Intro to Cell Bio Exam 3

For the experiment shown in figure 11.9, which answer correctly states the prediction of the hypothesis or null hypothesis?

Prediction of hypothesis, antibodies to some membrane proteins will block cell cell adhesions

The mitotic spindle consists of two types of microtubules: kinetochore microtubules and nonkinetochore microtubules. In animal cells, these two types of microtubules function differently in the stages of mitosis. Complete the sentences by dragging the labels to the appropriate locations. Labels may be used once, more than once, or not at all.

1) During prophase, the microtubules of the mitotic spindle________. lengthen 2) During anaphase, the nonkinetochore microtubules _______ and move past each other, and the kinetochore microtubules________. lengthen, shorten 3) During telophase, the nonkinetochore microtubules______. disassemble

1. After a carbohydrate meal glucose concentration increases in the blood and glucose enters the beta cells through ______ transporters. 2. Increased glucose concentration leads to an increase in the intracellular concentration of _______ from the process of oxidative metabolism. 3. During the resting state of the beta cells there are many open KATP channels that allows the continuous _____ of K+ ions from the cell and this ion movement is a major component involved in the setting of the _____ membrane potential at -70 mV. 4. The binding affinity of ATP for the allosteric site on the KATP channels is very ______ meaning that the Km for binding is ______ . 5. Only when ATP levels significantly increase will there be any significant binding to the KATP channels but when ATP does bind it ______ a gate in these channels which leads to a significant ______ of the membrane due to the retention of many positively charged K+ ions that previously _____ from the cell. 6. When the depolarization of the beta membrane reaches ________ mV which is the _______ voltage, numerous voltage-gated _______ channels open leading to a _______ of calcium ions. 7. The calcium signal leads to the ______ of the secretory vesicles, which are storing ______.

1. GLUT 2. ATP 3. Leakage, Resting 4. Low, high 5. closes, depolarization, leakage 6. -55, threshold, calcium, influx 7. exocytosis, insulin

1. Cells divide by constriction of a ring of protein. 2. The presence of a cell wall prevents the cell from dividing by constriction. 3. Tubulin subunits or tubulin-like molecules function in the division of the cell.

1. TTF 2. FFT 3. TFT

Explain the difference between a ligand-gated K+ channel and a voltage-gated K+ channel.

1. The ligand-gated channel opens or closes in response to binding by a small molecule. 2. The voltage-gated channel opens or closes in response to changes in membrane potential.

Mitosis and cell cycle terminology As in most areas of biology, the study of mitosis and the cell cycle involves a lot of new terminology. Knowing what the different terms mean is essential to understanding and describing the processes occurring in the cell.

1.) DNA replication produces two identical DNA molecules called _____, which separate during mitosis. sister chromatid(s) 2.) After chromosomes condense, the _____ is the region where the identical DNA molecules are most tightly attached to each other. centromere(s) 3.) During mitosis, microtubules attach to chromosomes at the _____. kinetochore 4.) In diving cells, most of the cells growth occurs during ____. interphase 5.) The ____ is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division. mitotic spindle(s) 6.) During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called ____. chromatin 7.) In most eukaryotes, division of the nucleus is followed by ____, when the rest of the cell divides. cytokinesis 8.) The ____ are the organizing centers for microtubules involved in separating chromosomes during mitosis. centrosome

Complete the flowchart showing the process of epinephrine signal transduction from the epinephrine receptor on liver cell membranes. Note that the hormone epinephrine is released from the adrenal glands and to help get you started the first cell in the flowchard should be filled with the statement "Adrenal Gland releases hormone"

Adrenal Gland releases Hormone Epinephrine binds to G protein-coupled receptor in liver cell G protein changes shape causing dissociation of GDP GTP binds to G protein, producing two activated complexes The alpha complex activates the enzyme adenylyl cyclase The amplifier enzyme produces the second message cAMP The second messenger activates numerous protein kinase a enzyme The G protein is switched off by converting GTP to GDP

Based on what you have learned about how cells ensure that proteins end up in the right place (Chapter 7), what type of signal would you expect to be exposed on a cytosolic receptor after a steroid hormone changes the receptor's conformation?

Amino acids required for transport through the nuclear pore complex

Which answer correctly associates a phase of mitosis with what happens to chromosomes during that phase?

Anaphase: Sister chromatids separate.

What evidence suggests that during anaphase, kinetochore microtubules shorten at the kinetochore?

Daughter chromosomes were observed to move toward the pole faster than do the marked regions of fluorescently labeled kinetochore microtubules

Which answer correctly identifies a cell-cycle checkpoint with a criterion for passing it?

G2 checkpoint: Chromosomes have replicated successfully.

Which statement is most accurate concerning how the molecular composition of a plant cell wall compares with the ECM of animal cells?

Plant cell wall fibers consist primarily of carbohydrates ECM fibers are dominated by proteins

In which mitotic phase do the chromosomes condense and does the mitotic spindle begin to form?

Prophase

Mitosis unfolds through a sequence of stages marked by specific events in the cell. The structural changes in the cell are brought about by a series of tightly coordinated underlying mechanisms. Sort each process into the appropriate bin to indicate the stage of mitosis in which it occurs. If a process occurs in more than one stage, sort it to the stage when it first occurs.

Prophase: 5-Tubulins assemble into spindle microtubules and 7-Cohesions join sister chromatids of duplicated chromosomes. Prometaphase: 3- Microtubules attach to kinetochores. Metaphase: 2- Kinetochores are motionless in relation to poles of cell Anaphase: 6- Cohesions break down and 4- Kinetochores move toward poles of the cell Telophase: 1- Spindle microtubules disassemble

Explain which ion flow or flows are responsible for each part. Drag the appropriate items to their respective bins.

Resting Potential: K Na and Ca are at equilibrium with respect to their electrochemical gradients Depolarization: Na channels are open Repolarization: K channels open Hyperpolaryzation: K channels have remained open

What would happen if the kinase that adds the inhibitory phosphate to Cdk were defective?

The M phase would begin prematurely

Cytokinesis in animal cells is accomplished by constriction of the cell along the plane of cell division (formation of a cleavage furrow). In plant cells, which have cell walls, a completely different mechanism of cytokinesis has evolved. Which of the following statements are true of cytokinesis in plant cells? Select the two that apply.

The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells. Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.

Which statement about the daughter cells following mitosis and cytokinesis is correct?

They are genetically identical with each other and with the parent cell.

Voltage-gated channels and the action potential The fixed pattern of changes in membrane potential during an action potential is coordinated by the sequential opening and closing of voltage-gated ion channels. Can you identify the status (open/closed) of the voltage-gated Na+ and K+ channels during each phase of an action potential?

a.) resting potential Na+ channels are close, K+ channels are closed b.) rising potential Na+ channels open K+ channels closed c.) falling phase Na+ channels closed K+ channels open d.) undershoot Na+ channel closed K+ channels open e.) resting potential Na+ channels closed K+ channels closed

In all cells, separation of replicated chromosomes is a prerequisite for cell division. However, the mechanism of chromosome separation in bacteria is distinct from that in eukaryotes in several ways.

bacteria only: chromosome separation begins at the origin of replication on DNA eukaryotes only: before separation duplicated chromosomes condense, nuclear envelope fragments permitting chromosome separation, two copies of the duplicated chromosome are attached at their centromeres before separating both bacteria and eukaryotes: chromosomes replicate before cell division, replicated chromosomes separate by attaching to some other structural feature of the cell

The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?

cleavage furrow formation and cytokinesis

The most abundant protein found in the extracellular matrix of animal cells is _____.

collagen

The division of the cytoplasm following mitosis is called _____.

cytokinesis

The strength of a stimulus (for example, whether you feel a slight pain versus an intense pain) determines the number of action potentials sent along an axon. As the graphs show, a strong stimulus produces more action potentials spaced more closely together than a weak stimulus. The time between when a first action potential ends and a second action potential can be triggered is determined by the axon's refractory period. A second action potential cannot be triggered until the end of the refractory period. Which of the following characteristics determines when the refractory period ends?

how long it takes for the voltage-gated Na+ channels to reactivate at the end of an action potential

Initiating an action potential Under most circumstances, once an axon's membrane potential reaches threshold (about -55 mV in mammals), an action potential is automatically triggered. The graph below shows the changes in membrane potential that occur in an axon membrane that is initially at resting potential. In response to a stimulus, the membrane slowly depolarizes until the membrane potential reaches a particular value, called threshold. At threshold, a rapid depolarization of the membrane occurs and an action potential is initiated.

membrane potential reaches threshold ---> many Na+ voltage-gated channels open ---> Na+ ions rush into the cell ---> membrane potential rises (depolarizes) rapidly

how can a hormone that is present in very small quantities within the bloodstream elicit such a large response within a cell?

the message from the hormone is amplified many times within the cell

Identify the events in the cell cycle that must be completed successfully for daughter cells to share an identical complement of chromosomes.

the spindle apparatus must connect with the kinetochores of each sister chromatid in pro metaphase all the chromosomes must be replicated during the S phase the sister chromatids of each replicated chromosome must be partitioned in anaphase and fully separated into daughter cells by cytokinesis

Consider an animal cell in which motor proteins in the kinetochores normally pull the chromosomes along the kinetochore microtubules during mitosis. Suppose, however, that during metaphase, this cell was treated with an inhibitor that blocks the function of the motor proteins in the kinetochore, but allows the kinetochore to remain attached to the spindle. The inhibitor has no effect on any other mitotic process, including the function of the nonkinetochore microtubules. Answer yes or no to the following three questions concerning this animal cell that has been treated with the inhibitor: 1. Will this cell elongate during mitosis? (yes or no?) yes 2. Will the sister chromatids separate from each other? (yes or no?) yes 3. Will the chromosomes move to the poles of the cell? (yes or no?) no

yes, yes, no