PITZER FIU BSC2010 EXAM 2 CH 6,7,13

Metabolism

is the totality of an organisms chemical reactions.

Metabolism is an

emergent property of life that arises from interactions between molecules between the cell

A metabolic pathway begins with

a specific molecule and ends with a product.

Each step is catalyzed by

a specific enzyme

Catabolic pathways release

energy by breaking down complex molecules into simpler compounds

One example of catabolism is

cellular respiration, the breakdown of glucose and other organic fuels to carbon dioxide and water.

Anabolic pathways

consume energy to build complex molecules from simpler ones

The synthesis of proteins from amino acids is an example of

anabolism

Bioenergetics

is the study of how energy flows through living organisms

Catalysis:

accelerate, action, kinetic energy

Enzyme:

Speed us a reaction and aren't catalysts

Energy:

The capacity to do work

Kinetic Energy:

The energy of motion

Potential Energy:

Stored energy

Energy can take many forms:

Mechanical Electric current Heat Light

First Law of Thermodynamics:

Energy cannot be created or destroyed

Energy can only be converted from

one form to another

All energy winds up being

heat

Second Law of Thermodynamics

Disorder is more likely than order

Entropy:

Disorder in the universe

The 2nd Law of Thermodynamics states that entropy is

always increasing.

Most forms of energy can be converted to

heat energy.

Heat energy is measured in

kilocalories.

One calorie:

The approximate amount of energy needed to raise the temperature of one gram of water by one degree Celsius at a pressure of one atmosphere.

1 kilocalorie (kcal) =

1000 calories

Calories is an estimate of

heat

Calories are

smaller than kilocalories

Potential energy stored in

chemical bonds can be transferred from one molecule to another by way of electrons.

Oxidation:

Loss of electrons

Reduction:

Gain of electrons

Redox reactions are

coupled together

Free energy:

The energy available to do work

Denoted by the symbol G

(Gibb's free energy)

Enthalpy:

Energy contained in a molecules chemical bonds

Free Energy =

Enthalpy - (Entropy x Temp) G = H - TS

H

stands for heat

Products

= TS

Chemical reactions can create changes in free energy:

When products contain more free energy than reactants - DG is positive and When reactant contains more free energy than products - DG is negative

Endergonic reaction:

A reaction requiring an input of energy - DG is positive ex. if you put energy to make it happen

Exergonic reaction:

A reaction that releases free energy - DG is negative ex.If you remove energy to make it happen

Most reactions require

some energy to get started.

Activation energy:

Extra energy needed to get a reaction started Destabilizes existing chemical bonds and Required even for exergonic reactions

Catalysts:

Substances that lower the activation energy of a reaction

Enzyme is the

catalyst

ATP =

Adenosine triphosphate

- The energy "currency" of cells

ATP

ATP structure:

Ribose is a 5-carbon and Adenine and Three phosphates

ATP stores energy in the

bonds between phosphates.

Phosphates are highly negative therefore

The phosphates repel each other Much energy is required to keep the phosphates bound to each other Much energy is released when the bond between two phosphates is broken

P in ATP and ADP is everywhere there are

tons of them

ADP =

adenosine diphosphate

Pi =

inorganic phosphate

When the bond between phosphates is broken energy is released

This reaction is reversible.

The structure of this molecule consists of a

purine base (adenine) attached to the 1 carbon atoms of a pentose sugar (ribose). Three phosphate groups are attached at the 5 carbon atom of the pentose sugar. It is the addition and removal of these phosphate groups that inter-convert ATP, ADP and AMP.

The energy released when ATP is broken down to ADP can be used to

fuel endergonic reactions.

The energy released from an exergonic reaction can be used to

fuel the production from ADP + Pi

Enzymes

Biological catalysts

Enzymes:

molecules that catalyze reactions in living cells. They are catalysts.

Most enzymes are proteins

but A LOT are not proteins.

Lower the activation energy for

enzymes required for a reaction

Enzymes are not

changed or consumed by the reaction

A catalyst is a

chemical agent that speeds up a reaction without being consumed by the reaction

An enzyme is a

catalytic protein

Hydrolysis of sucrose by the enzyme sucrase is an example of

an enzyme-catalyzed reaction

Sucrase by itself is a

catalysts

Sucrase with Sucrose is an

enzyme

Most metabolic pathways are

allosteric

Enzymes interact with

substrates.

Substrate:

Molecule that will undergo a reaction

Active site:

Region of the enzyme that binds to the substrate

Binding of an enzyme to a substrate causes

the enzyme to change shape, producing a bettie induced fit between the molecules.

Multienzyme complexes:

offer certain advantage: The product of one reaction can be directly delivered to the next enzyme. The possibility of unwanted side reactions is eliminated. All of the reactions can be controlled as a unit.

Ribozymes:

RNA with enzymatic abilities

Enzyme Function

Rate of enzyme-catalyzed reaction depends on concentrations of substrate and enzyme

Any chemical or physical conditions that affects the enzyme's 3 dimensional she can

change rate Optimum temperature Optimum PH

ligand

a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose.

How are enzyme-catalyzed reactions controlled/inhibited?

Competitive inhibitors Noncompetitive inhibitors and Allosteric enzyme

Competitive inhibitors:

complete with the substrate for binding to the same active site

Noncompetitive inhibitors:

Bind to sites other than the enzymes's active site. Causes shape change that makes enzyme unable to bind substrate.

Allosteric enzyme:

exists in either an active or inactive site

Possess an allosteric site where

molecules other than the substrate bind.

Allosteric inhibitors bind to the

allosteric site to inactivate the enzymes

Allosteric activators bind to the

allosteric site to activate the enzyme

Metabolism:

All chemical reactions occurring in an organism. Occur in sequence. Product of one reaction is the substrate for the next. Many steps take place in organelles.

Anabolism:

Chemical reactions that expand energy to make new chemical bonds

Catabolism:

Chemical reactions that harvest energy when bonds are broken

Some enzymes require additional molecules for proper enzymatic activity

These molecules could be:, Cofactors and Coenzymes

Cofactors:

Usually metal ions found in the active site participating in catalysis

Coenzymes:

Nonprotein organic molecules often used as an electron donor or acceptor in a redox reaction.

Biochemical pathways are a series of

reactions in which the product of one reaction becomes the substrate for the next reaction.

Biochemical pathways are often regulated by

feedback inhibition in which the end product of the pathways is an allosteric inhibitor of an earlier enzyme in the pathway.

C6H12O6 + 6 O2 + + 6H2O → 6 CO2 + 12H2O

how cells harvest energy

Metabolic process that use energy to build large molecules from smaller ones

are what kind of pathways?, Anabolic

Which statement about glycolysis is true?

It occurs in the cytoplasm

The complete oxidation of glucose proceeds in stages. Which of these is NOT one of these stages?

Fermentation

Organisms can be classified based on how they obtain energy:

Autotrophs and Chemoautothrophs heterotrophs

Autotrophs:

Are able to produce their own organic molecules through photosynthesis

Chemoautothrophs heterotrophs:

live on organic compounds produced by other organisms

All organisms use cellular respiration to

extract energy from organic molecules.

Cellular Respiration: is a series of reactions that:

are oxidations - loss of electrons are also dehydrogenations - lost electrons are accompanied by hydrogen