Cell Biology Chapter 5 True or False

DNA molecules, like proteins, consist of a single, long polymeric chain that is assembled from small monomeric subunits.

False. (DNA is double-stranded. It is actually made of two polymers that are complementary in sequence.)

Gene expression is the process of duplicating genes during DNA replication.

False. (Gene expression is the process of going from gene sequence to RNA sequence, to protein sequence.)

Histone proteins have a lower-than-average number of lysines and arginines in their polypeptide chains

False. (Histones have a higher number of lysines and arginines than most proteins. These amino acids are positively charged and help to increase the nonspecific affinity between the histones and the negatively charged phosphates in the DNA backbone)

Hydrogen bonds between each nucleotide hold individual DNA strands together.

False. (Nucleotides are linked covalently through phosphodiester bonds. Hydrogen-bonding between nucleotides from opposite strands holds the DNA molecule together.)

All functional DNA sequences inside a cell code for protein products.

False. (Some sequences encode only RNA molecules, some bind to specific regulatory proteins, and others are sites where specific chromosomal protein structures are built (for example, centromeric and telomeric DNA).)

The telomere is a specialized DNA sequence where microtubules from the mitotic spindle attach to the chromosome so that duplicate copies move to opposite ends of the dividing cell.

False. (The telomere is a specialized DNA sequence, but not for the attachment of spindle microtubules. Telomeres form special caps that stabilize the ends of linear chromosomes)

There are five different nucleotides that become incorporated into a DNA strand.

False. (There are four different nucleotides that are used to make a DNA polymer: adenine, thymine, guanine, and cytosine. A fifth nucleotide, uracil, is found exclusively in RNA molecules, replacing thymine nucleotides in the DNA sequence.)

Comparing the relative number of chromosome pairs is a good way to determine whether two species are closely related.

False. (There are several examples of closely related species that have a drastically different number of chromosome pairs. Two related species of deer—Chinese and Indian muntjac—have 23 and 3, respectively.)

Gene sequences correspond exactly to the respective protein sequences produced from them.

False. (This statement is false for two reasons. First, genes often contain intron sequences. Second, genes always contain nucleotides flanking the protein-coding sequences that are required for the regulation of transcription and translation.)

Interphase chromosomes represent a physical state of the chromatin with the highest order of packaging

False. (When cells enter mitosis, the interphase chromosomes undergo at least one more level of packaging, which facilitates the segregation of sister chromatids.)

The histone proteins that constitute the core nucleosome include tetramers of histones H2A, H2B, H3, and H4.

False. (When the core nucleosome is analyzed, it is revealed that there are H2A/H2B tetramers and H3/H4 tetramers in solution. Each of the tetramers has two subunits of the respective histone proteins. )

Linker histones help compact genomic DNA by influencing the path of the DNA after it has wrapped about the nucleosome core.

True

Chromosomes exist at different levels of condensation, depending on the stage of the cell cycle.

True.

Each strand of DNA contains all the information needed to create a new double stranded DNA molecule with the same sequence information.

True.

Eukaryotic chromosomes contain many different sites where DNA replication can be initiated.

True.

The polarity of a DNA strand results from the polarity of the nucleotide subunits.

True.