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WorksheetsTougaloo Cell Bio Final
Total questions: 122
Worksheet time: 2hrs 2mins
What could be defined as an organized network of extracellular materials found beyond the immediate vicinity of the plasma membrane?
intracellular matrix
extracellular matrix
extracellular netrax
intercellular material
What substance joins proteoglycans together into gigantic complexes called proteoglycan aggregates? These complexes can occupy very large volumes.
hyaluronidase
hyaluronic acid
proteoglycase
fibronectin
laminin
What integral membrane protein family made of two membrane-spanning chains a and B is involved in attaching cells to their extracellular microenvironment?
laminins
fibronectins
integrins
myosins
cadherins
To what is the cytoplasmic domain of integrins in the region of a focal adhesion connected via various adaptors?
Tubulins of the cytoskeleton
actinin of the cytoskeleton
actin of the cytoskeleton
dynein of the cytoskeleton
The tightest attachment between a cell and its extracellular matrix is seen at the site where an epithelial cell is attached to the underlying basement membrane. The specialized adhesive structure found at such a site is called a(n) _______.
tight junction
desmosome
plasmodesma
hemidesmosome
Filaments connected to the dense plaque underlying the membrane in a hemidesmosome course outward into the cytoplasm. These filaments are composed of the protein _____ and are best known as ____.
actin, microfilaments
keratin, microfilaments
actin, intermediate filaments
keratin, intermediate filaments
tubulin, intermediate filaments
Focal adhesions _______.
may act as a type of sensory structure
collect information about the physical properties of the extracellular environment
collect information about the chemical properties of the extracellular environment
transmit information to the cell interior that may lead to changes in cell adhesion, proliferation or survival
All of these are correct.
_____ are members of an integral membrane glycoprotein family that bind to specific sugar arrangements in oligosaccharides that project from the surfaces of other cells.
Selectins
Integrins
Immunoglobulin super family proteins
Cadherins
Calmodulins
What is the function of most IgSFs?
cell adhesion
cell division
mediating specific interactions of epithelial cells with cells needed for immune response
mediating specific interactions of lymphocytes with cells needed for the immune response
cell fusion
You genetically engineer nonadhesive cells to express one variety of cadherins and then mix the cells in various combinations. You then monitor their interactions. What do you observe?
The genetically engineered cells adhered preferentially to cells expressing one of the other cadherins
The genetically engineered cells adhered preferentially to cells expressing the same cadherins
The genetically engineered cells did not stick to any other cells.
The genetically engineered cells died.
The genetically engineered cells migrated to a different location.
What determines the strength of adhesion between opposing cells held together by cadherins?
the length of the cadherins connecting to the cells
the width of the cadherins connecting to the cells
the amount of tryptophan in the cadherins connecting the cells
the number of cadherins in a cluster connecting the cells
the number of tyrosine residues in the cadherins connecting the cells
The activation of a membrane integrin by the binding of its cytoplasmic portion to molecules in the cytoplasm and the resultant increase in its affinity for an extracellular ligand is called _____.
inside-out signaling
outside-in signaling
right-side-out signaling
simple signaling
When tight junctions , adherens junctions and desmosomes are arranged in a specific array, the assortment of surface specializations is called a(n) ______.
junctional array
synaptonemal complex
belt complex
junctional complex
What type of cell adhesion molecule is associated with cells being held together by adherens junctions at the site of the junction?
adherins
selectins
IgSFs
integrins
cadherins
Cadherin clusters of adherens junctions _____. (select all correct answers)
connect the external environment to the actin cytoskeleton
connect cell to the extracellular matrix
provide a pathway for signals to be transmitted from the cell exterior to the cytoplasm
connect the external environment to the vimentin cytoskeleton
Desmosomes are particularly numerous in tissues ______.
that are subjected to mechanical stress
like cardiac muscle
like the epithelial layers of the skin
like the epithelial layers of the uterine cervix
all of these are correct
What forms the barrier of the tight junctions that seals off the space between adjacent cells?
paired rows of aligned integral membrane proteins
paired rows of aligned phospholipids
paired rows of carbohydrates
paired rows of polynucleotides
interdigitating integral membrane proteins
What kind of molecule does not pass through gap junction
ions
cAMP
inositol phosphates
ribosomes
cGMP
Which of the following is a function associated with the smooth endoplasmic reticulum in at least some cells?
synthesis of steroid hormones
detoxification of many organic compounds, like barbiturates and ethanol
release of glucose into the bloodstream
sequestration of calcium Ca2+ ions within the cisternal space
all of these are correct
What is the arrangement of organelles in a secretory cell from the basal end to the apical end, an arrangement that reflects the flow of secretory products from synthesis to discharge?
nucleus and RER - Golgi complex - secretory vesicles
Golgi complex - nucleus and RER - secretory vesicles
nucleus and RER - secretory vesicles - Golgi complex
Golgi complex - secretory vesicles - nucleus and RER
secretory vesicles - nucleus and RER - Golgi complex
What are the 2 sites within a cell at which protein synthesis is generally thought to occur?
cytosolic surface of RER and cisternal surface of RER
cytosolic of RER and free ribosomes
cisternal surface of RER and free ribosomes
free ribosomes and cytosolic surface of SER
cytosolic surface of RER and cytosolic surface of SER
What are the differences between ribosomes that make secretory proteins and those that make proteins intended for the cytosol
the ribosomes that make secretory proteins are smaller
the ribosomes that make cytosolic proteins are larger
there are no differences between them
the ribosomes that make secretory proteins are denser
the ribosomes that secretory proteins have extra subunits
What effect does the binding of the SRP to the growing polypeptide chain and the ribosome have on the protein synthesis?
protein synthesis accelerates
protein synthesis ceases temporarily
protein synthesis ceases permanently
proteins synthesis is terminated
the ribosome dissociates
Why is the ER so well-suited and ideally constructed for its role as a port of entry for secretory proteins?
It has a large surface area allowing the attachment of many ribosomes
The ER cisternae lumen favors unfolding and disassembly of proteins
The RER can segregate secretory, lysosomal and cytoplasmic proteins from other newly made proteins, allowing their modification, and sends them to their final destination
The ER cisternae lumen favors folding and assembly of proteins
How are integral membrane proteins thought to enter the lipid bilayer?
They insert into the membrane from the RER lumen after their synthesis is complete.
The aqueous translocon channel seems to have a gate that continuously opens and closes, giving each nascent polypeptide segment a chance to partition itself into the lipid bilayer's hydrophobic care
They insert into the membrane from the cytosol after their synthesis is complete.
It is thought that they burrow into the lipid bilayer
It is thought that they are enzymatically implanted in the lipid bilayer
How and where is the asymmetry of the phospholipid bilayers initially established?
It is initially established in the Golgi complex during the lipid and protein modification
It is initially established in the ER during lipid and protein synthesis
It is initially established in the secretory vesicles during lipid and protein modification
It is initially established in the mitochondria by random insertion into the membranes
Which of the proteins below is (are) not made on the membrane-bound ribosomes of the RER?
Peripheral proteins of the inner surface of the plasma membrane
soluble lysosomal proteins
vacuolar enzymes
proteins of the extracellular matrix
all of these are correct
Which part of the Golgi complex is thought to function primarily as a sorting station that distinguishes between proteins to be shipped back to the ER and those that are allowed to proceed to the next Golgi station?
the cis cisternae
the cis Golgi Network
the medial cisternae
the trans cisternae
the trans-Golgi network
What kind(s) of modifications are made in proteins as they move through the Golgi complex?
The protein's carbohydrates are modified by a series of stepwise enzymatic reactions
Amino acids can be added to either end of the polypeptide chain
Amino acids in the proteins may be chemically altered into nucleic acids
Small segments of amino acids can be added into the center of an existing protein
All of these are correct
How do protein coats select the cargo molecules to be carried by the vesicles they help to form?
They electromagnetically attract the correct cargo proteins
the protein coats have a specific affinity for the cytosolic tails of integral membrane proteins that reside in the donor membrane
The coats have a specific affinity for the luminal tails of integral membrane proteins that reside in the donor membrane
The coat proteins directly attach to the cargo proteins in the lumen of the forming vesicle
The coat proteins attach to the extracellular matrix
The coat of vesicles that transport materials around the cell interior______
is composed of two distinct protein layers
possesses an outer cage or scaffolding that forms the framework for the coat
possesses adaptors that are able to select specific cargo molecules
possesses an inner layer of adaptors that serves primarily to bind the vesicle's cargo
all of these are correct
Which coated vesicles move materials in the retrograde direction from the ERGIC and Golgi stack backwards towards to ER?
COPII-coated vesicles
COPI-coated vesicles
clathrin-coated vesicles
cadmium-coated vesicles
both COPII-coated vesicles and COPI-coated vesicles
What mediates the interaction between integral membrane proteins to be transported in COPII-coated vesicles and the COPII-coat?
ER export signals in the luminal tails of integral ER membrane proteins
ER export signals in the cytosolic tails of integral ER membrane proteins
ER export signals in the ER phospholipids that interact with the membrane proteins
ER export signals in carbohydrates on the cytosolic tails of integral ER membrane proteins
ER export signals in carbohydrates on the luminal tails of integral ER membrane proteins
Where in the Golgi complex does most protein sorting out to be sent to the destination occur?
the medial cisternae
the Trans Golgi network
the Cis Golgi Network
the cis cisternae
the trans cisternae
Lysosomal enzymes are transported from the Trans Golgi network in vesicles coated with what protein?
clathrin
lysozyme
dyamin
COPI
COPII
What is thought to direct the movement of vesicles through the cytoplasm to their final destination?
microfilaments
microtubules
intermediate filaments
collagen
keratin
Which if the following enzymes are typically found in lysosomes?
hydrolytic enzymes (acid hydrolases)
oxidoreductase
transderases
lyases
ligases
What is thought to sheild lysosomal membranes against attack by their enclosed enzymes?
DNA
basic RNA
carbohydrate chains attached to integral membrane proteins
carbohydrate chains attached to peripheral membrane proteins
the lipid bilayer itself
Which of the following are proposed functions of autophagy?
it plays a role in organelle turnover
it is used to cannibalize organelles when a cell is deprived of nutrients
it protects organisms against intracellular threats like abnormal protein aggregates and invading bacteria
it plays a role in the regulated destruction of the cell's own organelles and their replacement
all of these are correct
The two separate (basic) categories of uptake of extracellular materials into cytoplasmic vesicles are _____ and _____.
phagocytosis, exocytosis
pinocytosis, exocytosis
phagocytosis, endocytosis
pinocytosis, endocytosis
exocytosis, endocytosis
What types of molecules below can a cell internalize by receptor-mediated endocytosis?
hormones and growth factors
enzymes
bloode-borne proteins carrying certain nutrients
hormones and growth factors and enzymes
all of these are correct
Which of the following is a function performed by cytoskeleton?
provides structural support that determines cell shape and resists deforming forces
positions various organelles within the cell interior
provides a network of tracks over which materials like mRNA and organelles move within cells
serves as a force-generating apparatus that moves cells from one place to another
all of these choices
Given that axons growing out of a neuron require the growth outward of microtubules to support the lengthening axon, what would be likely to happen to axons growing out from a neuron when they are exposed to colchicine, which functions in preventing microtubules assemble?
Axons would grow more rapidly
Axonal outgrowth would cease
Axons would branch more often
axonal outgrowth would change direction more frequently
There would be no change in axonal outgrowth
In what form are proteins and neurotransmitters usually transported down the axon of a nerve cell?
individually by diffusion
in groups of ten
inside transport vesicles
inside the Golgi complex
tied individually to microtubules
Which of the following molecular motors is associated with microfilaments?
kinesins
dyneins
myosins
kinesins and dyneins
kinesins and myosins
Which of the following molecular motors is known to travel in retrograde direction along microtubules (from plus end to the minus end)?
kinesins
dyneins
myosins
kinesins and myosins
kinesins and dyneins
What is the direct source of energy that powers molecular motors?
hydrolysis of GTP
hydrolysis of ATP
a proton gradient
a H+ gradient
condensation of ATP
What part of the molecular motor kinesin is responsible for binding to the cargo to be hauled?
the motor domain
the neck
the rod-like stalk
the fan-shaped tail
the motor domain and the neck
The current model for the nucleation of microtubules is that a helical array of y-tubulin subunits forms an open, lock-washer-like ring-shaped template upon which the first row of aB-tubulin dimers assembles. How does this model account for the polarity of mictrotubules?
Only the a-tubulin of a heterodimer can bind to the ring of y-subunits
Only B-tubulin of a heterodimer can bind to the ring of y-subunits
The ring structure straightens out the microtubule
The ring structure interacts with a homodimer instead of a heterodimer
Only the a-tubulin of a heterodimer can bind to the ring of y-subunits and the ring structure straightens out the microtubule
The building blocks of a nucleotide are _____.
a pentose sugar and a phosphate group
a pentose sugar and a nitrogenous base
a phosphate group and a nitrogenous base
a pentose sugar, a phosphate group and a nitrogenous base
a pentose sugar, a phosphate group and an amino acid
With which of the following structures are intermediate filaments associated?
the nuclear envelope in the center of the cell
hemidesmosomes
desmosomes
the neurofilaments of neuron axons
all of these choices are correct
The backbone of a DNA molecule is ____.
made up of sugars alone
made up of nitrogenous bases alone
made up of phosphate groups alone
made up of alternating phosphate and sugar groups
made up of alternating sugars and nitrogenous bases
____ refers to the fact that the sequence of one DNA strand specifies the sequence of the other strand in the double helix
interdirectionality
complexity
complementarity
similarity
compulsivity
The information encoded in DNA resides in ____.
phosphates in the backbone
sugars in the backbone
the DNA base sequence
the sugars and phosphate groups together
the phosphodiester linkages
Which type of DNA sequence is typified by short sequences of DNA (five to a a few hundred base pairs in length) repeated a large number of times in tandem to form very large clusters, each containing up to several million base pairs of DNA?
satellite DNAs
minisatellite DNAs
microsatellite DNAs
consensus sequences
microminisatellite DNAs
DNA sequences in bacteria that on rare occasions moved from one place in the genome to another are called
movers
jumpons
transposons
transpodons
jumposons
Histone is an abundant protein inside the eukaryotic cells. The gene encodes for histone belongs to ___________ in the genome.
single copy non repetitive DNA sequence
highly repeated DNA sequence
moderately repeated DNA sequence
No answer text provided
Retrotransposon is a type of jumping element in the eukaryotic cells. It can cause the genome instability by ________ mechanism.
cut-and-paste
copy-and-paste
copy-and-cut
no answer text provided
The enzyme in eukaryotes that is responsible for the synthesis of RNA from a DNA template is called _____.
DNA-dependent DNA polymerase
DNA-dependent RNA polymerase
RNA-dependent RNA polymerase
RNA-dependent DNA polymerase
The site on DNA to which RNA polymerases bind before initiating transcription is called the ______.
terminator
operator
promoter
silencer
Which of the following is not a normal property of eukaryotic mRNAs?
They contain a continuous nucleotide sequence encoding a specific polypeptide
They are found in the cytoplasm and inside the Golgi complex
They are attached to the ribosomes when they are translated
Most have significant noncoding segment that does not direct assembly of amino acids
Eukaryotic mRNAs have special modifications at their 5' and 3' termini
The macromolecular complex that associates with each intron and splices it is called a(n) _____.
splicer
acrosome
spliceosome
splicing body
splice engine
Which of the phenomena below is responsible for the ability of one gene to code for more than one polypeptide?
transcription
alternative splicing
transposition
hybridization
exon shuffling
A tRNA has an anticodon with the sequence 5'-CAU-3'. What would be the sequence of the complementary codon? For the moment do not consider the wobble hypothesis.
3'-UAC-5'
'3-AUG-5'
5'-AUG- 3'
5'-AUC-3'
5'-ATG-3'
The greatest similarities among codons that specify the same amino acid occur _______.
in the first two nucleotides of the triplet
in the last two nucleotides of the triplet
in the first and third nucleotides of the triplet
in the third nucleotide of the triplet
in the middle nucleotide of the triplet
What enzyme is responsible for covalently linking amino acids to the 3'- end of the cognate tRNA?
peptidyltransferase
aminoacyl-tRNA synthetase
glutamine synthetase
RNA polymerase
ATP synthase
Which of the following is not required for protein synthesis?
All of the various tRNAs with their attached amino acids
ribosomes
mRNA
transcription factors
What are the three distinct activites of protein synthesis in the correct order?
initiation, elongation, termination
termination, initiation, elongation
initiation, termination, elongation
elongation, initiation, termination
elongation, termination, initiation
The initiator tRNA enters the 60S ribosomal subunit at the ____ during eukaryotic protein synthesis
A site
P site
E site
Q site
60S attachment point
the specific site on the bacterial chromosome at which replication begins is called the _____.
beginnging
origin
initiation site
initiator
replicon
Replication moves outward from the origin in _____ direction(s) and is said to be _____.
both, unidirectional
both, bidirectional
one, bidirectional
unique, unidirectional
one, unidirectional
Why is an intact, linear double helix an effective template for DNA polymerase?
It has a 3'-hydroxyl group, but lacks a template
It lacks a 3'-hydroxyl group, but has a template
It lacks a 3'-hydroxyl group and a template
it has a 3'-hydroxyl group and has a template
It lacks a 5'-hydroxyl group and has a template
Why is a single-stranded, circular DNA an ineffective template for DNA polymerase?
It has a 3'-hydroxyl group, but lacks a template.
It lacks a 3'-hydroxly group, but has a template.
It lacks a 3'-hydroxly group and a template.
It has a 3'-hydroxly group and has a template.
It lacks a 5'-hydroxly group and has a template.
All DNA polymerases lay down nucleotides in a _____ direction and move along the template in a _____ direction.
3'-->5' , 5'-->3'
N-->C. C-->N
5'-->3' , 3'-->5'
C-->N, N-->C
N-->C, 5'-->3'
During replication, DNA is constructed in small segments called____ that are rapidly linked to longer pieces of DNZ synthesized earlier.
Watson fragments
Tokyo fragments
Osaka fragments
Okazaki fragments
Ouabain fragments
The enzyme that joins the small fragments of the lagging strand together into a continuous strand is called____.
DNA gyrase
DNA ligase
DNA polymerase
primase
deoxyribonuclease
Strand initiation during replication is carried out by an enzyme that makes a short RNA molecule that is used as a primer; the enzyme is a distinct type of RNA polymerase, called_____.
RNA gyrase
RNA ligase
ribonuclease
primase
deoxyribonuclease
Which of the following may be a further advantage of using RNA primers during initiation of a strand in replication?
Using primers may decrease mistakes; such errors as mismatched bases are more likely during initiation than elongation, and the use of a short, removable RNA segment avoids inclusion of mismatched bases.
Using primers is faster.
The RNA of the primers is more stable.
The RNA of the primers is more likely to lead to changes in base sequence, which enhances the rate of mutation and thus evolution.
The RNA of the primers allows more efficient packing of the chromosomes after its removal.
What proteins bind selectively to single-stranded DNA and are responsible for keeping it extended and preventing it from being rewound?
DNA helicase
DNA gyrase
single-stranded DNA binding (SSB) proteins
ATPase
DNA unwindase
What is the name of the noncatalytic component of the DNA polymerase III holoenzyme that keeps the polymerase associated with the DNA template?
B-pleated sheet
a-helix
a-clamp
B-clamp
y-clamp
What is the function of the 5'--->3' exonuclease activity of DNA polymerase I ?
It removes mismatched nucleotides that have been incorporated by mistake.
It replaces mismatched nucleotides with the correctly matched nucleotides.
It removes the DNA primer laid down by the primase at the 5' end of the Okazaki fragment.
It removes the RNA primer laid down by the primase at the 5' end of the Okazaki fragment.
It nicks DNA to create a primer in the middle of a DNA chain.
Which type of DNA repair removes via a cut-and-patch mechanism a variety of bulky lesions, like pyrimidine dimers and nucleotides to which various chemical groups have been attached?
nucleotide excision repair
base excision repair
mismatch repair
double-strand breakage repair
All of these are correct.
What is the advantage of transcription-coupled repair?
It allows the cell to do two things at once.
It ensures that the genes of least importance to the cell receive the highest priority on the repair list.
It ensures that the genes of greatest importance to the cell receive the highest priority on the repair list.
It is repairs noncoding sequences preferentially.
It is the most accurate method of repair.
What must the mismatch repair system be able to distinguish in order to tell which nucleotide of a mismatched pair to replace?
It must be able to distinguish the newly-made strand from the parental strand.
It must be able to distinguish which chain possesses the newest phosphate groups.
It must be able distinguish which chain contains the ribose sugars.
It must be able to distinguish which chain contains the oldest phosphate groups.
A double-stranded breakage repair pathway that requires the presence of a second chromosome carrying the same sequence of genes as the damaged chromosomes is called____.
nonhomologous end joining repair
homologous recombination
NHEJ
DNA methylation repair
nonhomologous recombination
Which of the following statements accurately characterize cells?
Cells are highly complex and organized.
Cells possess a genetic program and the means to use it.
Cells are capable of producing more of themselves.
Cells acquire and utilize energy.
All choices are correct.
You are conducting an experiment by trying to reproduce the work performed in 1891 by Hans Driesch, a German embryologist. Working with a fertilized sea urchin egg, you allow it to complete the first cell division after fertilization. You then carefully separate the two cells of the embryo and allow their development to continue. Based on Driesch's experiment, which results below would you expect to happen?
Both of the cells will die.
Both of the cells will develop into complete and normal embryos.
One cell will develop into a normal, though smaller, embryo; the other dies.
One cell will develop into half an embryo; the other will develop into the other half of the embryo.
One cell will develop into a defective embryo and the other will die.
The genectic material of a prokaryotic cell is present in the ____, a poorly defined region of the cell that lacks a boundary membrane to separate it from the surrounding cytoplasm.
nucleus
chromatic region
nucleoid
mitochondria
Some bacteria can pass a piece of DNA from a donor bacterial cell to a recipient bacterial cell through a structure called a pilus. What is this process called?
transmission
transduction
transformation
conjugation
fission
The process by which a relatively unspecialized cell becomes highly specialized is called______.
differentiation
determination
degeneracy
denaturation
renaturation
Which of the following is NOT a feature shared by all cells?
plasma membrane with similar chemical construction
genetic information encoded in DNA nucleotides
shared metabolic pathways
division of cells into nucleus and cytoplasm
similar energy storing chemicals such as ATP
Which organelle is found in both eukaryotes and prokaryotes?
nucleus
mitochondria
endoplasmic reticulum
ribosome
Golgi apparatus
Which of these cell types does NOT possess membrane-bound organelles?
human cells
cat cells
E. coli
yeast cells
plants cells
Which of the following statements about viruses is NOT true?
All viruses are obligatory intracellular parasites
All viruses are obligatory intercellular parasites
Viruses occur in a wide variety of very different shapes, sizes, and constructions
A viral host may be a plant, animal, or bacterial cell
viral genetic material can be either RNA or DNA
Which of the following is NOT typically a behavior exhibited by a cell with a proviral infection?
immediate production of new viruses and subsequent lysis of the host cell
Normal behavior until exposure to a stimulus, live UV radiation, that activates dormant viral DNA, leading to lysis of the host cell and release of viral progeny
Production of new viral progeny that bud at the cell surface without lysing the infected cell
loss of control in animal cells over their growth and division followed by malignancy
Which of the folowing is a tenet of the Cell theory? (select all correct choices)
All organisms are composed of one or more cells
The cell is the structural unit of life
Cells can arise only by division from a preexisting cell
Cells divide only by fission
What factor of factors discovered with electron microscopy distinguished prokaryotic from eukaryotic cells? (Select all correct choices)
their size
their shape
the types of their internal structures or organelles
their plasma membrane structure
Which of the following description of adult stem cells is wrong __________.
They are undifferentiated cells
They are capable of self-renewal
They are capable of giving rise to other kinds of cells
They can differentiate into every type of cell in the body
They can be used for the cell replacement therapy
Which of the following is NOT a function of membranes?
transporting solutes
providing a scaffold for biochemical activities
energy transduction
protein degradation
signal transduction
Gorder and Grendel extracted lipids from human red blood cells. They calculated the total surface area for these red blood cell lipids and found it to be 36 µm2. How much surface area would these lipids cover once they were spread across the surface of water?
72 µm2
36 µm2
18 µm2
144 µm2
30 µm2
What kind of membrane protein is found entirely outside the bilayer on either the extracellular or cytoplasmic surface and is covalently linked to a membrane lipid situated within the bilayer?
integral proteins
lipid-anchored protein
peripheral proteins
carbohydrate-anchored protein
transmembrane
What characterizes the amino acids that are found in a-helical segment that spans a membrane?
exclusively circular
predominantly hydrophilic
predominantly hydrophobic
predominantly antiparallel
totally parallel
Which of the following is an observed function of integral membrane proteins?
mechanical support for membrane
enzyme activity
receptor activity
factors that transmit transmembrane signals
While culturing some cells, you lower the temperature of the culture. WHat happens immediately to the membrane fluidity?
Nothing happens
The membrane becomes less fluid
The membrane becomes more fluid
The membrane fluidity fluctuates back and forth from high to low
The membrane fluidity fluctuates back and forth from low to high
Which of the following cell processes depend on the movement of membrane components and would probably not be possible if membranes were rigid, nonfluid structures?
cell movement
cell division
formation of intercellular junctions
endocytosis
all of these are correct
Which substance will cross a plasma membrane least effectively?
Molecule AA with an octanol-water partition coefficient of 5
Molecule AB with an octanol-water partition coefficient of 0.5
Molecule AC with an octanal-water partition coefficient of 50
Molecule AD with an octanol-water partition coefficient of 0.05
A channel that opens in response to the binding of a specific molecule, which is usually not the solute that passes through the channel is called a _______.
voltage-gated channel
charge-gated channel
ligand-gated channel
positive-gated channel
electric-gated channel
An important aspect of transport by facilitated transporters and pumps is ________.
conformation change
rigidity
softness
a-helix secondary structure
The sodium-potassium pump makes the cell interior more _______ by pumping _______ sodium ions out of the cell for every ________ potassium ions pumped in
negative, 3, 2
negative, 2, 3
positive,3,2
positive, 2, 3
What is the distinguishing characteristic of a P-type pump?
It must be pumped during the cycle
It must be phosphorylated during the cycle
It must be protonated during the cycle
It must be methylated during the cycle
In the Na+/glucose cotransporter, ________ moving down its gradient drive the transport of ________ against it gradient.
Na+ ions, K+ ions
Na+ ions, glucose
glucose, Na+ ions
glucose, K+ ions
K+ ions, glucose
What factor(s) directly or indirectly determine the transition temperature? (Select all correct choices)
the ability of lipid molecules to be packed together
whether the fatty acid chains of the lipids are saturated or unsaturated
the extent to which the fatty acid chains of the lipids contain double bonds
the length of the fatty acid chains
In what way can a given solute get through a membrane? (Select all correct choices)
The solute can pass through the bilayer
The solute can pass through cholesterol
The solute can pass through an aqueous channel
The solute can pass through a pore
What advantage do the cristae confer on the mitochondria?
They allow the mitochondria to shrink
They greatly increase the surface area for aerobic respiration machinery
They confer resiliency on the cells
They allow swelling of mitochondria
They activate the matrix
Mitochondria are site of the ________. (Select all correct choices)
synthesis of certain amino acids
synthesis of heme groups
uptake of Ca2+ ions
release of Ca2+ ions
In which two alternative ways can pyruvate and NADH be metabolized?
fermentation; hydrolysis of PGAL
condensation of PGAL; fermentation
aerobic processes using the Krebs cycle; fermentation
anaerobic processes using the Krebs cycle; fermentation
What happens to the carbons of pyruvate that do not enter the Krebs cycle?
They are converted to carbohydrates
They are converted to CO2
They are converted to glucose
They are converted to ATP
They are converted to carbon monoxide (CO)
Where are most of the enzymes of the Krebs cycle located?
in the intercristal space
on the cristae
on the ribosomes
in the soluble phase of the mitochondrial matrix
in the intermembrane space
What is the terminal electron acceptor of the electron-transport chain in cells undergoing aerobic respiration?
water
O2
CO2
glucose
How do mitochondria generate and store the energy used to produce most of the ATP made during aerobic respiration?
by producing heat
by generating a heat gradient
by generating a proton gradient
by generating a Cl- ion gradient
by generating a Na+ ion gradient
What properties do mitochondria share with peroxisomes?
Both form by splitting from preexisting organelles, using some of the same proteins to accomplish the feat.
Both import preformed proteins from the cytosol
Both engage in similar types of oxidative metabolism
At least one enzyme is found in the mitochondria of some mammals and the peroxisomes of others
All of these are correct
Of the five types of electron carriers, which is/are able to move freely in the mitochondrial inner membrane or the inter membrane space to transfer electrons from the electron donor to the electron receiver?
Complex I
cytochromes
Complex II
ubiquinone
complex III
