energy is inevitably lost as heat during the performance of work by machines or living organisms
HSP70 performs what essential function in the cell
binds and releasese hydrophobic regions of proteins during their synthesis to prevent their association
which level of structure in proteins is hl together b intramolecule amino acid R group interactions?
a reaction involving the gain or one or more electrons is an/a ??? reaction.
??? = reduction.
A major way of regulating enzymes is the reversible addition of ____ groups, which can allosterically activate or inhibit the enzyme
where are hydrophobic interactions mostly likely to be observed?
within core of a water-soluble protein
which bond holds hte glucose monomers of cellulose together toform this plentiful polysaccharide?
beta (1>4) glycosidic linkages
identify the correct order, from stronger to weaker, of the following list of biological reducing agents
NADH, FADH2, reduced Ubiquinone, H2O
inner mitochondrial membrane of some cells contains proteins that allow protons to move from the intermembrane space to the matrix without concomitant synthesis of ATP. These proteins are called...
Which organelles below are found in both plants and animals?
peroxisomes and mitochondria
feedback inhibition is an example of a particular type of inhibition, which statement is most accurate?
noncompetitive inhibition, Vmax is reduced while Km is unaffected
Which of the following is not a marcomolecule formed by the polymerization of potentially large numbers of monomers?
Protein fmailies that have evolved with the function of helping unfolded or misfolded proteins aachieve proper 3-dimensional conformation are called ___ ?
Enzymes worky by ___
lowering the activation energy barrier of a reaction and thus speeding up the reaction
Where are the enzymes that synthesize carbohydrates from CO2 located in plant cell?
In chloroplasts, a proton gradient is established with a higher concentration of protons found is the ___ and a lower concentration in the ___ .
thylakoid lumen, stroma
What is produced when the electrons leave the mitochondrial electron transport chain and bind to the final electron acceptor for the chain?
In what molecule is most of the energy of glucose stroed at the end of glycolysis?
for what purpose(s) does photosystem II use absorbed light energy?
remvoing electrons from water
Which statement about the RNApII promoter element sequence "TATAAA" is most accurate?
present on DNA non-template strand
termination of eukaryotic RNApII transcription requires which of the following events?
synthesis of a 5'-AAUAAA-3' sequence followed by cleavage 20 nucleotides downstream of this region
Termination of prokaryotic RNAp transcription may require which of the following events?
binding of Rho to the nascent mRNA transcript
Which histone typically resides outside the nucleosome core particle and binds part of the linker DNA to connect adjacent nucleosomes yielding a 30nm fiber?
Which of the following proteins are most directly involved in the restricton of paracellular transport?
attachment of the sigma factor ...
increases the core enezyme's affinity for DNA promoter sites and mediates unwinding of the promoter DNA
the initiator tRNA enters the 30S ribosomal subunit at what will become the ___during prokaryotic protein synthesis
which molecule below would be least likely to pass thru a gap junction?
Protein Kinase A
The stretch of amino acids that serves as a signal direction proteins out of the nucleus is called the ___
nuclear export signal
Whcih statement(s) best describes fibronectins
-composed of several modular domains involved in binding other ECM components
-contain a RGD loop region that mediates interaction with a cell surface receptor
What properties of chromatin have been shown to depend upon histone modification patterns?
-whether a region of chromatin is heterochromatic or euchromatic
-the likelihood that a gene or cluster of genes will be translated
What determines the Lac and Trp repressor's ability to bind to operator sequences?
-repressor's shape determines its ability to bind to the operator
-key metabolites allosterically affect the repressor's conformation
Alternative splicing explains ____.
how one gene can code for more than one polypeptide
kinase activity associated with TFIIHH is important for what?
-mediate transition from initiation to elongation by disrupting contacts with TFIID
-phosphorate the carboxyl-terminal domain of RNApII
-create binding sites for factors involved in pre-mRMA processing events such as plicing
integrins play role in the following...
hemidesmosomes and focal adhesions
coat a plastic dish with fibronectins and proteoglycans and grow eukaryotic cells on the dish. cells adhere to the dish. repeat the experiment but this time you only coat the dish with fibronectins. what happens?
cells adhere as they normally do
what type of cell adhesion molecule is associated with cells being held together by adherens junctions?
what enzyme whether produced by cancer cells or the cells surrounding a tumor helps cancer cells penetrate the extracellular matrix by digesting the extracellular matrix.
MMP - matrix metalloproteinases
which of the following codon changes represents a nonsense mutation?
CGA to UGA
how do exon-junction complexes mark messages as having a nonsense mutation?
after the initial translation, EJCs should be removed if translation of the whole mRNA has occurred.
which heterotrimeric G proteins function by inhibiting adenylyl cyclase?
protein kinase C is activated by which of the following second messengers?
ribosomal DNA clusters are gathered together to form what cellular structure?
what directly/indirectly determines transition temp. of a lipid bilayer.
-ability of lipid moelcules to pack together
-whether fatty acid chains of lipids are saturated/unsaturated
-the extent to whcih fatty acid chains of lipids contain double bonds
-length of fatty acid chains
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
membrane-associated carbohydrates exhibit a major asymmetry in distribution. what is it?
=plasma membrane assoicated carbohydrates face outside cells into the extracellular space
-membrane-assocaited carbhyrates face away from cytoplasm in all cases
what are the general building blocks of a phosphoglyceride
glycerol + 1 phosphate groups + 2 fatty acids
Which end of a MT is the fast growing end?
plus end, end with beta-tubulin at tip
microscopic beads are coated with kinesin and subjected to an in vitro mobility assay. which direction and along what cytoskeletal element are the beads seen to move
toward plus end of MT
structure that contains two barrel-shaped centrioles surround by amorphous, electro - dense pericentriolar material is called a(n) ___.
channel that opens in response to the binding of a specific molecules is called a ____
fuse together cells at differ stages of the cell cycle and then observe the behavior of ea. nucleus residing in combined cytoplasm of the two cells. what would occurs if you fused a G2 cell to a cell in the S phase.
G2 nucleus did not initate DNA synthesis, but the S phase nucleus continued replication
When cyclin concentration is low,
kinase of MPF lacks the cyclin subunits and is thus inactive
ATR is a ...
protein kinase that is acctivated by DNA lesion resulting from incompletely replicated DNA of UV irradition
what would be likely to happen to cultured cells if you were able to treat them with an inhibitor that blocked the activity of wee1 kinase
Cdk would become activated somewhat earlier than usual
what enzymes removes phosphatse from Cdk and can thus turn on its kinase activity in the process?
At the outer surface of the centromere of each chromatid is a proteinaceous, buttonlike structure called the ...
Which organelles remain relatively intact thru mitosis?
when MT grow out of a centrosome, which end is associated wit hthe centrosome?