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Wanganui High School
Wanganui High School

... cystic fibrosis: disease caused by a recessive gene causes breathing problems due to mucus forming in the breathing system diploid: cell with the full complement of chromosomes (46 in humans) discontinuous variation: variation that is “either/or” eg blood groups, ability to roll tongue or not DNA: t ...
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Karyotyping and Pedigrees

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Biology Study Guide/Test Review CH 11
Biology Study Guide/Test Review CH 11

... Define CROSSING OVER and be sure you understand the diagram of crossing over! Unlike mitosis, meiosis results in the formation of __________________ genetically _____________ cells. Gametes are produced by the process of ___________________. An organisms gametes have ________________ the # of chromo ...
Snurfle Meiosis - sciencecounts2
Snurfle Meiosis - sciencecounts2

... 31. In ______________________________ the sister chromatids split up. 32. In Telophase II, ________________ ________________ daughter cells are being formed. They are called ______________________ . 33. Each newly formed cell will form a _____________________________ around the chromosomes. 34. The ...
Study guide: Ch 4: Due Thursday (Test Friday)
Study guide: Ch 4: Due Thursday (Test Friday)

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17. CHROMOSome - WordPress.com
17. CHROMOSome - WordPress.com

... • The highest order of DNA coiling • Each species has a characteristic number and size of chromosomes, known as karyotype. • The normal number of Xsomes in a nucleus: diploid (2n) • During gametogenesos 2n is halved  one of eachpair = haploid (n) ...
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Mitosis Assignment - hrsbstaff.ednet.ns.ca
Mitosis Assignment - hrsbstaff.ednet.ns.ca

... 8. When a cell has reached its maximum size, what two alternatives does it have? When does the cell carry out one alternative over the other? 9. What would happen if you ingested a drug that prevented mitosis? What if it only prevented spindle fibre formation? 10. A cell from a tissue culture has 38 ...
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... D. In what organelle is DNA stored in all eukaryotic cells, like human cells? Answer: DNA is stored in the ____________. E. All of your body cells have the exact same full set of _________, the same complete set of _____________, but many different _______________. This is because they use different ...
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Ch. 12 - Crestwood Local Schools
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Biology 3 Study Guide – Exam #3
Biology 3 Study Guide – Exam #3

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Adaptation and Inheritance
Adaptation and Inheritance

... Our genetic material is found in the ________________________ of the cell. The genetic material stored in the cell is made of a chemical called _____________. The genetic material is organised into long strands called ________________________________. A small section of a chromosome is called a ____ ...
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... 3a. What happens during each of the four phases of mitosis? Write one or two sentences for each phase. 3a. Prophase: DNA in the nucleus condenses and the spindle fibers begin to form. Metaphase: The chromosomes line up and the spindle fibers attach to the centromeres. Anaphase: The chromosomes separ ...
Unit 3 PowerPoint
Unit 3 PowerPoint

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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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