BME 235 Exam 1 | Complete Solutions (Verified)

BME 235 Exam 1 | Complete Solutions (Verified) After cytokinesis, the cell enters the G1 phase. True or False? False Choose the correct statements regarding types of levers. Check all that apply. 1. A first-class lever is one with the fulcrum in the middle. 2. A second-class lever has the resistance in the middle. 3. A second class lever occurs at the atlanto-occipital joint of the neck, where the muscles of the back of the neck pull down on the occipital bone of the skull and oppose the tendency of the head to tip forward. 4. In a third-class lever, the effort is applied between the fulcrum and resistance. 5. Most musculoskeletal levers are first-class levers. 1, 2, 4, 5 An action potential causes depolarization of the T tubule membrane. True or False? True The presence of calcium in the sarcoplasm is directly responsible for _____ exposing the binding sites on actin Rigor mortis occurs after death because detachment of crossbridges does not occur due to the lack of ATP Thin filaments connect to and extend from either side of a __________. These thin filaments are composed largely of the myofilament __________ z disc; actin n heads directly use __________ to transition to their __________ conformation, which enables them ready to bind to actin. ATP; energized On the thin filament, active sites are open for the binding of __________ heads, which allows the contraction to begin. myosin In the ______________, action potentials open voltage-gated ion channels, which leads to the release of calcium ions from the SR into the cytosol. T-Tubules Excitation-contraction coupling refers to the events that link the action potentials on the sarcolemma to activation of the _________________. It begins with the arrival of the _________________ at the neuromuscular junction. myofilaments; action potential Next, a wave of action potentials spreads from the end plate in all directions, reaching the T tubules, then the __________________. Sarcoplasm Calcium will bind to the ____________ of the thin filaments. Troponin Which of the following DNA sequences is complementary to 5' TAGAC 3'? 5' GTCTA 3' What are the 3 components of a nucleotide? Which component varies from one nucleotide to another in DNA? sugar, phosphate group, nitrogenous base The step in which the muscle fiber develops tension and may shorten, is called _____________ It begins after the active site on actin is exposed. Contraction The myosin head must have an ____________ molecule bound to it to initiate the process. ATP The head extends toward the exposed ___________ on the thin filament. active site A _______________ is formed by the attachment of the myosin head to the thin filament. cross-bridge The myosin head pushes forward, moving the thin filament toward the M line. This is called the ________________ power stroke Once more ATP binds, myosin will release from the actin and hydrolyze another ATP. This is called the ________________ recovery stroke The __________________ are found deep in the diaphyses of long bones and are filled with yellow marrow in the adult. medullary cavities Located in the middle of osteons, the ______________ contain the blood vessels, and nervous supply of the compact bones. central canals Filled with _____________, which are osteoblasts encased in matrix, ___________ are found between layers of concentric lamellae. osteocytes; lacunae Osteocytes maintain contact with neighboring osteocytes in adjacent lamellae via dendrite-like extensions through _____________. canaliculi When levels of blood calcium _______________, parathyroid hormone is released from the four nodular parathyroid glands located on the posterior thyroid. Decrease Parathyroid hormone causes an increase in the number of ____________ and greater rates of bone resorption. Osteoclasts At the level of the kidney, parathyroid hormone will decrease the amount of calcium excreted by increasing ________________ from the kidney tubules. Reabsorption Parathyroid hormone increases the renal conversion of __________________,, which secondarily works to increase calcium levels in the blood. calcidiol to calcitriol Inhibition of _____________ by parathyroid hormone occurs as a result of a decreased production of organic matrix. osteoblasts As a result of direct actions on the target cells of the bone and kidneys along with an indirect action on the small intestine (calcitriol), parathyroid hormone works to____________ blood calcium levels. increase Describe the role of collagen and seed crystals in bone mineralization. Bone mineral is initially deposited in "hole" zones between the ends of collagen fibrils of the matrix. As bone matures, hydroxyapatite crystals enlarge and by crystal growth and aggregation. Determine which option below will result in the mechanical advantage of a lever being speed. 1. If LE, the length of the effort arm is (300mm) and LR, the length of the resistance arm is (150mm). 2. If LE, the length of the effort arm is (100mm) and LR, the length of the resistance arm is (100mm). 3. If LE, the length of the effort arm is (55mm) and LR, the length of the resistance arm is (200mm). 4. All of choices 5. None of the above Each of the following complications listed below is a result of a homeostatic calcium imbalance. Which would not be life threatening? 1. A deficit of appositional bone growth 2. Inability to maintain the resting membrane potential 3. Declining neuronal communication 4. Decreased blood clotting ability In an adult, which of the following is a bone that does not contain red bone marrow? 1. Rib 2. Sternum 3. Skull 4. Radius 5. Vertebra The connective tissue that surrounds each muscle fiber is called the _________ Endomysium The specific name for a muscle fiber's plasma membrane is the _______________ Sarcolemma Each myofibril is made of up of several _____________ Myofilaments Terminal cisternae are a structural feature of the organelle called the ________________. sarcoplasmic reticulum In a muscle fiber the ___________ is adjacent to the terminal cisternae so the action potential can stimulate calcium ion channels. T-Tubule In an adult, a compound fracture of the __________ could lead to a "fat" embolism entering the blood stream. 1. tibia 2. sternum 3. skull 4. ribs Elongation of bones is accomplished via ________ growth. Interstitial Growth in the epiphyseal plate adds to the ___________ of a bone until the plate is depleted in early adulthood. length The ____________ is a layer of hyaline cartilage with a metaphysis on each side epiphyseal plate When the cartliage is depleted, the _____________ close and the bone can get no longer. epiphyseal plates The internal mark in the bone left behind by the closed epiphyseal plate is called the __________________ epiphyseal line A(n) __________would not involve damage to the structures that comprise the skeletal system. 1. erosion of the articular cartilage 2. fracture involving the growth plate 3. tear of the anterior cruciate ligament 4. ruptured calcaneal (Achilles) tendon Thick filaments Myosin, Myosin heads Thin filaments Actin, Troponin, Tropomyosin, Active sites Neither thick nor thin filaments Dystrophin, Elastic filament Which of the following statements about DNA replication is TRUE? . Both the leading and lagging strands are replicated continuously. 2. Both the leading and lagging strands are replicated discontinuously. 3. Each of the leading and lagging strands is replicated both continuously and discontinuously. 4. The leading strand is replicated continuously, while the lagging strand is replicated discontinuously. 5. The leading strand is replicated discontinuously, while the lagging strand is replicated continuously. The point where separation of the DNA occurs is called the replication fork. True or False? True What is the difference between a myofilament and a myofibril? Microfilament: long, thin, and stringy proteins (mainly actin) in CELLS Myofibril: Microfilaments that are found in muscles Placing muscle in a solution containing ATP and calcium Excitability Action potentials in the center of the fiber radiating to the ends Conductivity Depolarization of a single muscle fiber causing depolarization of adjacent muscle fibers Conductivity Creation of a force Contractibility Pulling two bones closer together Contractibility Actively resisting the separation of two bones Contractibility A stretched muscle returning to its original length Elasticity Passively resisting the separation of two bones Elasticity Stretching of a muscle Extensibility Increasing sarcomere length Extensibility Explain why DNA replication is called semiconservative. Each DNA double helix becomes two double helixes after replication. Half of the DNA remains intact to create another strand