Cell Structure and Function- Lecture 11-13(Unit 3)

Cellular respiration

harvests the energy remaining in pyruvate and NADH from glycolysis

external

Cellular respiration uses an _________ electron acceptor to
oxidize substrates completely to CO2

aerobic respiration

the terminal electron acceptor is oxygen, and the reduced form is water

CO2

With O2 as the terminal electron acceptor, pyruvate can be
oxidized completely to ____

More ATP

Having oxygen as the terminal electron acceptor allows for the
generation of _____ than glycolysis alone

Oxygen

provides a means of continuous reoxidation of NADH
and other reduced coenzymes

Mitochondria

___________ are found in virtually all aerobic cells of eukaryotes

chemotrophic and phototrophic

Mitochondria They are present in both ___________ and ____________ cells

need for ATP

Mitochondria are frequently clustered in regions of cells with the greatest __________, such as muscle cells

mitochondria

What is the brown stuff in this muscle cell

porins

outer membrane(mitochondria) contains ________ that allow passage of solutes with molecular weights up to 5000

intermembrane space

The _______________ between the inner and outer membranes(mitochondria)

intermembrane space and mitochondrial matrix

The inner membrane is impermeable to most solutes, partitioning the mitochondrion into two separate compartments that _________ and __________

cristae

The inner membrane of most mitochondria has many infoldings called _________

They increase surface area of the inner membrane and
provide more space for electron transport to take place

Benefits of having cristae in the mitochondria

cytosol

95% of proteins in mito are encoded by nuclear genes
and are synthesized in ________

Transit sequences

__________ are targeting signals located on the N-
terminal of a polypeptide

Transit peptidase

____________ are enzymes that remove the transit
sequence once the polypeptide has arrived

Special transport complexes

______________ on the outer and inner membrane of the mitochondria allow for uptake of polypeptide chains

TOM and TIM

Two pores for transport into and out of the mito are

TOM

translocase of the outer membrane

TIM

translocase of the inner membrane

Transit sequence receptors

component of transport complex that recognizes
transit sequences

Chaperone proteins

bind polypeptides targeted to the mitochondria to help maintain
the unfolded state

1st step for transporting polypeptides into the mitochondrial matrix

Hsp70 chaperone proteins bind to the polypeptide. Help unfold

2nd step for transporting polypeptides into the mitochondrial matrix

TOM transit sequence receptor binds the N-terminus of the polypeptide

3rd step for transporting polypeptides into the mitochondrial matrix

Chaperone proteins are released, and ATP is hydrolyzed as polypeptide moves through the TOM and TIM pores

4th step for transporting polypeptides into the mitochondrial matrix

Transit sequence is removed by transit peptidase in the matrix as
soon as the transit sequence enters the matrix

5th step for transporting polypeptides into the mitochondrial matrix

Mitochondrial Hsp70 chaperone proteins bind polypeptide as it
enters the matrix

6th step for transporting polypeptides into the mitochondrial matrix

Often, mitochondrial Hsp60 chaperone proteins bind the
polypeptide and assist in proper folding

drive ATP synthesis

In the presence of oxygen, pyruvate is oxidized fully to
carbon dioxide with the released energy used to ___________

tricarboxylic acid cycle, TCA cycle

The citric acid cycle is also known as ______ and ________

citrate

in the citric acid cycle, _______ is an important intermediate

Krebs cycle

The citric acid cycle is also called the _______ after Hans Krebs, whose lab played a key role in elucidating the cycle

carbons,  CO2, oxaloacetate

Each round of the citric acid cycle involves the entry of two ______, the release of two _____, and the regeneration of _________

electrons

The overall TCA cycle, in each case the _______ are accepted by coenzymes

pyruvate

The glycolytic pathway ends with _________, which can enter the intermembrane space of the mitochondrion

transports pyruvate into the matrix

At the inner mitochondrial membrane, a specific symporter ________________ , along with a proton

pyruvate dehydrogenase complex (PDH).

After being transported into the matrix pyruvate is converted
to acetyl CoA by _________________

3 carbon compound, 4 C compound, decarboxylations, NADH, FADH2, GTP

Summary of TCA cycle:

• Start with ___________
– Cleave off one CO2 in bridging reaction
– Add the other two to __________ to make their cleavage easier
• Two ___________
• 3 ______ produced, 1 ______, and 1 ___

CoA

_____ is co-enzyme co-substrate in bridging reaction and in cycle

they would have two protons added and it would be FADH2

What would be added to the Nitrogen’s on FAD after it it reduced

3, CO,  COA - SH

The citric acid cycle can be summarized as follows:

acetyl COA + _NAD + FAD + ADP + Pi=
2___ + _NADH + FADH + _______ + ATP

10NAD, 2FAD, 6CO2

Including glycolysis, pyruvate decarboxylation, and the
citric acid cycle, the overall reaction is as follows: 

glucose + __NAD + _FAD + 4ADP + 4Pi =
_CO + __NADH + _FADH + 4ATP

allosteric regulation

Most of the control of the TCA cycle involves ____________ of four key enzymes by specific effector molecules

Substrates of TCA

CoA, NAD+, FAD, and ADP

Products of TCA

3NADH, FADH2, 2CO2, and ATP

NAD H, ATP, and acetyl CoA

are allosteric inhibitors of enzymes in this cycle

NAD+, ADP, and AMP

each activate at least one regulator enzyme in this cycle

four, two, two, ATP, NADH and FADH2

Chemotrophic energy metabolism through the citric acid
cycle accounts for synthesis of ____ ATP per glucose
– ___ from glycolysis
– ___ from the citric acid cycle
▪ GTP gets converted to ____

• The remainder is stored in _____ and ______

electron transport

Transfer of electrons from reduced cofactors (NADH,
FADH2) to oxygen is called ___________

functionally linked

Electron transport and ATP generation are not independent processes; they are_____________ to each other.

electron transport chain (ETC).

Electron transfer is carried out as a multistep process
involving an ordered series of reversibly oxidized electron carriers functioning together.
• This is called the ________________

inner mitochondrial membrane, plasma membrane

The ETC contains a number of integral membrane proteins that are found in the ____________________ (or ___________ of bacteria)

I, III, and IV

Complexes _________ are found in the inner
mitochondrial membrane

II

Complex __ is involved in succinate oxidation

10 protons are pumped from the matrix into
the intermembrane space

For each pair of electrons transported through complexes
I, III, and IV, _______________________________

Complex I, NADH dehydrogenase

__________ transfers electrons from NADH to CoQ and is called the NADH–coenzyme Q oxidation complex (or____________ )

FMN cofactor

Complex I receives electrons from NADH and transfers them to a bound ________. The electrons are transferred to an Fe-S center, which passes them to a mobile pool of CoQ

Fe-S center, CoQ

Complex I transfers the electrons to an Fe-S center, which
passes them to a mobile pool of ___

4 protons

From complex 1 when 2 electrons are transferred, _____ are pumped across the membrane

Complex II

transfers electrons from succinate to FAD (generating FADH2; this is reaction CAC-6). The electrons in FADH2 are transferred through three Fe-S centers to CoQ

0

In complex II _ protons are pumped during this reaction

succinate–coenzyme Q oxidoreductase complex, or succinate dehydrogenase

This complex(II) is called the ____________________

cytochrome complex

Complex III is called the _____________ because two
cytochromes are prominent components

coenzyme Q–cytochrome c oxidoreductase complex

Complex III is also called ____________________________ because it accepts electrons from CoQ and transfers them to cytochrome c

4

In complex III when 2 electrons are transferred, _ protons are pumped across the membrane

cytochrome c oxidase

Complex IV is called ____________

Fe atom in the heme, cytochrome a3, copper atoms

In complex IV electrons transfer from cytochrome c to an __________, A cofactor of cytochrome a then to _________. There are two ________ which each receive one electron

four electrons

In complex IV, _____________ are needed to reduce O2 to H2O

two

In complex IV, ___ protons are pumped across the membrane for each electron pair

Cytochrome c oxidase (complex IV)

is the terminal oxidase, transferring electrons directly to oxygen

Cyanide and azide ions, Fe-Cu

_____________ are poisons
– bind the ____ center of cytochrome c oxidase, blocking final electron transport

DNA and protein synthesizing

Mitochondria contain their own ________________
machinery

cytosol

more than 95% of proteins residing in the mitochondria
are encoded by nuclear DNA and synthesized in the _______

– Complex I, II, III, IV proteins
– tRNAs
– Mitochondrial rRNA

Genes encoded by mito DNA include

Complexes I and III, incomplete reduction

______________ can also transfer electrons to oxygen,
resulting in its ___________

O2, H2O2

Complex I and III transfering electrons to oxygen can generate toxic superoxide anion ____ or hydrogen peroxide ______, both of which contribute to cellular aging

antioxidants

Role of _________ in cells is to soak up these highly
reactive oxidants(O2, H2O2) and prevent cellular damage

mitochondrial inner membrane

The electron transport chain generates a proton gradient
across the ___________________

ATP synthesis

The electrochemical proton gradient drives ___________

electrochemical proton gradient

The crucial link between electron transport and ATP production
is an ________________________

coupled

ATP synthesis is _______ to electron transport

peter mitchell

In 1961 __________ proposed the chemiosmotic coupling model

electrochemical potential across a membrane

The essential feature of the chemiosmotic coupling model is that the link between electron transport and ATP formation is the _________________

respiratory complexes

The electrochemical potential is created by the pumping of
protons across a membrane as electrons are transferred
through the _______________

NADH, 10 protons

The transfer of two electrons from _______ is accompanied by the pumping of a total of _________

2.5 - 3 ATP

_______ per NADH oxidation

1.5 - 2 ATP

________ per FADH2 oxidation

glycolysis and TCA

Some of the energy of glucose is stored in reduced NADH
and FADH2
– Generated in both _____ and _____

F1Fo ATPase

_________ generates ATP by coupling H+ transport with ATP
synthesis

inner membrane

The F1 complex is attached to the Fo complex that is embedded in the ______________

proton translocator

Fo acts as a ____________, the channel through which protons flow across the membrane

Fo

provides a channel for exergonic flow of protons across
the membrane

F1

carries out the ATP synthesis, driven by the energy of the proton gradient

ATP synthase.

Together(F1 and Fo), they form a complete ___________

two, ten

Fo subunit has ___  b subunits, and __ c subunits

static, gear

The a and b subunits are _____. The c subunits form a ring that act as a ____ and can rotate

a subunit

The ________ is the proton channel

two b subunits

The _________ form the stator stalk, which connects the Fo and F1 complexes