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Ap Bio Mod 26
| Question | Answer |
|---|---|
| What is Meiosis? | the process of reduction division in which the number of chromosomes per cell is cut in half throughout the separation of homologous chromosomes in a diploid cell. |
| What is the point of meiosis | to create genetically unique sex cells for sexual reproduction, reducing the chromosome number by half (from diploid to haploid) and generating genetic diversity through shuffling parental DNA |
| How many and what type of daughter cells are made during meiosis | Four haploid daughter cells that are genetically different form each other and the parent cell |
| What is a diploid number and what is a haploid number? | Diploid cells have two sets of chromosomes (2n), one from each parent, forming homologous pairs, -Haploid cells have only one set of chromosomes (n) |
| What is the production of egg cells called? | Oogenesis. |
| What is the production of sperm cells called? | Spermatogenesis. |
| Gametes | Sexual reporduction cells -Ex: Sperm and Eggs |
| Tetrads | the structure formed in Prophase I when two homologous chromosomes link together -this structure has four chromatids (2 from each chromosomes) hence the name "tetra" |
| Name the different phases of Meiosis I in order. | Prophase I, Metaphase I, Anaphase I, Telophase I, and Cytokinesis I. |
| Name the different phases of Meiosis II in order. | Prophase II, Metaphase II, Anaphase II, Telophase II, and Cytokinesis II. |
| Recombinant chromosomes: | Chromosomes that have new combinations of alleles due to genetic recombination, -typically formed when crossing over occurs between homologous chromosomes during prophase I of meiosis. |
| Homologous chromosomes | -matching pairs of chromosomes in a organism, -have the same length, centromere position, and carry the same genes in the same order - one inherited from each parent, |
| Alleles | alleles are the different forms that a specific gene can take - Ex: the allele for brown eyes vs. the allele for blue eyes). - eye color is the specific gene while the varying color are the alleles |
| Sister Chromatids | two identical copies of a single, replicated chromosome, |
| Non-sister chromatids | the chromatids on homologous chromosomes (one maternal, one paternal) that pair up during meiosis, |
| zygote | the diploid cell formed by the fusion of two gametes |
| karyotype | a visual display of an organism's pairs of chromosomes |
| Synapsis | The process during prophase I in which homolous chrosmomes perfectly line up next to each other before carrying out crossing over |
| chiasmata | visible points of contact between homologous chromosomes where crossing over has occurred during prophase I of meiosis, holding homologs together as genetic material is exchanged. |
| Phenotype: | observable traits or physical characteristics -Ex: Hair color or eye color |
| Genotype | An organism’s genetic makeup—the specific alleles it carries for a gene or set of genes. |
| Benefits of sexual reproduction | - increases genetic variation by producing offspring with different trait combinations as they come from two parents -this helps populations adapt to environmental changes, resist diseases , and overall survive |
| autosomes | all of the other chromosomes in the body that are not sex cells (gamates) |
| How many sex chromosomes pairs and autosome chromosome pairs are there in humans? | -22 autosome pairs -1 sex chromosome (gamete) pair |
| Describe the sperm cells that are the products of male animal meiosis | -they are similar in size to each other - they have a head that contains the nucleus and thus genetic information -they also have a tail that allow them to move in order to locate the egg |
| Describe the haploid cells cells that are the products of female animal meiosis | one large functional egg is produced, and the other three haploid cells become small polar bodies that usually degenerate. |
| What are three main sources of genetic diversity created by sexual reproduction | Crossing over, -Indepedent (random) assortment Fertilization |
| Crossing over (recombination): | : Exchange of DNA between non-sister chromatids of homologous chromosomes during prophase I, producing recombinant chromosomes. |
| Independent (random) assortment | During meiosis I, homologous chromosome pairs line up randomly at the metaphase plate, producing different combinations of maternal and paternal chromosomes in gametes. |
| Fertilization | Random fusion of gametes from two parents, combining different genetic backgrounds and creating unique offspring genotypes. |
| Asexual reproduction | a method where a single parent produces genetically identical offspring (clones) without needing a mate or the fusion of sex cells (gametes) |
| How does meiosis relate to fertilization | Meiosis produces haploid gametes (sperm and egg) with half the chromosome number of the parent, Fertilization occurs when a haploid sperm and haploid egg fuse, producing a diploid cell number in the zygote. |
| Ploidy | the number of complete sets of chromosomes in a cell, -Ex: Haploid (n) or diploid (2n) |
| Why is random assortment also called independent assortment | -because the arrangement of one pair of chromosomes is independent of the arrangement of another pair |
| How do the two daughters at the end of telophase I of meiosis I comapre to the parent cell? | -the two daughter cells contain 2 copies of half of the genetic information -(each daughter cell only has two copies of either parental or maternal chromosomes, not both) |
| How do the four daughters at the end of telophase II of meiosis II comapre to the parent cell? | -the two daughter cells contain 1 copy of half of the genetic information -(each daughter cell only has 1 copy of either parental or maternal chromosomes, not both) |
| Spermatids | Haploid cells produced at the end of meiosis II in male gamete formation -They turn into mature sperm through a process called spermiogenesis, gaining tails and other structures to be used for movement. |
| Describe Prophase I | Homologous chromosomes condense and pair together in a process called synapsis, - Crossing over occurs between non-sister chromatids, exchanging DNA -The nuclear envelope disappears, and the mitotic spindles begins to form. |
| Metaphase I | Homologous chromosomes line up at the metaphase plate -chromosomes randomly arrange them themselves on the plate (independent assortment.) |
| Anaphase I | Homologous chromosomes separate to opposite poles of the cell -sister chromatids remain together. |
| Telophase I | chromosomes arrive at opposite poles, begin to decondense into chromatin, the nuclear envelope reforms, and the mitotic spindle breaks down. |
| Cytokinesis I | cytoplasm is split and cells divide into two genetically unique haploid cells. |
| Prophase II | Chromosomes re-condense, spindle forms, nuclear envelope breaks down if reformed |
| Metaphase II | Chromosomes line up singly at the metaphase plate. |
| Anaphase II | Sister chromatids separate and move to opposite poles. |
| Telophase II / | chromosomes arrive at opposite poles, begin to decondense into chromatin, the nuclear envelope reforms, and the mitotic spindle breaks down. |
| Cytokinesis II | cytoplasm is split and cells divide into four genetically unique haploid cells. |
| What are Sporophyte: | The diploid life stage in plants that produces haploid spores by meiosis, which develop into gametophytes. |
| Gametophyte | The haploid (n) life stage in plants that produces haploid gametes (sperm and egg) by mitosis, which fuse during fertilization to form a new sporophyte. |
| Nondisjunction | Failure of homologous chromosomes or sister chromatids to separate properly during meiosis, leading to gametes with abnormal chromosome numbers. |
| Random Fertilization: | refers to the concept that any of the genetically unique sperm created by a male can join with any of the genetically unique eggs created by any female. -This produces offspring with a genetically unique combination of chromosomes |
| The law of segregation | During gamete formation, the two alleles for a gene separate (one per parent) - each gamete receives only one allele. - Fertilization restores the two alleles in the offspring by combining parental genes |
| Loci | refers to specific locations, on a chromosome -homologous chromosomes have the same genes at the same loci |
| Describe chromosome # in humans | Humans have 46 chromosomes total in their somatic cells ( 23 chromosomes from each of their parents) - they have 23 in their gametes |
Created by:
KenechukwuIE