Unit 3

which of the following statements about communication among bacteria is correct?
Click the card to flip 👆
1 / 87
Terms in this set (87)
which of the following statements about communication among bacteria is correct?
cellular communication in bacteria is based on the same principles as communication within multicellular organisms
bacterial communication requires a receptor molecule
small peptides can stimulate a DNA uptake response
at higher population density, a higher concentration of signaling molecules is typically observed
Mammalian steroid hormones are signaling molecules that function in which of the following types of cell signaling?
endocrine
which type of signal receptor often transmits signals by modifying levels of cyclic-AMP, a second messenger?
G-protein coupled receptor
consider a mutant form of the EGF receptor kinase called Her2/neu. the mutant form of the receptor kinase is linked to cancer because the receptor molecule is locked in the "on" position. which of the following mechanisms could cause this to occur?
the mutant receptor dimerizes in the absence of the signaling molecule
Phosphatases are a family of enzymes that remove phosphate groups from proteins, deactivating them and shutting down a signal. Triuvec is a drug that inhibits phosphatases in eukaryotic cells. what effect would Triuvec have on the response of cells to signals recieved by G-protein coupled receptors?
the response of the cell would last longer than it normally would
choose from the following terms to fill in the blanks in the correct order:
a- ligand
b- signaling cell
c- receptor
d- responding cell
in communication between cells, the __ which produces the signaling molecule, also known as the __; the __ produces the __, to which the signaling molecule binds.
signaling cell (B); ligand (A); responding cell (D); receptor (C)
The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on:
the presence of the appropriate receptors on the cells of the target tissue or organ
which of the following statements about intracellular transport is true?
myosin moves substances toward the "plus end" of microfilaments and kinesin does the same movement in microtubules
a G-protein receptor with GTP bound to it:
is in its active state
the enzyme that release tension from the parental DNA double helix is:
topoisomerase 2
when we say the DNA is semiconservative we mean that:when DNA is replicated, each new double helix contains one parental strand and one newly synthesized daughter strandregarding the following figure which statement is incorrect?the replication of the bottom strand, but not the top, will require the enzymes primase and DNA polymerase 1Similar to linear DNA, circular DNA replication in most prokaryotesproduces okazaki fragments during lagging strand synthesisSuppose you add fluorescent ribonucleotides to a cell undergoing DNA replication so that the RNA primers used in DNA synthesis glow when viewed with a fluorescent microscope. You notice that, near each replication fork, one strand glows more than the other. Which strand is it that glows more, and why?the lagging strand glows more because its RNA primer is nearer the replication forkduring DNA replication in a cell, RNA primase synthesizes a primer that is complementary to the region in the sequence below shown in underline. 5' GAAACCTACAAC 3' what is the primer sequence?5' GUUGUAGGUUC 3'which of the following steps in prokaryotic binary fission is correct?the replicating chromosomes are attached to the plasma membranewhich of the following are true about gametes?they are called egg and sperm in animalsthe M cyclin-CDK complex:triggers phosphorylation of certain nuclear proteins, resulting in breakdown of the nuclear envelope during prophasePut the following steps of DNA replication in chronological order: 1. single-stranded binding proteins attach to DNA strands to prevent them from coming back together 2. helicase breaks hydrogen bonds between base pairs of antiparallel strands 3. primase binds to the site of origin. 4. DNA polymerase binds to the template strand. 5. an RNA primer is created.2, 1, 3, 5, 4malignancies develop stepwise over time because:it takes multiple mutations of multiple genes to allow cancer cells to rapidly divide and invade tissues as suggested by the multiple mutation modelpredict what would happen if a chromosome only connected to one mitotic spindle at its centromere?one of the daughter cells would have an extra copy of that chromosome the sister chromatids would not seperatecolchicine is a drug that is used in plant breeding. it blocks the assembly of microtubules leading to the arrest of mitosis. if dividing cells are treated with colchicine, at what stage of mitosis would you predict the arrest would occur (what phase are microtubules first apparent?)prophasethe genetic information of daughter cells is the same as the genetic information of the parent in binary fission and mitosis.falsep53 is an example of a(n):tumor suppressorThe amount of _____ is fairly constant throughout the cell cycle, but the amount of _____ varies.cyclin dependent kinase; DNA AND cyclin dependent kinase; cyclinswhich of the following statements would be true if a cell has a mutation in the p53 gene such that the p53 protein is always phosphorylated?the amount of p53 protein in the nucleus would remain high regardless of the presence of DNA damage, inhibiting the movement from G1 to SParamecium is a single-cell eukaryotic organism that can reproduce by mitotic cell division. Prior to the M phase of the cell cycle, which of the following must occur?the cell must replicate its chromosomes and damaged DNA must be repairedof the following, the most likely to contribute to uncontrolled cell proliferation (cancer) is:a mutant cyclin that is always present in the cell or a mutant CDK that is active in the absence of cyclinssistmatch each of the proteins involved in DNA replication with its function: 1. DNA helicase 2. topoisomerase 2 3. single-stranded binding proteins 4. DNA polymerase -extends DNA nucleotides from an RNA primer -unwinds the DNA duplex -relieves the stress on the replication fork caused by unwinding -proofreads the growing DNA strands and replaces mismatched nucleotides -prevents strands of DNA from rejoining after being unwound4 1 2 4 3one of the two DNA strands within a replication bubble (between two replication forks) acts as a template strand that produces:one leading strand and one lagging strandwhich of these are necessary for PCR?template DNAhomologous chromosomes can be defined as:pairs of chromosomes that have the same genes, in the same order, although the version of the genes may differwhat is the advantage of the proofreading function of DNA polymeraseDNA polymerase can repair most mutations as they occur during DNA replication allows the polymerase to detect the insertion of an incorrect base during replicationwhat would happen during cell division if the cell is deficient in actin?the cell would not dividethe epithelial cells in the skin of a diploid animal have 24 chromosomes. How many chromosomes are present in the gametes of this animal?12during the cell cycle, the cell must pass through several checkpoints that confirm that the cell is ready to progress to the next phase of the cycle. if the requirements of one phase have not been met, the cell cannot proceed to the next phase. these checkpoints help control the rate of cell division. if a mutation disables one of these checkpoints, what is most likely to happen?the cell begins dividing too often, forming a tumorproto-oncogenes are genes that have the potential to become oncogenes through mutation or increased expression. which of the following describes proto-oncogenes?mutations that increase activity of these genes may lead to cancer these genes code for proteins that normally promote cell divisionHaving two copies of each chromosome in the genome referred to as being:diploida transmembrane protein with an extracellular ligand binding site is an example of which of the following elements of cellular communication?a receptor moleculephosphate groups play a key role in receptor kinase activation by:providing binding sites to recruit and activate signal-transduction proteinsNicotine from cigarette smoke acts as a ligand and associates with specific cells in the nervous system. Nicotine eventually produces feelings of pleasure and well-being. Below are the events that happen in the cellular response to nicotine. Place the events in the correct order to describe the steps in the signaling pathway: 1. The acetylcholine receptor is an ion channel, and, when a ligand binds, the ion channel opens. 2. An influx of ions carries the signal to the brain. 3. Nicotine binds to the transmembrane protein that normally binds the neurotransmitter acetylcholine. 4. The signal causes release of dopamine in the brain, which causes good feelings. 4. Nicotine is quickly eliminated from the body (causing cravings for more cigarettes to produce good feelings).3 1 2 4 5in addition to receiving signals, cells must also shut down signal pathways to end the response. some cancers are related to the inability to shut signals off. which of the following explains why some Ras proteins cannot be switched off?mutations to Ras affect its ability to convert GTP to GDPwhich of the following is a common feature of binary fission and mitotic cell division?cellular growth DNA synthesis pinching of the parent cell into two daughter cells by the cytoskeleton or cytoskeleton-like proteins replication of DNAan imaginary organism has a 2n (diploid) number of 8 chromosomes. this means that:at metaphase 1 of meiosis, 4 pairs of chromosomes (each consisting of 2 sister chromatids) will line up at the midline of the cellresearchers tried to explain how vesicular transport occurs in cells by attempting to assemble the transport components. They set up microtubular tracks along which vesicles could be transported, and they added vesicles and ATP (because they knew the transport process requires energy). Yet, when they put everything together, there was no movement or transport of vesicles. What were they missing?motor proteinsin the figure to the right, what major event is taking place during this phase of meiosisanaphase 1, the homologues separateone advantage of sexual reproduction is hypothesized to be:increase genetic diversity of offspring and escape from parasitesfor the male lubber grasshopper, shown in the karyotype to the right, what are the haploid number (1), ploidy (2) and the number of total chromosomes (3)?haploid number: 12 ploidy: 2n total: 23cancer can be caused by mutations. genetic analysis of a tumor found in a patient we shall call anna shows that the cell proliferation was triggered by a somatic mutation in the MYC gene, causing this gene to be inappropriately activated. anna is concerned about passing this cancer on to the children she plans to have in the future, should she be concerned?no, she should not worry about her children because this did not happen in a germ line cellwhich of the following steps in prokaryotic binary fission is incorrect?the nuclear envelope is reformed prior to cell divisionthe G1/S cyclin-CDK complex:triggers phosphorylation of transcription factors to initiate the synthesis or proteins that prepare the cell for DNA replicationduring DNA replication in a cell, RNA primase synthesizes a primer that is complementary to the region in the sequence below shown in underline. 5' GTTTCATGCAAC 3' what is the primer sequence?5' CAAAGUACGUUG 3'fill in the blanks: 1. diploid 2. homologous chromosomes 3. sister chromatids 4. meiosis 5. haploid 6. mitosis a male rattlesnake has 21 pairs of chromosomes in its scale cells (skin). 21 represents the __ chromosome number. as the snake sheds its outer scales, nearby cells divide through __ to produce new scales. the scale cells produced by mitosis in the boa have a __ chromosome number and are produced after __ are pulled apart into separate daughter cells.5 6 1 3fill in the blanks: 1. diploid 2. homologous chromosomes 3. sister chromatids 4. meiosis 5. haploid 6. mitosis germ cells within the snake's testes undergo __ to produce sperm. the cells produced by meiosis 1 in the rattlesnake have a __ chromosome number and are produced after __ have been pulled apart into separate daughter cells. the cells produced by meiosis 2 in this animal have a __ chromosome number and are produced after __ have been pulled apart into separate daughter cells.4 5 2 5 3the sperm cells in the testes of an animal have 16 chromosomes. how many chromosomes are present in the somatic cells of this diploid animal?32cyclins are examples of:proto-oncogenespredict what would happen if a mutation caused the replication checkpoint to be bypassed during the cell cycle.the cell might enter mitosis before replication is comletesister chromatids can be defined as:identical double helices of DNA that are products of DNA replicationwhich of the following would be a consequence of the inability of the cell to produce microtubules during cell division or meiosis?the sister chromatids would not separate the mitotic spindle would not form homologous chromosomes would not separate plant cells could not construct the cell plate and would not undergo cytokinesisin general, what causes normal cells to become cancer cells?loss of cell cycle controldelta and notch are signaling molecules that function through:contact dependent signalingtumor supressor genes are genes involved in the control of the cell cycle. which of the following statements describe tumor supressor genes? 1. genes that code for proteins that normally inhibit cell cycle progression 2. mutations that increase activity for these genes may lead to cancer 3. mutations that decrease activity of these genes may lead to cancer 4. some products of these genes normally function in detecting damaged DNA 5. these genes code for proteins that normally promote cell division1 3 4which type of signal receptor can transmit signals by activating Ras?receptor kinaseG-protein receptor with GDP bound to it:is in its inactive stateClassify each of the genetic consequences as: a. C b. error during meiosis 1 c. error during meiosis 2 d. error during either meiosis 1 or 2 e. error in either mitosis or meiosis 1. chromosomal damage during sister chromatid separation 2. homologous chromosomes pair incorrectly 3. an error that is passed on to a zygote 4. unregulated cellular division and tumor formation1. error in either mitosis or meiosis (E) 2. error during meiosis 1 (B) 3. error during either meiosis 1 or 2 (D) 4. error during either meiosis 1 or 2 (A)colchicine is a drug that disrupts the normal assembly and disassembly of microtubules. based on this information what would not be affected by colchicine?vesicle trafficking by myosinhow does an "activated" receptor transfer information into the cell?through conformational change of the receptorwhat are the first 5 nucleotides of the new lagging strand synthesized from the top parental strand? 3' [(1)ATTTAACTGATCT] G [(3)TTATATTATCAT] 5' 5' [(2)TAAATTGACTAGA] C [(4)AATATAATAGTA] 3'3' UAAAU 5'which strands are lagging? 3' [(1)ATTTAACTGATCT] G [(3)TTATATTATCAT] 5' 5' [(2)TAAATTGACTAGA] C [(4)AATATAATAGTA] 3'1 4what are the first 5 nucleotides of the new leading strand synthesized from the bottom parental strand? 3' [(1)ATTTAACTGATCT] G [(3)TTATATTATCAT] 5' 5' [(2)TAAATTGACTAGA] C [(4)AATATAATAGTA] 3'5' GUCUA 3'What causes the inactivation of a G protein?The alpha subunit catalyzes the hydrolysis of GTP to GDP and inorganic phosphate.at which stage of the cell cycle could you see sister chromatids with a microscope?Mthe microtubules that form the mitotic spindle extend out from the centrosome. where would you expect to find the plus (fast-assembling) end of a spindle microtubule?away from the centrosome and toward the kinetochorewhich of these choices would block the activity DNA polymerase?removal of the 5' prime phosphates from the nucleotides used by DNA polymerase removal of primase from the DNA replication process removal of the 3' -OH from the last nucleotide of the daughter strandYou attach a yellow or blue fluorescent marker to nucleotides of DNA. Chromosomes composed of yellow nucleotides in both strands glow yellow under a microscope. When both strands are composed of blue nucleotides the DNA glows blue. When one strand is labeled yellow and the other blue the chromosomes glow green. You first grow yeast cells in the presence of "yellow" nucleotides until both DNA strands of all chromosomes glow yellow. Then, you allow cells with yellow labeled DNA undergo two rounds of replication in the presence of "blue" nucleotides so that newly synthesized strands are composed entirely of blue nucleotides. What color would you expect to see for sister chromatids following the second replication?one chromatid will be blue and the other will be greensexual reproduction results:in offspring that are not genetically identical from combining genetic material from two gametes in a new generation that is not genetically identical to its parents in a new generation with the same number of chromosomes as each parentdyenin motor proteins use the energy from ATP to:carry vesicles along a microtubule within a cell in a plus-to-minus directionwhich term refers to the activation of transcription to turn on genes important for cell division as part of receptor kinase signaling?responseYou strip off all proteins on the cell surface by using a protease (an enzyme that destroys proteins). Now, when you add a specific signaling molecule, the cell still responds. What is the most reasonable explanation of this?the signaling molecule is nonpolar and can diffuse into the cell where it binds the receptorwhen a ligand binds to a G-protein coupled receptor, which of the answer choices would you expect to happen before any of the others?adenylyl cyclase activity increasesplatelet derived growth factor (PDGF) is a signaling molecule released by platelets at wound sites to cause nearby cells to undergo cell division, promoting healing. what type of signaling does this represent?paracrine signalingYou are a cancer biologist analyzing a patient's sample of cancer cells and blood. You already sequenced the genes that encode the signaling molecule proteins and detected no mutations associated with cancer (in other words, the proteins fold into the expected tertiary structures). However the cells' signaling transduction cascade is over-active, and as a result they divide rapidly. Which of the following hypotheses regarding your observations would you test?the concentration of a signaling molecule in the patient is higher than usual the cells taken from the patient have more growth factor receptors than normalthe polymerase chain reaction (PCR) has generated 128 copies of a region of amplified DNA has undergone how many cycles?7the cell cycle of yeast can be synchronized meaning that the cells in a culture of growing yeast progress at the same time through the same stage of the cell cycle. as a scientist in a lab studying yeast cell cycling you examine the culture across 5 time periods and measure the total content of DNA present in each cell. your graphed results indicate which? most of the cells examined in interval 3 were in:G2 phasethe cell cycle of yeast can be synchronized meaning that the cells in a culture of growing yeast progress at the same time through the same stage of the cell cycle. as a scientist in a lab studying yeast cell cycling you examine the culture across 5 time periods and measure the total content of DNA present in each cell. your graphed results indicate which? most of the cells examined during interval 5 were in:cytokinesis or G1 phasethe cell cycle of yeast can be synchronized meaning that the cells in a culture of growing yeast progress at the same time through the same stage of the cell cycle. as a scientist in a lab studying yeast cell cycling you examine the culture across 5 time periods and measure the total content of DNA present in each cell. your graphed results indicate which? during which timepoint would the spindle assembly checkpoint occur?4you examine a cell line in which Ras is always activated even in the absence of a signaling molecule. this causes constant activation of the kinases in the MAP kinase pathway. which condition would be most likely to turn off this abnormally active signaling pathway?the addition of a drug that decrease the binding affinity of Ras for MAP kinase enzymes (such as Raf) in the cytoplasm