Chapter 13 Questions Flashcards
A human cell containing 22 autosomes and a Y chromosome is
a sperm
Which life cycle stage is found in plants but not animals?
multicellular haploid
Homologous chromosomes move toward opposite poles of a dividing cell during
meiosis I
Meiosis II is similar to mitosis in that
the daughter cells are diploid
If the DNA content of a diploid cell in the G1 phase of the cell cycle is x, then the DNA content of the same cell at metaphase of meiosis I would be
2x
If we continued to follow the cell lineage from question 5, then the DNA content of a single cell at metaphase of meiosis II would be
x
How many different combinations of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8 (2n = 8)?
16
Asexual reproduction _____.
produces offspring genetically identical to the parent
-Only one individual makes a genetic contribution to the offspring.
What number and types of chromosomes are found in a human somatic cell?
44 autosomes and 2 sex chromosomes
-Human somatic cells contain 22 pairs of autosomes and either two X chromosomes (in females) or an X and a Y chromosome (in males).
For what purpose(s) might a karyotype be prepared?
- for prenatal screening, to determine if a fetus has the correct number of chromosomes
- to determine whether a fetus is male or female
- to detect the possible presence of chromosomal abnormalities such as deletions, inversions, or translocations
-Karyotypes can show if all of the chromosomes are present, and whether an individual is male (XY) or female (XX). In addition, by staining the chromosomes and examining the resulting banding patterns, it is possible to detect defects such as deletions, translocations, and inversions.
In alternation of generations, what is the diploid stage of a plant that follows fertilization called?
sporophyte
-The sporophyte is the diploid, multicellular stage of the plant that produces haploid spores by meiosis.
How are sister chromatids and homologous chromosomes different from each other?
Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication.
-One homologous chromosome comes from the father, and the other comes from the mother. Sister chromatids are identical copies of each other.
Mitosis results in the formation of how many cells; meiosis results in the formation of how many cells?
two diploid cells … four haploid cells
-In mitosis a cell that has doubled its genetic material divides to produce two diploid daughter cells. In meiosis a cell that has doubled its genetic material undergoes two rounds of division, producing four haploid cells.
Which of the following occurs during meiosis but not during mitosis?
Synapsis occurs.
-The pairing of homologous chromosomes that only occurs during prophase I of meiosis is called synapsis.
What is crossing over?
the exchange of homologous portions of nonsister chromatids
-The result is new combinations of genetic material (genetic recombination).
Genetic variation occurs when chromosomes are shuffled in fertilization and what other process?.
meiosis
-Variation is produced as a result of independent assortment and crossing over.
Heritable variation is required for which of the following?
evolution
-Variation is the raw material of evolution.
Human gametes are produced by _____.
meiosis
-Meiosis produces haploid gametes from a diploid parental cell.
Normal human gametes carry _____ chromosomes.
23
-This is the number of chromosomes in a single set of human chromosomes.
Once meiosis I is completed,
cells are haploid.
A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.
16
-16 is half of 32.
Meiosis I produces _____ cells, each of which is _____.
two … haploid
-At the end of meiosis I there are two haploid cells.
Meiosis II typically produces _____ cells, each of which is _____.
four … haploid
-At the end of meiosis II there are typically 4 haploid cells.
The events of prophase II are essentially the same as those of
mitotic prophase except that prophase II cells are haploid.
During anaphase II sister chromatids
separate and migrate to opposite poles.
Four haploid cells are present at the end of
telophase II and cytokinesis.
During _____ sister chromatids separate.
anaphase II
-Anaphase II is essentially the same as mitotic anaphase except that the cell is haploid.
At the end of telophase I and cytokinesis there are
two haploid cells
At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.
telophase I
-At the end of telophase I and cytokinesis, there are two haploid cells with chromosomes that consist of two sister chromatids each.
Homologous chromosomes pair during
prophase I
Metaphase II is essentially the same as
mitotic metaphase except that the cells are haploid.
During metaphase I
tetrads align along the metaphase plate.
Synapsis occurs during _____.
prophase I
-Synapsis, the pairing of homologous chromosomes, occurs during prophase I.
Homologous chromosomes migrate to opposite poles during _____.
anaphase I
-During anaphase I sister chromatids remain attached at their centromeres, and homologous chromosomes move to opposite poles.
During _____ chromosomes align single file along the equator of a haploid cell.
metaphase II
-Metaphase II is essentially the same as mitotic metaphase except that the cell is haploid.