Quiz 4 The Cell Cycle and Cell Junctions Extracellular Matrix

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Florence-Darlington Technical College *

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Biology

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Apr 3, 2024

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docx

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tructions The quiz:  Covers the Learn material from Module 7: Week 7 – Module 8: Week 8 .  Contains 50 multiple-choice questions.  Is limited to 75 minutes .  Allows 1 attempt .  Is worth 125 points . Submit this assignment by 11:59 p.m. (ET) on Friday of Module 8: Week 8. Attempt History Attempt Time LATEST Attempt 1 63 minutes Correct answers are hidden. Score for this quiz: 115 out of 125 Submitted Dec 14 at 9:01am This attempt took 63 minutes. Question 1 2.5 / 2.5 pts If cells that have started mitosis are treated with nocodazole, a drug that depolymerizes microtubules, what would you expect to happen? Where would you expect Mad2 protein to be localized? The cells would arrest in prometaphase; Mad2 would be localized to the spindle poles. The cells would arrest in telophase; Mad2 would be localized to the spindle poles. The cells would immediately enter anaphase, finish mitosis, and enter G 1 ; Mad2 would be localized to the spindle poles. The cells would arrest in prometaphase; Mad2 would be localized to almost all kinetochores.

The cells would arrest in telophase; Mad2 would be localized to almost all kinetochores. Question 2 2.5 / 2.5 pts In the following schematic drawing of a vertebrate prometaphase chromosome as seen under a microscope, indicate whether the chromosome is more likely to be closer to pole A or pole B. Write down A or B as your answer. A B Question 3 2.5 / 2.5 pts Indicate true (T) and false (F) statements below regarding cytokinesis in animal cells. Your answer would be a four-letter string composed of letters T and F only, e.g. TFFF. ( ) The force for cytokinesis is generated by kinesin motors on microtubule bundles that form the contractile ring. ( ) As the contractile ring constricts, its thickness increases to keep a constant volume. ( ) The midbody forms from bundles of actin and myosin II. ( ) Local activation of Ran GTPase triggers the assembly and contraction of the contractile ring. TFFF FTFF

FFFF TTTF FTFT Question 4 2.5 / 2.5 pts Indicate true (T) and false (F) statements below regarding meiosis in eukaryotic cells. Your answer would be a four-letter string composed of letters T and F only, e.g. TFFF. ( ) Bivalents form before prophase I. ( ) Crossing-over begins before the synaptonemal complex assembly. ( ) Chiasmata can first be seen under the microscope after the disassembly of the synaptonemal complexes. ( ) All recombination events lead to crossovers. FTTF TFFT FTFT TTTF FTFF Question 5 2.5 / 2.5 pts

Mammalian Cdk inhibitor proteins (CKIs) can be grouped into two families based on their structural and functional differences. The Cip/Kip family proteins (e.g. p21) have a broad binding specificity. These proteins bind preferentially to already formed cyclin– Cdk complexes and thus enhance complex formation. However, they inhibit the kinase activity of most complexes (e.g. S-Cdks), except in the case of G 1 -Cdk complexes where no inhibition occurs. Consequently, Cip/Kip family proteins have an overall positive effect on Cdk4/6 activity due to their help in bringing the subunits together. In contrast, the inhibitors of the INK4 family (e.g. p16) bind only to the Cdk subunit of G 1 - Cdks and prevent binding of both the G 1 cyclins and the Cip/Kip family CKIs. Based solely on these findings, would you expect p16 to activate (A) or inactivate (I) the S- Cdks in the presence of limited amounts of p21? Activate Inactivate Question 6 2.5 / 2.5 pts Type IV collagen molecules can interact at their C-termini to form dimers and at their N- termini to form tetramers. What category do you think this type of collagen belongs to? Fibrillar Fibril-associated Network-forming Proteoglycan core Anchorage fibril

Question 7 2.5 / 2.5 pts The following schematic drawing shows two integrin molecules. Which molecule (a or b) is depicted in its active configuration? Which side of the plasma membrane (1 or 2) represents the cytosol? a; 1 a; 2 b; 1 b; 2 Question 8 2.5 / 2.5 pts Formin nucleates the growth of parallel actin bundles in the cell. Additionally, myosin motor activity is positively regulated by phosphorylation. The monomeric G protein RhoA is important in cytokinesis, because it directly or indirectly … activates formins and inactivates myosin light-chain phosphatase.

inactivates formins and activates myosin light-chain kinases. activates formins as well as myosin light-chain phosphatases. inactivates formins as well as myosin light-chain kinases. None of the above. 27.In most mammalian cells, low M-cyclin protein levels are maintained during G 1 phase. What is mainly responsible for maintaining these low levels? a. Cdc20–APC/C *b.Cdh1–APC/C c. Skp2–SCF d. β-trCP–SCF e. p27 Question 9 2.5 / 2.5 pts How is centrosome duplication similar to DNA replication? They both use a semiconservative mechanism. They are initiated at around the same time in the cell cycle, near the G 1 /S transition. They are both controlled in such a way that they replicate once and only once per cell cycle. They are both separated from their sister copies in mitosis. All of the above.

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