Wiley Quizzes Flashcards
Polar molecules are _ nonpolar molecules are _
hydrophilic, hydrophobic
The function of a buffer is to?
generate slight changes in pH
What macromolecules contain only polymers?
proteins, nucleic acids, polysaccharides
Distinct regions of a protein that fold independently of one another and often function in a semi independent manner are called:
domains
Where are the polar groups on membrane lipids directed?
aqueous environment
where are the hydrophobic regions of a membrane directed towards?
one another
fusing two cells causes what to happen after a period of time?
uniform distribution of labels
saturated fatty acids:
have straight fatty acyl chains
membranes contain lipids, including:
cholesterol, phosphoglycerides and sphingolipids
What serves as a fence around portions of the membrane to restrict the distance an integral protein can travel?
membranes underlying cytoskeleton
How do Na ions enter a neuron when an AP is initiated?
a voltage gated Na channel
Observations of mitochondria within living cells have shown:
they can exist as a highly branched, interconnected tubular network
In what form does a portion of a product of glycolysis enter the TCA cycle?
Acetyl CoA
Types of carriers found in the ETC of the inner mitochondrial membrane include:
flavoproteins
- cytochromes
- iron sulfur proteins
- ubiquinone
- NOT NAD (for some reason)
What is the domain of the inner mitochondrial membrane that is present within the interior of the mitochondrion as a series of invaginated sheets called?
cristae
Collagen is largely produced by:
fibroblasts
Can more than one type of collagen be found in a single fiber?
yes
What are four major components of the ECM in eukaryotes?
collagen
fibronectin
proteoglycans
laminin
The addition of a peptide containing an RGD sequence would ___ the binding of cultured cells possessing surface receptors for fibronectin to a fibronectin coated dish
INHIBIT
What are four roles of integrins?
- anchor cells to substrate
- transmit signals to intracellular compartment
- participate in inside out signalling
- bind to a diverse array of ligands
Integrins:
are receptors found on the cell SURFACE
___ 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
Why do cells flatten when they make contact with a surface?>
they send out projections that make increasingly stable attachments
the endocytic pathway:
moves materials from outside the cell to inside the cell
major advantage of using GFP rather than autoradiography is that:
it can be used in living cells
the smooth Er has 4 functions including -
storing calcium ions
- synthesizing steroid hormones
- detoxifying drugs
- oxidizing hydrophobic compounds into hydrophillic compounds
The endocytic pathway:
moves materials from outside the cell to inside the cell
An investigator can visualize biochemical processes within a cell by determining the location of radioactivley labelled materials by this process:
Autoradiography
The endomembrane system when homogenized is broken up into vesicles, which are heterogenous but similar in size. these vesicles can be purified and after purification often retain biological activity, these are known as:
microsomes
misfolded proteins:
are destroyed
The unfolded protein response (4)
- occurs when there are too many misfolded proteins in the ER
- is inhibited by BiP
- involves the synthesis of more chaperones in the ER
- inhibits enzymes involved in protein synthesis
What type of cytoskeletal element is characterized as a long hollow unbranched tube with walls composed of tubulin?
microtubules
Which cytoskeletal element is found in both the cytoplasm and nucleus?
intermediate filaments
The substrate for kinesin motors are:
microtubules
assembly of tubulin dimers requires that __ must be bound to the tubulin subunit
GTP
The core of a cilium is called the___
axoneme
What controls the assembly and disassembly of intermediate filaments?
phosphorylation and dephosphorlyation
What motor is associated with microfilaments
MYOSIN is the motor, actin is the filament
Before incorporation into a filament, an actin monomer binds a molecule of___
ATP
The myosin motor is driven by ___
hydrolysis if ATP
What effect does the binding of the SRP to the growing polypeptide chain and the ribosome have on protein synthesis?
protein synthesis ceases temporarily
The signal sequence is typically found on the _____ of a peptide designated to be inserted into the lumen of the RER
amino terminus
Cells are infected with a virus carrying a temp sensitive mutant VSVG gene that encodes a protein that cannot leave the ER of infected cells grown at restricted temperatures (40C). Thus at higher temperatures:
The VSVG protein cannot leave the ER
During the process of meiosis is the number of chromosomes doubled or reduced by half?
reduced by half
When two genes are located on the same chromosome what can you estimate / assume?
that the frequency of recombination between genes allows one to estimate the distance between them
Do telomeres play a role in recombination during meiosis?
no they do not
The fact that chromosomes become shorter with each replication is known as the
end replication problem
Alleles are:
different forms of a gene for the same trait
When examining chromosomes in cells starting meiosis. Sutton observed the chromosomes were organized in pairs that came to be called ___ pairs; the members of each pair formed a complex called a:
homologous, bivalent
What are the four parts of DNA structure proposed by Watson and crick? (4)
- DNA is helical
-Large #s of H bonds hold DNA in a stable configuration but breaking individual bonds allows the strands to separate - The two strands are complimentary to one another
- Pyrimidines bind to purines
Fluorescent in situ hybridization FISH is used to:
locate sequences of DNA on a chromosome
How is DNA denaturation usually measured?
Absorbance of UV light by DNA increases as DNA denatures
Transposable elements are segments of DNA that may be ____
mobile
What causes unequal crossing over?
a pair of homologous chromosomes aligns imperfectly during meiosis followed by genetic exchange
Constitutive heterochromatin is ____
permanently compacted and not transcribed
What makes adult females genetic mosaics?
inactivated X chromosomes can be from either parent in each cell
Histones are: (4)
- involved with packaging eukaryotic chromatin
- highly conserved
- positiviley charged
- contain high amounts of arginine and lysine
The formation of heterochromatin: (4)
- is related to the state of the histones
- is involved in X inactivation
- is identified by methylation of certain residues in the histones
- results in patterns that may be transmitted to daughter cells
Order levels of chromosomal organization from most dispersed to most condensed
- nucleosomes
- 30nm filaments
- supercoiled loops
- mitotic chromosomes
Epigenetic inheritance:
Is not encoded by DNA
Differences in the epigenomes of identical twins:
are thought to arise due to differences in environmental conditions
How many X chromosomes are active in female and male cells?
1 in each
What is the advantage of the highly condensed state of the DNA of mitotic chromosomes?
favours delivery of an intact package of DNA to daughter cells
In bacterial cells, a single ___ contains a cluster of related genes that can be coordinately regulated by switching transcription of these regulated genes on and off at a site called the ___
operon, operator
What kind of molecules must pass between the nucleus and the cytoplasm?
DNA and RNA
Identical alleles that display different levels of activity based upon wether they are present on the maternal chromosome or on the paternal chromosome are said to be _____
imprinted
What molecule binds at the core promoter sites associated with RNA polymerase?
general transcription factors
THe extent to which a given gene is transcribed presumably depends on:
the combination of transcription factors bound to upstream regulatory elements
Alternate splicing measns that?
the same gene can encode for multiple protiens
The miRNAs that regulated mRNA translation and stability:
typically bind to sites in the 3’UTR of their target mRNAs
What are three mechanisms used as translational level control of gene expression?
- localization of mRNA
- controlled if mRNA is translated
- controlling length of time mRNA is translated
_____ can degrade proteins that have been targeted by the attachment of _____
proteasomes, polyubiquitin chain
Eukaryotes regulate gene expression at all levels except :
replication
In a cell that produces only one type of protein, what is the size relationship between hnRNA and mRNA?
hnRNA is always larger than mRNA
Introns are ___ of the final mRNA
cut out
are mRNAs in prokaryotes and eukaryotes similar in structure?
no
Peptide bond formation is catalyzed by _____ in the ___
ribozymes in the large ribosomal subunit
Prokaryotic mRNA may be _____ before ____ is complete
translated, transcription
Polysomes (polyribosomes) are a group of ribosomes joined together by ____
a single mRNA
The mechanical changed that ribosomes undergo is driven by energy from ____
GTP hydrolysis
Chromosome regions containing rDNA are located in the ____
nucleoli!
What is the origin of virtually all of the signals that regulate cellular activities?
cell surface
Sometimes an enzyme is activated by a receptor and generates a second messenger. This enzyme is called ____
an EFFECTOR
The Gprotein coupled receptor family contain seven ______ as a structural motif
transmembrane a helices
_______ are enzymes that phosphorylate specific tyrosine residues on protein substrates
Protein-tyrosine kinases
Once the kinase domain of receptor protein tyrosine kinase has been activated, what does the activated receptor PTK do?
each receptor subunit phosphorylates its partner on tyrosine residues found in regions adjacent to the kinase domain
The activation of RTKs is characterized by:
dimerization and autophosphorylation
Okazaki fragments are synthesized using the ____ strand in the ____ direction
lagging, 5-3
The function of DNA ligase in replication is to:
link Okazaki fragments
Replication is said to be _________
semidiscontinuous
a replicating prokaryotic chromosome has _______ replication forks, a eukaryotic chromosome has _____
two,
many
In eukaryotes, which dna polymerase is thought to be the primary DNA synthesizing enzyme during replication of the LAGGING strand?
DNA pol δ
Which DNA polymerase in bacteria is mostly involved in DNA repair and removing RNA primers at the 5’ ends of Okazaki fragments?
DNA pol I
If a cell in the G2 phase is fused with a cell in the M phase:::
the G2 nucleus will enter the M phase
DNA synthesis occurs during which phase of the cell cycle?
S phase
When the cyclin concentration ____, CDK is activated, causing ____
rises, enter the M phase
What are the two major phases in the cell cycle?
Mphase, interphase
What major event occurs during anaphase?
sister chromatids separate and are pulled to opposite poles
IN what phase do microtubules attach to kinetochores?
prometaphase
