Building Blocks of Life: DNA, RNA, and Protein Quiz

Answer: All of these

Although it is often thought that "nucleotides" are simply the A, C, G, and T bases, they are actually made up of the 5'-phosphate group, and deoxyribose sugar (or ribose in RNA), in addition to the specific base. Nucleotides are joined together through a phosphodiester link between the two sugar residues.

Answer: Hydrogen bonds

Hydrogen bonding between bases allows for stabilization of the double helix. It is important because while these bonds are strong enough to hold the helix shape, they can also be broken under appropriate conditions in order to allow for the two strands which make up the helix to separate for replication or transcription.

Answer: Semiconservative

In DNA replication one "parental" DNA molecule generates two "daughter" DNA molecules. In semiconservative replication, each daughter DNA molecule contains one "old" strand from the parent and one "new" strand generated with free nucleotides using the enzyme DNA polymerase.

The new DNA molecule is therefore the identical base sequence as the parent, using one parental strand as the template to generate a complementary new strand, and thus a new DNA molecule. This process was proved through an experiment by scientists Matthew Meselson and Franklin Stahl in 1958.

Answer: Nucleus

In eukaryotic cells, the DNA is held within the nucleus to ensure it is protected from damage. Since DNA does not leave the nucleus, and this genetic material is required for transcription, this process occurs inside the nucleus. Once the RNA transcript is generated, it is modified to ensure stability, and it leaves the nucleus to be translated into protein.

Answer: All of these

In order for successful translation to occur in the cytoplasm of the cell, all of these modifications must occur. Introns represent RNA which does not code for protein, and are thus removed through splicing before translation. The 5' cap is used to properly position the mRNA on the ribosome for translation.

The poly-A tail at the 3' end can consist of up to 200 "A" nucleotides and is related to message stability.

Answer: tRNA

All tRNAs share generally the same structure. Each one is attached to a specific amino acid based on the anti-codon sequence which it contains. The anti-codon sequence is complementary to the codon sequence, a series of three nucleotides in the mRNA molecule. In this way, the mRNA sequence encodes for the correct sequence of amino acids needed to make a protein!

Answer: 20

Proteins are polymers of 20 different types of alpha amino acids. Every alpha amino acid contains an amino group attached to an alpha carbon which is attached to a carboxyl group. The alpha carbon is also attached to a side chain, which is different in each amino acid. Different side chains allow us to name and distinguish different amino acids!

Answer: Peptide bond

Amino acids are linked together by peptide bonds between the carboxyl group of one amino acid with the amino group of another. This can also be called an amide bond.

Answer: Ribosome

The ribosome is the site of protein synthesis. The mRNA molecule is bound to the ribosome, and this is also where the aminoacyl tRNA (tRNA bound to the appropriate amino acid) binds to the complementary codon. Ribosomes are also present in the rough endoplasmic reticulum. This is why it is called rough! One cell can contain thousands of ribosomes!

Answer: 4

Proteins have four levels of structural organization. The "primary" level is the amino acid sequence. The "secondary" level is local regular folding of that amino acid chain, typically into alpha helices or beta sheets. The "tertiary" level is overall folding of the polypeptide in which the helices or sheets become even more compact. Finally, the "quaternary" level of protein organization is the close association of multiple polypeptide chains to form a functional protein molecule.