Unit 3 Energy Transformations

metabolism

the totality of an organism’s chemical reactions

metabolic rate

the total energy an organism uses over time

smaller organisms have a ? metabolic rate

higher

smaller organisms have greater SA:V ratio so they lose more energy

metabolic pathway

begins with a specific molecule and ends with a product

each step is ctalyzed by a specific enzyme

catabolic pathways

release energy by breaking down complex molecules into simpler compounds

ex: digestive enzymes break down food → release energy

anabolic pathways

consume energy to build complex molecules from simpler ones

ex: amino acids link to form muscle energy

enzyme-substrate complex

every chemical reaction between molecules involves bond ? and bond ?

breaking, forming

activation energy

the initial energy needed to start a chemical reaction is called the free energy of activation

how activation energy plays in a reaction

enzymes catalyze reactions by lowering the activation energy barrier

free energy (ΔG)

represents the energy available in a system to do work.

what does positive or negative free energy mean?

ΔG < 0 = exergonic reaction (spontaneous, no need for additional energy input)

ΔG > 0 = endergonic reaction (nonspontaneous, reqiires energy input)

ΔG = 0 equilibirum

products of a reaction are at a ? free energy state than reactants

lower

energy

capacity to cause change

• Kinetic energy is energy associated with motion

• Heat (thermal energy) is kinetic energy associated with random movement of atoms or molecules

• Potential energy is energy that matter possesses because of its location or structure

• Chemical energy is potential energy available    for release in a chemical reaction

thermodynamics

study of energy transformations

isolated system

no interactions with environment

open system

energy and matter can be transferred between the system and its surroundings

ex: organisms

first law of thermodynamics

energy of the universe is constant

energy can be transferred and transformed, cannot be created or destroyed+

second law of thermodynamics

every energy transfer or transformation increases the entropy of the universe. this si because during every energy transfer or transformation, some energy is unusable, often lost as heat

entropy

a measure of disorder or randomness within a system

spontaneous processes

occur without energy and can happen quickly or slowly

means energetically favorable = -ΔG = increased entropy = more stability of system

energy flows into an ecoystem in the form of ? and exits in the form of ?

light, heat

exergonic reaction

net relase of free energy

spontaneous

endergonic reaction

absorbs free energy from its surroundings and is nonspontaenous

changes in free energy in a cell

in catabolic reactions, the products have ? energy than reactants

in anabolic reactions, the products have ? energy

lower, higher

energy coupling

the use of an exergonic process to drive an endergonic one

most energy coupling in cells is mediated by ATP

atp hydrolysis

catabolic/exergonic reaction where a molecule of ATP is broken down into ADP + P + energy

addition of water molecule breaks a high-energy phosphoanhydride bond between the second and third phosphate groups whic is catalyzed by the enzyme ATP hydrolase

released energy can be used for vaerious cellular processes

atp drives energonic reactions by ?

phospholryation which then changes shape and becoems more reactive

atp regeneration

enzyme

catalytic protein

induced fit

substrate brings chemical groups of the active site into positions that enhance their ability to ctayalyze the raction

active site can ? an E_A barrier

lower

factors that can affect an enzyme’s activity

• General environmental factors, such as temperature and pH

• Chemicals that specifically influence the enzyme

optimal conditions favor the most active shape for the enzyme molecule

optimal temp for human enzyme

37 degrees celsius

opyimal ph for stomach enzyme pepsin and optimal ph for trypsin (intensinal enzyme)

2, 8

cofactors

nonprotein enzyme helpers; help to catalyze reactions

competitive inhibitors

bind to the active site of an enzyme, competing with the substrate

to compete with his, more substrate is needed to outcompete with inhibitor

noncompetitive inhibitors

bind to another part of an enzyme, causing the enzyme to change hsape and making the active site less effective

ex: toxins, poisons, pesticifes, and antibiotics

allosteric regulation

may either inhibit or stimulate an enzyme’s activity

occurs when a regulatory molecule binds to a protein at one site and affects the protein’s function at another site

allosteric regulators as activators

activators bind to allosteric site and change the shape of the enzyem so the usbstrate now fits in enzyme

allosteric regulators as inhibitors

inhibitors bind to allosteric site and change the shape of the enzyme so substrate can’t bind to active site

feedback inhibition

end product of a metabolic pathway shits down the pathway

prevents a cell fromw asting chemical resources by synthesizing more product than is needed

cooperativity

form of allosteric regulation that can amplfiy enzyme activity

• One substrate molecule primes an enzyme to act on additional substrate molecules more readily

• Cooperativity is allosteric because binding by a substrate to one active site affects catalysis in a different active site

aerobic respiration

cellular respiration

• oxygen required

• more energy released through the oxidation of glucose

anaerobic respiration

fermentation

• no oxygen required

• less energy released through partial splitting of glucose

aerobic pathway

glycolysis

first step in cellular respiration

occurs in the cytosol

turns glucose into 2 3-C sister pyruvates/pyruvic acids

takes 2 atp to start , forms 4 atp

NET total: 2 pyruvates + 2H20, 2ATP, 2 NADH + 2H

redox reaction

allows energy to be released from glucose in a series of steps that will capture the maximum amount of energy that is released from it

electrons lose energy as they’re transferred from a less to a more electronegative atom

coenzyme NAD+ will serve as an intermediate electron acceptor throughout the process and FAD serves as an electron carrier as FADH2

NADH will eventually give up the electrons to the ETC and they will gradually be transferred to a lower energy level (through oxidation/reduction) and their energy will be harnessed

substrate level phosphorylation

a biochemical reaction where a phosphate group is directly transferred from a high-energy phosphorylated intermediate to ADP (or GDP) to produce ATP (or GTP)

what happens after glycolysis but before enetering the citric acid cycle?

2 pyruvates are transformed to 2 actetyl coA

through NAD+ → NADH and removal of Co2 and addition of coenzyme A

citric acid cycle (krebs cycle)

occurs in the mitochondrial matrix

acetyl coa enters the cycle and is added to oxaloacetate to produce citrate

through redox reactions, 2 ATP is produced