Free USABO Genetics and Cell Biology Questions and Answers

Question 1

In the extracellular matrix of an animal cell, you would like to test the binding partner of integrins in vitro. Integrins would most likely require a firm attachment to which of these options?

Accepted Answer

Actin

Answer

Explanation:
Integrins are transmembrane proteins that serve as receptors for extracellular matrix components, such as fibronectin, collagen, and laminin. They play a crucial role in cell adhesion, migration, and signaling. Integrins typically bind to actin filaments inside the cell, forming focal adhesions that anchor the cell to the extracellular matrix. This interaction provides a firm attachment for cell adhesion and movement. Myosin, dynein, and kinesin are motor proteins involved in intracellular transport and movement along cytoskeletal filaments, while cyclin is a regulatory protein involved in cell cycle control and not directly associated with integrin binding in the extracellular matrix.

Question 2

You are working with Dr. Lee at the University of Wisconsin-Madison to investigate cytokinesis in a newly discovered marine worm. You generated antibodies to conserved proteins involved in cell division in another organism to look for proteins that localize to important structures during cell division. What molecular motor protein should you look for in the contractile ring?

Accepted Answer

Myosin

Answer

Explanation:
The contractile ring, which forms during cytokinesis, is primarily composed of actin and myosin filaments. Myosin II, a molecular motor protein, interacts with actin filaments and plays a central role in generating contractile force during cytokinesis. As the contractile ring contracts, myosin motors slide actin filaments inward, leading to the division of the cell into two daughter cells. Therefore, when investigating proteins that localize to the contractile ring during cytokinesis, one should look for myosin, which is essential for its function.

Question 3

An unnamed acid has a pKa value of 4.76. Which of the following is closest to the ratio of the concentration of its protonated to deprotonated forms in a pH environment of 6.8?

Accepted Answer

1:100

Answer

Explanation:
The pH of the environment is higher than the pKa of the acid, so it's mostly deprotonated. When comparing the deprotonated form (A-) to the protonated form (HA), the ratio is approximately 1:100.

Question 4

Which scientist(s) is incorrectly matched with his/her/their discoveries?

Accepted Answer

Frederick Griffith – discovery of transformation through bacteriophages.

Answer

Explanation:
Frederick Griffith is incorrectly matched with his discovery. He is not associated with the discovery of transformation through bacteriophages. Instead, Frederick Griffith is known for his experiments with Streptococcus pneumoniae bacteria, which demonstrated the phenomenon of bacterial transformation, where harmless bacteria could become virulent through the uptake of genetic material from other bacteria.

Question 5

Which of the following amino-acid substitutions is LEAST likely to be disruptive to protein function?

Accepted Answer

Alanine to valine

Answer

Explanation:
Both alanine and valine are similar in size and hydrophobicity, so the change is less likely to cause significant disruption to the protein's structure or function compared to the other options.

USABO - USA Biology Olympiad Practice Test

USABO - USA Biology Olympiad Practice Test

Free USABO Genetics and Cell Biology Questions and Answers