Cell and Molecular Biology- Chapter 2

What are the five principles important to cell biology?

Characteristics of carbon, characteristics of water, selectively permeable membranes, synthesis by polymerization of small molecules, and self-assembly.

What is organic chemistry?

The study of carbon-containing compounds.

What does biological chemistry (biochemistry) study?

The chemistry of living systems.

What is the valence of a carbon atom?

What types of bonds do carbon atoms typically form?

Covalent bonds with other carbon atoms, oxygen, hydrogen, nitrogen, and sulfur.

What is a covalent bond?

The sharing of a pair of electrons between two atoms.

What elements are commonly found in biological compounds?

Carbon, hydrogen, oxygen, nitrogen, phosphorus, or sulfur.

What are functional groups?

Common arrangements of atoms that confer specific chemical properties on a molecule.

Name two important negatively charged functional groups.

Carboxyl and phosphate groups.

What is a polar bond?

A bond where electrons are not shared equally between two atoms.

What is the significance of water in biological systems?

Water is the universal solvent and the single most abundant component of cells and organisms.

What is osmosis?

The process of water moving across cellular membranes based on the concentration of solutes present.

What is a function of aquaporins?

Specialized channel proteins that allow water to move quickly across membranes.

Why is water considered a polar molecule?

Due to the unequal distribution of electrons, giving it a partial negative charge at one end and a partial positive charge around the hydrogen atoms.

What results from the network of hydrogen bonds in water?

Cohesiveness, high surface tension, high boiling point, specific heat, and heat of vaporization.

How does water's high specific heat protect living systems?

It absorbs a lot of heat before changing temperature, protecting systems from extreme temperature changes.

What are hydrophilic molecules?

Solutes that have an affinity for water and dissolve easily in it.

What are hydrophobic molecules?

Molecules that are not easily soluble in water, such as lipids and proteins in membranes.

What is the role of the cell membrane?

To act as a barrier between the cell contents and the outside environment, being selectively permeable.

What are phospholipids?

Amphipathic molecules that form the primary component of cellular membranes.

What characterizes the lipid bilayer of a membrane?

Hydrophobic tails facing inward and polar heads facing outward toward the aqueous environment.

How is the lipid bilayer selectively permeable?

It is permeable to nonpolar molecules but impermeable to most polar molecules and ions.

How are ions transported across a membrane?

Through specialized transport proteins, as they cannot diffuse across a membrane.