bio

Histamine is a chemical substance released in inflammatory and allergic responses. The histamine H1 receptor on target cells is a G protein-coupled receptor that activates phospholipase C in response to the binding of histamine. Which statements are true about the binding of histamine to the histamine H1 receptor? Select all that apply.

-Histamine binds extracellularly to the H1 receptor.-When histamine binds to the H1 receptor. the receptor undergoes a conformation change and binds the inactive G protein. -Once the G protein is active, it binds to the enzyme phospholipase C, activating it. -Histamine is likely hydrophilic. When histamine encounters a target cell, it binds extracellularly to the H1 receptor, causing a change in the shape of the receptor. This change in shape allows the G protein to bind to the H1 receptor, causing a GTP molecule to displace a GDP molecule and activating the G protein. The active G protein dissociates from the H1 receptor and binds to the enzyme phospholipase C, activating it. The active phospholipase C triggers a cellular response. The G protein then functions as a GTPase and hydrolyzes the GTP to GDP. The G protein dissociates from the enzyme and is inactive again and ready for reuse.

Cell signaling involves converting extracellular signals to specific responses inside the target cell. Different molecules are involved at each stage of the process. In this activity, you will sort items based on which stage they are involved in: reception, transduction, or response.

-Reception: G protein-coupled receptor, receptor tyrosine kinase, signaling molecule -Transduction: phosphorylation cascade, second messenger, adenylyl cyclase, Ca2+, cAMP, IP3 -Response: protein synthesis Receptor proteins (located in the plasma membrane or inside the cell) bind signaling molecules. The reception of the signal causes a shape change in the receptor molecule, to which other molecules inside the cell respond. The message is then relayed through signal transduction, which may involve a phosphorylation cascade or second messengers such as cAMP, Ca2+, or IP3. Possible responses to the signal may include synthesis of a particular protein or regulation of a particular enzyme.

Histamine is a chemical substance released in inflammatory and allergic responses. The histamine H1 receptor is a G protein-coupled receptor that activates phospholipase C in response to the binding of histamine. Complete the flowchart showing the process of histamine signal transduction from the H1 receptor. Drag the labels to their appropriate locations in the flowchart. Some labels will not be used.

1. Enzyme cleaves PIP2, forming DAG and IP3. 2. IP3 binds to a ligand-gated ion channel in the ER membrane. 3. Calcium ions flow through the ligand-gated ion channel. 4. Calcium ion concentration increases in the cytosol. 5. Calcium ions activate a protein, leading to a cellular response. After the reception of the histamine signaling molecule, the active G protein activates the enzyme phospholipase C. Phospholipase C cleaves PIP2 into DAG and IP3. IP3 diffuses through the cytosol and binds to an IP3-gated calcium channel in the ER membrane, causing it to open. As a result, Ca2+ ions flow out of the ER and into the cytosol. The increase in the calcium ion concentration in the cytosol helps activate the cellular response.Signal transduction pathways that involve phosphorylation cascades or multiple second messengers, such as histamine's signal transduction pathway, enable a signal to be amplified and regulated at different points. Similarly, multistep pathways can facilitate the coordination of cellular responses to multiple signals.

Arrange the steps in order to complete your model. Not all labels will be used. See Hint 1 for help getting started.

1. S.aureus grow at low density on skin surface 2. S. aureus enter tissue through a wound 3. S. aureus grow to high density inside tissue. 4. S. aureus sense quorum through both the agr and TRAP pathways 5. S. aureus secrete toxin The data demonstrate that both the agr and TRAP quorum-sensing pathways are involved in regulating toxin secretion, and that they work together. When only one pathway is blocked, some toxin secretion results, indicating that neither pathway is completely responsible. Only when both pathways are blocked is toxin secretion (nearly) eliminated.

Consider three questions concerning the animal cell that has been treated with the inhibitor. Drag the terms to answer the questions. Terms may be used once, more than once, or not at all.

1. Will this cell elongate during mitosis? yes 2. Will the sister chromatids separate from each other? yes 3. Will the chromosomes move to the poles of the cell? no The inhibitor does not affect the cleavage of cohesins (the proteins that hold the sister chromatids together), the attachment of the chromosomes to the kinetochore microtubules, or the elongation of the cell due to the nonkinetochore microtubules. The inhibitor only affects the motor protein that pulls the chromosome along the kinetochore microtubule in anaphase. Thus, in the treated cell, the sister chromatids can still separate at the beginning of anaphase due to the fact that the cell is elongating (the centrosomes at the poles of the cell are moving farther apart) and the kinetochore microtubules still connect the chromosomes to the centrosomes. However, because the chromosomes cannot move along the kinetochore microtubules, they will never reach the poles of the cell.

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

16. 16 is half of 32

The cell cycle controls systems of cancer cells differ from those of normal cells. Select the best explanation for this fact.

1st choice: Cancer cells divide excessively and invade other tissues. Although cancer is defined by uncontrollable growth and malignancy (the spread of cancer cells to new tissues), these changes are a consequence of, rather than an explanation for, the fact that cancer cells have escaped normal cell cycle controls. Actual answer: Genetic changes alter control systems of cancer cell's protein products. The underlying basis of cancer is almost always a change in one or more genes that alters the function of their protein products, resulting in faulty cell cycle control.

Given the fact that 1 fg of DNA = 9.78 ×× 105 base pairs (on average), you can estimate the rate of DNA synthesis in Saccharomyces cerevisiae. Approximately how many base pairs per minute were synthesized during the S phase of these yeast cells?

200,000 (2.0 ×× 105) base pairs per minute Because the S phase took place from approximately the 1-hour mark to the 3-hour mark, start by finding the difference between the amount of DNA at 3 hours and the amount at 1 hour: 47.0 fg - 24.0 fg = 23.0 fg. Now calculate the rate of fg synthesized per minute by dividing that amount by the number of minutes in two hours: 23.0 fg/ 120 minutes = 0.192 fg/min. Finally, you need to convert from fg/min to base pairs/min: 0.192 fg/min ×× (9.78 ×× 105 base pairs/fg) = 187,800, or approximately 200,000 base pairs/min.

Normal human gametes carry _____ chromosomes.

23. This is the number of chromosomes in a single set of human chromosomes.

What number and types of chromosomes are found in a human somatic cell? See Concept 13.2 (Page)

44 autosomes and 2 sex chromosomes Human somatic cells contain 22 pairs of autosomes and either two X chromosomes (in females) or an X and a Y chromosome (in males).

Consider a diploid cell where 2n = 6. During metaphase I of meiosis, as the pairs of homologous chromosomes line up on the metaphase plate, each pair may orient with its maternal or paternal homolog closer to a given pole. There are four equally probable arrangements of the homologous pairs at metaphase I. (Note that this problem assumes that no crossing over has occurred.)

ARRANGEMENT 1: 3 & 8 ARRANGEMENT 2:1 & 5 ARRANGEMENT 3:6 & 2 ARRANGEMENT 4:4 & 7 One aspect of meiosis that generates genetic variation is the random orientation of homologous pairs of chromosomes at metaphase I. Each pair can orient with either its maternal or paternal homolog closer to a given pole; as a result, each pair sorts into daughter cells independently of every other pair. Due to independent assortment alone, a diploid cell with 2n chromosomes can produce 2 n possible combinations of maternal and paternal chromosomes in its daughter cells. For the cell in this problem (n = 3), there are 23, or 8, possible combinations; for humans (n = 23), there are 223, or 8.4 million, possible combinations. Note that when crossing over occurs, the number of possible combinations is even greater.

To what does the term "ligand" refer in cell biology? See Concept 11.2 (Page)

Any small molecule that can bind in a specific manner to a larger one Ligands are the small signaling molecules that bind specifically to corresponding protein-receptor molecules.

Meiosis II typically produces _____ cells, each of which is _____.

At the end of meiosis II there are typically 4 haploid cells.

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.

At the end of telophase I and cytokinesis, there are two haploid cells with chromosomes that consist of two sister chromatids each.

At the end of _____ and cytokinesis there are four haploid cells.

At the end of telophase II and cytokinesis there are four haploid cells.

Which of these gametes contains one or more recombinant chromosomes?

B and C. Each of the chromosomes in gametes B and C are composed of material derived from both parents.

Unlike steroid hormones, signaling molecules that are large and/or hydrophilic cannot pass through the cell's plasma membrane and therefore must bind extracellularly to receptor molecules in the plasma membrane. Two types of signal receptors embedded in the cell's plasma membrane are G protein-coupled receptors and receptor tyrosine kinases. Classify each phrase by whether it applies to G protein-coupled receptors only, receptor tyrosine kinases only, both receptors, or neither receptor.

Both G protein-coupled receptors and receptor tyrosine kinases are transmembrane receptors that have a binding domain located on the extracellular side of the plasma membrane. The binding of a signaling molecule to these receptors is the first step in a signaling pathway. However, what happens after a signaling molecule binds is different for each receptor. An activated G protein-coupled receptor activates a G protein inside the cell, which involves the release of GDP and the binding of GTP. The activated G protein then activates an associated enzyme, leading to a cellular response. Receptor tyrosine kinases form dimers after binding signaling molecules. The tyrosines are then phosphorylated, fully activating the receptor. Each phosphorylated tyrosine can bind a relay protein, each of which can trigger a transduction pathway. In this way, a single signaling-molecule binding event can trigger multiple signal transduction pathways and thus multiple cellular responses.

Which of these cells is (are) haploid?

C and D. Once meiosis I is completed, cells are haploid.

Cortisol is a steroid hormone that can pass through the plasma membrane. Complete the flowchart describing the interaction of cortisol with intracellular receptors.

Cortisol is a small, hydrophobic steroid hormone that can pass through the plasma membrane of cells. In target cells, cortisol binds to the intracellular receptor protein in the cytoplasm, forming a hormone-receptor complex. The hormone-receptor complex then moves into the nucleus and acts as a transcription factor, binding to specific genes and activating their transcription into mRNA. The mRNA that is produced is eventually translated into specific proteins. Proteins produced in response to the cortisol signal function in the stress response. For example, some of these proteins aid in elevating glucose levels in the blood, helping an animal to meet the demands of starvation or intense physical activity.

What can you conclude about the relationship between toxin secretion and culture density in S. aureus? Select the three statements that are true.

Cultures grown at high density secrete significant amounts of toxin. Cultures grown at low density do not secrete significant amounts of toxin. The transition from culture densities that do not secrete toxin to those that do secrete toxin occurs quickly after a threshold is reached. The ability of S. aureus to secrete toxin and become pathogenic is dependent on the density of the bacteria present in the population. On the skin surface, the population density remains low, since few nutrients are available on the skin surface. In this environment, toxins are not secreted, and S. aureus is not pathogenic. Once a certain population density threshold is reached, however, S. aureus quickly changes to secrete toxin and become pathogenic. In medical practice, this occurs when S. aureus gains entry inside tissue, either through a wound or as contamination on a medical instrument. In this environment rich with nutrients, S. aureus multiplies quickly and is a serious medical challenge, especially if the strain involved is resistant to traditional antibiotics such as methicillin.

The parent cell that enters meiosis is diploid, whereas the four daughter cells that result are haploid. Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II?

DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II. During anaphase of both meiosis I and meiosis II, the DNA content (number of copies of chromosomes) in a cell is halved. However, the ploidy level changes only when the number of unique chromosome sets in the cell changes. This occurs only in meiosis I (where separation of homologous chromosomes decreases the ploidy level from 2n to n and produces daughter cells with a single chromosome set).

Homologous chromosomes migrate to opposite poles during _____.

During anaphase I sister chromatids remain attached at their centromeres, and homologous chromosomes move to opposite poles.

Which statement provides the best description of the interphase portion of the cell cycle?

During interphase, a cell is metabolically active. Interphase accounts for about 90% of cell cycle and includes many key events critical to the cell cycle. It is not a resting stage; the cell is metabolically active during this phase.

If a eukaryotic cell is in the G1 phase of the cell cycle, which statement about the cell's chromosomes must be correct?

Each chromosome is made of complex DNA and associated proteins Eukaryotic nucleus contains chromatin, a complex of DNA and associated protein molecules. The proteins maintain the structure of the chromosomes and help control gene activity.

Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue. Cell A is most likely in

G1.

How are sister chromatids and homologous chromosomes different from each other? See Concept 13.3 (Page)

Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication. One homologous chromosome comes from the father, and the other comes from the mother. Sister chromatids are identical copies of each other.

For what purpose(s) might a karyotype be prepared? See Concept 13.2 (Page)

Karyotypes can show if all of the chromosomes are present, and whether an individual is male (XY) or female (XX). In addition, by staining the chromosomes and examining the resulting banding patterns, it is possible to detect defects such as deletions, translocations, and inversions.

In the life cycle of an organism, meiosis is paired with the process of fertilization. Understanding the life cycle of an organism is the key to understanding how sexual reproduction ensures the inheritance of traits from both parents and also introduces genetic variation.

Meiosis creates gametes (eggs and sperm) with only a single chromosome set (haploid or n) from parental cells with two chromosome sets (diploid or 2n). During fertilization, the haploid sperm (n) and egg (n) fuse, producing a diploid zygote (2n). The cells of the zygote then divide by mitosis (which does not change the ploidy level) to produce an adult organism (still 2n) of the next generation. In sexual life cycles, meiosis and fertilization keep the number of chromosomes constant from generation to generation.

Human gametes are produced by _____.

Meiosis produces haploid gametes from a diploid parental cell.

During _____ chromosomes align single file along the equator of a haploid cell.

Metaphase II is essentially the same as mitotic metaphase except that the cell is haploid.

Which of the following statements best describes microtubules? Microtubules are permanent cellular structures that help the cell to move from place to place. Microtubules are made up of subunits of actin, and function in muscle contraction and changes in cell shape. Microtubules are fibrous proteins coiled into cables that maintain cell shape and anchor the nucleus. Microtubules are made up of subunits of tubulin, and are structures along which substances are transported in the cell.

Microtubules are made up of subunits of tubulin, and are structures along which substances are transported in the cell. If you had trouble with this question, review the following material: Microtubules—hollow rods constructed from globular proteins called tubulins—shape and support the cell and serve as tracks along which organelles equipped with motor proteins can move. Microfilaments are made up of subunits of actin, and function in muscle contraction and changes in cell shape. Intermediate filaments are fibrous proteins coiled into cables that maintain cell shape and anchor the nucleus.

The video compares the key similarities and differences between mitosis and meiosis. Determine which events occur in mitosis, meiosis, or in both mitosis and meiosis. Sort each event to the appropriate bin.

Mitosis: End result is two diploid cells that are genetically identical to each other and the parent cell A single division occurs, separating sister chromatids Duplicated chromosomes line up individually on the metaphase plate in a diploid cell Meiosis; Homologous pairs of chromosomes line up on the metaphase plate The first division separates homologous pairs; the second division separates sister chromatids End result is four haploid cells that are genetically different from each other and the parent cell Homologous chromosomes pair up and form chiasmata Daughter cells contain recombinant chromosomes Both mitosis and meiosis: Process starts with a diploid cell Chromosomes duplicate during interphase Mitosis and meiosis serve different functions in cells, and therefore, have different outcomes. Mitosis contributes to growth and results in genetically identical cells to the parent cell. Meiosis, on the other hand, functions in the development of gametes, forming genetically different cells from the parent cell. Mitosis involves a single division of the parent cell after chromosome duplication, resulting in two genetically identical daughter cells that are diploid. In contrast, meiosis involves two cell divisions, called meiosis I and meiosis II. Meiosis I splits up homologous chromosome pairs, resulting in two haploid cells. Meiosis II then separates the sister chromatids of those haploid cells, resulting in four daughter cells that are also haploid. The four daughter cells are genetically distinct from the parent cell because they are haploid instead of diploid and because the homologous pairs undergo crossing over prior to the first cell division. Crossing over results in recombinant chromosomes in the daughter cells.

Do these data alone suggest that humans infected with antibiotic-resistant S. aureus can be effectively treated with peptides 1 + 2?

No. Not enough information is provided about the integrity of the study design (for example, number of samples, replicates) and the statistical difference between treatment groups. More data is needed to confirm the results. Before a treatment approach for S. aureus infections in humans is prescribed, human trials are needed. Further information should also be provided about the integrity of the study design and the statistical strength of the experimental results stemming from the in vitro experiments.

Based on these data alone, identify the most appropriate hypothesis that explains the effect of peptides 1 and 2 on the quorum-sensing pathways of S. aureus.

Peptides 1 and 2 acted additively, suggesting that they inhibit different quorum-sensing pathways. Peptides 1 and 2 act additively because when peptides 1 and 2 are used in combination, they reduce toxin secretion more than either peptide does on it own. Therefore, you can conclude that peptides 1 and 2 inhibit different quorum-sensing pathways.

Synapsis occurs during _____.

Prophase I. Synapsis, the pairing of homologous chromosomes, occurs during prophase I.

During _____ a spindle forms in a haploid cell.

Prophase II is essentially the same as mitotic prophase except that the cells are haploid.

Which of the following phases make up the stages of mitosis?

Prophase, prometaphase, metaphase, anaphase, and telophase If you had trouble with this question, review the following material: Mitosis is conventionally broken down into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. Overlapping with the latter stages of mitosis, cytokinesis completes the mitotic phase (M phase) but is separate from mitosis. Interphase, accounting for the remainder of the cell cycle, can be divided into three subphases: G1 phase, S phase, and G2 phase.

Which property is necessary for protein A to bind to protein B?

Protein A must have regions of shape and charge that are complementary to those on Protein B. Molecular shape determines how biological molecules recognize and respond to one another with specificity. Biological molecules often bind temporarily to each other by forming weak interactions, but only if their shapes are complementary, and if their functional groups and surface charges are compatible. The role of molecular shape illustrates how biological organization leads to a match between structure and function, one of biology's unifying themes.

A signal transduction pathway is initiated when a _____ binds to a receptor.

The binding of a signal molecule to a receptor initiates a signal transduction pathway.

1. During prophase, the microtubules of the mitotic spindle lengthen. 2. During anaphase, the nonkinetochore microtubules lengthen and move past each other, and the kinetochore microtubules shorten. 3. During telophase, the nonkinetochore microtubules disassemble.

The mitotic spindle is the machinery that guides the separation of chromosomes in anaphase. Prior to metaphase, the mitotic spindle is constructed by lengthening microtubules that extend from each centrosome. In metaphase, the kinetochore microtubules have attached each pair of sister chromatids, and the nonkinetochore microtubules overlap extensively at the metaphase plate. During anaphase, the kinetochore microtubules shorten as the chromosomes move toward the poles of the cell. At the same time, the nonkinetochore microtubules lengthen and push past each other, elongating the cell. By the end of telophase, all the microtubules associated with the mitotic spindle have disassembled.

Which of the following provides molecular evidence that signal transduction pathways evolved early in the history of life? See Concept 11.1 (Page)

The molecular details of cell signaling are quite similar in organisms whose last common ancestor was a billion years ago. Yeast and mammal cells, for example, are very distantly related yet share many similarities in cell signaling.

Which of the following occurs during meiosis but not during mitosis? See Concept 13.3 (Page)

The pairing of homologous chromosomes that only occurs during prophase I of meiosis is called synapsis.

What must happen to a chromosome before a cell starts mitosis?

The single DNA molecule in the chromosome must be replicated. If you had trouble with this question, review the following material: Before a cell starts mitosis, its chromosomes must be duplicated. This includes replicating the single DNA molecule of a chromosome, resulting in two sister chromatids of a duplicated chromosome that are attached along their lengths. The chromosomes condense during prophase of mitosis.

You have isolated a previously unstudied protein, identified its complete structure in detail, and determined that it is an enzyme that catalyzes the breakdown of a large substrate. You notice it has two binding sites: one large and one small. Speculate about how this enzyme might function.

The small site is probably a binding site for a small molecule whose binding affects the enzyme's shape and function—its breakdown of the large substrate. Allosteric regulation is the term used to describe any case in which a protein's function at one site is affected by the binding of a small regulatory molecule to a separate site. In the simplest kind of allosteric regulation, an activating or inhibiting regulatory molecule binds to a regulatory site (sometimes called an allosteric site). The binding of an activator to a regulatory site stabilizes the shape that has functional active sites, whereas the binding of an inhibitor stabilizes the inactive form of the enzyme.

Drag the labels to the appropriate blanks to complete the sentences. Labels may be used once, more than once, or not at all.

The three peptides you identified are not all equivalent. Peptides 1 and 3 do not act additively, suggesting that they inhibit the same quorum-sensing pathway. Conversely, peptides 1 and 2 (and peptides 2 and 3) do act additively, suggesting that they inhibit different quorum-sensing pathways. In your next experiment, you decide to test the effect of these peptides on agr- and TRAP- mutants to determine which pathway each peptide inhibits.

This chromosome has two chromatids, joined at the centromere. What process led to the formation of the two chromatids?

The two chromatids were formed by duplication of a chromosome.

Assume that an organism exists in which crossing over does not occur, but that all other processes associated with meiosis occur normally. Consider how the absence of crossing over would affect the outcome of meiosis. If crossing over did not occur, which of the following statements about meiosis would be true? Select all that apply.

There would be less genetic variation among gametes.[Crossing over contributes significantly to the genetic variation seen in gametes. This is because the exchange of maternal and paternal genes between the nonsister chromatids of a homologous chromosome pair creates recombinant chromosomes with unique combinations of alleles. However, crossing over is not the only process that introduces genetic variation in meiosis I. The independent assortment of homologous chromosomes (which are never identical) in meiosis I produces daughter cells that differ from each other.The effect of crossing over on genetic variation is shown below. Without crossing over, sister chromatids remain identical and thus, pairs of daughter cells would be identical. With crossing over, however, all four daughter cells are genetically unique.]

Which of the following is true of kinetochores? See Concept 12.2 (Page)

They are sites at which microtubules attach to chromosomes. As the spindle depolymerizes, the kinetochores appear to move along the spindle fiber, dragging the attached chromosomes with them.

What is true of all cancers?

They have escaped normal cell cycle controls.

Which of the following is true of benign tumors, but not malignant tumors? See Concept 12.3 (Page)

They remain confined to their original site. Benign tumors can often be surgically removed because their boundaries are well defined, whereas some significant malignant tumors go on to metastasize.

Drag the labels to their appropriate targets to correctly identify the various chromosome structures. Labels can be used more than once.

a) non-homologous chromosomes b) sister chromatids c) homologous chromosomes d) centromere e) non-sister chromatids f) homologous chromosomes g)sister chromatids To understand the process of meiosis, it is essential that you can differentiate between sister chromatids, nonsister chromatids, homologous chromosomes, and non-homologous chromosomes.

During _____ sister chromatids separate.

anaphase II Anaphase II is essentially the same as mitotic anaphase except that the cell is haploid.

Which of the following sequences is correct? See Concept 11.3 (Page)

binding of a growth factor to its receptor → phosphorylation cascade → activation of transcription factor → transcription binding of a signaling molecule to its receptor → G protein activation → adenylyl cyclase activation → cAMP production → protein phosphorylation binding of a signaling molecule to its receptor → G protein activation → phospholipase C activation → IP3 production → increase in cytoplasmic calcium concentration diffusion of a signaling molecule across the plasma membrane → binding of the signaling molecule to its receptor → movement of the signaling molecule-receptor complex into the nucleus → transcription All of the choices are correct.

The graphs below show the results of an experiment you ran in which you added each peptide to a culture of the TRAP- mutant of S. aureus and a culture of the agr- mutant of S. aureus. Use this data to determine which quorum-sensing pathway each peptide inhibits. Sort each peptide to the correct bin. For help interpreting the graphs, see Hint 1.

blocks TRAP pathway:peptide 2\ blocks agr pathway:peptide 1, peptide 3 blocks both pathways:n/a Using mutants that are already blocked for one of the pathways is a simple way to determine which pathway each peptide acts on. Peptides 1 and 3 both inhibit toxin secretion in the TRAP- mutant, which has a working agr pathway. Therefore, you know that peptides 1 and 3 block the agr pathway. By similar logic, peptide 2 inhibits toxin secretion in the agr- mutant, which has a working TRAP pathway. Therefore, you know that peptide 2 blocks the TRAP pathway. Now that you have identified potent in vitro inhibitors of TRAP and agr quorum-sensing pathways, you decide to test their usefulness in live tissue using an in vivo mouse model.

Which of the following are among the most common second messengers? See Concept 11.3 (Page)

calcium ion and cAMP. These are the most commonly observed second messengers.

What is apoptosis? See Concept 11.5 (Page)

controlled cell suicide

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to

disruption of mitotic spindle formation.

Comparison video of mitosis and meiosis

https://mediaplayer.pearsoncmg.com/assets/sci-bio-fw-a-comparison-of-mitosis-and-meiosis

Are both Fus3 kinase and formin required for directional cell growth during mating in yeast?

https://quizlet.com/159242189/bio181-chapter-11-masteringbiology-homework-flash-cards/#:~:text=What%20hypothesis%20was%20being%20tested,pathway%20leading%20to%20shmoo%20formation.

What is the function of tyrosine-kinase receptors? See Concept 11.2 (Page)

https://www.easynotecards.com/notecard_set/31884 enzymatic phosphorylation of tyrosine in the receptor protein Phosphorylated tyrosine-kinase receptors then interact with relay proteins within the cell.

Which processes lead to most genetic variation in sexually reproducing organisms?

independent assortment of chromosomes in meiosis crossing over random fertilization

The following statements discuss events associated with meiosis. Determine which statements are true and which are false. Drag "True" or "False" to the end of each statement

meiosis reduces the chromosome number from diploid to haploid. true

Asexual reproduction _____. See Concept 13.1 (Page)

produces offspring genetically identical to the parent

Which of the following does not occur during mitosis?

replication of DNA (occurs pre-mitosis, during interphase)

The decline of MPF activity at the end of mitosis is due to

the degradation of cyclin(any of a number of proteins associated with the cycle of cell division that are thought to initiate certain processes of mitosis.)

What is crossing over? See Concept 13.3 (Page)

the exchange of homologous portions of nonsister chromatids The result is new combinations of genetic material (genetic recombination).

Meiosis I produces _____ cells, each of which is _____.

two ... haploid. At the end of meiosis I there are two haploid cells.

The histamine H1 receptor is one of several existing histamine G protein-coupled receptors. Depending on many factors, including the type of receptor, histamine can trigger a variety of responses, including vasodilation, smooth muscle contraction, stimulation of gastric secretion, cardiac stimulation, and increased vascular permeability (causing runny nose and watery eyes). Which of the following could account for the different cellular responses to histamine? Select all that apply.

•the type of histamine receptor •the type of cell in which the receptor is located •the enzyme that is activated by the G protein associated with the receptor •the types of second messengers involved in the signal transduction pathway •the proteins activated by the second messengers Signaling molecules can trigger a multitude of cellular responses, which may ultimately affect the transcription of genes, the activity of proteins, or cell growth and division.