Ch 9 Flashcards
three key pathways of respiration
glycolysis, the citric acid cycle and oxidative phosphorylation
organic compounds posses potential energy because
of the arrangement of electrons in the bonds between their atoms
cells systematically degrade molecules that are rich in potential energy into
simpler waste products that have less energy
compounds that can participate in exergonic reactions can act as
fuels
fermentation
catabolic process where there is a partial degradation of sugars or other organic fuels that occurs without the use of oxygen
aerobic respiration
a prevalent and efficient catabolic process in which oxygen is consumed as a reactant along with the organic fuel
what kinds of cells can carry out aerobic respiration
the cells of most eukaryotic and prokaryotic organisms
anaerobic respiration
substances other than oxygen are used as reactants in a process that harvests chemical energy without oxygen
cellular respiration
both aerobic and anaerobic respiration
summarize aerobic respiration
organic compounds+ O= CO2 +H2O +Energy
degradation of the sugar glucose (as opposed to other carbohydrates, fats, and proteins)
C6H12O6+ 6O2= 6CO2+ 6H2O +Energy (ATP+ Heat)
fuel that most cells most often use
glucose
the break down of glucose is _gonic
exer-
How do catabolic pathways that decompose organic fuels yield energy?
the relocation of electrons releases energy stored in organic molecules and this energy synthesizes ATP
redox reactions
there is a transfer of one or more electrons (e-) from one reactant to another. these e- transfers are called oxidation-reduction reactions
oxidation
the loss of e- from one substance in a redox reaction
reduction
the addition of e- to another substance (called such because e- lower positivity in atoms)
reducing agent
e- donor
oxidizing agent
e- acceptor
generalized redox
Xe- + Y= X + Ye-
some redox reaction do not involve the complete transfer of electrons but
some change in the degree of sharing in covalent bonds
the most potent of all oxidizing agents and why
oxygen, electronegativity
in general organic molecule that have an abundance of hydrogen are excellent
fuels, because of the bonds to their electrons are at the “top of the hill”
in respiration, hydrogen is transferred from
glucose to oxygen
in respiration, the oxidation of glucose transfers electrons to a lower energy state,
liberating energy for ATP synthesis
what holds back the energy rich molecules
the barrier of activation
glucose and other organic fuels are broken down in
steps catalyzed by enzymes
at key steps e- are ___ from glucose
stripped
in oxidation reactions, electrons travel with
a proton: as a hydrogen atom
NAD+
since hydrogen atoms aren’t transferred directly to oxygen, it is passed to this coenzyme instead.it is well suited as it can cycle between its oxidized (NAD+) and its reduced (NADH) forms easily. During respiration it is an oxidizing agent
How does NAD+ trap electrons from organic molecules like glucose
- enzymes called dehydrogenases remove a pair of hydrogen atoms (2 protons and 2e-) from the substrate, oxidizing it
- the enzyme then delivers 2 e- and 1 proton to its coenzyme NAD+
- the other proton is released as a hydrogen ion (H+)
NAD+ to NADH formula
H-C-OH +NAD+ Dehydrogenase-C=O +NADH+ H+
When reduced to NADH, NAD+’S charge is
neutralized
the most versatile e- acceptor in cellular respiration and functions in several redox steps during the breakdown of glucose
NAD+
during the transfer from glucose to NAD+ e-
lose very little of their potential energy
electron transport chain
consists of a number of molecules, mostly proteins, built into the inner membrane of the mitochondria of eukaryotic cells and the plasma membrane of aerobically respiring prokaryotes
electron transfer from NADH to oxygen is an ___gonic reaction
exer-
electron path during cellular respiration
glucose to NADH to electron transport chain to oxygen