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Meiosis I
Meiosis I

... Meiosis consists of two cell divisions that produce haploid daughter cells that are not genetically identical. ...
Meiosis I - My Teacher Site
Meiosis I - My Teacher Site

... of mitosis similar to and different from the chromosomes in a cell at metaphase at meiosis II? • 2) Given that the synaptonemal complex disappears by the end of prophase, how would the two homologs be associated if crossing over did not occur? What ...
Biol. 303 EXAM I 9/22/08 Name
Biol. 303 EXAM I 9/22/08 Name

... In the cross AaBbCcDdEE x AaBbCcDdEe, how many different phenotypes should appear among the offspring? (Assume independent assortment, simple dominance/recessiveness for each gene, and no epistasis or other gene interactions.) A. 32 B. 27 C 4 D. 16 29. In the cross described in question 28, how diff ...
Ch. 38 Plant reproduction and development
Ch. 38 Plant reproduction and development

... Floral organs: sepals, petals, stamens (male ), carpels (female) •complete: all 4 floral organs •incomplete: lacking 1 or more floral organs •perfect: both stamens and carpels on 1 flower •imperfect: lacking either a stamen or carpel •monoecious: staminate and carpellate flowers on 1 plant) •dioecio ...
Biol
Biol

... genotype “aa” is lethal during embryonic development. Consider a second gene with alleles “B” and “b” that assorts independently from the first gene and has no interactions with the first gene. In a cross between two individuals, AaBb x AaBb, what percentage of the offspring should die during embryo ...
Dragon Meiosis
Dragon Meiosis

... each of the homologous chromosomes in pair one and cut them in half. Now take each piece and tape it to the piece from the opposite chromatid. Reassemble the chromatids into the homologous chromosomes. You should now have 4 genetically different sister chromatids. Repeat this process for pair 2 and ...
Meiosis Notes November 14, 2012
Meiosis Notes November 14, 2012

... • The end result is two haploid cells, each with half the number of chromosomes as the original cell. The chromosome exists as sister chromatids at this point. ...
topic 4 genetics
topic 4 genetics

... Nuclear membrane breaks down Chromosomes supercoil Centrioles move to the poles and spindle microtubules develop ...
Evolution Free Response
Evolution Free Response

... More chances of surviving ...
Interphase - Cloudfront.net
Interphase - Cloudfront.net

... • Mitosis = nuclear division • Mitosis is followed by cytokinesis (cell division) • The steps of mitosis ensure that each new cell has the exact same number of chromosomes as the original ...
Interactive Notebook Meiosis
Interactive Notebook Meiosis

... Sex cells are made during meiosis. Meiosis is a copying process that produces cells with half the usual number of chromosomes. Meiosis keeps the total number of chromosomes the same from one generation to the next. In meiosis, each sex cell that is made gets only one chromosome from each homologous ...
chromosomes
chromosomes

... In body cells, chromosomes are found in pairs. Body cells are all the cells except sperm and egg cells. ...
file - Athens Academy
file - Athens Academy

... Survey of CentC arrays and CenPC3 in Zea Maize centromeres are mainly composed of two different repetitive sequences: a retrotransposon, CRM, and a 156bp tandem repeat, CentC. In domesticated maize CRM levels are fairly consistent while the amount of CentC varies greatly between inbred lines, land r ...
Female Male Human chromosomal abnormalities may be numerical
Female Male Human chromosomal abnormalities may be numerical

... In women, however, only one gamete is produced from each meiosis. The other three haploid equivalents are discarded in structures called the first and second polar bodies. ...
Hands-On Activities That Relate Mendelian Genetics To Cell
Hands-On Activities That Relate Mendelian Genetics To Cell

... be heterozygous for that trait.If an individual has two alleles of the same type, for example two alleles for brown eyes, then it is called homozygous. Gregor Mendel, the founder of modern genetics, discovered that alleles separate during meiosis and end up in different gametes. We now call this the ...
Ch - TeacherWeb
Ch - TeacherWeb

... diploid (2n) zygote is formed. o 23 pairs of homologous chromosomes are formed when two human gametes combine ...
Ch. 8 Cellular Basis of Reproduction and Inheritance (updated)
Ch. 8 Cellular Basis of Reproduction and Inheritance (updated)

... A common leukemia that affects cells that give rise to white blood cells (leukocytes), and results from part of chromosome 22 switching places with a small fragment from a tip of chromosome 9. Chromosome 9 Chromosome 22 ...
Cell division -1
Cell division -1

... the chromosomes are tightly coiled, with sister chromatids joined together, The nucleoli disappear. The mitotic spindle begins to form and appears to push the centrosomes away from each other towards opposite ends (poles) of the cell. ‫ قبل اإلستوائية‬the nuclear envelope fragments and microtubules ...
DNA – Chromosomes - Genes - Science
DNA – Chromosomes - Genes - Science

... • Different kinds of organisms have different numbers of chromosomes. • Humans have 23 pairs of chromosomes, 46 in all: 44 autosomes and two sex chromosomes. • Each parent contributes one chromosome to each pair, so children get half of their chromosomes from their mothers and half from their father ...
Cell Division
Cell Division

... the chromosomes are tightly coiled, with sister chromatids joined together, The nucleoli disappear. The mitotic spindle begins to form and appears to push the centrosomes away from each other towards opposite ends (poles) of the cell. ‫ قبل اإلستوائية‬the nuclear envelope fragments and microtubules ...
Cell Reproduction - South Kingstown High School
Cell Reproduction - South Kingstown High School

... exchanged between homologous chromosomes. This insures that the chromosomes in sex cells produced are not identical to the parents chromosomes. This is one reason each offspring produced by a parent is unique from any other. ...
Name Period _____ Date
Name Period _____ Date

... only during ___________________ 13) Label ...
6.2 Process of Meiosis
6.2 Process of Meiosis

... – Meiosis has two cell divisions while mitosis has one. – In mitosis, homologous chromosomes never pair up. – Meiosis results in haploid cells; mitosis results in diploid cells. ...
1. The molecular “machines” (those components that do things) of
1. The molecular “machines” (those components that do things) of

... an inversion will usually occur. 89. If two genes are almost always found in the same gamete, they are a. located on non-homologous chromosomes. b. located close together on the same chromosome. c. located far apart on the same chromosome. d. found on the sex chromosome. 90. If the paternal chromoso ...
chromosomal
chromosomal

... • Inversion = chromosome piece reattaches to original chromosome, but in reverse orientation. • Translocation = chromosome piece reattaches to a nonhomologous chromosome. ...
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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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