Which of the following statements regarding the double-helix of DNA is true?

Human chromosomes are divided into two arms, a long q arm and a short p arm. Akaryotypeis the organization of a human cell’s total genetic complement. A typical karyotype is generated by ordering chromosome 1 to chromosome 23 in order of decreasing size.

When viewing a karyotype, it can often become apparent that changes in chromosome number, arrangement, or structure are present. Among the most common genetic changes are Robertsonian translocations, involving transposition of chromosomal material between long arms of certain chromosomes to form onederivative chromosome．Chromosomes 14 and 21, for example, often undergo a Robertsonian translocation, as below.

A karyotype of this individual for chromosomes 14 and 21 would thus appear as follows:

Though an individual with aberrations such as a Robertsonian translocation may be phenotypically normal, they can generate gametes through meiosis that have atypical organizations of chromosomes, resulting in recurrent fetal abnormalities or miscarriages.

Which of the following is true of the DNA component of a standard chromosome 14?

I. The intra-strand bonds are covalent

II. The inter-strand bonds are covalent

III. During replication, Okazaki fragments are found on the leading strand

Human chromosomes are divided into two arms, a long q arm and a short p arm. Akaryotypeis the organization of a human cell’s total genetic complement. A typical karyotype is generated by ordering chromosome 1 to chromosome 23 in order of decreasing size.

When viewing a karyotype, it can often become apparent that changes in chromosome number, arrangement, or structure are present. Among the most common genetic changes are Robertsonian translocations, involving transposition of chromosomal material between long arms of certain chromosomes to form onederivative chromosome．Chromosomes 14 and 21, for example, often undergo a Robertsonian translocation, as below.

A karyotype of this individual for chromosomes 14 and 21 would thus appear as follows:

Though an individual with aberrations such as a Robertsonian translocation may be phenotypically normal, they can generate gametes through meiosis that have atypical organizations of chromosomes, resulting in recurrent fetal abnormalities or miscarriages.

Which of the following are important differences between the DNA and histone components of chromosome 21?

I. DNA contains carbohydrates; histones do not

II. Histones contain amino acids; DNA does not

III. DNA contains nitrogenous bases, while histones are nitrogen-free

Of the following groups of nitrogenous bases, which does not contain a purine?

Scientists use a process calledFlourescentIn-SituHybridization, orFISH, to study genetic disorders in humans. FISH is a technique that uses spectrographic analysis to determine the presence or absence, as well as the relative abundance, of genetic material in human cells.

To use FISH, scientists apply fluorescently-labeled bits of DNA of a known color, calledprobes, to samples of test DNA. These probes anneal to the sample DNA, and scientists can read the colors that result using laboratory equipment. One common use of FISH is to determine the presence of extra DNA in conditions ofaneuploidy, a state in which a human cell has an abnormal number ofchromosomes．Chromosomes are collections of DNA, the totality of which makes up a cell’sgenome．另一个典型的使用是癌症研究的cells, where scientists use FISH labels to ascertain if genes have moved inappropriately in a cell’s genome.

Using red fluorescent tags, scientists label probe DNA for a gene known to be expressed more heavily in cancer cells than normal cells. They then label a probe for an immediately adjacent DNA sequence with a green fluorescent tag. Both probes are then added to three dishes, shown below. In dish 1 human bladder cells are incubated with the probes, in dish 2 human epithelial cells are incubated, and in dish 3 known non-cancerous cells are used. The relative luminescence observed in regions of interest in all dishes is shown below.

When probe DNA binds with target DNA, what is the main bonding mechanism likely at play?

In which of the following ways does RNA differ from DNA?

Which of the following is NOT found in both RNA and DNA?

Which of the following statements is not true about DNA and RNA?

DNA is comprised of a double-stranded helix in which purine bases are paired with pyrimidine bases. Which base pairing requires more energy to separate?

Humans must generate an enormous array of antibodies to account for all the possible patterns that they must recognize on pathogens. In fact, the diversity needed in antibody chains cannot be explained by DNA sequence variation. As a result, segments of DNA are physically rearranged in a process called VDJ rearrangement in order to create unique antibody chains. In order to carry out this process, DNA bonds must be broken. What kinds of intra-strand DNA bonds are most likely broken in this process?