Study "Cell Biology", a flashcard deck on FORKSAI.
Which of the following statements best describes the role of weak interactions in biological systems?
B
A segment of DNA contains 150 base pairs. If 40% of these base pairs are Guanine-Cytosine (G-C) pairs, how many hydrogen bonds are present in this segment?
First, calculate the number of G-C pairs: 150 base pairs * 0.40 = 60 G-C pairs. Each G-C pair has 3 hydrogen bonds, so 60 * 3 = 180 hydrogen bonds from G-C pairs. Next, calculate the number of Adenine-Thymine (A-T) pairs: 150 - 60 = 90 A-T pairs. Each A-T pair has 2 hydrogen bonds, so 90 * 2 = 180 hydrogen bonds from A-T pairs. The total number of hydrogen bonds is 180 + 180 = 360 hydrogen bonds.
Distinguish between the O-H bonds within a water molecule and the hydrogen bonds that form between different water molecules.
The O-H bonds within a single water molecule are covalent bonds, formed by the sharing of electrons between oxygen and hydrogen atoms. In contrast, hydrogen bonds occur between different water molecules, representing an attractive force between a hydrogen atom covalently bonded to an electronegative atom (like oxygen) and another electronegative atom on a separate molecule.
Explain how hydrogen bonds contribute to the unique properties of water and their significance in biological contexts.
Hydrogen bonds between water molecules are responsible for many of water's unique properties, such as its high boiling point, cohesion, surface tension, and excellent solvent capabilities. Biologically, these properties are vital for maintaining cellular environments, facilitating nutrient transport, and regulating temperature within organisms.
A scientist is studying a newly discovered protein that maintains its tertiary structure even under conditions that typically disrupt hydrogen bonds. Which of the following interactions is most likely playing a significant role in stabilizing this protein's tertiary structure under these conditions?
C
Describe the nature of Van der Waals forces and their biological importance, particularly considering their individual weakness.
Van der Waals forces are weak attractions caused by temporary fluctuations in electron distribution, occurring between all atoms and molecules, even non-polar ones. Individually, they are extremely weak and effective only at very short distances. However, their biological importance arises when thousands occur simultaneously, contributing significantly to the stabilization of protein folding, cell membranes, and molecular recognition processes.
Which of the following interactions is incorrectly matched with its primary biological role?
D
Explain why G-C base pairs are considered stronger than A-T base pairs in DNA structure.
G-C base pairs are stronger than A-T base pairs because they form three hydrogen bonds, whereas A-T base pairs form only two hydrogen bonds. The greater number of hydrogen bonds in G-C pairs results in a more stable interaction, requiring more energy to separate.
A researcher observes that a particular enzyme loses its specific 3D shape and function when exposed to a non-polar solvent. This suggests the disruption of which type of weak interaction that is crucial for maintaining the protein's folded structure?
C
Define a hydrogen bond and list the electronegative atoms commonly involved in its formation.
A hydrogen bond forms when a hydrogen atom covalently bonded to an electronegative atom is attracted to another electronegative atom. The electronegative atoms usually involved in hydrogen bonding are oxygen (O), nitrogen (N), and fluorine (F).