10 Meiosis and Sexual Life Cycles Flashcards
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).
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.
Meiosis I produces _____ cells, each of which is _____.
two … haploid
Meiosis II typically produces _____ cells, each of which is _____.
four … haploid
prophase II
The events of prophase II are essentially the same as those of mitotic prophase except that prophase II cells are haploid.
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 _____ 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.
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.
At the end of _____ and cytokinesis there are four haploid cells.
telophase II
At the end of telophase II and cytokinesis there are four haploid cells.
During _____ a spindle forms in a haploid cell.
prophase II
Prophase II is essentially the same as mitotic prophase except that the cells are haploid.
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?
A.Chromosomes condense.
B. Chromosomes align at the metaphase plate.
C. A spindle apparatus forms.
D. Synapsis occurs.
E. Chromosomes migrate to opposite poles.
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.
A human cell containing 22 autosomes and a Y chromosome is
a sperm.
Homologous chromosomes move toward opposite poles of a dividing cell during
meiosis I