Cell Bio Chapter 3 Chemical Component of Cells

Enzymes

proteins that catalyze (accelerate) reactions that a particular molecule could undergo by reducing activation energy

Metabolism

the sum total of the chemical reactions that take place in the cells of a living organism

Catabolism

set of enzyme catalyzed reactions by which complex molecules are degraded to simpler one with release of energy (heat energy in food catabolism); intermediates in these reactions are sometimes called catabolites

Anabolism

set of metabolic pathways by which large molecules are made from smaller ones

Energy conversion through H2O formation

energy is released when a bond between H and O is formed, causing kinetic energy of the molecules that is distributed throughout the environment through heat transfer

Photosynthesis

process by which plants, algae, and some bacteria use the energy of sunlight to drive the synthesis of organic molecules (sugars) from carbon dioxide and water

Photosynthesis converts

electromagnetic energy in sunlight into chemical bond energy in cells

ATP and NADPH

carriers activated by the capture of light energy in photosynthesis that are used to manufacture sugar

Cellular respiration

takes place in most living organisms; uses O2 to oxidize organic molecules, releasing carbon atoms in the form of carbon dioxide to return carbon dioxide to the atmosphere

Carbon cycles

the entire biosphere, moving between organisms and the environment

Photosynthesis prevalence

this process predates cellular respiration as billion of years of respiration are needed to support respiration

Oxidation

removal of electrons from an atom, as occurs during the addition of oxygen to a carbon atom or when a hydrogen atom is removed from a carbon atom; can also refer to a partial shift of electrons between atoms linked by a covalent bond

Reduction

addition of electrons to an atom, as occurs during the addition of hydrogen to a carbon atom or the removal of oxygen from it; can also refer to a partial shift of electrons between atoms linked by a covalent bond

Oxidized state

when there is a smaller amount of atomic radius and a partial positive charge on one atom

Reduced state

when there is a larger amount of atomic radius and a partial negative charge on one atom

Not

enzymes are ___ permanently altered by the reaction

Free energy

energy that can be harnessed to do work, such as driving a chemical reaction; represented by G

Energetically favorable reactions

reactions that create disorder in the universe by decreasing the free energy; have a negative G value

Free energy change

denoted as delta G, in a chemical reaction, the difference in free energy between reactant and product molecules; large negative value indicates reaction has a strong tendency to occur

Equilibrium

state in which the forward and reverse rates of a chemical reaction are equal so that no net chemical change occurs; conversions still occur in this state due to thermal bombardments but net G for forward and backward reactions is zero

Chemical reactions that cause disorder

Changes in bond energy or decreasing order in a cell by breaking a bond or preventing bond rotation

Standard free energy change (delta G0)

free energy change measured at a defined concentration, temperature, and pressure

Coupled reactions

share one or more intermediates with a standard free energy change equivalent to the sum of the free energy change values of each reaction; energy from one reaction drives the other reaction

High energy bonds

bonds present in acetyl phosphate and ATP that have a large negative standard G of hydrolysis

Activated carriers

small molecules that store energy or chemical groups in a form that can be donated to many different metabolic reactions; ex. ATP, acetyl CoA, and NADH

Creatine phosphate

intermediate energy storage that transfers a phosphate group to ADP when ATP concentrations are low

ATP

activated carrier that serves as the principal carrier of energy in cells; a nucleoside triphosphate composed of adenine, ribose, and three phosphate groups

ADP

produced from the hydrolysis of the terminal phosphate of ATP

Phosphorylation

energetically favorable reaction that converts an energy rich phosphoanhydride bond in ATP to a less energy rich phosphoester bond in the phosphate accepting bond

NADH

activated carrier of electrons that is widely used in the energy producing breakdown of sugar; strong electron acceptor, effective oxidizing agent

NADPH

activated carrier closely related to NADH and used as an electron donor in biosynthetic pathways; oxidized to NADP+; strong electron donor that can serve as a reducing agent for anabolic reactions

Nicotinamide ring

part of NADPH that allows the carrier to accept and donate electrons

Acetyl CoA (Acetyl coenzyme A)

Activated carrier that donates the carbon atoms in its readily transferable acetyl group to many metabolic reactions, including the citric acid cycle and fatty acid biosynthesis; the acetyl group is linked to coenzyme A (CoA) by a thioester bond that releases a large amount of energy when hydrolyzed