Week 13: Mitosis II and Meiosis I Flashcards
Briefly describe what happens in mitosis (Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis)
Interphase: period of growth and preparation
Prophase: Chromosomes condense, the nuclear envelope breaks down, and spindle fibers begin to form.
Metaphase: Chromosomes align in the middle, and spindle fibers attach to the centromeres.
Anaphase: Sister chromatids are separated and pulled to opposite poles of the cell
Telophase: Chromosomes de-condense, a nuclear envelope forms around each set of chromosomes, and the cell prepares for division.
Cytokinesis: The division of the cell’s cytoplasm and organelles into two daughter cells.
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C
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D
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B and E
The two daughter cells resulting from mitosis are, apart from any mutations occurring during DNA replication, identical to the parent cell.
A) True
B) False
A) True
Genetic diversity comes from different alleles. What are alleles
Alleles are the different DNA sequences that may be present for a given gene.
Alleles are alternative forms of a gene that occupy the same position, or locus, on a chromosome. Genes are segments of DNA that code for specific traits, and alleles are the different versions or variants of those genes. Each individual inherits one allele for each gene from each parent.
For example, consider a gene that codes for eye color. The gene may have different alleles, such as one for brown eyes and another for blue eyes. In this case, “brown” and “blue” are the different alleles of the eye color gene.
what is a gene
segment of DNA that codes for specific traits
what are traits
Traits are the phenotypes expressed in individual organisms.
Why is meiosis necessary for sexual reproduction?
A. It produces genetically variable gametes.
B. It produces gametes that are identical to the
parent cell.
C. It produces gametes with 1⁄2 of the chromosomes that the offspring will need.
D. It produces 4 gametes, each with 1⁄4 of the chromosomes that the offspring will need.
C. It produces gametes with 1⁄2 of the chromosomes that the offspring will need.
briefly and simply explain how meiosis works
Meiosis is a process of cell division that occurs in sexually reproducing organisms to produce gametes (sperm and egg cells) with half the number of chromosomes as the parent cell. The key steps of meiosis are:
Meiosis I:
Prophase I: Chromosomes condense, and homologous chromosomes (chromosomes with similar genetic information) pair up in a process called synapsis. This pairing allows for genetic exchange through a process called crossing-over.
Metaphase I: Paired homologous chromosomes align at the cell’s equator.
Anaphase I: Homologous chromosomes separate and move to opposite poles of the cell.
Telophase I: The cell divides into two, resulting in two cells, each with half the original chromosome number. Each chromosome still consists of two sister chromatids.
Cytokinesis I: The cell membrane pinches, dividing the cell into two daughter cells.
The two daughter cells then enter a second round of division without chromosome replication:
Prophase II: Chromosomes in each cell condense again.
Metaphase II: Chromosomes align at the equator of each cell.
Anaphase II: Sister chromatids finally separate and move to opposite poles.
Telophase II: Each cell divides, resulting in a total of four haploid cells (gametes), each with a unique combination of chromosomes due to crossing-over in Prophase I.
Cytokinesis II: The final step where the cells fully divide, producing four haploid gametes, each with half the chromosome number of the original cell.
how many haploids do you end up with at the end of meiosis
N = 4
how many diploids do you end up with at the end of mitosis
2N = 4
how are chromosomes positioned in mitosis compared to meiosis in metaphase 1
Mitosis: Chromosomes stacked END TO END
Meiosis: Chromosomes stacked SIDE BY SIDE
what are the multiple reasons why offspring are genetically different from their parents and one another in regards, to crossing over, Independent assortment and alleles from two parents
Crossing Over (or Crossing Over and Recombination): This occurs during meiosis, the cell division process that produces gametes. Homologous chromosomes pair up, and sections of chromatids are exchanged between them. This results in a shuffling of genetic material, and the offspring inherit a combination of genetic material from both parents.
Independent Assortment: During meiosis, homologous chromosomes separate independently of each other into different gametes. This means that the combination of chromosomes in a gamete is random. The number of possible combinations is 2^n, where n is the number of chromosome pairs. This random assortment contributes to genetic diversity in the offspring.
Alleles come from two parents: Each parent donates his or her own set of genetic material
