10.3 Study Guide Flashcards
(8 cards)
Define sexual and asexual reproduction. Explain the primary differences between the two.
Sexual reproduction is a form of reproduction in which the gene sequence of the offspring is a random combination of the gene sequences of two parent organisms. Asexual reproduction is a form of reproduction in which the gene sequence of the offspring is identical to the gene sequence of the single parent organism (excluding random mutations). Sexual reproduction requires two members of the same species that are different sexes/produce opposite gametes, and it usually takes longer and requires more resources and energy to perform. Asexual reproduction requires only one organism of a species, and it usually takes less time and requires fewer resources and less energy.
State the phases of meiosis in order. Include ALL phases.
Prophase –> Metaphase –> Anaphase –> Telephase + Cytokinesis –> Prophase –> Metaphase –> Anaphase –> Telephase + Cytokinesis
Define meiosis. In what ways does it differ from mitosis, and what is its purpose?
Meiosis is a form of cell division in which a cell divides into two cells, each with a random half of the parent cell’s chromosomes/gene sequence. This is different from mitosis, which is a form of cell division in which a cell divides into two cells with the exact same chromosomes/gene sequence as the parent. The purpose of meiosis is to produce gametes, or sex cells, which combine with the opposite gamete to combine their halves and form a fertilized cell with the full amount of required chromosomes (which is how reproduction begins).
Explain how the appearance of a cell changes throughout meiosis. You need only describe one of the two meiosis processes.
The appearance of a cell goes through a similar transition during meiosis to what it goes through during mitosis. During both processes, the cell’s nucleus is dissolved and its chromosomes are condensed, making them easier to see. As the cell moves its chromosomes to its equator and splits them using its spindle fibers, the cell itself begins to stretch. It stretches more and more as its chromosomes (or, more specifically during meiosis II, chromatids) and organelles move to either side, and eventually it splits into two bodies that quickly repair any damages and become full cells.
Compare the pros and cons of sexual and asexual reproduction. Why is it that sexual reproduction tends to produce higher population survival rates?
The main reason why asexual reproduction works for many organisms is because, compared to sexual reproduction, it is simpler, takes drastically less time, and uses up fewer resources. Additionally, any member of an asexually-reproducing population can reproduce by itself, without the need of another member, which increases both its frequency and the rate of genetic mutation. However, while sexual reproduction takes more time and resources to perform and is more difficult to initiate, its recombination of genes from both parents to the offspring produces much higher genetic diversity than asexual reproduction and has been observed to produce higher survival rates. This is because sexually-reproducing populations are constantly in competition and conflict with each other, and any mutation and/or recombination that gives an advantage to one population forces all others nearby to advance as well to survive.
True or false: The human life cycle is classified as haploid-dominant.
False. The human life cycle is classified as diploid-dominant.
Define sister chromatids. How are they different from homologous chromosomes?
Sister chromatids are two identical copies of a single chromosome strand that are condensed and bound together at a point known as the centromere. Homologous chromosomes, on the other hand, are two similar but unidentical versions of the same chromosome that have minor differences in their genetic sequences.
Explain how meiosis I differs from meiosis II and mitosis. Define tetrads and explain crossing over and independent assortment.
While the overall processes of meiosis I, meiosis II, and mitosis are very similar, the primary distinction of meiosis I is that instead of splitting apart sister chromatids pairs, it splits apart homologous chromosome pairs. During metaphase I, a cell will line up both replicated versions of each homologous chromosome pair together at its equator. Here, the chromosomes perform a process called synapsis, in which they bond somewhat and form a single body called a tetrad. As they do this, their ‘arms/legs’ cross over each other and often go through a process in which similar pieces of each chromosome will detach and swap, reattaching to the other chromosome. This is known as independent assortment and is another method by which cells produce genetic diversity during sexual reproduction.
