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Section 11-1
Section 11-1

... - in mammals females have two X-chromosomes (XX) - in mammals males have an X and a Y chromosome (XY) - the Y chromosome has a gene (SRY) that makes the embryo male - but Y has fewer genes than X and so males only get one copy of some genes on the Y - genes that males only get one copy of are sex-li ...
Chapter 13 Notes
Chapter 13 Notes

... All essential genetic material is present so the children appear normal ...
Mutations - Fulton County Schools
Mutations - Fulton County Schools

...  Genetic Mutation – a change in the amount or ...
Hi Linda - Greeley-Evans School District 6
Hi Linda - Greeley-Evans School District 6

... period of nuclear cell division in which two daughter cells are formed, each containing a complete set of chromosomes prophase, metaphase, anaphase, telophase ...
chapter 3 transmission genetics – chromosomes, recombination and
chapter 3 transmission genetics – chromosomes, recombination and

... Mendel further hypothesized that one unit factor (i.e. allele) is dominant to the other recessive factor (i.e. the dominant allele masks the effect of the recessive allele), based on the phenotypes he found in the F1 and F2 (Law 2, Table 3.1). For example, the allele for tall (D) is dominant and the ...
Midterm Key - Berkeley MCB
Midterm Key - Berkeley MCB

... and no Y chromosome. Explain what could have happened to generate this cat. Be specific. (5 points) Because the cat is black, it inherited its only X chromosome from its mother; we know from the previous question that the father is an orange cat.  A nondisjunction event occurred during either meiosi ...
Modern Genetics
Modern Genetics

... Gene Linkage: If the genes of two different traits (non-allelic) are located on the same chromosome pair (homologous chromosomes) they are said to be linked, and are therefore inherited together. Crossing Over: In Meiosis 1(in Prophase) the chromatids of a pair of homologous chromosomes often twist ...
Chromosomal theory of inheritance
Chromosomal theory of inheritance

... differences for another trait ...
Revision of B5 - Blackpool Aspire Academy
Revision of B5 - Blackpool Aspire Academy

... – The chromosomes are copied when the two strands of each DNA molecule separate and new strands form alongside them 2. Mitosis during which – Copies of the chromosomes separate – The cell divides ...
Chapter 8 Power Point
Chapter 8 Power Point

...  As prophase ends, metaphase, or the second phase of mitosis, begins  Chromosomes attach to the spindle fibers and line up in the center of the cell  Microtubules connect the centromere of each chromosome to the poles of the spindle  Because of their starlike arrangement around the poles of the ...
sex in drosophila
sex in drosophila

... triple-X females is slightly greater than that in the general population, but most XXX females have normal intelligence. Much rarer are females whose cells contain four or five X chromosomes. These females usually have normal female anatomy but are mentally retarded and have a number of physical pro ...
08-Heredity
08-Heredity

...  Genes specify the amino acid sequence of proteins  The amino acid sequence determines the shape and activity of proteins  Proteins determine in large measure what the body looks like and how it functions  Mutations in a gene result in alleles  This ultimately leads to a change in the amino aci ...
Reading Guide 09 - Cell Cycle, DNA Replication, and Mitosis
Reading Guide 09 - Cell Cycle, DNA Replication, and Mitosis

... description of it here, making sure to use the terms “parental” and “daughter” strands, as well as DNA polymerase, and which bases pair together. ...
Reading Guide_09_EB_Mitosis
Reading Guide_09_EB_Mitosis

... description of it here, making sure to use the terms “parental” and “daughter” strands, as well as DNA polymerase, and which bases pair together. ...
HB-ATAR-Unit-2
HB-ATAR-Unit-2

... in  the  body   ...
power point presentation
power point presentation

... • Fewer females with sexlinked disorders Males are hemizygous • a condition where only one copy of a gene is present in a diploid organism • More males than females have x-linked disorders ...
Dragon Genetics Assignment Document
Dragon Genetics Assignment Document

... The mother dragon is heterozygous for the wing gene (Ww) and the horn gene (Hh). The father is homozygous recessive for the wing gene (ww) and the horn gene (hh). What phenotypic traits will each parent have? (Phenotypic traits are the observable bodily characteristics.) Draw the appropriate charact ...
Inheritance Patterns & Human Genetics
Inheritance Patterns & Human Genetics

... He studied the fruit fly, Drosophila, which has 4 homologous pairs of chromosomes He found that one set of chromosomes in females looked the same, while in males one was smaller He surmised (correctly) that these controlled the sex of the individual He labeled the female XX & the male XY During meio ...
teacher version
teacher version

... of long sequences of DNA that provide the information needed to construct an organism. If you were to line up the DNA from just one of your cells end-to-end, it would be over 7 feet long. That’s about 80 billion miles of DNA from all the cells in an average adult human! A human genome can be divided ...
Section 14-1
Section 14-1

... Karyotype – chart of chromosome pairs that may be used to determine a genetic disorder. Homologous- matching chromosomes ...
Meiosis and Reproduction
Meiosis and Reproduction

... e.g. mRNA processing ...
Lecture_15_Pop Dynamics_Humans_Part II
Lecture_15_Pop Dynamics_Humans_Part II

... (2010) found about 60 mutations, 30 from each parent, that occurred during meiosis. ...
Mendelian Genetics - Mill Creek High School
Mendelian Genetics - Mill Creek High School

... *German biologist *stained cells with dye and saw tiny, threadlike structures in the nucleus  CHROMOSOMES!!! *observed and described MITOSIS -- noted that a full set of chromosomes was being passed on to each ...
Introduction to Genetics
Introduction to Genetics

... No one really knows what determines the number of chromosomes in an organism, though related species tend to have similar chromosome numbers. This is because chromosomes may split or combine during evolution and speciation. While humans have 46, other great apes have 48. It is important to remember ...
7-5 Cell cycle
7-5 Cell cycle

... Prophase I – homologous chromosomes pair up (synapsis) – chromatids of homologous chromosomes may cross over, exchanging portions of genetic material – crossing over occurs at chiasmata – generates novel combinations of genetic material ...
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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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