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    Cell Cycle Post Test

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    QUIZ

    Cell Cycle Post Test

    Cell Cycle Post Test 61%

    27 8th - 9th Biology Stacey Butler 3 years

    10 Qs

    1. Multiple-choice 30 seconds Q.

    Carrie made a model of the cell cycle. She included pictures of stoplights at certain points in the cell cycle to show that the cell cycle has controls, or checkpoints. What can occur if a mutation affects the proteins associated with the checkpoints Carrie has shown in her model?

    answer choices

    Independent assortment and crossing occur at a much greater rate

    The cell cycle switches from mitosis to meiosis and gametes are produced.

    Growth and division of cells proceeds in an uncontrolled way which might result in cancer.

    The cell cycle continues, but the number of chromosomes in each cell produced is increased.

    2. Multiple-choice 30 seconds Q.

    Joacquin and Marie prepared flashcards with statements to describe the importance of the cell cycle and mitosis to an organism. In which statement have they made an error?

    answer choices

    . The cell cycle and mitosis are important to produce identical new cells so that a multicellular eukaryote can grow larger.

    The cell cycle and mitosis are important to produce identical new cells so that a unicellular eukaryote can reproduce.

    The cell cycle and mitosis are important to produce identical new cells so that a multicellular eukaryote can repair damaged tissue.

    The cell cycle and mitosis are important to produce identical new cells so that a multicellular eukaryote can reproduce.

    3. Multiple-choice 30 seconds Q.

    A microbiologist looks through a microscope at dividing cells. He focuses on the cell seen. Which identifies what is happening in this stage of cell cycle?

    answer choices

    synthesis: the chromosomes in the cell are replicating

    Prophase: the cell is preparing to divide.

    Metaphase I of meiosis: the replicated chromosomes are lined up across from the other half of the homologous pair.

    Metaphase of mitosis: the replicated chromosomes are lined up on the cell equator.

    4. Multiple-choice 30 seconds Q.

    The diagram above shows two strawberry plants. Plant 2 is produced asexually from Plant 1. If the leaf cells of Plant 1 have 56 chromosomes, how many chromosomes will be found in the leaf cells of Plant 2?

    answer choices 14 28 56 112 5. Multiple-choice 30 seconds Q.

    Cancer is often characterized by tumors. Which would most likely trigger the formation of a tumor?

    answer choices

    A parasite that both lived and reproduced within the human body.

    A mutation in a gene that codes for a protein regulating cell division.

    A change in the DNA sequence of a gene that codes for skin coloration.

    A bacterial infection that caused inflammation and swelling in body tissues.

    6. Multiple-choice 30 seconds Q.

    The cell cycle is a repeating sequence of cellular growth and division during the life of an organism. Which of the following is not a true statement concerning cell division of body cells?

    answer choices

    Cells divide in a process called mitosis.

    Cells divide in order to maintain homeostasis.

    Cells divide when the parent cell gets too big.

    Cells divide in order to repair themselves when damaged.

    7. Multiple-choice 30 seconds Q.

    Construction workers attach ropes and pulley to wooden timbers on an old bridge. They use the rope and pulley system like the one in the diagram below to move the timbers away from each other, in order to dismantle the bridge.

    answer choices anaphase metaphase prophase telophase 8. Multiple-choice 30 seconds Q.

    As a part of the cell cycle, a cell produces new daughter cells that are identical to the original cell. During which phase are the two daughter cells physically separated?

    answer choices cytokinesis synthesis phase first growth phase second growth phase 9. Multiple-choice 1 minute Q.

    Why would it be important to replicate DNA before a cell divides in mitosis or meiosis?

    answer choices

    In order for genetic information to be transferred into daughter cells.

    In order for the cell to be able to increase in size.

    In order for the DNA to be contained in the nucleus.

    In order for the cell to re-order the DNA sequencing in the new cells.

    10. Multiple-choice 3 minutes Q.

    Put the following actions in order: DNA replicates, cell grows, cell divides, cell prepares for mitosis.

    answer choices

    DNA replicates, cell grows, cell prepares for mitosis, cell divides

    cell grows, cell prepares for mitosis, DNA replicates, cell divides

    cell grows, DNA replicates, cell prepares for mitosis, cell divides

    DNA replicates, cell prepares for mitosis, cell grows, cell divides

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    The Development and Causes of Cancer

    The fundamental abnormality resulting in the development of cancer is the continual unregulated proliferation of cancer cells. Rather than responding appropriately to the signals that control normal cell behavior, cancer cells grow and divide in an uncontrolled manner, invading normal tissues and organs and eventually spreading throughout the body. The generalized loss of growth control exhibited by cancer cells is the net result of accumulated abnormalities in multiple cell regulatory systems and is reflected in several aspects of cell behavior that distinguish cancer cells from their normal counterparts.

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    The Cell: A Molecular Approach. 2nd edition.

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    The Development and Causes of Cancer

    The fundamental abnormality resulting in the development of cancer is the continual unregulated proliferation of cancer cells. Rather than responding appropriately to the signals that control normal cell behavior, cancer cells grow and divide in an uncontrolled manner, invading normal tissues and organs and eventually spreading throughout the body. The generalized loss of growth control exhibited by cancer cells is the net result of accumulated abnormalities in multiple cell regulatory systems and is reflected in several aspects of cell behavior that distinguish cancer cells from their normal counterparts.

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    Types of Cancer

    Cancer can result from abnormal proliferation of any of the different kinds of cells in the body, so there are more than a hundred distinct types of cancer, which can vary substantially in their behavior and response to treatment. The most important issue in cancer pathology is the distinction between benign and malignant tumors (Figure 15.1). A tumor is any abnormal proliferation of cells, which may be either benign or malignant. A benign tumor, such as a common skin wart, remains confined to its original location, neither invading surrounding normal tissue nor spreading to distant body sites. A malignant tumor, however, is capable of both invading surrounding normal tissue and spreading throughout the body via the circulatory or lymphatic systems (metastasis). Only malignant tumors are properly referred to as cancers, and it is their ability to invade and metastasize that makes cancer so dangerous. Whereas benign tumors can usually be removed surgically, the spread of malignant tumors to distant body sites frequently makes them resistant to such localized treatment.

    Figure 15.1

    A malignant tumor of the uterus. Micrographs of normal uterus (A) and a section of a uterine sarcoma (B). Note that the cancer cells (darkly stained) have invaded the surrounding normal tissue. (Cecil Fox/Molecular Histology, Inc.)

    Both benign and malignant tumors are classified according to the type of cell from which they arise. Most cancers fall into one of three main groups: carcinomas, sarcomas, and leukemias or lymphomas. Carcinomas, which include approximately 90% of human cancers, are malignancies of epithelial cells. Sarcomas, which are rare in humans, are solid tumors of connective tissues, such as muscle, bone, cartilage, and fibrous tissue. Leukemias and lymphomas, which account for approximately 8% of human malignancies, arise from the blood-forming cells and from cells of the immune system, respectively. Tumors are further classified according to tissue of origin (e.g., lung or breast carcinomas) and the type of cell involved. For example, fibrosarcomas arise from fibroblasts, and erythroid leukemias from precursors of erythrocytes (red blood cells).

    Although there are many kinds of cancer, only a few occur frequently (Table 15.1). More than a million cases of cancer are diagnosed annually in the United States, and more than 500,000 Americans die of cancer each year. Cancers of 10 different body sites account for more than 75% of this total cancer incidence. The four most common cancers, accounting for more than half of all cancer cases, are those of the breast, prostate, lung, and colon/rectum. Lung cancer, by far the most lethal, is responsible for nearly 30% of all cancer deaths.

    Table 15.1

    Ten Most Frequent Cancers in the United States.

    Go to:

    The Development of Cancer

    One of the fundamental features of cancer is tumor clonality, the development of tumors from single cells that begin to proliferate abnormally. The single-cell origin of many tumors has been demonstrated by analysis of X chromosome inactivation (Figure 15.2). As discussed in Chapter 8, one member of the X chromosome pair is inactivated by being converted to heterochromatin in female cells. X inactivation occurs randomly during embryonic development, so one X chromosome is inactivated in some cells, while the other X chromosome is inactivated in other cells. Thus, if a female is heterozygous for an X chromosome gene, different alleles will be expressed in different cells. Normal tissues are composed of mixtures of cells with different inactive X chromosomes, so expression of both alleles is detected in normal tissues of heterozygous females. In contrast, tumor tissues generally express only one allele of a heterozygous X chromosome gene. The implication is that all of the cells constituting such a tumor were derived from a single cell of origin, in which the pattern of X inactivation was fixed before the tumor began to develop.

    Figure 15.2

    Tumor clonality. Normal tissue is a mosaic of cells in which different X chromosomes (X1 and X2) have been inactivated. Tumors develop from a single initially altered cell, so each tumor cell displays the same pattern of X inactivation (X1 inactive, X (more...)

    Source : www.ncbi.nlm.nih.gov

    Cancer and the cell cycle

    How cancer can be linked to overactive positive cell cycle regulators (oncogenes) or inactive negative regulators (tumor suppressors).

    Regulation of cell cycle

    Cancer and the cell cycle

    How cancer can be linked to overactive positive cell cycle regulators (oncogenes) or inactive negative regulators (tumor suppressors).

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    Introduction

    Does cell cycle control matter? If you ask an oncologist – a doctor who treats cancer patients – she or he will likely answer with a resounding yes.

    Cancer is basically a disease of uncontrolled cell division. Its development and progression are usually linked to a series of changes in the activity of cell cycle regulators. For example, inhibitors of the cell cycle keep cells from dividing when conditions aren’t right, so too little activity of these inhibitors can promote cancer. Similarly, positive regulators of cell division can lead to cancer if they are too active. In most cases, these changes in activity are due to mutations in the genes that encode cell cycle regulator proteins.

    Here, we’ll look in more detail at what's wrong with cancer cells. We'll also see how abnormal forms of cell cycle regulators can contribute to cancer.

    What’s wrong with cancer cells?

    Cancer cells behave differently than normal cells in the body. Many of these differences are related to cell division behavior.

    For example, cancer cells can multiply in culture (outside of the body in a dish) without any growth factors, or growth-stimulating protein signals, being added. This is different from normal cells, which need growth factors to grow in culture.

    Cancer cells may make their own growth factors, have growth factor pathways that are stuck in the "on" position, or, in the context of the body, even trick neighboring cells into producing growth factors to sustain them

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    Diagram showing different responses of normal and cancer cells to growth factor presence or absence.

    Normal cells in a culture dish will not divide without the addition of growth factors.

    Cancer cells in a culture dish will divide whether growth factors are provided or not.

    Cancer cells also ignore signals that should cause them to stop dividing. For instance, when normal cells grown in a dish are crowded by neighbors on all sides, they will no longer divide. Cancer cells, in contrast, keep dividing and pile on top of each other in lumpy layers.

    The environment in a dish is different from the environment in the human body, but scientists think that the loss of contact inhibition in plate-grown cancer cells reflects the loss of a mechanism that normally maintains tissue balance in the body

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    Another hallmark of cancer cells is their "replicative immortality," a fancy term for the fact that they can divide many more times than a normal cell of the body. In general, human cells can go through only about 40-60 rounds of division before they lose the capacity to divide, "grow old," and eventually die

    ^3 3 cubed .

    Cancer cells can divide many more times than this, largely because they express an enzyme called telomerase, which reverses the wearing down of chromosome ends that normally happens during each cell division

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    Cancer cells are also different from normal cells in other ways that aren’t directly cell cycle-related. These differences help them grow, divide, and form tumors. For instance, cancer cells gain the ability to migrate to other parts of the body, a process called metastasis, and to promote growth of new blood vessels, a process called angiogenesis (which gives tumor cells a source of oxygen and nutrients). Cancer cells also fail to undergo programmed cell death, or apoptosis, under conditions when normal cells would (e.g., due to DNA damage). In addition, emerging research shows that cancer cells may undergo metabolic changes that support increased cell growth and division

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    Diagram showing different responses of normal and cancer cells to conditions that would typically trigger apoptosis.

    A normal cell with unfixable DNA damaged will undergo apoptosis.

    A cancer cell with unfixable DNA damage will not undergo apoptosis and will instead continue dividing.

    How cancer develops

    Cells have many different mechanisms to restrict cell division, repair DNA damage, and prevent the development of cancer. Because of this, it’s thought that cancer develops in a multi-step process, in which multiple mechanisms must fail before a critical mass is reached and cells become cancerous. Specifically, most cancers arise as cells acquire a series of mutations (changes in DNA) that make them divide more quickly, escape internal and external controls on division, and avoid programmed cell death

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    How might this process work? In a hypothetical example, a cell might first lose activity of a cell cycle inhibitor, an event that would make the cell’s descendants divide a little more rapidly. It’s unlikely that they would be cancerous, but they might form a benign tumor, a mass of cells that divide too much but don’t have the potential to invade other tissues (metastasize)

    Source : www.khanacademy.org

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