BIO 353 Exam #4 Worksheets Practice Questions and Answers

BIO 353 Exam #4 Worksheets Practice Questions and Answers Which of the following statements about actin is false? - Ans:-The dynamic instability of actin filaments is important for cell movement The hydrolysis of bound ATP to ADP in actin filament ________ the strength of binding between monomers in the filament. - Ans:-Decreases Actin at the cell cortex helps govern the shape of the plasma membrane. - Ans:-True Actin filaments are nucleated at the site of existing actin filaments in lamellipodia. - Ans:-True The thin sheetlike structures that a fibroblast regularly extends during cell crawling are called: - Ans:- Lamellapodia Myosins are motor proteins that use the energy of ATP hydrolysis to move along actin filaments. - Ans:-True Which of the following examples are characterized by having actin microfilaments arranged in bundles of opposite polarities? - Ans:-Contractile rings and adhesion belts ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 2/10 All of the following are examples are characterized by having actin microfilaments arranged in tight bundles and thin sheets and are structurally polar except: - Ans:-Stress fibers (Included answers: microvilli, lamellipodia, filopodia) Gel-like networks are characterized by having F-actin arranged in a loose yet highly viscous 3D open array with many interconnections and mixed polarity. - Ans:-True __________ is a molecule derived from the very poisonous Amanita phalloides and promotes actin polymerization by binding directly to and stabilizing the filaments. - Ans:-Phalloidin _______ is an actin molecular motor that is crucial for the movement of opposite oriented F-actin; it generates tension in stress fibers, contractile ring adhesion belts, and muscle contraction. - Ans:- Myosin II The basal lamina is constructed from components supplied by different cell types, commonly by epithelial cells on one side and fibroblasts on the other. - Ans:-True Proteoglycans in the extracellular matrix of animal tissues: - Ans:-Help tissues resist mechanical compression; allow cartilage to resist compression ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER 2024 Page 3/10 General name for long, linear, highly charged polysaccharides composed of a repeating pair of sugars, one of each is always an amino sugar that is found covalently linked to a protein core in the extracellular matrix. - Ans:-Glycosaminoglycan (GAGs) Which are features of collagen structure? - Ans:--Triple helix -Glycine rich polypeptide chains -Single collagen alpha-chain forms a left handed helix -Strong side-by-side interactions within the triple helix Fibronectin is capable of linking which two proteins? - Ans:-Collagen and integrins Like many other extracellular proteins, newly synthesized collagen molecules undergo post-translational processing inside the cell then convert them into their mature form, and are then secreted and self- assembled into fibrils in the extracellular space. - Ans:-False Desmosome junctions are structurally similar to adherence junctions but l