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The Living World
The Living World

... In humans, a gamete receives one homologue of each of the 23 chromosomes Humans have 23 pairs of chromosomes 223 combinations in an egg or sperm 8,388,608 possible kinds of gametes Copyright ©The McGraw-Hill Companies, Inc. Permission required for reproduction or display ...
PowerPoint
PowerPoint

... about 10% of the residents at his asylum resembled each other and could be easily distinguished from the rest of his patients • Took geneticists another 90 years to determine the correct human chromosome number and it was not until 1959 that it was known that individuals with Down Syndrome have 3 co ...
Biology Summer Packet Major themes covered in this packet
Biology Summer Packet Major themes covered in this packet

... b. It breaks down old, damaged macromolecules. c. It packages new protein molecules into vesicles. d. It determines which protein molecules to synthesize. In many eukaryotic cells, DNA stored in the nucleus is transcribed into messenger RNA. The mRNA is then transported into the cytoplasm where ribo ...
Linkage Groups & Chromosome Maps
Linkage Groups & Chromosome Maps

... Question: How would you explain these results? ...
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Stages of Mitosis

... The cells (H) show the very last stage of mitosis. The cell walls are not quite fully developed across the equator of the cell. The left side of the wall is a little more advanced than the right side. Some fibers still can be seen on the right side, though not too clearly. The cells at (A) have fini ...
Cell Division chapt09
Cell Division chapt09

... Meiosis produces haploid cells that are not identical to each other. Genetic differences in these cells arise from: ...
CIBI3031-091 Midterm Examination III November 2005
CIBI3031-091 Midterm Examination III November 2005

... ____ 36. Red-green color blindness is an X-linked recessive trait in humans. A color-blind woman and a man with normal vision have a son. What is the probability that the son is color blind? a. 100 percent b. 50 percent c. 75 percent ____ 37. If ALL offspring of a cross have the genotype Aa, the par ...
CIBI3031-070 Midterm Examination III November 2005
CIBI3031-070 Midterm Examination III November 2005

... ____ 43. The chromosomes are moving to opposite poles during a. metaphase. b. anaphase. c. interphase. ____ 44. Meiosis typically results in the production of a. four diploid cells. b. four haploid cells. c. two diploid cells. ____ 45. Which of the following does NOT produce variation? a. asexual re ...
Mitosis and Cytokinesis
Mitosis and Cytokinesis

... • Mitosis is the process by which the nucleus of the cell is divided into two nuclei with the same set of chromosomes as the parent cell. ...
Mendelian Genetics
Mendelian Genetics

... • How can we tell the genotype of an individual with the dominant phenotype? • Such an individual must have one dominant allele, but the individual could be either homozygous dominant or heterozygous • The answer is to carry out a testcross: breeding the mystery individual with a homozygous recessiv ...
The Cell Cycle - Cloudfront.net
The Cell Cycle - Cloudfront.net

... In the cell, p53 protein binds DNA, which in turn stimulates another gene to produce a protein called p21 that interacts with a cell division-stimulating protein (cdk2). When p21 is complexed with cdk2 the cell cannot pass through to the next stage of cell division. Mutant p53 can no longer bind DNA ...
Keystone Biology
Keystone Biology

... 1. Which statement best describes a difference between prokaryotic cells and eukaryotic cells? A. Both cell types contain DNA and ribosomes; prokaryotes have less-complex cell organization. B. Prokaryotes have less-complex cell organization and are generally smaller than eukaryotes. C. Key: Eukaryo ...
Name: ______KEY Per: _____ Date: ______ GALLO XBIO Cell
Name: ______KEY Per: _____ Date: ______ GALLO XBIO Cell

... The process of mitosis (division of the nucleus) is divided into four stages (Prophase, Metaphase, Anaphase, and Telophase). Immediately following nuclear division (mitosis), the cell membrane must also divide (cytokinesis). Animal cells divide the cytoplasm by constricting the cell membrane in the ...
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... Arise from double-strand DNA breaks Such artificial ends are very transient and rapidly join together Rejoining may restore the chromosome or may result in any imaginable combination of joined fragments Recovery of those products follows certain rules: 1. Each product must have no more nor less than ...
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... Binary fission - form of asexual reproduction which produces 2 genetically identical cells For example, bacteria reproduce by binary fission. ...
Notes - J Co Review
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... Human Karyotype For both males and females, chromosomes 1-22 appear as two homologous X’s. The 23rd chromosome appears as two X’s in females, and an X & Y in males. ...
Student Investigations
Student Investigations

... SC.7.L.16.3 Compare and contrast the general processes of sexual reproduction requiring meiosis and asexual reproduction requiring mitosis. SC.7.L.16.4 Recognize and explore the impact of biotechnology (cloning, genetic engineering, artificial selection) on the individual, society and the environmen ...
Unit 10 Powerpoint
Unit 10 Powerpoint

... has three alleles: IA,IB, and i  different combinations of the three alleles produce four different phenotypes, or blood types (A, B, AB, and O)  both IA and IB are dominant over i and also ...
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... • Meiosis is the basis of sexual reproduction • After meiotic division 2 gametes appear in the process • In reproduction two gametes conjugate to a zygote wich will become the new individual • Hence genetic information is shared between the parents in order to create new offspring ...
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... • concluded that these genes do not assort independently – body color and wing size are inherited together – reasoned that they were on the same chromosome ...
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... c) Chromosomal rearrangements are more likely to occur during mitosis than during meiosis. d) An individual that is homozygous for a deletion of a certain gene is likely to be more damaged than one that is homozygous for a duplication of that same gene because loss of a function can be lethal. © 201 ...
Chromosomes, Chromosome Anomalies
Chromosomes, Chromosome Anomalies

... Transmission to descendants (constitutional anomalies) At meiosis, where there is pairing of homologous chromosome segments (normal chromosomes form a bivalent), followed by crossing-over, translocations may form a quadrivalent (tetravalent, in Greek) and this leads to segregation problems. At meios ...
You Light Up My Life
You Light Up My Life

... • Mendel concluded that the two “units” for the first trait were to be assorted into gametes independently of the two “units” for the other trait • Members of each pair of homologous chromosomes are sorted into gametes at random during meiosis ...
Asexual Reproduction Webquest perfected
Asexual Reproduction Webquest perfected

... Asexual Reproduction: ...
Asexual Reproduction Webquest perfected
Asexual Reproduction Webquest perfected

... Asexual Reproduction: ...
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Meiosis



Meiosis /maɪˈoʊsɨs/ is a specialized type of cell division which reduces the chromosome number by half. This process occurs in all sexually reproducing single-celled and multi-celled eukaryotes, including animals, plants, and fungi. Errors in meiosis resulting in aneuploidy are the leading known cause of miscarriage and the most frequent genetic cause of developmental disabilities. In meiosis, DNA replication is followed by two rounds of cell division to produce four daughter cells each with half the number of chromosomes as the original parent cell. The two meiotic divisions are known as meiosis I and meiosis II. Before meiosis begins, during S phase of the cell cycle, the DNA of each chromosome is replicated so that it consists of two identical sister chromatids. In meiosis I, homologous chromosomes pair with each other and can exchange genetic material in a process called chromosomal crossover. The homologous chromosomes are then segregated into two new daughter cells, each containing half the number of chromosomes as the parent cell. At the end of meiosis I, sister chromatids remain attached and may differ from one another if crossing-over occurred. In meiosis II, the two cells produced during meiosis I divide again. Sister chromatids segregate from one another to produce four total daughter cells. These cells can mature into various types of gametes such as ova, sperm, spores, or pollen.Because the number of chromosomes is halved during meiosis, gametes can fuse (i.e. fertilization) to form a zygote with a complete chromosome count containing a combination of paternal and maternal chromosomes. Thus, meiosis and fertilization facilitate sexual reproduction with successive generations maintaining the same number of chromosomes. For example, a typical diploid human cell contains 23 pairs of chromosomes (46 total, half of maternal origin and half of paternal origin). Meiosis produces haploid gametes with one set of 23 chromosomes. When two gametes (an egg and a sperm) fuse, the resulting zygote is once again diploid, with the mother and father each contributing 23 chromosomes. This same pattern, but not the same number of chromosomes, occurs in all organisms that utilize meiosis. Thus, if a species has 30 chromosomes in its somatic cells, it will produce gametes with 15 chromosomes.
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