Test 3 Review Flashcards
After isolating the rough ER, you purify. What would you expect from the rough ER? A: soluble secreted protiens B:ER membrane proteins C:Neither D: Both A and B
A: soluble secreted protiens
B:ER membrane proteins
Which of the following states about vesicle budding from Golgi Apparatus is false?
A: Clathrin molecules are important for binding to and selecting cargoes for transport
B:Adaptins interact with clathrin
C:Once vesicle budding occurs and the vesicle comes into close proximity with the target membrane, clathrin molecules are released from the vesicle
D: Clathrin molecules act at the cytosolic surface of the Golgi membrane
A: Clathrin molecules are important for binding to and selecting cargoes for transport
Which of the following statements is true?
A: The signal sequence on mitochondrial proteins are nomally C-terminal
B: Most mitochondrial proteins are not imported from the cytosol but are synthesized inside the mitochondria
C: Chapterone proteins in the mitochondria facilitate the movement of proteins across the outer and inner mitochondrial membranes
D: Mitochondrial proteins cross the membrane in their native, folded state
C: Chapterone proteins in the mitochondria facilitate the movement of proteins across the outer and inner mitochondrial membranes
Glucogenesis refers to?
The synthesis of glucose from small molecules like pyruvate
Useful energy is obtained by cells when?
sugars are broken down by glycolysis, citric acid cycle, and oxidative phosphorylation
What is the name of the specialized junction between neuron and target cells?
synapses
T/F
Each of the three respiratory enzyme complexes includes metal atoms tat are tightly bound to protiens
true
The localization information for protein signaling in a eukaryotic cell is contained in _______ of the proteins.
amino acid sequences
Proteins enter the nucleus in their ______ forms.
folded
Proteins that remain in the cytosol don’t contain a ________.
signal sequence
The proteins transported in to the ER by _______ in their _____ forms.
protein translocators
unfolded
What drives the production of ATP from ADP and Pi by ATP synthase?
A proton gradient
The drug dinitrophenol (DNP) makes the inner mitochondrial membrane permeable to hydrogen ions. When added to mitochondria DNP does?
decreases production of ATP and affect the PH gradient across the membrane
Which component of the electron transport chain is required to combine the electrons with molecular oxygen?
Cytochrome C oxidase
What is a characteristic or measurment used to study the action potentials?
effects of a depolarizing stimulus
Which of the following statements about the endoplasmic reticulum is true?
A: The ER is the major site of new membrane synthesis in the cell
B: Proteins are to be delivered to the ER are synthesized on the ribosome of the rough ER
C: Neither
D: Both A and B
Both A and B
What is the order through which a protein destined for the plasma membrane travels?
Er> Golgi>Plasma membrane
Which of the following statements about the unfolded protein response (UPR) is false?
A: Misfolded proteins bind to receptors that stimulare the production of a transcription regulator
B: Activation of UPR results in chaperon production of more chaperon proteins
C:Actications of the UPR results in the transcript. Regulator translocation to nucleus
D: None of the above
None of the above
T/F
In secretory cells the regulated and constitutive pathways of exocytosis diverge the trans golgi network. A constitutive secretory pathways is one that operates only when extracellular signal stimulates their secretion
False
What is the role of the nuclear localization sequence in a nuclear protein?
A: it is bound by cytoplasmic nuclear receptor proteins that direct the nuclear protein to the nuclear pore
B: It is a hydrophobic sequence that enables the protein to enter the nuclear membranes
C: It aids in protein unfolding so that the protein can threat through nuclear pores
D: It prevents the protein from difffusing out of the nucleus through nuclear pores
it is bound by cytoplasmic nuclear receptor proteins that direct the nuclear protein to the nuclear pore
N-linked oligosaccharides on secreted gylcoproteins are attached to
A: The cytosolic face of the ER
B: The serine or threonine residue in the growing polypeptide chain
C: The NH2 of an asparagine residue in the growing polypeptide chain
D: None of the above
The NH2 of an asparagine residue in the growing polypeptide chain
ATP molecules produced in the cytosol and glucose being converted to pyruvate are both what parts of oxidative phosphorylation?
Neither are part
During an action potential which of the following actions does not help return membrane to its resting potential?
opening of voltage gated Na+ channels
Most proteins destined to enter the ER are:
A: Transported across the membrane after synthesis is complete
B: Synthesized on ribosomes bound to ER membrane
C: Begin to cross membrane while still being synthesized
D: Both B and C
Both B and C
- Synthesized on ribosomes bound to ER membrane
- `Begin to cross membrane while still being synthesized
(During ATP synthesis) In chemiosmosis useful energy is harnessed by the cell from the movement of _____________ across the inner mitochondrial matric _______ its concentration gradient.
Protons; down
T/F The enzyme that catalyzes the last irreversible reaction in glycolysis (STEP 10) yeilding a molecule each of ATP and pyruvate is called hexokinase.
False
-> The actual molecule is called pyruvate kinase
Which of the following protein familes are involved in directing transport vesicles to the target membrane?
A: Snares
B: Rabs
C: Tethering proteins
D: All of the above
All of the above
Which of the following statements concerning the ER signal sequence and/or the SRP is true?
A: THe SRP binds to the exposed ER signal sequence and to the ribosome, thereby slowing protein synthesis by the ribosome
B: The SRP-ribosome complex binds to an SRP receptor in the ER membrane
C: The SRP gets released, passing the ribosome to a translocation channel in the ER membrane
D: All of the above
All of the above
Describe events involved in propagation of an action potential?
A: An initial influx of Na+ though a small cluster of channels causes local depolarization of the membrane
B: Local depolarization causes nearby NA+ channels to open
C: Channels in depolarized regions of membrane are inactivated until the resting membrane potential is reestablished
D: All of the above
All of the above
Experimental Evidence supporting chemiosmotic hypothesis was gathered by using artificial vesicles containing a protein that can pump protons in one direction across the vesicle membrane to create a protein gradient. What protein is it?
Bacteriorhodopsin
What mechanism does the inhibitory neurotransmitter prevent the postsynaptic cell from firing an action potential?
By opening Cl- channels
The mitochondrial ATP synthase consists of several different protein subunits. Which subunit binds to ADP +P and catalyzes the synthesis of ATP as a result of conformational change?
F1 ATPase Head
Pyruvate is an important metabolic intermediate that can be converted into several other compounds, depending on which enzyme is catalyzing the reaction. Which of the following cannot be produced from pyruvate in a single enzyme-catalyzed reaction?
A: Lactate B: Oxaloacetate C: Alanine D: All of the Above E: None of the Above
None of the above
What is the final ATP count during glycolysis?
3
Final ATP of pyruvate oxidation of acetyl CoA
5
Final ATP of complete acetyl CoA oxidation?
15
Total ATP production?
30
What are the functions of lysosomes
degradation of worn out organelles
What is the function of the smooth ER?
steriod hormone synthesis
What is the function of the golgi?
modify secreted proteins
What is chemiosmotic coupling?
The linkage of electron transport, proton pumping and ATP sunthesis
What intracellular membrane bound structure contain both their own DNA and RNA?
mitochondria
In an area of high ATP ultilization, what membrane bound organelle might you find there? AKA-> By a cardiac muscle cell
mitochondira
What are the 4 seperate compartments of mitochondria?
Matrix, Inner membrane, Outer membrane, Intermembrane space
Hundred of Enzymes are located in this space, such as the enzymes required for oxidation of pyruvate and fatty acids for the citric acid cycle. What section of the mitochondria is this? A:Matrix B: Inner membrane C: Outer membrane D:Intermembrane space
Matrix
This space is folded into numerous cristae and contains proteins that carry out oxidative phosphorylation, including ATP synthase and the electron transport chain. What section of the mitochondria is this? A:Matrix B: Inner membrane C: Outer membrane D:Intermembrane space
Inner membrane
Containing large channel-forming proteins called porins, what section of the mitochondria is this? A:Matrix B: Inner membrane C: Outer membrane D:Intermembrane space
Outer membrane
This space contains several enzymes that use the ATP passing out of the matric to phosphorylate other nucleotides. What section of the mitochondria is this?
Intermembrane space
NADH donates it’s high energy electrons to?
the electron transport chain
The chemiosmotic mechanism for ATP synthesis is called?
oxidative phosphorylation
Protons are pumped across the inner mitochondrial membrane as the net product of this is?
3 NADH
1 FADH
1 GTP
2 CO2
The three respiratory enzyme complexes that perform proton pumping, in the order in which they receive electrons are?
NADH dehydrogenase complex
cytochrome c reductase complex
cytochrome c oxidase complex
Each respiratory enzyme complex contains ______ and other chemical groups that act as stepping stones to facilitate the passage of electrons.
metal ions
What two things serve as carriers that ferry electrons from one respiratory enzyme complex to another?
Ubiquinone and cytochrome C
What is the net equation for the process of energy conservation?
2NADH+O2-> 2NAD+ + 2H2O
How does NADH dehydrogenase accept electrons from NADH?
in the form of a hydride ion
What does proton motive force do?
pulls H+ back accross the membrane
What makes of the large force in the electrochemical H+ gradient?
the membrane potential
What is the large, multisubunit protein embedded in the inner mitochondrial membrane
ATP synthase
T/F
ATP synthase can operate in reverse, using the energy of ATP hydrolysis to pump protons “uphill” against electrochemical gradient across the membrane
True
What are F1 and F0 and what do they have to do with ATP synthase?
F1 is the stationary head of the multiunit protein
F0 is the rotating portion
F1 can do what when detatched from the from the F0 part of the complex?
carry out the reverse reaction
The high energy electrons donated by NADH and FADH after passing along the electron transport chain eventually combine with what?
O2 to form H2O
What is much of the energy harnessed from electron transfers along the respiratory chain used to do?
Pump H+ out of the matrix
What molecules are using symport transportation across the mitochondrial membrane?
H+ uses their electrochemical gradient to drive the import of pyruvate and Pi
What molecules are using antiport transportation across the mitochondrial membrane?
ATP is pumped out and ADP is pumped in depending on membrane potential
One glucose oxidation produced about?
30 ATP
What does poison cyanide do to the inner mitochondrial membrane?
Blocks electron transport
DNP stands for?
2, 4 dinitrophenol
What does DNP do?
prevents ATP from being made
How does DNP prevent ATP from being made?
by causing the inner membrane to be permeable to protons, allowing H+ to flow into mitochondrion without passing through ATP synthase so that ATP can no longer be made
When bacteriorhodopsin is added to artificial vesicles the protein does what?
generates a proton gradient in response to light
In artificial vesicles containing both bacteriorhodopsin and ATP synthase the proton gradient created drives?
the formation of ATP
If an uncoupling agent is present, will ATP be produced?
no
T/F
Protons in water are highly mobile and electron transfer can cause the transfer of entire hydrogen atoms, because protons are readlily accepted from water or donated to water.
True
What carries electrons within the lipid bilayer?
quinones, one of which being ubiquinone
T/F
With each of the three respiratory enzyme complexes, electrons move mainly between metal atoms that are tightly bound to the proteins. Electrons carried between the different complexes by molecules that diffuse alond the lipid bilayer, pick up electrons from one complex and deliver them to another.
True
_______ are the only electron carriers in electron transport chains that can function without being tightly bound to a protein
Quinones
what confines ubiquinone to the membrane?
it’s long hydrophobic tail
Where does ubiquinone pick up electrons from?
NADH or FADH2
Where does ubiquinone drop electrons off?
ctyochrome B-c1 complex
T/F
Cytochrome C is a small protein and contains just over 100 amino acids and is held loosely on the outer face of the inner membrane by ionic interaction
True
___________ is a protein complex that recieves electrons from cytochrome c and donates these to electrons to O2
Cytochrome oxidase
What two subunits does Cytochrome oxidase contain?
I and II
When elextrons pass through Cytochrome oxidase to it’s bound O2 molecule, what occurs?
The cause the protein to pump protons cross the membrane
What two metal atoms does cytochrome oxidase contain?
it contains a complex of a heme iron atom juxtaposed with a tightly bound copper atom.
What are the two strategies for isloating and organizing different chemical reactions?
1-Prokaryotic/Euaryotic aggregate enzymes required to catalyze reactions into large multiponent complexes
2-Eukaryotic- contains them within different membrane enclosed compartments
In eukaryotic cells, these membrane enclosed compartments are called?
membrane-enclosed organelles
The nucleus has what type of membrane?
a double membrane known as the nuclear envelope
What is the major site for synthesis of new membranes?
Endoplasmic reticulum
What is the purpose of liver cells?
detoxyify alcohol
Adrenal glands in the smooth ER do what?
produce new steroid hormones
What does the smooth ER have to do with muscle cells?
it sequesters Ca2+ from the cytosol and the release of Ca2+ to cytosol triggers secretion of signal molecules and the contractions of muscle cells
What does the Golgi Apparatus do?
recieves proteins and lipis from the ER, modifies them, and then dispatches them to other destinations
Lysosomes perform what function?
small sacs of digestive enzymes degrade worn-out organelles as well as macromolecules taken into the cell by endocytosis
What are peroxisomes?
small organelles containing a single membrane that break down lipids and destroy toxic molecules
In one hepatocyte, what are the # of mitochondria, ER, nucleus, golgi and cytosol?
1700 Mitochondria
1 of everything else
How did nuclear membranes and the ER thought to evolve?
by and invagination of the outer plasma membrane
How was mitochondria thought to evolve?
Mitochondria was actually thought to be it’s own seperate cell, which was engulfed by larger eukaryotic cell
-chloroplasts were thought to have evolved the same way
What are the three mechanisms for import of protein?
1) Transport through nuclear poer
2) Transport across membrane
3) Transport by vesicles
What is a sorting signal?
directs the protein to the organelle in which it is required. Proteins that lack such signals remain in the cytosol
How does transport through nuclear pores work?
proteins move from the cytosol into the nucleus are transported through the pores than penetrate the inner and outer nuclear membrane
Where does a import signal begin?
It begins at the N-terminus
->However, if the protein needs to STAY in the ER, it has a short sequence on the very end that keeps it there
T/F
The outer nuclear membrane is continuous with the ER membrane
True!
How many proteins is the nuclear pore composed of?
30
What helps ‘guide’ proteins through the nuclear pore?
the meshwork pattern on the inside of the nuclear pore
T/F the nuclear pores are large enough to accept protein in fully folded conformation
true
After a protein has passed through the nuclear pore, what “catches” the protein?
a basket like structure made of protein fibrils
What is a nuclear localization signal?
the signal sequence that directs a protein from the cytosol into the nucleus typically consisits of one or two short sequences contaiing several positively charges lysine or arginines
What binds to the nuclear localization sequence on newly synthesized proteins?
Nuclear transport receptors
What do nuclear transport receptors do?
guide the protein through the nuclear pore into the nucleus
When the protein has been delivered inside of the nucleus, what happens to the nuclear transport receptor?
it is returned to the cytosol via the nuclear pore for reuse
Energy derived from _______ ________ drives nuclear transport.
GTP hydrolysis
What binds to the nuclear transport receptor inside of the nucleus that causes it to release it’s cargo?
Ran-GTP
Once the nuclear transport receptor has passed through the pore and is back in the cytosol, what occurs?
an accessory protein triggers Ran to hydrolyze its bound GTP to GDP. Then Ran-GDP falls off the nuclear transport receptor where it is free to bind with another cargo protein
T/F
Proteins are imported into mitochondria in unfolded form
true
Give the steps for the import of a protein into the mitochondria-
*hint: 4
1) Mitochondrial signal sequence of the precursor protein is recognized by receptor located on outer mitochondrial membrane
2) Complex of receptor and protein diffuses laterally in the membrane on a contact site
- protein on contact sight is translocated across both membranes by a protein translocator
3) Signal sequence is cleaved by signal peptidase
4) Chaperone proteins help to pull protein across the membrane
Chaperone proteins help to pull protein across membrane, why is this needed?
They help pull protein across membrane so that no “backpeddling” occurs in through the transporter
The __________________ __________ has the most extensive membrane network in eukaryotic cells
endoplasmic reticulum
What are attached to the cytosolic side of the ER membrane and are making proteins that are translocated to the ER?
A: mRNA
B:Membrane-bound ribosomes
C: SRP complexes
D: Free ribosomes
B-Membrabe-bound ribosomes
What are unattached to any membrane and are making all of the other proteins encoded by the nuclear DNA A: mRNA B:Membrane-bound ribosomes C: SRP complexes D: Free ribosomes
D: Free ribosomes
How is a polyribosome formed?
many ribosomes bind to each mRNA molecule
What are the two components that direct a ribosome to the ER membrane? A: mRNA B:ER signal sequence C: SRP complexes D: Free ribosomes E: Both B and C
Both B and C
B:ER signal sequence
C: SRP complexes
A SRP complex stands for?
Signal Recognition Particle
_________ binds to the exposed ER signal sequence and to the ribosome, thereby slowing protein synthesis by the ribosome
Signal Recognition Particle
After a Signal Recognition Particle binds to the exposed ER signal sequence and to the ribosome, thereby slowing protein synthesis by the ribosome, what occurs?
The SRP-complex binds to an SRP receptor in the ER membrane
After the SRP-complex binds to an SRP receptor in the ER membrane, what occurs?
The SRP is released, passing ribosome to a translocation channel in ER membrane
After a ribosome is placed by the SRP into a translocation channel, the translocation channel does what?
inserts the polypeptide chain into the membrane and starts to transfer it across the lipid bilayer
During the translocation process of the translocation channel, the signal sequence is?
cleaved from the growing protein by a signal peptidase
Translocation channels in the ER transport the protein across the lipid bilayer in what formation?
a loop like formation
What occurs to the cleaved signal sequence after the protein is translocated?
it is ejected into the bilayer
T/F
A single pass transmembrane protein is retained in the lipid bilayer
True
Transmembrane proteins contain what two components that allow them to be integrated into the ER membrane?
a N-terminus ER signal sequence and a hydrophobic stop-transfer sequence
T/F
A double pass transmembanse protein uses an internal start-transfer sequence to integrate into the ER membrane
True
Double pass transmembrane proteins form what structure in the ER?
a loop like structure within the lumen and free ends within the cytosol
Cleavage of signal sequences occur in all translocated proteins except?
single and double pass proteins
What are the Eukaryotic membrane-enclosed organelles?
ER, Golgi, lysosomes, endosomes, mitochondria, and peroxisomes
T/F
Proteins that remain in the cytosol have a cytosol signalling sequence
FALSE—> since most proteins are made in the cytosol, cytosolic proteins don’t have a signaling sequence, since they are already located in their final destination
T/F
Mitchondrial proteins must be unfolded to allow them to pass through the mitochondrial membrane
True!
Only nuclear pores are big enough to allow fully folded confirmations through
Soluble proteins destined for secretion for for the lumen of an organelle pass?
completly into the ER lumen
What carries soluble protein and membrane between cell compartments?
transport vesicles
outward Secretory Pathway is also known as?
Exocytosis
inward secretory pathway is also known as?
Endocytosis
In the outward Secretory Pathway what is the order which the protein travels?
ER>golgi>plasma membrane
In the inward Secretory Pathway what is the order which the protein travels
Plasma membrane>lysosomes
_______ forms basket-like cage that helps shape membranes into vesicles
Clathrin
What is the structure of Clathrin?
a three pronged structure
Before Clathrin can create it’’s cage like structure, what must first occur?
Adaptins capture the cargo receptors with their bound cargo molecules
What proteins assemble around neck of budding vesicles, hydrolyze their GTP and pinch off the vesicle
dynamin
Rab proteins are located on the surface of vesicles, and bind to ___________ ________ ____________ that allows the vesicle to dock on its target membrane
filamentous tethering protein
After Rab proteins bind with the filamentous tethering proteins, a ________ on the vesicle binds to a complementary ______ on target membrane.
v-snare
t-snare
T/F
Rab and tethering proteins provide the inital recognition between a vesicle and its target membrane, the pairing of complementary SNAREs also helps ensure that transport vesicles reach their appropriate target membrane.
True
T/F
SNARE proteins play a central role in membrane function
True
What squeezes out any water molecules between the two membranes, allowing their lipid to flow together to form a continous bilayer
The force of the SNARE winding together
An oligosaccharide is a?
multiple sugar unit
The most common linkage on a glycoprotein is?
N-linked oligosaccharide side cahains
T/F
Chaperones prevent misfolded or partially assembled proteins from leaving ER
True
Misfolded proteins bind to receptors that stimulate the production of?
a transcription regulator
unfolded protein repsonse is?
the transcription regulators that are activated when a misfolded protein occurs that activate genes in the nucleus that encode chaperones and other ER components, thus promoting the proper folding and processing of proteins.
