of Thermodynamics

In every energy transfer or conversion, some of the useful energy in the system becomes unstable and increases the entropy of the universe

Spontaneous Change

One that will continue to occur on its own once its underway. A match that is lit will continue to burn

Free Energy

Energy that can do useful work.

Coupling Reactions

The transfer of energy from one reaction to another in order to drive the second reaction

ATP

Directly supplies the energy that powers nearly every cellular function (transport of ions, contraction of muscles, moving of chromosomes in cell divison, driving endergonic reactions, beating of cilia)

Oxidation

When an atom or molecule loses electrons to another atom

Reduction

When an atom or molecule gains electrons

Cellular Respiration

Our bodies use sugars to produce cellular energy. Steps for this are glycolysis and pyruvate oxidation, kreb cycle, etc and chemiosmosis

Glycolysis

-In the cytoplasm of the cell

-Oxygen is not required

-Means sugar splitting and it is accomplished in ten steps involving different enzymes at each one

Pyruvate Oxidation

Pyruvate enters the matrix and the is converted into an acetyl group which is then temporarily bonded to a sulfur atom on the end of a large molecule called coenzyme a or CoA. This results in an acetyel-CoA complex

Krebs Cycle

-Consists of ight-enzyme coupled reactions

-Results in the oxidation of acetyl groups to CO2, accompanied by the synthesis of ATP, NADH, and FAD

ETC

Electrons are passed from one member of the transport chain to another in a series of redox reactions. Energy released in these reactions is captured as a proton gradient, which is then used to make ATP

Chemiosmosis

It’s turned by the flow of H+ ions moving down their electrochemical gradient. As ATP synthase turns, it catalyzes the addition of a phosphate to ADP, capturing energy from the proton gradient as ATP.

Regulating Cellular Respiration

PFK is able to regulate glycolysis through allosteric inhibition, and in this way, the cell can increase or decrease the rate of glycolysis in response to the cell's energy requirements.

Anaerobic Pathways

In the absence of oxygen, cells can take glucose and use glycolysis for ATP production

Alcohol Fermentation

Occurs in bacteria and yeasts. Pyruvate loses a CO2 and becomes acetaldehyde, acetaldehyde becomes reduced to ethanol and NADH become oxidized to NAD+

Lactic Acid Fermentation

Is used as a primary energy pathway in some bacteria and occurs in our muscle cells during strenuous activity. Pyruvate gains two elctrons and becomes reduced and NADH loses two electrons and becomes oxidized and forms NAD+ that can re-enter glycolysis

Fats in Cellular Respiration

Glycerol enters as G3P in glycolysis and fatty acids enter as acetyl groups

Proteins in Cellular Respiration

Amino group is removed and the remainder of the molecule enters as pyruvate, acetyl units or intermediates of the kreb cycle

Photosynthesis

The process by which the energy of sunlight (photon) is converted into the energy of glucose, it occurs in the chloroplast of the plants and photosynthetic organisms

Light Absorption

Photosynthesis depends on the absorption of light by chlorophylls and carotenoids acting in combination. The effectiveness of light of various wavelengths in driving photosynthesis is plotted as an action spectrum for photosynthesis

Action Spectrum

A plot of the effectiveness of light energy of different wavelengths in a driving chemical process

Pigment

Photosynthetic compounds that can absorb energy from certain wavelengths

Photosystem I

A collection of pigment proteins that includes chlorophyll a and absorbs light at the 700nm wavelength

Photosystem II

A collection of pigment proteins that includes chlorophyll a and absorbs light at the 680nm wavelength

Antenna Complex

A cluster of light-absorbing embedded in the thylakoid membrane able to capture and transfer energy to special chlorophyll molecules in the reaction center

First Outcome

Excited electron simply returns to its ground state, its energy is released as thermal or fluorescence

Second Outcome

The energy of the excited electron is transferred to an electron in a neighboring pigment molecule. This now high-energy electron in the second pigment molecule is excited and the original electron returns to its ground state

Third Outcome

Excited electron may be transferred to a nearby electron-accepting molecule

Primary Electron Acceptor

A molecule capable of accepting electrons and becoming reduced during photosynthesis

Reaction Center

A complex of proteins and pigments that contains the primary electron acceptor

Chlorophylls

The major photosynthetic pigments in plants, green algae and cyanobacteria

Chlorphyll a

Absorbs violet and orange light the most

Chlorophyll b

Absorbs mostly blue and yellow light

Carotenoids

Absorbs green, violet, and blue and reflects red-yellow

Falvinoids

Reflect red, blue, purple or magenta

Two Stages of Photosynthesis

-Light dependent

-Light independent

Light Dependent Reactions

The first stage of photosynthesis during which water molecules are split as light energy is absorbed and transferred into chemical energy in ATP and NADH

Light Independent Reactions

The second stage of photosynthesis that uses ATP and NADH to convert CO2 to sugars

Chloroplasts

An organelle within the cells of plants where photosynthesis occurs

Cyclic Electron Transport

Ferredoxin donates elEctrons back to PQ so PQ gets continually reduced and oxidized and keeps moving protons across the thylakoid membrane without the movement of PS11

Carbon Fixation

Conversion of carbon from inorganic to organic form. CO2 reacts with a molecule of RuBP to produce two 3-carbon molecules of phosphoglycerate

Reducation

Each phosphoglycerate gets an additional phosphate from the hydrolysis of ATP. This molecule is subsequently reduced by high energy electrons from NADH, producing G3P

Regeneration

The G3P molecules are combined and rearranged to regenerate the RuBP that is required to start the cycle all over again

Rubsico

Enzyme that helps catalyze the reaction between RuBP and CO2

Entropy

A degree of disorder or randomness

Non-spontaneous Reaction

Cannot happen without a continual input of energy

Dehydrogenases

They facilitate the transfer of high-energy electrons from food to molecules that act as energy carriers or shuttles

Substrate-level Phosphorylation

When enzymes remove a "high-energy" phosphate from a substrate and directly transfer it to ADP

Oxidative Phosphorylation

Occurs when electrons move through an ETC and produce a proton-motive force that drives ATP synthase