chapter8 – Flashcard
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An unfertilized egg from a Venuzuelan gecko has a very low number of chromosomes - only 16. Thus, the entire ____ consists of 32 chromosomes and each chromosome consists of ____ and proteins.
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genome, nucleosomes
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Somatic cells in a goldfish have 92 chromosomes. An egg produced by a female would be ____ and have ____ chromosomes.
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haploid, 46
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A mutation in a gene coding for the p53 protein prevents the protein from functioning normally. What is most likely to occur as a result of this mutation?
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Growth and replication of damaged cells.
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In a skin cell, long telomeres indicate that the cell has undergone ____ divisions.
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few
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After a visit to a specialist, Dan was diagnosed with liver cancer. Six months later additional tumors were found in his stomach and small intestine. This is an example of ____.
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metastasis
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A gene that codes for a receptor for a growth factor is mutated. A normally functioning receptor binds with a growth factor and then sends a signal into the cell. However, the abnormal receptor sends a constant signal into the cell whether or not it binds with the growth factor. The gene that codes for the abnormal receptor is ____:
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an oncogene
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Webbing of digits (fingers) in humans, or syndactyly, typically occurs during the sixth to eighth weeks of embryonic life. One of every 2000 - 2500 births have syndactyly and it is more common among Caucasian males. Syndactyly is caused by the failure of what process?
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apoptosis
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Which of the following will move fastest in an electrophoresis gel
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TCG
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Order the following events into the correct sequence for PCR. i. raise temperature to separate DNA strand ii. isolate DNA sequence of interest iii. add taq DNA polymerase iv. lower temperatures so primers will attach
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ii, i, iii, iv
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From Investigating Life: "Cutting off a Tumor´s Supply Lines in the War on Cancer." "How endostatins used to treat cancerous cells?"
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they prevent angiogenesis by cancerous cells
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Where does mitosis occur within this figure
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cd
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Which of the following is incorrectly paired In this figure, the lagging strand is ____
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b
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Which of the following is incorrectly paired?
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ligase -- adds new primers to the lagging strand
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List the following in order from smallest to largest.
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nucleotide, histone, chromatin, chromosome
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Which of the following is part of the interphase of the cell cycle?
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S phase
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Place these cells in order of occurance for the stages of mitosis
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Cell D, Cell B, Cell A, and Cell C
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What can occur if a cell fails in the G1 checkpoint?
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The cell can undergo apoptosis. DNA can be repaired.
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Which of the following is not true about telomeres?
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They produce telomerase.
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What are oncogenes
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mutated variants of genes that code for cell division
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Increating Dolly
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a nucleus was extracted from a somatic cell of an adult animal
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Explain the roles of mitotic cell division, meiosis, and fertilization in the human life cycle.
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Mitosis allows for growth and repair from the fertilized egg to the adult. In reproductively mature individuals, meiosis creates gametes with half the genetic material. The male gamete then fertilizes the female gamete during sexual reproduction, forming a zygote with a full set of genetic material.
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Why are both cell division and apoptosis necessary for the development of an organism
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Cell division is needed to produce the large number of cells necessary to form the individual. Combined with apoptosis, the structures in the organism can be carved out and constantly recycled
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Why does DNA replicate?
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DNA replicates before a cell divides to give a complete set of genetic instructions to each daughter cell.
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What is semiconservative replication?
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Semiconservative replication means that only one strand of a DNA molecule is newly formed. The other strand is original DNA from the parent cell.
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What are the steps of DNA replication
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The helicase enzyme unwinds and separates a double-stranded DNA molecule; the primase enzyme forms a short stretch of complementary RNA on each DNA template; starting at the end of the RNA primer, DNA polymerase adds DNA nucleotides that are complementary to the template strand, proofreading and correcting errors as it goes; RNA primers are removed; on the lagging strand, the enzyme ligase joins fragments of DNA.
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What is the role of RNA primers in DNA replication
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The RNA primer is added to the start of the DNA segment being replicated and acts to attract the DNA polymerase, which can only add nucleotides to an existing strand
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What happens if DNA polymerase fails to correct an error
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A mutation occurs
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What is the relationship between chromosomes and chromatin
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Chromosomes are chromatin coiled tightly on itself
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How does DNA interact with histones
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A stretch of DNA wraps around a cluster of eight histones to form a nucleosome.
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What are the main parts of a chromosome
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The main parts include two identical sister chromatids and the centromere where they are attached
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What are the three main events of the cell cycle?
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The three main events are interphase, during which the cell grows and replicates its DNA, mitosis, during which the DNA divides, and cytokinesis, during which the cytoplasm divides.
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What happens during interphase
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During interphase, a cell grows and produces proteins so that its normal biochemical functions proceed. DNA replicates during interphase as a cell prepares to divide.
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How does the mitotic spindle form, and what is its function?
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The mitotic spindle is composed of microtubules associated with cytoskeleton proteins. The spindle originates from centrosomes that are at opposite ends of the cell. Spindle fibers grow across to join at the midline of the cell. The function of the mitotic spindle is to form "trackways" for the movements of chromosomes as cells divide
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What happens during each phase of mitosis?
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The events of mitosis include: • Prophase: chromosomes condense and become visible; mitotic spindle forms • Prometaphase: nuclear envelope breaks up; spindle fibers attach to kinetochores on each chromosome • Metaphase: chromosomes line up on equator of cell • Anaphase: sister chromatids separate and move to opposite poles of the cell • Telophase: nuclear membranes reassemble around the daughter nuclei; chromosomes decondense; spindle disappears
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Distinguish between mitosis and cytokinesis.
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Mitosis is the division of duplicated chromosomes into new daughter nuclei. Cytokinesis is the division of cytoplasm and organelles into two new daughter cells and the separation of these cells.
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What prevents normal cells from dividing when they are not supposed to
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Interactions between signaling proteins produces checkpoints in the cell cycle to ensure that cells do not divide at improper times
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What happens at cell cycle checkpoints
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At cell cycle checkpoints, the cell cycle is controlled, ensuring that each stage of the cycle is completed before the next stage begins. A cell will only proceed into mitosis if the G1, S, and G2 checkpoints have been successfully passed. If they have not, the cell may stop or suspend the cell cycle, or may enter apoptosis and die
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What is the difference between a benign and a malignant tumor
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Benign tumors do not spread to other areas of the body and do not invade nearby tissues. A malignant tumor does invade nearby tissues and may metastasize to colonize other areas of the body
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How do cancer cells differ from normal cells
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Cancer cells are different from normal cells in that they have lost the normal controls on the cell cycle. Cancer cells therefore divide in an unregulated fashion. Cancer cells look different from normal cells and lose some of the special features of the parent cell. Cancer cells may have their own growth factors that signal when they should divide. Cancer cells lack contact inhibition; in addition, they are essentially immortal and lack apoptosis. Cancer cells can stimulate the growth of new blood vessels that supply them with nourishment and remove wastes
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What is the relationship between mutations and cancer
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Mutations cause changes to the signaling proteins that act as checkpoints on division or that signal apoptosis. These changes result in cells that continually divide and do not undergo cell death.
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How does a person acquire the mutations associated with cancer?
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Mutations can be inherited or caused by exposure to mutagens such as UV radiation or tobacco chemicals. Some sexually transmitted viruses also cause cancer. Lifestyle choices such as eating right and exercising might help prevent mutations associated with cancer
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Distinguish among the treatments for cancer.
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Surgical tumor removal is a direct and local treatment that removes just the cancerous mass and often nearby lymph nodes. Chemotherapy and radiation treatments are both "blunt" tools that target any rapidly dividing cell types, though radiation treatment is much more localized.
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What events happen in a cell undergoing apoptosis
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A cell undergoing apoptosis first receives a signal at a membrane protein called a death receptor. The signal triggers the release of enzymes that destroy the cell from within. Eventually, immune system cells engulf the dying cell, degrading or recycling its components
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Describe two functions of apoptosis.
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Apoptosis carves out excess cells to form a body structure, and it eliminates damaged or aging cells.
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Describe the differences between embryonic, adult, and induced pluripotent stem cells
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Embryonic stem cells are totipotent and give rise to any cell in the body. Adult stem cells are pluripotent, with the ability to become most (but not all) cell types.. Induced pluripotent stem cells are adult stem cells that have gene expression manipulated in such a way that they become like embryonic stem cells
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What are the potential medical benefits of stem cells
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Stem cells help illustrate how animals develop and grow; they may be useful in treating diseases that involve tissue loss or damage, also they are useful in observing the development of a disease from its start. Finally, stem cells may also be useful in drug testing.
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Why is the cloning technique called somatic cell nuclear transfer
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The nucleus of a somatic body cell is used rather than the nucleus of a sex cell
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Summarize the steps scientists use to clone an adult mammal
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Cells from the animal to be cloned are grown in culture, and then the nucleus of one of those cells is removed. That nucleus is then fused with a denucleated cell from an egg donor. The fused cell is allowed to divide into an embryo and is then implanted into the surrogate where it is allowed to develop to birth.
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. How do researchers use the Sanger method and DNA microarrays to deduce a DNA sequence
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The Sanger method uses 4 test tubes with the materials needed to replicate many copies of DNA. Included in each test tube are special terminator nucleotides which result in replicated strands of various lengths indicating the positions of A, C, T, and G in the unknown DNA. When the replicated strands are added to a gel electrophoresis plate the complimentary DNA sequence can be determined. Microarrays also determine unknown DNA sequences as the small segments bind to complimentary sequences on the microarray chip. A computer then pieces together the overlaps in sequences to determine the original sequence.
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How do target DNA, primers, nucleotides, and Taq DNA polymerase interact in PCR
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The primers attach to both ends of the target DNA to give the DNA polymerase the necessary nucleotides. The Taq form of the polymerase is not denatured by the heating process that occurs in PCR, and the nucleotides provide the raw material the polymerase needs to replicate the strand.
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Why is PCR useful
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PCR creates many copies of a tiny DNA sequence for analysis, especially in forensics. It can also be used to increase the amount of DNA recovered from a microorganism to aid in diagnosis or from a fossil to aid in evolutionary classification.
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What are STRs, and how are they used in DNA profiling
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Short tandem repeats are a series of just a few repeating nucleotides that occur in noncoding portions of DNA. Each individual varies in the number of repeats they possess, so by combining analysis of several STR sites between individuals, a DNA profile can be produced
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Why does mitochondrial DNA provide different information from nuclear DNA?
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Mitochondrial DNA is much shorter than nuclear DNA and exists in many copies between all the mitochondria in a cell. It is inherited only from the female parent and does not contain a recombination of male and female nuclear DNA. For this reason it cannot be used to distinguish between siblings.
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Why doesn't endostatin select for drug-resistant cancer cells, as other chemotherapy drugs do?
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Since cancer cells divide so rapidly, mutations are common, and a drug that selects for a particular drug-resistant cell wouldn't work on a cell with a different resistance mutation. By inhibiting the formation of new blood vessels, however, endostatin can treat a cancer no matter what its mutations may be
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Suppose you learn of a study in which ginger slowed tumor growth in mice for 30 days. What questions would you ask before deciding whether to recommend that a cancer-stricken relative eat more ginger?
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You would want to know what variables were controlled for; perhaps there was another combined variable that had the inhibition effect. You might want to know about any potential side effects. You might also want to know if any human trials had been done and if the results in the human trials were comparable to those in mice.
