Chapter 6 Flashcards
All cells need to accomplish two fundamental tasks
- Synthesize new parts
- Harvest energy to power reactions
Sum of all chemical reaction in a cell:
metabolism
two types of metabolism
Catabolism
Anabolism
- Degradation of compounds to release energy
- Cells capture energy to make ATP
catabolism
- Assemble subunits of macromolecules
- Use ATP to drive reactions
Anabolism
another name for Anabolism
Biosynthesis
Produced during
catabolism
Precursor metabolites
Contains just glucose, inorganic salts
glucose-salts medium
source of energy for glucose-salts medium
glucose
is starting point for all
cellular components
glucose
glucose molecules
are broken into smaller
precursor metabolites
why do the precursor
metabolites exit the catabolic
pathway early
to be used in biosynthesis
are intermediates of
catabolism that can be used in anabolism
Precursor metabolites
is the capacity to do work
Energy
Two types of energy
potential and kinetic
stored energy
Potential
energy of movement
Kinetic
Energy in universe cannot be
created or destroyed,
what can energy do to change
it can be converted between forms
Light powers synthesis of organic compounds from CO2
Photosynthetic organisms
what powers Photosynthetic organisms
Light powers synthesis of organic
compounds from CO2
what kind of energy does Photosynthetic organisms convert
kinetic energy
what does Photosynthetic organisms convert KE to
potential energy of chemical bonds
Obtain energy by degrading organic matter to make other organic compounds
Chemoorganotrophs
how do Chemoorganotrophs get energy
degrading organic matter to make other organic compounds
what kind of energy does Chemoorganotrophs convert
potential energy of chemical
bonds
what does Chemoorganotrophs convert PE to
other potential energy of
chemical bonds
is energy available to do work
Free energy
Energy released when chemical bond is brok
free energy
Energy is released in reaction
Exergonic reactions
what has more energy in Exergonic reactions product or reactants
reactants
Reaction requires input of energy
Endergonic reactions
what has more energy in
Endergonic reactions product or reactants
products
series of chemical reactions
that convert starting compound to an end product
Metabolic pathways
types of Metabolic pathways
linear, branched, cyclical
energy currency of
the cell
ATP (Adenosine triphospate)
accepts free energy
ADP
releases free energy
ATP
Cells produce ATP by adding what to ADP using energy
Pi
Three processes to generate ATP
-Substrate-level phosphorylation (chemoorganotrophs)
-Oxidative phosphorylation (chemoorganotrophs)
-* Photophosphorylation (photoautotrophs)
Addition of phosphate using energy released during an
exergonic reaction
Substrate-level phosphorylation
Using energy from a proton motive force powered by the
oxidation of nutrients
Oxidative phosphorylation
Using energy from a proton motive force powered by sunlight
Photophosphorylation
what kind of trophs use Photophosphorylation
photoautotrophs
what kind of trophs use Substrate-level phosphorylation
chemoorganotrophs
what kind of trophs use Oxidative phosphorylation
chemoorganotrophs
Electrons removed through series of
oxidation-reduction
reactions or redox reactions
Substance that loses electrons is
oxidized
Substance that gains electrons is
reduced
what atom usually does the moving
Electron-proton pair, or hydrogen atom,
Dehydrogenation
oxidation
Hydrogenation
reduction
OILRIG
Oxidation Is Loss
Reduction Is Gain
what happens when Some atoms, molecules are more electronegative than
others
Greater affinity for electrons
electrons move from molecule
that has low affinity for
electrons
(energy source)
Energy released when
electrons move from molecule
that has low affinity for electrons
(energy source)
to a molecule that has high
affinity for electrons (terminal
electron acceptor)
electrons move from molecule
that has low affinity for electrons
(energy source)
to a molecule that has high
affinity for
electrons (terminal
electron acceptor)
More energy released when
difference in electronegativity is
greater
used as energy source
Organic (ex: glucose), inorganic
compounds (ex; H2S)
used as terminal electron acceptor
O2 (for aerobes), other molecules
transfer electrons to the terminal electron acceptor
Electron Carriers
Electrons transferred to
Electron Carriers
(oxidized) Electron Carriers
NAD+
(reduced) Electron Carriers
NADH
Electron carriers represent
reducing power
why do Electron carriers represent reducing power
because they easily transfer electrons to chemicals with higher affinity for electrons
speed up conversion of substrate into
product
Biological catalysts:
how do Biological catalysts speed up conversion of substrate into
products
by lowering activation energy
energy required to
start a reaction
activation energy
are biological catalysts, they increase the rate of a reaction
Enzymes
how are Enzymes named
ends in –ase
on surface of enzyme binds substrate(s)
weakly
Active site
Causes enzyme shape to change slightly
Active site
what do Active site do to activation energy
lower
are used to break large molecules into smaller ones or to build large molecules from its subunits
Enzymes
Some enzymes require the assistance of an attached non-protein component called
Cofactors
are organic cofactors
Coenzymes
are organic cofactors
Coenzymes
increase doubles speed of enzymatic reaction up
until maximum
10°C
Proteins denature at
higher temperatures
Enzyme activity can be controlled by regulatory molecules binding
to allosteric site
Allosteric Regulation
Enzyme activity can be controlled by regulatory molecules binding
to
allosteric site
Distorts enzyme shape, prevents or enhances binding of substrate
to active site
Allosteric Regulation
Regulatory molecule is usually
end product
Regulatory molecule is usually end product
feedback inhibition
inhibitor binds to active site
Competitive inhibition
Chemical structure of inhibitor usually similar to
substrate
Blocks substrate
Competitive inhibition
inhibitor binds to a site
different than the active site
Non-competitive inhibition
Allosteric inhibitors are example of what
Non-competitive inhibition
are all Non-competitive inhibition reversible
no
Central metabolic pathway
- Glycolysis
- Pentose phosphate pathway
- Tricarboxylic acid cycle
Key outcomes of Catabolism
- ATP
- Reducing power
- Precursor metabolites
The Central Metabolic Pathways
1) glycolysis
2) pentose phosphate pathway
3) Tricarboxylic acid cycle (TCA)
types of Reducing power
NADH
FADH2
NADPH
two fates of Glucose molecule
- Can be completely oxidized to CO2 for maximum ATP
- Can be siphoned off as precursor metabolite for use in
biosynthesis
Gradually oxidize glucose to
CO2
central metabolic are catabolic or anabolic
catabolic
Pathways generate what?
precursor metabolites + reducing
power (for use in biosynthesis)
Splits glucose (6C) to two pyruvate (3C)
Glycolysis
Glycolysis splits glucose into how many pyruvate
2
what does Glycolysis use to make pyruvate
glucose
Primary role is production precursor metabolites, NADPH
Pentose phosphate pathway
primary role of Pentose phosphate pathway
production of precursor metabolites, NADPH
Oxidizes pyruvates from glycolysis
Tricarboxylic acid cycle (TCA)
primary role of Tricarboxylic acid cycle (TCA)
Generates reducing power, precursor metabolites, ATP
does aerobic respiration use electron transport chain
yes
what terminal electron acceptor does aerobic respiration use
O2
does anaerobic respiration use electron transport chain
yes
what terminal electron acceptor does aerobic respiration use
anything other than O2
usually nitrate, nitrite, sulfate
does fermentation use electron transport chain
no
what terminal electron acceptor does fermentation use
organic molecule (pyruvate or derivative)
ATP made by substrate-level phosphorylation with aerobic respiration
4
ATP made by oxidative phosphorylation with aerobic respiration
34
total ATP made with aerobic respiration
38
ATP made by substrate-level phosphorylation with anaerobic respiration
less than aerobic respiration
ATP made by oxidative phosphorylation with anaerobic respiration
less than aerobic respiration
total ATP made with anaerobic respiration
less than aerobic respiration
ATP made by substrate-level phosphorylation with fermentation
2
ATP made by oxidative phosphorylation with fermentation
o
total ATP made with fermentation
2
net gain of Glycolysis
2 ATP and 2 NADH
Glycolysis phases
Investment phase
Pay-off phase
which steps of Glycolysis is the investment phase
Step 1 through 5
which steps of Glycolysis is the pay-off phase
Step 6 through 10
trick to know glycolysis products
“Girls Get Fine Food; Gentlemen Dine
Girls; Boys Prefer to Pick up Pepperoni
Pizza”
Glucose
Glu-6-P
Fru-6-P
Fru-1,6-bP
G3P + DHAP
2x G3P
2x 1,3-BPG
2x 3-PG
2x 2-PG
2x PEP
2x Pyr
Breaks down glucose
Pentose Phosphate Pathway
why is Pentose Phosphate Pathway important
it produces precursor metabolites for
biosynthesis
Produces reducing power: Variable amount of NADPH (Yields
vary depending upon alternative taken)
Pentose Phosphate Pathway
which product of Pentose Phosphate Pathway can enter glycolysis
glyceraldehyde-3-phosphate
does Pentose Phosphate Pathway require o2
no
where does Pentose Phosphate Pathway occur
cytoplasm or chloroplast (plants)
Does Pentose Phosphate Pathway produce or use ATP
no
what happens in the Transition Step
- CO2 is removed from pyruvate
- Coenzyme A added to 2-carbon acetyl group to form acetyl-CoA
- Produces reducing power
- Produces 1 precursor metabolite:
CO2 is removed from pyruvate
decarboxylation step
added to 2-carbon acetyl group to form acetyl-CoA
Coenzyme A
where does the transition step occur
cytoplasm (prokaryotes)
or
mitochondria (eukaryotes)
Kreb’s Starting Substrate For Making
Oxaloacetate
Citrate
cool way to remember kreb cycle products
“Our City Is Kept Safe & Secure From Monsters”
Oxaloacetate
Citrate
Isocitrate
α-ketoglutarate
Succinyl
CoA
Succinate
Fumarate
Malate
Completes oxidation of glucose
Tricarboxylic Acid (TCA) Cycle
how many turns of Tricarboxylic Acid (TCA) Cycle occur for one molecule of glucose
2
what do two turns of Tricarboxylic Acid (TCA) Cycle produce
- 4 CO2
- 2 ATP (energy)
- 6 NADH (reducing power)
- 2 FADH2 (reducing power)
tricarboxylic Acid (TCA) Cycle Produces which 2 precursor metabolites
α-ketoglutarate;
oxaloacetate
does the TCA cycle require O2
yes
where does the TCA cycle occur
cytoplasm (prokaryotes)
or
mitochondria (eukaryotes)
transfers electrons from glucose to electron transport chain
Respiration
how is reducing power generated
glycolysis,
transition step, and TCA cycle to synthesize ATP
what are the two processes involved in respiration
➢Electron transport chain
➢Harvested to make ATP
generates proton motive force using
reducing powers
Electron transport chain
Harvested to make ATP by
ATP synthase
ATP is generated by
oxidative phosphorylation
O2 is terminal electron acceptor
Aerobic respiration
Molecule other than O2 as terminal electron acceptor
Anaerobic respiration
is membrane-embedded
electron carriers
Electron transport chain
the Electron transport chain accepts electron from?
NADH and FADH2
how does the Electron transport chain pass electrons
sequentially (energy gradually released), eject protons in process
Protons pumped across the membrane create electrochemical
gradient =
proton motive force
is used to synthesize ATP
proton motive force
does the Electron transport chain need O2
yes
where is the electron transport chain located
cytoplasm (prokaryotes)
or
mitochondria (eukaryotes)
Most carriers grouped into large protein complexes that
function as
proton pumps
Lipid-soluble, move freely, can transfer electrons between
complexes
Quinones
Contain heme, a molecule that holds and iron atom in its center
Cytochromes
example of Quinones
ubiquinone (“ubiquitous quinone”)
can be used to distinguish bacteria
Cytochromes
Proteins to which a flavin is attached
Flavoproteins
Some carriers accept only hydrogen atom
proton-electron
pairs
When hydrogen carrier accepts electron from electron carrier,
it picks up proton from
from inside cell (or mitochondrial matrix)
When hydrogen carrier passes electrons to electron carrier,
protons released to
outside of cell (or intermembrane space of mitochondria)
is movement of protons across membrane to create a concentration gradient
Net effect
another name for Complex I
NADH dehydrogenase complex
Accepts electrons from TCA cycle via FADH2, “downstream” of
those carried by NADH
Complex II
Complex II Transfers electrons to
ubiquinone
another name for Complex II
(succinate dehydrogenase complex
Accepts electrons from ubiquinone from Complex I or II
Complex III
how many protons are pumped by Complex III
4
electrons transferred to cytochrome c
Complex III
Accepts electrons from NADH, transfers to ubiquinone
Complex I
how many protons does Complex I pump
4
another name for Complex III
cytochrome bc1 complex
another name for Complex IV
cytochrome c oxidase complex
how many protons does Complex IV pump
2
Accepts electrons from cytochrome c
Complex IV
meaning transfers electrons to
terminal electron acceptor (O2)
Terminal oxidoreductase,
what kind of oxidoreductase is complex IV
Terminal oxidoreductase,
- Can use 2 different NADH dehydrogenases
- Succinate dehydrogenase
- Lack equivalents of complex III or cytochrome c
- Quinones shuttle electrons directly to functional equivalent
of complex IV - Ubiquinol oxidase
Aerobic respiration in E. coli
(one is equivalent to complex I of mitochondria)
2 different NADH dehydrogenases
(equivalent to complex II of
mitochondria)
Succinate dehydrogenase
what does Aerobic respiration in E. coli lack
equivalents of complex III or cytochrome c
shuttle electrons directly to functional equivalent of complex IV
Quinones
equivalent to complex IV of
mitochondria
Ubiquinol oxidase
another terminal oxidoreductase
Ubiquinol oxidase
- Harvests less energy
– Lower electron affinities of terminal electron acceptors
- Terminal electron acceptor is not O2
Anaerobic respiration in E. coli
Harvests less energy than aerobic respiration
Anaerobic respiration in E. coli
what is the terminal electron of Anaerobic respiration in E. coli
- can be nitrate and produce nitrite
- can be Sulfate-reducers use sulfate and produce hydrogen sulfide (H2S)
why does Harvests Anaerobic respiration in E. coli less energy than aerobic respiration
Lower electron affinities of terminal electron acceptors
Harvesting the Proton Motive Force
to Synthesize ATP
ATP Synthase
allows protons to flow down gradient in controlled manner
ATP Synthase
does ATP Synthase use energy to add phosphate group to ADP
yes
1 ATP formed from how many protons
3
how many ATP from 1 NADH
3
how many ATP from 1 FADH2
2
total ATP yield from proton
motive force In prokaryotes
34
ATP yield in glycolysis from proton motive force In prokaryotes
2 NADH→ 6 ATP
ATP yield in transition step from proton motive force In prokaryotes
2 NADH → 6 ATP
ATP yield in TCA Cycle from proton motive force In prokaryotes
6 NADH → 18 ATP
and
2 FADH2 → 4 ATP
total ATP yield from Substrate-level phosphorylation In prokaryotes
4 ATP
ATP yield in glycolysis from Substrate-level phosphorylation In prokaryotes
2 ATP
total ATP yield from oxidative phosphorylation In prokaryotes
34
ATP yield in glycolysis from oxidative phosphorylation In prokaryotes
6
ATP yield in transition step from oxidative phosphorylation In prokaryotes
6
ATP yield in TCA Cycle from oxidative phosphorylation In prokaryotes
22
total ATP yield from Aerobic Respiration In prokaryotes
38
If cells cannot respire, will run out of carriers available to
accept/transfer electrons
Fermentation
what molecule can’t be broken down in fermentation
glucose
uses pyruvate or derivative as terminal electron acceptor to
regenerate NAD
fermentation
what step doesn’t fermentation have
TCA
when when respiration not an option what is done
fermentation
when is another time where fermentation is the only option
When the organism lacks electron transport chain
serve as a terminal electron acceptor to regenerate NADH into NAD+ needed during glycolysis
Pyruvate or derivatives
end products of fermentation
- Lactic acid
- Ethanol
- Butyric acid
- Propionic acid
- 2,3-Butanediol
- Mixed acids
Secrete hydrolytic enzymes
Microbes
Transport subunits into cell
Microbes
Microbes are degraded further to what
appropriate precursor metabolites
examples of Polysaccharides
- Starch
- Cellulose
Digested by the enzyme amylase
starch
Digested by the enzyme cellulase
cellulose
where is cellulose located
in fungi and bacteria of ruminants
example of Disaccharides
Lactose, maltose and sucrose
types of lipids
Fats (fatty acids + glycerol)
hydrolyzed by lipases
Fats (fatty acids + glycerol)
Glycerol converted and enters
glycolysis
Fatty acids degraded and enter
TCA cycle
Hydrolyzed by proteases
proteins
Amino group removed
deaminated
converted into precursor molecules
Carbon skeletons
Prokaryotes unique in ability to use reduced inorganic compounds as
sources of energy
may serve as energy source for another
Waste products of one organism
examples of Waste products of one organism may serve as energy
source for another
hydrogen sulfide (H2S)
and
ammonia (NH3)
Produced by anaerobic respiration from inorganic molecules
(sulfate, nitrate) serving as terminal electron acceptors
hydrogen sulfide (H2S)
and
ammonia (NH3)
Used as energy sources for sulfur bacteria and nitrifying
bacteria
hydrogen sulfide (H2S)
and
ammonia (NH3)
is the source of carbon
CO2
energy from sunlight
carbon from CO2
Photoautotrophs:
energy from sunlight
carbon from organic compounds
Photoheterotrophs
energy from inorganic compound
carbon from CO2
Chemolithoautotrophs
or
chemoautotrophs,
or
chemolithotrophs
energy and carbon from organic compounds
Chemoorganoheterotrophs
or
chemoheterotrophs,
or
chemoorganotrophs
Four general groups of chemolithotrophs
- Hydrogen bacteria oxidize
- Sulfur bacteria
- Iron bacteria
- Nitrifying bacteria
can use simple organic compounds for energy
Hydrogen bacteria oxidize
can live in pH of less then 1
Sulfur bacteria
has iron oxide present in sheaths
Iron bacteria
important in nitrogen cycle
Nitrifying bacteria
extract electrons from inorganic energy sources
Chemolithotrophs
Pass electrons to an electron transport chain that generates
proton motive force
incorporate CO2 into an organic form
chemolithotrophs
capture and conversion of radiant
energy into chemical energy
Photosynthesis
In cyanobacteria and photosynthetic eukaryotic cells
Oxygen
In Purple and green bacteria
sulfur
Two distinct stages in photosynthesis
Light reactions
Light-independent reactions
light-dependent reactions)
Light reactions
Capture radiant energy and use it to generate ATP and reducing power
Light reactions
(dark reactions)
Light-independent reactions
Use ATP and reducing power to synthesize organic
compounds
Light-independent reactions
Involves carbon fixation
Light-independent reactions
Photosynthetic pigments
- Chlorophylls
- Bacteriochlorophyll
- Carotenoids
- Phycobilins
(in plants, algae, cyanobacteria)
Chlorophylls
in anoxygenic bacteria
Bacteriochlorophylls
Absorb different wavelengths than chlorophylls
Bacteriochlorophylls
many photosynthetic prokaryotes and eukaryotes
Carotenoids
cyanobacteria, red algae
Phycobilins
Pigments are located in protein complexes
photosystems
capture and use light energy
Photosystems
funnel light energy to the reaction-center pigments
Antennae pigments
excited by radiant energy (=energy
of light); emit electrons
that are passed to the
electron transport chain
Reaction-center
pigments
photosystems in membranes of
thylakoids (inside cell)
Cyanobacteria
what goes through Light-dependent reactions:
cyanobacteria and eukaryotes
(plants and algae)
Two distinct photosystems (I and II)
Cyclic photophosphorylation
Non-cyclic photophosphorylation
– Photosystem I alone
– Produces ATP (using energy from the proton motive force)
– Reaction-center chlorophyll is the electron donor and the
terminal electron acceptor
Cyclic photophosphorylation
is the electron donor and the
terminal electron acceptor of Cyclic photophosphorylation
Reaction-center chlorophyll
what does Cyclic photophosphorylation produce
ATP
– Produces both ATP and reducing power
– Electrons from photosystem II drive photophosphorylation
– Electrons are then donated to photosystem I
– Photosystem II replenishes electrons by splitting water
– Generates oxygen (process is oxygenic)
– Electrons from photosystem I reduce NADP+ to NADPH
Non-cyclic photophosphorylation
what does Non-cyclic photophosphorylation produce
both ATP and reducing power
what does Non-cyclic photophosphorylation generate
oxygen
replenishes electrons by splitting wate
Photosystem II
Electrons from photosystem II drive
photophosphorylation
anoxygenic photosynthetic
bacteria
Light-dependent reactions
how many photosystems does Light-dependent reactions have
one
can Light-dependent reactions use water
no
what electron donors does Light-dependent reactions use
hydrogen gas (H2)
hydrogen sulfide (H2S)
organic compounds
photosystem similar to photosystem II
Purple bacteria
photosystem similar to photosystem I
Green bacteria
Chemolithoautotrophs and photoautotrophs use CO2 to
synthesize organic compounds:
carbon fixation
Consumes lots of ATP, reducing power
carbon fixation
most commonly used to fix carbon but others are possible
Calvin cycle
Three essential stages
- Incorporation of CO2 into organic compounds
- Reduction of resulting molecule
- Regeneration of starting compound
