Chapter 8 Review

Front 1

Metabolism

Back 1

The totality of an organism's chemical reactions. (greek: metabole= change

Emergent property of life that arises from ordinary interactions between molecules.

Front 2

Catabolism

Back 2

exergonic, meaning that catabolism releases energy. Catabolism must occur to get to the use of energy (anabolism).

catabolism breaks down complex molecules into simpler compounds. (proteins)

Front 3

Anabolism

Back 3

Consumes or uses energy.

This occurs with the synthesis of an amino acid from simpler compunds or the synthesis of a protein from amino acids.

Front 4

1st 2 laws of thermodynamics

Back 4

1) Energy cannot be created or destroyed, only TRANSFORMED
2) Disorder (s) or entropy of the universe increases

Cells must be open systems because if they were at equilibrium or closed, then all cellular processes would not exist or take place.

Front 5

Free energy

Back 5

Energy of a system that can do work (@ uninform system temperature) (i.e.- cells). The overall sequence of reactions is kept going by a huge free energy difference (endergonic/exergonic)

Calculated as such: G=H-T S

For G to be negative, either H must be negative (system gives up enthalpy and H decreases) Or T S must be positive (system gives up order and (S) entropy increases), or both. If G is negative, the product is less than the reactant. If G is positive the product is greater than the reactant.

Front 6

exergonic/endergonic

Back 6

Exergonic reactions proceed with a net release of free energy. The greater the decrease in free energy, the greater the amount of work that can be done. If H (enthalpy decreases) then TS (entropy) must be positive, which means the system gives up order (S) increases.
Endergonic reactions proceed with an investment of free energy, this reaction absorbs energy. This reaction stores free energy in molecules.

Spontaneous= energetically favorable (exergonic reactions), endergonic reactions are non-spontaneous or non-energetically favorable because they require or store energy.
if G is @ 0, the system is at max stability or equilibrium: no work to be done. NOT TRUE OF LIVING CELLS

Energy coupling: an exergonic reaction must occur and couple with the endergonic reaction to make the endergonic reaction occur.

Front 7

Exergonic/Endergonic coupling

Back 7

ATP hydrolysis is an example of energy coupling. Water must first break the phosphate bonds of ATP to get ADP + P. Breaking the phosphate bonds releases stored energy.

Front 8

What type of monomer is ATP?

Back 8

ATP is a nucleotide used to make RNA. It's base is Adenine base + ribose, there are 3 phosphates, and it is energy rich. It's chemical energy is liberated through its hydrolysis, hydrolysis is coupled to endergonic reactions. Ex: Glutamic acid + ammonia+ energy (ATP) -------> Glutamine. ATP is also used/ Produced in cellular respiration (ETC having the greatest net yield)

Front 9

What is activation energy (Ea) of a reaction?

Back 9

Is the energy required to contort the reactant molecules so the bonds can break. Kinetic energy that can do this is heat, though heat can denature proteins and is non-specific. Enzymes help overcome Ea by reducing the amount of energy needed to start the reaction. Enzymes have specificity.

Front 10

Substrates/Binding to active sites: how does it bind?

Back 10

Enzymes bind to active site via "lock and key fit" the substrate or enzymes have specificity for that site and sometimes create a microenvironment . enzyme substrate complex = enzyme active sites + substrates. enzymes reduce the amount of Ea needed- Substrate binds in the enzyme substrate complex, substrate is converted to products, products are released and enzyme substrate complex is free again for more substrate to bind. Enzymes orient 2 substrates, puts stress on the bonds of molecules, and creates a microenvironment

Front 11

What is an allosteric site and how does it effect an enzymes functioning? what about active sites?

Back 11

An allosteric site is "backdoor" inhibition. a non-competitive inhibitor binds to the allosteric site, thus changing the shape of the active site, which means that the substrate can no longer bind properly to the active site. Essentially, an allosteric site allows a regulatory molecule to bind to it thus affecting the binding of a protein or substrate at a different site. Allosteric regulation (NON- Competitive Inhibition) my be positive. All enzymes have active sites, yet not all enzymes have an allosteric site. Allosteric sites are dependent on the type of enzyme that it is.

Front 12

Explain how substrate concentration, enzyme concentration, temperature, and pH affect the rate of an enzyme catalyzed reaction. Which of these are subject to change in cells?

Back 12

Every enzyme has its optimal temperature (in terms of increasing rxn rate), if you apply more heat than the optimal temperature, you run the risk of denaturing the protein and therefore drastically decreasing the rate of the reaction, the same is also true of pH- if more acidity/basicity is applied than the optimal amount, you run the risk of denaturing the protein and slowing reaction rate down. Within the cellulite environment the two that are most likely to change are substrate concentration and enzyme concentration, since temperature and pH within the cell are homeostatic by nature.

Front 13

Compare and contrast competitive and noncompetitive inhibition. Which can be overcome by additional substrate?

Back 13

In competitive inhibition the inhibitor is able to and does bind to the active site, making it so that the original substrate cannot bind to its intended active site on the enzyme. Noncompetitive inhibition is where a regulatory molecule binds to a protein at one site, thus affecting the function of a protein atat a different site. (back door inhibition)- binding in the allosteric site changes the shape of the active site of the enzyme.
Competitive inhibition may be countered by more substrate- as an increase in substrate can then outcompete the competitive inhibitor, whereas increasing the amount of substrate in noncompetitive inhibition is futile, as the presence of the noncompetitive (allosteric) inhibitor will deform the shape of where the substrate is supposed to bind, rendering that enzyme useless.

Front 14

Explain how feedback inhibition regulates the abundance of a given biomolecule.

Back 14

Feedback inhibition involves the end product. An example of this is the biosynthesis of Isoleucine: The presence of isoleucine regulates the whole pathway, Isoleucine is going to regulate the enzyme threonine deaminase from turning threonine into Intermediate A. Once Isoleucine is concentrated enough, it will loop back to the first enzyme (threonine deaminase) and shut off the whole pathway.

Front 15

Explain three ways that cells localize their enzymes for more efficient functioning in metabolic pathways.

Back 15

Cells localize their enzymes in the organelles in the cell, they are localized as membrane proteins (e.g. : rough ER) and in multi-enzyme complexes.