BIOL 221 Lec 2 Covalent Bonds

Which of the following is NOT caused by hydrogen bonding?

Hydronium ions form in water

Van der Waals (hydrophobic) interactions occur when ____.

a random charge fluctuation sets up a transient dipole in a non-ionic molecule

Two molecules with polar covalent bonds are attracted to each other. The resulting bond could be a

Hydrogen bond

Weak bonds are caused by ___________

Charge interactions

Why is it important that most intermolecular interactions in cells are weak bonds?

They are more easily reversible

What happens when water hydrates itself?

H3 O + and OH - ions form

The pH inside a bacterial cell is 7. The pH outside is 6. What is the size of the H + gradient?

There are 10 times as many protons outside the cell than inside.

A C-C bond in molecule A undergoes a random charge fluctuation. As molecule A comes close to

a C-C bond in molecule B, what will happen to molecule B?

A dipole will be induced which will weakly attract molecule B to molecule A.

The hydrophobic effect is used to explain ____.

how micelles form in an aqueous environment

A difference between strong bonds and weak bonds is that ____.

weak bonds involve charge attraction between two molecules or within a large molecule

The pH of bacterial cytoplasm is 7, and the pH of the environment where the bacterium is growing

is 5. How much difference is there in the H + concentration between the inside and outside of the

bacterial cell?

The outside of the cell has 100 times as many protons as the inside.

Which of the following statements is true about polar covalent bonds (P.C.B.s)?

Electrons in a P.C.B. spend more time around one of the bond atoms than the other.

What advantage is it for biological systems to use hundreds of weak bonds rather than one strong

bond to hold two molecules together?

Weak bonds can be broken with less energy input than strong bonds.

Which of the following is a consequence of water forming hydrogen bond networks?

Water dissolves polar molecules and ions easily.

An acidiphilic bacterium lives in an environment with an external pH of 3. There are

approximately ___.

0,000 times as many H + outside than inside the cell

What makes a biological strong bond?

Electron sharing between atoms in the bond

How can the R-group of leucine interact with the R-group of valine?

A temporary dipole in leucine's R-group can induce another dipole in valine's.

Which of the following is a consequence of the unique structure of water molecules?

There are a small number of ions even in pure water.

Two molecules are composed of the same atoms, but the molecules have different molecular

weights. This can be explained by the existence of ____.

isotopes

In a biological context, which of the following describes a strong bond?

Electron sharing between atoms with an electronegativity difference less than 1.6

Which of the following is most important in the formation of micelles from a collection of phospholipids? Why?

The hydrophobic effect since without water the micelle will fall apart.

In order to make ATP, a bacterium needs a △pH of about 2. Assume ions can pass through porins

freely. If the bacterium is growing in a neutral solution, what must be the proton concentration in the

bacterial cytoplasm?

10 ^-9 molar

What can you say about the element Phosphorus from its entry in the periodic table

With a full outer energy shell it would be a (-3) ion

Which of the following is NOT a description of the hydrophobic effect?

A transient interaction between temporary dipoles