Chromosome Structure and Replication, Exams of Biology

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Portage BIOD 151 Final Exam AND Genetics Final

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List two organs contained in the abdominal cavity. - CORRECT ANSWER- - The abdominal cavity contains the stomach, intestines, spleen and liver a. The purpose of cellular respiration is to produce ADP. (T or F) - CORRECT ANSWER- - a. False- (ATP is produced, not ADP) b. Peripheral proteins are found on the outer surface of a cell membrane. (T or F) - CORRECT ANSWER- - b. True c. Exocytosis is the process that occurs to bring biomacromolecules inside the cell. (T or F)

• CORRECT ANSWER- - c. False- (This process is called endocytosis) d. Receptor mediated endocytosis uses a signaling molecule from another cell, binding to the cell membrane to bring about changes within the cell proteins. (T or F) - CORRECT ANSWER- - d. True e. Endocytosis is a passive process. It does not require cellular energy expenditure.(T or F) - CORRECT ANSWER- - e. False- (Endocytosis is an active process and requires cellular energy) In your own words, discuss Tay Sachs disease. What organelle within the cell is impacted? What are the symptoms of the disease and why do they occur? - CORRECT ANSWER- - (1)Lysosomes (2) buildup of toxic lipids inside the cell (biomacromolecules) (3) disability and death, In the genetic disease known as Tay Sachs, one of the normally present digestive enzymes inside lysosomes is lacking. Thus, a toxic lipid in the brain cells cannot

be broken down. The resulting buildup of lipids in these cells can cause intellectual disability and death. You are observing two cells under the microscope. They are the same type of eukaryotic cell but one appears much larger. Based on appearance alone, which one would you expect to be carrying out respiration at a more active rate, the larger or smaller cell? Explain why. - CORRECT ANSWER- - The smaller cell. Cells need to remain relatively small because as a cell expands the amount of surface area relative to the volume of the cell decreases. The smaller cell is more active because relative to its volume, its surface area is larger than a bigger cell. With a larger surface area (relative to its volume) this allows the metabolic processes to occur faster. Explain what happens to the soft palate during swallowing. Why? - CORRECT ANSWER- - The upward movement of the soft palate prevents food or liquid from entering the nasal passages during swallowing. Air and food pass in which one of the following areas: Trachea, Nasopharynx, Oropharynx, Alveoli - CORRECT ANSWER- - Oropharynx Label the following five items from the diagram: - CORRECT ANSWER- - Label B- Oral Cavity, Label D- Epiglottis, Label E- Glottis, Label F- Trachea, Label G- Esophagus From widest to narrowest, the branches of the bronchial tree are: - CORRECT ANSWER- - Primary bronchi, secondary bronchi, tertiary bronchi, bronchioles Explain why someone who has hypergastrinemia (excessive secretion of gastrin) might develop gastric/stomach ulcers. - CORRECT ANSWER- - Gastrin stimulates the secretions of pepsinogens and hydrochloric acid. Excess amounts would lead to erosion of the stomach lining.

When extensor digitorum contracts, what action(s) occurs? - CORRECT ANSWER- - F. B&D: B. Wrist extension, D. Extension of digits 2- 5 Would you expect a male to have estrogen in their bloodstream? Explain why or why not. - CORRECT ANSWER- - (1)Yes. Both male and female bodies produce "all" the sex hormones. However, the ratios are different., (2) The adrenal glands are largely responsible for producing this "opposite" hormone that the testis would not. List the hormone(s) that best describes the statement below: I promote the reabsorption of water at the collecting ducts of the kidneys. - CORRECT ANSWER- - ADH List the hormone(s) that best describes the statement below: I am secreted by the beta cells of the pancreas. - CORRECT ANSWER- - Insulin Aldosterone is involved in the regulation of sodium and potassium in the body. Explain how too much aldosterone could contribute to high blood pressure. - CORRECT ANSWER- - Aldosterone's primary target organ is the kidney, where it promotes renal absorption of sodium and renal excretion of potassium. The blood sodium level is particularly important to the maintenance of blood pressure. Too much sodium causes retention of fluid and increases blood pressure. Therefore, too much aldosterone will cause increased and potentially high blood pressure. A. Identify the sensory cell receptor highlighted in blue, below, also indicated by the arrow. B. What sensory information is detected by this type of receptor? - CORRECT ANSWER- - A) Meisner's corpuscles; B) Detects light touch and vibration (mechanoreceptor) Match the cell with its single best description, using each description only once. - CORRECT ANSWER- - Keratinocytes: Produces a protein to protect the skin, Fibroblasts: Produces collagen, Melanocytes: Produces a pigment that absorbs UV rays, Langerhans cells: Assists in immune responses

What is the name and function of the structure below? (Highlighted in blue, also indicated by the arrow) - CORRECT ANSWER- - Sebaceous gland (oil gland) produces oil (sebum) to protect the skin and hair from drying. The enzyme that some organisms use to replicate DNA at the 5' ends of chromosomes is called: A) DNA polymerase B) telomerase C) DNA ligase D) replicase - CORRECT ANSWER- - B) telomerase Which of the following is not usually seen when a cell loses telomerase activity? A) Telomeres shorten slightly with each cell division. B) After 30-50 divisions cells show signs of senescence and then die. C) In the immune system certain capacity for protection is gradually lost. D) Many normal somatic cells gain the ability to divide indefinitely - CORRECT ANSWER- - D) Many normal somatic cells gain the ability to divide indefinitely The chromosome can be considered a dynamic organelle for _______________ of DNA. A) expression B) segregation C) replication D) packaging E) all of the above - CORRECT ANSWER- - E) All of the above The components of a chromosome include one long DNA molecule and: A) phospholipids B) proteins

A) different functions for different tissues, such as tissue-specific transcription factors B) activity at different moments in the life cycle C) centromere function activity D) all of the above - CORRECT ANSWER- - D) All of the above The first level of compaction of DNA consists of: A) DNA winding around histones to form small nucleosomes. B) tight coiling of DNA with nucleosomes into higher order structures. C) high level compaction into metaphase-type chromosomes. D) histone, DNA, and nonhistone covalent bonding - CORRECT ANSWER- - A) DNA winding around histones to form small nucleosomes An electron micrograph of chromatin, which looks like a bead on a string, allowsmeasurement of structural dimensions. The beads appear to have a diameter of about ________ Å and the string a diameter of about ________ Å. A) 20, 100 B) 20, 0. C) 100, 20 D) 120, 100 - CORRECT ANSWER- - C) 100, 20 Nucleosomal chromatin with a diameter of 100Å supercoils into a 300Å superhelix. Thehistone that appears to be responsible for this compaction is: A) H4. B) H3. C) H2. D) H1 - CORRECT ANSWER- - D) H

In DNA, the 300Å fiber is formed into structural loops. Responsibility for this functionappears to lie with: A) histone H4. B) nucleosomase. C) histone H1. D) certain nonhistone proteins - CORRECT ANSWER- - D) certain nonhistone proteins At what stage of mitosis do we first see a chromosome that is compacted 250-fold over the 40 - fold compacted 300Å fiber? A) prophase B) metaphase C) anaphase D) telophase E) never achieves this level of compaction - CORRECT ANSWER- - B) metaphase Which of the following is not a piece of evidence that supports the radial loop- scaffoldmodel of DNA packaging?A) Histone-depleted metaphase chromosomes still maintain their X-like shapes. B) Electron micrographs of whole-mounted mitotic chromosomes show loops of chromatinat the periphery of the chromosomes. C) Topoisomerase II assists in 100Å packaging. D) Special, irregularly spaced repetitive base sequences associate with nonhistone proteinsto define the chromatin loops. E) All of the above are such evidence - CORRECT ANSWER- - C) Topisomerase II assists in 100 packaging The total compaction of DNA as seen in metaphase chromosomes is approximately ______ fold.

In the medical literature can be found a case history of a young boy with defects in four X- linked traits. When looking at the banding patterns in his karyotype, which of thefollowing can be seen that apparently explains the situation? A) A duplication near the centromere. B) Loss of all interband regions. C) Deletion of a small white band between two darker bands. D) A fusion of two small chromosomes to form the number two chromosome - CORRECT ANSWER- - C) Deletion of a small white band between two darker bands With regard to the typical human cell, which of the following appears to be true? A) There is only one origin of replication. B) There are multiple origins of replication that function consecutively. C) There are multiple origins of replication that function simultaneously. D) Replication is not understood well enough to postulate on replication origins - CORRECT ANSWER- - C) There are multiple origins of replication that function simultaneously. In mammalian cells, replication proceeds: A) unidirectionally. B) bidirectionally. C) unidirectionally from many origins. D) bidirectionally from only one origin - CORRECT ANSWER- - B) bidrectionally The 10,000 origins of replication in mammalian cells suggests that concerning origin of replication there is: A) at least one per loop of DNA B) probably one every other loop of DNA.

C) a random distribution across the genome. D) a precise pattern of distribution relative to other replication points - CORRECT ANSWER-

• A) at least one per loop of DNA Yeast research with autonomously replicating sequences (ARS), along with digestion of chromatin with DNase I, have led scientists to determine that: A) DNA is not protected inside a nucleosome. B) ARSs are really plasmids. C) RSs bond irreversibly to replication enzymes. D) origins of replication are accessible regions of DNA devoid of nucleosomes. - CORRECT ANSWER- - D) origins of replication are accessible regions of DNA devoid of nucleosomes Which of the following is not true about DNA polymerase?A) It cannot begin the 5' end of a new strand without a primer. B) It can only travel in the 5'-to-3' direction. C) It can reconstruct the 3' end of each newly made DNA strand. D) It can replace RNA primer with DNA at the 5' end. - CORRECT ANSWER- - D) It can replace RNA primer with DAN at the 5' end Which of the following are properties of telomeres? A) Consist of special repetitive DNA sequences. B) Prevent the loss of DNA through incomplete replication. C) Cap the ends of each chromosome. D) Number of repeats varies with cell type. E) All of the above - CORRECT ANSWER- - E) All of the above Telomeres appear to function in at least two ways during the replication of chromosomes. One way is to provide a primer for DNA polymerase. The second is to:

E) all of the above - CORRECT ANSWER- - A) Hold sister chromatids together During mitosis, kinetochores develop during: A) telophase. B) anaphase. C) metaphase. D) prophase. - CORRECT ANSWER- - D) Prophase n yeast chromosomes, centromeres: A) help distinguish one chromosome from another. B) are closely related in sequence. C) are only 10-15 bp long. D) play various roles in chromosome segregation - CORRECT ANSWER- - B) are closed related in sequence In higher eukaryotes, kinetochores attach to: A) one spindle fiber. B) one spindle fiber on each side. C) multiple spindle fibers. D) multiple repeating structural subunits - CORRECT ANSWER- - C) multiple spindle fibers The single-celled yeast, Saccharomyces cerevisiae, was the organism of choice as rawmaterial for constructing artificial chromosomes because of all the following except: A) it is easy to manipulate. B) it is unicellular. C) its genetic machinery is similar to the one in higher organisms.

D) its origins of replication have been defined as discrete, small segments of DNA - CORRECT ANSWER- - B) it is unicellular A yeast artificial chromosome (YAC) usually consists of: A) a yeast centromere. B) a yeast origin of replication. C) telomere sequences. D) suitable selectable markers. E) all of the above - CORRECT ANSWER- - E) All of the above Which of the following appears to be true concerning yeast artificial chromosomes(YACs) and segregation errors during cell division? A) 11,000 bp YACs show 50% errors. B) 55,000 bp YACs show 1.5% errors. C) >100,000 bp YACs show 0.3% errors. D) all of the above are true - CORRECT ANSWER- - D) All of the above Even though not well understood, certain chromosome features, known as _________,restrict DNA unwinding to specific regions and prevent decompaction from spreading beyond a certain point. A) rosettes B) telomerases C) nucleosomes D) boundary elements - CORRECT ANSWER- - D) boundary elements Many, but not all, DNase hypersensitive (DH) sites are found: A) at the 5' ends of genes to be transcribed by the cell.

In the position effect variegation of red and white eye color in Drosophila, eyes are produced: A) one red and one white .B) red or white depending on which gene is dominant. C) with every other eye facet red or white. D) with varying sizes and positions of red and white patches. E) none of the above - CORRECT ANSWER- - D) with varying size and positions of red and white patches In which of the following cases will a Barr body be seen? A) XX B) XY C) XO D) XXY E) both a and d - CORRECT ANSWER- - E) both a and d During development, an XX female embryo will form one of the X chromosomes ineach cell into a Barr body. This usually occurs: A) about two weeks after zygote formation. B) by the end of the first trimester. C) at the 16-cell stage. D) in the X that is the most recessive - CORRECT ANSWER- - A) about two weeks after zygote formation Drosophila polytene chromosomes go through 10 rounds of replication withoutundergoing mitosis. The resulting sister chromatids will consist of ________ doublehelixes.

A) 2,

B) 1,

C) twice as many D) 10 times as many - CORRECT ANSWER- - B) 1, Drosophila chromosomes contain bands that range in size from 3 kb to more than 150kb. These bands total about ________. A) 5, B) 2, C) 2, D) 4,000 - CORRECT ANSWER- - A) 5, At certain times, a region of the polytene chromosome may swell to form a large,diffuse structure called a: A) lampbrush B) centromere C) chromocenter D) chromosomal puff - CORRECT ANSWER- - D) Chromosomal Puff The nucleolus consists of: A) long loops of DNA from several chromosomes. B) ribosomal RNA (rRNA) genes. C) growing rRNA transcripts. D) completed transcripts from arrays of rRNA genes. E) all of the above - CORRECT ANSWER- - E) all of the above

E) none of the above - CORRECT ANSWER- - B) Duplication The type of chromosomal rearrangement which reorganizes the DNA sequence within one chromosome is known as a(n) A) inversion B) duplication C) deletion D) translocation E) none of the above - CORRECT ANSWER- - A) Inversion In general, which of the following usually has a greater chance of lethality than the others? A) inversion B) duplication C) deletion D) translocation E) all have an equal chance - CORRECT ANSWER- - C) deletion Sometimes a piece of one chromosome attaches to another chromosome. This is knownas a(n): A) inversion B) duplication C) deletion D) translocation E) none of the above - CORRECT ANSWER- - D) Translocation Sometimes a part of the genome moves from chromosome to chromosome. This isknown generally as a(n):

A) inversion B) duplication C) deletion D) translocation E) transposable element - CORRECT ANSWER- - E) transposable elements Rearrangements and changes in chromosome number may affect gene activity or genetransmission by altering the ________________________ of certain genes in a cell. A) position B) order C) number D) all of the above - CORRECT ANSWER- - D) All of the above Karyotypes generally remain constant within a species because: A) rearrangements occur frequently. B) changes in chromosome number occur infrequently. C) genetic instabilities produced by genomic changes usually are at a selective disadvantage. D) genetic imbalances are often at a selective advantage. - CORRECT ANSWER- - C) genetic instabilities produced by genomic changes usually are at a selective disadvantage Despite selection against chromosomal variations: A) related species almost always have the same karyotype. B) related species almost always have a different karyotype. C) closely related species diverge by many chromosomal rearrangements. D) distantly related species diverge by only a few chromosomal rearrangements - CORRECT ANSWER- - B) related species almost always have a different karyotype