These proteins are integral membrane proteins that bind cargo and thus aid in vesicle cargo selection
These proteins bind both the coat protein and the cargo recptors during the process of cargo selection
T/F If you remove a sorting signal from a protein normally found in the mitochondria, then that protein will remain in the ER
The hydrophobic amino acid sequence that halts the translocation of a transmembrane protein across the membrane is called:
stop transfer sequence
Which transport process occurs via vesicular transport?
transport from the ER to the Golgi
Which of the following transport processes is said to occur co-translationally?
transport into the ER
What process is part of the secretory pathway?
transport from the Golgi to the plasma membrane
What is NOT imported into the ER?
proteins destined for the mitochondria
Which type of proteins must unfold during transport?
proteins transported to the ER
Transport of proteins into the mitochondrial matrix occurs at:
Proteins moving along the secretory pathway exit the ER via vesicular transport and next move to the:
cis face of the Golgi
During nuclear import, what helps to guide the protein towards the pore?
What types of proteins can be subject to glycosylation?
The first step in protein glycosylation
takes place in the ER and involves the addition of a branches oligossaccharide to an asparagine side chain
Signaling that does not involve the secretion of a signaling molecule
signaling involving local mediators that are perceived by cells close to the signaling cell
signaling involving hormones that are released into the bloodstream
signaling involving the conversion of an electrical signal into a chemical signal
hyrdophobic molecules that are able to cross the plasma membrane
What would result DIRECTLY from binding of a neurotransmitter to an ion-channel linked receptor?
flow of ions across a membrane
Rhodopsin, with seven transmembrane spanning domains, is an example of a:
G-protein linked receptor
Binding of a signal to a receptor tyrosine kinase DIRECTLY results in:
dimerization and transphosphorylation of the receptor molecules
Signal -> G-protein linked receptor -> G protein -> ???? -> DAG + IP3 -> PKC -> phophorylation of target proteins
T/F the exchange of GDP for GTP by the alpha subunit results in dissociation of the complex into an active alpha-beta complex and an active lambda complex
The local mediator nitric oxide stimulates the intracellular enzyme guanylyl cyclase by:
diffusing into cells and stimulating the cyclase directly
What step would amplification of the original signal occur?
adenylyl cyclase produces cAMP
What protein is the target of a signaling pathway that results in a cellular response several hours after exposure of the cell to an extracellular signal molecule?
gene regulatory protein
Protein that gets activated in response to binding of a signal to a receptor tyrosine kinase and which passes the signal onward by initiating a MAP kinase cascade:
A kinase could act as an integrating device in signaling if it
has two sites at which the kinase itself is phophorylated by two different kinases
signal -> G-protein linked receptor -> G protein -> adenylyl cyclase -> cAMP -> ???? -> phophorylation of target proteins
What mutation would result in a constitutively active Ras protein?
mutation that decreases the ability of a bound GTP molecule to be hydrolyzed
Component of the cytoskeleton that forms stable structures such as cilia and flagella:
What would destabilize a microtubule?
low concentration of GTP within the cell
Component of the cytoskeleton assembled from 13 parallel protofilaments that come together to form a hollow tube:
What molecule acts as a molecular switch whose activity is regulated by whether it is bound to GTP or GDP?
Activation of what cell surface receptors directly results in a flow of ions across the plasma membrane?
ion channel couple receptor
bind to intracellular receptors that function as transcription regulators
T/F G-protein coupled receptors dimerize upon binding an extracellular signal
What protein is a direct target of heterotrimeric G proteins?
At what step does amplification of the ORIGINAL signal occur?
G protein couple receptor activates many G proteins
What protein is likely the target of a signaling pathway that only results in a cellular response twelve hours after exposure of the cell to an extracellular signal molecule?
T/F activation of tyrosine kinase receptors causes the assembly of a signaling complex on the extracellular tail of the receptor
What type of mutation (with chickens) would be expected to promote uncontrolled cell proliferation?
a mutation that inactivates the protein tyrosine phosphatase that normally removes the phosphates from tyrosines on the activated receptor
T/F: Cytosolic Ca2+ levels are kept high in the cell by active pumping of Ca2+ into the cell across the plasma membrane.
T/F: ion channels can only perform passive transport
T/F: In plant cells, there often exists a H+ (proton) gradient across the plasma membrane, whereas in animal cells, there is usually a gradient of Na+ ions across the plasma membrane.
T/F: Amino acyl tRNA synthetases attach the appropriate nucleotide to the tRNA
If uncorrected, deamination of cytosine in DNA is most likely to lead to:
substitution of an AT base pair for a CG base pair
What part of the chromosome is important for replicating the ends of the chromosomes?
mRNA is synthesize by:
RNA Polymerase II
What type of protein filaments form a long hollow cylindar?
T/F: motor proteins move in a directional fashion along microtubules by using inherent structural polarity of protofilament
the hydrolysis of GTP to GDP carried out by tubulin molecules:
allows the behavior of microtubules called dynamic instability
Kinesins and dyneins:
often move in opposite directions to each other
T/F: ATP-actin monomers bind less tightly to each other than ADP-actin monomers
This type of filament forms contractile bundles:
what element of the cytoskeleton is found at high concentration in the cell cortex and helps in cell movemovent?
What two things refer to a ciliary microtubule and not a microtubule of a mitotic spindle?
the basal body is the organizing center & it is arranged in a 9 + 2 array
Is the head of a motor protein attached to the tube or the tail?
What is a receptor for nitric oxide?
What are direct targets of G proteins
membrane-bound enzymes & ion channels
T/F: Each signal molecule can only bind to one type of receptor
T/F: Ras is inactivated by dephophorylation
T/F: JAKs are enzyme-coupled receptors
What are Akt's targets?
TOR and Bad
Four phases of the cell cycle in order
G1, S, G2, M
A cell contains the most DNA after?
A cell is smallest in size after?
A cell does no enter mitosis until it has completed:
One process contributing to changing activities of cyclin-dependent kinases (Cdk) during the cell cycle:
different Cdks binding different cyclins to become active
T/F: the cell-cycle control system can halt progression of a cell through the cell cycle
T/F: S-Cdk and M-Cdk trigger entry into M phase
T/F: Both the presence of a bound cyclin and the phosphorylation state of the Cdk determine whether a Cdk is enzymatically active
What mechanism does S-Cdk ensure that DNA replication is initiated only once per cell cycle?
phophorylation of Cdc6
Cells in the G zero state:
can remain in that state for a long time
Programmed cell death occurs:
by means of intracellular suicide program
Which of the following is true of necrosis but not apoptosis?
the causing of cells to swell and burst
T/F: Bcl-2 proteins inhibit the activity of Bax and Bak
apoptosis involves what mechanism?
activation of a family of proteases called caspases
T/F: Mitogens are extracellular signals that stimulate cell division while survival factors are extracellular signals that stimulate cell growth
How are Bax and Bak through to promote cell death?
they allow cytochrome c to be released from mitochondria
assemble into complexes on the DNA when phosphorylated by M-Cdk
What must be true of a person with sickle cell anemia?
both of their parents had mutations in their B-globin gene in a germ cell
What takes place during the dark reactions of photosynthesis?
carbon dioxide is used to make sugar using ATP and NADH
What type of bond stabilizeds the DNA molecule between complementary nitrogen-containing bases?
T/F: cells can alter chromatin structure using proteins called histone-modifying enzymes and DNA repair polymerases
this organelle is the location of both protein and lipid synthesis
What DNA damage results in two adjacent bases on one DNA strand being covalently bonded to each other?
What enzyme joins two DNA fragments by joining the 3 prime OH end of one fragment to the 5' phosphate of teh second DNA fragment?
The constricted region of a mitotic chromosome where the kinetochore attaches is called the:
What protein can change the structure and/or spacing of nucleosomes?
chromatin remodeling complex
T/F: individuals with mutations in genes that code for proteins involved in DNA mismatch repair will accumulate muations slower than normal individuals
T/F glycolysis requires oxygen
T/F: proteins generally bind their ligands by forming strong covalent bonds between the protein binding site and the ligand-these strong bonds are important to make the binding specific
What is required for transcription?
double-stranded DNA molecule, RNA polymerase, ribonucleotides
RNA is synthesized in the:
5' to 3' direction
The RNA molecule made by transcription of a particular DNA molecule is complementary to the
nonsense AND the template strand
What protein can change the structure of nucleosomes, making DNA more accessible to transcription factors?
chromatin remodeling complexes
In what part of the mitochondrion are the proteins of th electron transport chain located?
Name 3 roles of RNA in cells:
information carrier, structural, catalytic
The ER is important for what?
ONLY preotein synthesis and membrane synthesis
What type of DNA damage is most frequently repaired by nonhomologous end-joining?
double strand break
Any segment of a polypeptide chain that folds up independently into a compact stable structure that is associated with particular function is called a:
Do DNA strands run parallel?
No, they are complementary
What typically does NOT express genes: euchromatin or heterochromatin?
Telomeres are required components of chromosomes that participate in:
allowing for the complete replication of the end of the chromosome
Most of the ATP generate through photosynthesis in teh plant chloroplast is:
used by the chloroplast to incorporate carbon from CO2 into organic molecules
Where are disulfide bonds found?
outside the cell, golgi apparatus, ER and vesicles
contain a cluster of genes transcribed as a single mRNA
What conditions would the trp operon be transcribed?
low tryptophan levels
T/F: the lac repressor bind to the operator when lactose is present in the cell
T/F: RNAi is induced when double-stranded RNA is present in the cell
T/F: Riboswitches are short sequences of DNA that can undergo a conformation change
What event results the release of eukaryotic RNA polymerase II from the transcription initiation complex?
phosphorylation of RNA polymerase by TFIIH
What process requires the exon junction complex?>
export from the nucleus
What lipid movements occur readily in membranes?
lateral diffusion and rotation
Ligand-gated ion channels are:
What type of molecules diffuse readily across membranes?
small hydrophobic molecules
In eukaryotes, what binds to the TATA box causing a bend in the DNA?
a subunit of TFIID
What is a major control point of eukaryotic gene expression?
Sequences bound by gene regulatory proteins that promot transcription and which can be located thousands of nucleotides away from the transcription initiation site
When bacteria are grown in the presence of both glucose and lactose
CAP is inactive and not bound to its DNA regulatory sequence
Under what circumstances would the lac operon be ON?
no glucose, lactose
What is not important for splicing?
poly A tail
phopholipids, sterols, and proteins
Two types of adapter molecules that are required for translation are:
tRNAs and amino acyl tRNA synthetases
T/F: Amino acids are attached to the 5' end of the tRNA
How are eukaryotic transcription regulators able to affect transcription when their binding sites are far from the promoter?
by looping out the intervening DNA between their binding site and the promoter
T/F: The spliceosome physically associates with ribosomes during teh splicing reaction