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013368718X_CH11_159-178.indd
013368718X_CH11_159-178.indd

... Phases of Meiosis Meiosis is the process that separates homologous pairs of chromosomes in a diploid cell, forming a haploid gamete. The phases are as follows: Meiosis I, which is preceded by a replication of chromosomes. Its stages are  Prophase I: Each replicated chromosome pairs with its corresp ...
cell division
cell division

... • The process of the formation of the two daughter nuclei, mitosis, is usually followed by division of the cytoplasm, cytokinesis. • These processes take one cell and produce two cells that are the genetic equivalent of the parent. ...
Meiosis II
Meiosis II

... Meiosis is a specialized type of cell division that occurs in the formation of gametes such as egg and sperm. Although meiosis appears much more complicated than mitosis, it is really just two divisions in sequence, each one of which has strong similarities to mitosis. The illustrations used in the ...
Parent cells, daughter cells and the cell cycle
Parent cells, daughter cells and the cell cycle

... M is nuclear division (mitosis) where the cell eventually divides The line at the end of mitosis marks cytokenesis (cleavage of cytoplasm) The outside letters M and I represent mitosis (nuclear division) and interphase Before a cell can divide, the DNA of each chromosome centromere must be replicate ...
File
File

... nucleolus reappears in new nuclei chromosomes reappear as chromatin ...
1.2.2 MITOSIS
1.2.2 MITOSIS

... Final stage where the cytoplasm divides completely in to two, the nuclear envelopes reform, and the nuclei begin to reform resulting in two new cells. ...
136 color, while the cytoplasm is of a brownish hue. The cytoplasm
136 color, while the cytoplasm is of a brownish hue. The cytoplasm

... visible. This was always found to be the case whether one or several nucleoli were present. These filiaments radiating from many points on its periphery seem to hold it in position. Its position was influenced in the direction of attachment of the greatest number of nuclear fibres (Fig. 1). At a lat ...
Homologous chromosomes
Homologous chromosomes

... Each organism has a specific amount of chromosomes in  their cells.  The number of chromosomes is not related to  the complexity of an organism. Examples: Adder's Tongue Fern  1260(2n)  630(n) Fruit Fly 8(2n)  4(n) Humans 46(2n)  23(n) Autosomes­ chromosomes that contain genes for  characteristics  ...
Creating a Karyotype: A Chromosome Study
Creating a Karyotype: A Chromosome Study

... An examination of the chromosomes of a cell under high magnification can give a lot of information about an organism. If the cells are from an unborn human, its sex can be determined before it is born. It can also be determined if the unborn may have certain birth defects or problems caused by impro ...
Giant chromosomes
Giant chromosomes

... each corresponds to the loop of a sister chromatid. • The chromomere at the base of the loops consists of dense chromatin of the two sister chromatids • At the beginning of meiosis, when DNA replication is complete, the homologous pairs lie immediately next to each other and form characteristic stru ...
File
File

Chapter 10: Mendel`s Laws of Heredity
Chapter 10: Mendel`s Laws of Heredity

...  Mendel allowed pollination to occur within the same flower or between different flowers for his experiments  Fertilization: the male gamete unites with the female gamete to form a zygote (a fertilized cell) o In the case of pea plants, the zygote becomes a seed  Conducted crosses between pea pla ...
Meiosis Notes
Meiosis Notes

... 1st division - pairs split 2nd division – produces 4 gamete cells with ½ the original no. of chromosomes ...
Fathers and Mothers of Genetics
Fathers and Mothers of Genetics

... (1822 – January 6, 1884) a german monk; referred to as the "father of genetics" for his study of the inheritance of traits in pea plants. Mendel showed that the inheritance of traits follows particular laws, which were later named after him. The significance of Mendel's work was not recognized until ...
The questions and answers are HERE!
The questions and answers are HERE!

... The number of chromosomes in a sex cell are half that of the number found in the body cells. As an example, humans have 46 chromosomes in the body cells, but produce sex cells that contain only 23. When the sex cells combine in fertilization, 23 in the egg + 23 in the sperm = 46 in the zygote...the ...
Chromosomes Key - Iowa State University
Chromosomes Key - Iowa State University

... 26. Suppose you examined polytene chromosomes from the salivary glands of fruit fly larvae and counted the number of chromosomal puffs observed in different regions of DNA. 1. Would you expect to observe more puffs from euchromatin or from heterochromatin?Why? Euchromatin is less condensed and capab ...
View PDF
View PDF

... 1. What is the difference between autosomes and sex chromosomes? 2. List 1 disease associated to each: dominant, recessive and codominant alleles (3 total). 3. In terms of blood type groups, why is it possible for Type O people to donate blood to any blood type group? (HINT: Think about antigens/ ...
Lecture 5
Lecture 5

... Could this help explain how a female turkey could produce male progeny even when there are no male turkeys around to provide male gametes? ...
The Human Genome
The Human Genome

Biobowl 3
Biobowl 3

... BIOBOWL 3 – CH. 11, 15, 16 FALL 2008 1. When a DNA molecule replicates, a chromosome is then made up of two sister _______. 2. Eukaryotic DNA molecules are associated with ____________ proteins. 3. In general, the division of the cytoplasm, known as _______, occurs during telophase of mitosis. 4. In ...
BIO 10 Lecture 9 REPRODUCTION: MITOSIS AND MEIOSIS
BIO 10 Lecture 9 REPRODUCTION: MITOSIS AND MEIOSIS

... feed the rapidly dividing embryonic cells. – All mitochondria inherited by the baby are from the mother’s egg – Usually only one secondary oocyte is released per 28-day cycle in an adult woman. ...
Karyotyping
Karyotyping

... taken through a microscope) of the chromosomes from a cell in metaphase. The photographic images of the chromosomes are cut out and arranged in homologous pairs by their size and shape. The karyotype can be analyzed to determine the sex of the individual and whether there are any chromosomal abnorma ...
(lectures 24
(lectures 24

... to their relatives) . This may be owing to problems with sex-determination in XXYY individuals and owing to not being able to self-fertilize. 29. There are thought to have been at least two genome doublings in the lineage from the origin of vertebrates to us. 30. Angiosperm plants often have groups ...
HOMEWORK: PRACTICE FOR MEIOSIS QUIZ PERIOD: NAME
HOMEWORK: PRACTICE FOR MEIOSIS QUIZ PERIOD: NAME

... number of chromosomes in a species, from one generation to the next. Be sure to include the words: meiosis, sperm/egg cells, diploid, haploid, and fertilization. ...
Science EQT Study Guide: 2nd Quarter
Science EQT Study Guide: 2nd Quarter

... What is the process by which individuals that are better adapted to their environment survive and reproduce more successfully than others do? ...
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Chromosome



A chromosome (chromo- + -some) is a packaged and organized structure containing most of the DNA of a living organism. It is not usually found on its own, but rather is complexed with many structural proteins called histones as well as associated transcription (copying of genetic sequences) factors and several other macromolecules. Two ""sister"" chromatids (half a chromosome) join together at a protein junction called a centromere. Chromosomes are normally visible under a light microscope only when the cell is undergoing mitosis. Even then, the full chromosome containing both joined sister chromatids becomes visible only during a sequence of mitosis known as metaphase (when chromosomes align together, attached to the mitotic spindle and prepare to divide). This DNA and its associated proteins and macromolecules is collectively known as chromatin, which is further packaged along with its associated molecules into a discrete structure called a nucleosome. Chromatin is present in most cells, with a few exceptions - erythrocytes for example. Occurring only in the nucleus of eukaryotic cells, chromatin composes the vast majority of all DNA, except for a small amount inherited maternally which is found in mitochondria. In prokaryotic cells, chromatin occurs free-floating in cytoplasm, as these cells lack organelles and a defined nucleus. The main information-carrying macromolecule is a single piece of coiled double-stranded DNA, containing many genes, regulatory elements and other noncoding DNA. The DNA-bound macromolecules are proteins, which serve to package the DNA and control its functions. Chromosomes vary widely between different organisms. Some species such as certain bacteria also contain plasmids or other extrachromosomal DNA. These are circular structures in the cytoplasm which contain cellular DNA and play a role in horizontal gene transfer.Compaction of the duplicated chromosomes during cell division (mitosis or meiosis) results either in a four-arm structure (pictured to the right) if the centromere is located in the middle of the chromosome or a two-arm structure if the centromere is located near one of the ends. Chromosomal recombination during meiosis and subsequent sexual reproduction plays a vital role in genetic diversity. If these structures are manipulated incorrectly, through processes known as chromosomal instability and translocation, the cell may undergo mitotic catastrophe and die, or it may unexpectedly evade apoptosis leading to the progression of cancer.In prokaryotes (see nucleoids) and viruses, the DNA is often densely packed and organized. In the case of archaea by homologs to eukaryotic histones, in the case of bacteria by histone-like proteins. Small circular genomes called plasmids are often found in bacteria and also in mitochondria and chloroplasts, reflecting their bacterial origins.
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