BIOL 121 HW 5

Which type of cell would undergo meiosis?

Sperm precursor cell

The products of meiosis can be different from one another, while the products of mitosis are all the same (except for rare mutations). T or F?

T

During meiosis, the sister chromatids separate during

anaphase II.

Mitotic prophase differs from prophase I of meiosis in that

crossing over is characteristic of prophase I of meiosis but not of mitotic prophase.

In eukaryotic cells, translation occurs in the ________ and transcription occurs _________.

cytoplasm; in the nucleus

As a result of fertilization in which a single egg and sperm fuse, the number of chromosomes in the zygote _______ in comparison to the number of chromosomes in each of the gametes.

doubles

The synthesis of DNA from RNA is called

reverse transcription.

At the end of the first meiotic division, each chromosome consists of

two chromatids.

Before the details of transcription and translation were worked out, Crick hypothesized a unidirectional flow of information from ________ to ________ . He called this model the central dogma of molecular biology.

DNA; protein

Each diploid cell of a human female contains _______ of each type of chromosome.

2

The two members of a specific chromosome pair (for example, pair 1) are called sister chromatids. T or F?

F. For each pair of chromosomes in an individual, one member of the pair came from their mother and the other member came from their father. The two members of a specific chromosome pair bear corresponding, though not identical, genetic information. In many familiar eukaryotic organisms, the somatic cells contain two sets of chromosomes, and the chromosomes occur in pairs called homologous pairs.

homologous chromosome pairs usually contain slightly different versions of the same genetic information. T or F?

T

sister chromatids are joined during prophase I and metaphase I at their common centromere. T or F?

T

A researcher working with mammalian kidney cells grown in culture observed that cells treated with a proteolytic enzyme (an enzyme that breaks down proteins) lost the ability to respond to the hormone vasopressin but not to the hormone aldosterone. Which is a reasonable explanation for this observation?

The vasopressin receptor is embedded in the cell membrane with an external portion that binds its ligand, whereas the aldosterone receptor is an intracellular receptor.

When do cells become haploid during meiosis?

When homologous chromosomes are separated at the end of meiosis I

The members of a homologous pair of chromosomes

are similar in size and appearance.

The total DNA content of each daughter cell is reduced during meiosis because

chromosomes do not replicate between meiosis I and II.

A haploid cell is a cell

containing only one copy of each chromosome.

In most sexually reproducing organisms, the diploid phase of the life cycle begins at

fertilization.

The gene for the reverse transcriptase enzyme, which is used to reverse transcribe viral RNA into DNA in infected cells, is found in the

genome of retroviruses.

Receptors can be divided into two general classes according to their cellular location: _________ receptors and __________ receptors.

intracellular; membrane

Vitamin D is a relatively small, lipid-soluble molecule that can behave as a hormone. Its receptor, therefore, most likely

is located inside the cell.

Ligands that bind to intracellular receptors are generally _________, whereas ligands that bind to membrane receptors are generally __________.

nonpolar; polar