Ch. 2

RNA and proteins

A ribosome is composed of

transfer of electrons from one atom to the other.

An ionic bond between two atoms is formed as a result of the

rigid with respect to rotation

Carbon atoms can form double bonds with other carbon atoms, nitrogen atoms. Double bonds can have important consequences for biological molecules because they are__________compared to single covalent bonds.

Sharing of electrons

A covalent bond between two atoms is formed as a result of the

Nitrogen;carbon

A peptide bond along the backbone of a protein is between a ______ and a_______ .5

carbonyl; amino

A peptide bond is formed between the______ group of one amino acid and the________group of another amino acid.

electrostatic attractions

Although covalent bonds are 10-100 times stronger than noncovalent interactions, many bilological processes depend upon the number and type of noncovalent interactions between molecules. Which of the noncovalent interactions below will contribute most to the strong and specific binding of two molecules?

surface complementary between molecules

Macromolecules in the cell can offer interact as a result of noncovalent interactions. These weak interactions also produce stable, highly specific interactions between molecules. Which of the factors below is the most significant in deterring heather the interaction will be transient or stable?

noncovalent, intramolelcular bonds.

The three-dimensional shape of proteins is due to

Condensation; unfavorable

_________reactions are used in macromolecular synthesis and are energetically_________.

Hrudrogen bonds

Both DNA and RNA are synthesized by covalently linking a nucleoside triphosphate to the previous nucleotide, constantly adding to a growing chain. In the case of DNA, the new strand becomes part of a stable helix. The two strands are complementary in sequence and antiparallel in directionality. What is the principal force that holds these two strands together?

limit the rotation of the bonded atoms.

Double covalent bonds are both shorter and stronger than single covalent bonds, but they also limit the geometry of the molecule because they

water

Polar covalent bonds are formed when the electrons in the bond are not shared equally between the two nuclei. Which one of these molecules contains polar bonds?

50%

Proteins make up___________ of the dry mass of a cell.

aqueous

Select the answer that BEST completes the following statement: Chemical reactions in living systems occur in an________ environment, within a narrow range of temperatures.