《病理学含口腔病理学》由会员分享，可在线阅读，更多相关《病理学含口腔病理学（45页珍藏版）》请在金锄头文库上搜索。
1、陳玉昆副教授陳玉昆副教授: 高雄醫學大學高雄醫學大學 口腔病理科口腔病理科 07-31211012755 yukkwakmu.edu.twGenetics (2)基因學基因學 (2) Understanding:1.Chromosomes2.Mitosis3.Meiosis4.DNA, RNA, protein (transcription, translation)學 習 目 標1.Oral Pathology for the Dental Hygienist. Olga AC Ibsen, Joan Anderson Phelan, 4th edition, 2004, p. 216-45
2、 2.陳嘉芬陳嘉芬 現代遺傳學現代遺傳學 Chapter 2-6, p. 25-923.http:/ccms.nut.edu.tw/juang/JRH/Amino.htm4.www-rohan.sdsu.edu/sepa/genetics.htm5.http:/ehrweb.aaas.org/ehr/books/2_dominant.html6.http:/library.thinkquest.org/06aug/00440/superbibliography.html7.Tarjan I, et al. Early prosthetic treatment of patients with
3、ectodermal dysplasia: A clinical report. J Prosthet Dent 2005;93:419-248.www.genetic-programming.org 9.What you need to know about cancer. Sci Am 1996;289:28-11910.Gibbs WW. Untangling the roots of cancer. Sci Am 2003;289:56-6511.Bowden JR, et al. DNA microarray technology: insights for oral and max
4、illofacial surgeons. Br J Oral Maxillofac Surg 2004;42:542-512.Kuo WP, et al. Microarrays and clinical dentistry. JADA;2003;134-456-6213.Ralf D. The first discovery of DNA. Sci Am 2003;96:320-814.www.estrellamountain.edu/faculty/farabee/biobk/BioBookglossL.html15.juang.bst.ntu.edu.tw/BCbasics/A 18.h
5、ttp:/ for genetics (1) and (2):參考資料Refs. 1, 4 All living cells contain information which tells them how to develop. This information is contained in chromosomes, inside the cell nucleus, encoded in genes.What is a chromosome? Chromosomes: Tightly coiled microscopic structures made up mainly of DNA,
6、which consists of four different building blocks called bases (A, T, C, G). The four bases are repeated millions of times to form each chromosomeRefs. 1, 4 A chromosome is, minimally, a very long, continuous piece of DNA, which contains many genes, regulatory elements and other intervening nucleotid
7、e sequences. In the chromosomes of eukaryotes, the uncondensed DNA exists in a quasi-ordered structure inside the nucleus, where it wraps around histones (structural proteins), and where this composite material is called chromatinHuman chromosomes range in length from 50 million to 263 million bases
8、. With few exceptions (e.g., red blood cells), each of the trillions of cells in the human body contains a complete set of chromosomes-the genome. If all the bases in the human genome were spread out 1 millimeter apart, they would extend from Memphis (孟斐斯孟斐斯 - 美國田納西州美國田納西州) to Los Angeles (洛杉磯洛杉磯 -
9、美國加州美國加州) Refs. 1, 4 http:/ 1, 17During mitosis (nuclear division), the chromosomes are condensed and called metaphasic chromosomes. This is the only natural context in which DNA is visible with an optical microscope Refs. 1, 17Prokaryotes do not possess histones or nuclei. In its relaxed state, the
10、 DNA can be accessed for transcription, regulation, and replication Chromosomes were first observed by Karl Wilhelm von Ngeli in 1842 and their behavior later described in detail by Walther Flemming in 1882. In 1910, Thomas Hunt Morgan proved chromosomes to be the carriers of genes Different stages
11、of DNA condensation(1) Single DNA strand (2) Chromatin strand (DNA with histones) (3) Condensed chromatin during interphase with centromere (4) Condensed chromatin during prophase (5) Chromosome during metaphase Refs. 1, 17Refs. 1, 17, 181. Chromatid. One of the two identical parts of the chromosome
12、 2. Centromere. The point where the two chromatids touch, and where the microtubules attach 3. Short arm 4. Long armRefs. 1, 4 The complete set of chromosomes in the cells of an organism is its karyotypeThe karyotype of the human female contains 23 pairs of homologous chromosomes: 22 pairs of autoso
13、mes (any chromosome that is not a sex chromosome) 1 pair of X chromosomes The karyotype of the human male contains: the same 22 pairs of autosomes one X chromosome one Y chromosome Refs. 1, 16 Homo sapiens (human)46 Mus musculus (house mouse)40Zea mays (corn or maize)20Drosophila melanogaster (fruit
14、 fly)8Xenopus laevis (South African clawed frog)36Caenorhabditis elegans (microscopic roundworm)12Equisetum arvense (field horsetail, a plant)216Saccharomyces cerevisiae (budding yeast)32Canis familiaris (domestic dog)78Arabidopsis thaliana (plant in the mustard family)10Myrmecia pilosula (an ant)2P
15、arascaris equorum var. univalens (parasitic roundworm)2Cambarus clarkii (a crayfish)200The chromosomes in other living organisms differRefs. 1, 4 Refs. 1, 17 Species No. of chromosomesSpecies No. of chromosomesFruit fly8Human46Rye(黑麥黑麥)14Ape48Guinea Pig16Sheep54Dove(鳩鳩)16Horse64Ediblesnail(蝸牛蝸牛)24Ch
16、icken78Earthworm(蚯蚓蚯蚓)32Carp(鯉魚鯉魚)104Pig40Butterflies380Wheat(小麥小麥)42Fern(羊齒植物羊齒植物)1200Chromosomes in different speciesRefs. 1, 4 Gene-expression profiling is screening large numbers of genes to see whether or not they are active under various conditions. When a gene is expressed, it makes a transcr
17、ipt (抄本抄本)Refs. 1, 17 Chromosomal aberrations (1) The malfunction of either the chromosomal segregation or the crossover can lead to severe diseases. They can be divided into two classes: Chromosomal aberration or Partial chromosomal dysplasia (malformation), which are usually the result of a defect
18、ive crossoverRef. 17 Chromosomal aberrations (1) Examples are: Cri du chat syndrome, which is caused by the deletion of part of the short arm of chromosome 5. Victims make high-pitched cries that sounds like a cat. They have wide-set eyes, a small head and jaw and are mentally retarded. Wolf-Hirschh
19、orn syndrome, which is caused by partial deletion of the short arm of chromosome 4. It is characterized by severe growth retardation and mental defect. Refs. 2, 17 Chromosomal aberrations (2) Missing or additional chromosomes, called aneuploidy, which are the result of an incomplete chromosomal segr
20、egation, many of which are associated with cancer (Duesberg hypothesis). Example:Down syndrome (extra chromosome 21). This is also known as mongolism or trisomy 21. Symptoms are decreased muscle tone, asymmetrical skull, slanting eyes and mental retardationRefs. 2, 17 Chromosomal aberrations (2) Kli
21、nefelters Syndrome (XXY). Men with Klinefelter syndrome are usually sterile. They tend to have longer arms and legs and tend to be taller than their peers. Other common symptoms are lack of emotion, fatigue, apathy and an increased tendency to develop psychiatric disordersTurner syndrome (X instead
22、of XX or XY). In Turner syndrome, female sexual characteristics are present but underdeveloped. People with Turner syndrome often have a short stature, low hairline, abnormal eye features and bone development and a caved-in appearance to the chestRef. 1 All cells in the body, with the exception of o
23、va andspermatozo, and called somatic cells. Cellular divisionis achieved by mitosis during a part of the somatic cells life span, called mitotic cycleFunction of mitosis is to create an exact copy of eachchromosome and, through division of the original cell, distribute an identical set of chromosome
24、s toeach daughter cellRef. 1 G1(Gap 1)(Gap 2)S (DNAreplication)MitoticdivisionMitoticdivisionG2(Gap 2)NormalCell CycleCell enlargesand makesnew proteinsBeginningof cycleCell divides(mitosis)Cell preparesto divideCell replicatesas DNACell restsRestriction point:celldecides whetherto commit itself tot
25、he complete cycle崗崗 哨哨G1 arrest70次次Ref. 9 Normal Cell CycleRef. 18 Ref. 1 Mitosis is composed of 4 stages:metaphase, prophase, anaphase and telophaseIn each of these 4 stages, the chromosomes are distributed in a specific arrangementwww.lewport.wnyric.org/jwanamaker/animations.htmwww.educypedia.be/e
26、ducation/biologyanimations.htmIn metaphase, chromosomes stain intensely & arearranged almost symmetrically at both sides of equatorial plane of the cellThe appearance of a metaphase chromosome resemblesthe letter “X”Ref. 1 http:/ cell division takes place, each chromosome splitsvertically at the cen
27、tromere, and 46 chromatids (which now become chromosomes) form one daughter cell, while the other 46 chromatids form a second daughter cellRef. 18 Line UpCross-over(metaphase)SegmentexchangeRef. 1 DNA1n DNARef. 1 Ref. 18 MitosisMeiosisParent cellParent cellDNA replicatesDNA replicates2 daughtercell
28、s2 daughtercellscells4 daughterRef. 18 Ref. 2 Molecular composition of chromosomes Deoxyribonucleic acid (DNA) Chromosomes contain DNA DNA contains the basic code or template that carries all genetic information The basic unit of DNA is called a nucleotide A nucleotide is formed by a N-containing ba
29、se, 5-carbon sugar (deoxyribose), and a phosphateDeoxyribonucleic acid (DNA)Ref. 11 Molecular composition of chromosomes Deoxyribonucleic acid (DNA) Four bases are found in DNA : adenine (A), guanine (G), thymine (T) & cytosine (C) These chains of polynucleotides are coiled to form a double helix st
30、ructure The ratio of A/T (G/C) is always equal from bacteria to human G/C pairs = 4A/T pairs (in human)ATGCCodonHydrogen BondRef. 1 Ref. 11 Double helical structure of DNA showing the bases,sugar, and phosphate connect with each otherSugar-phosphatebackboneBase pairsSugar-phosphatebackboneMolecular
31、composition of chromosomes Deoxyribonucleic acid (DNA)Mitochondrial DNA : Found in the circular chromosome of the mitochondria Maternally inherited Passed from the mother to all her offspring regardless of sexMolecular composition of chromosomes Ribonucleic acid (RNA)Ref. 1 There are 4 types of RNA:
32、Messenger RNA (mRNA)Transfer RNA (tRNA)Ribosomal RNA (rRNA)Heterogenous RNA (hnRNA)RNA can be found in both the nucleus and cytoplasm of a cellMolecular composition of chromosomes Ribonucleic acid (RNA)Ref. 1 mRNA: blueprint of genetic DNA for the coding of proteinstRNA: carries message for DNA to r
33、ibosomes in cytoplasm, in which proteins are producedrRNA: transfers amino acids from cytoplasm to mRNA, positioning amino acids in proper sequence to form polypeptides and hence proteinshnRNA: found within nucleus (precursor of mRNA)When genes are expressed, the genetic information (base sequence)
34、on DNA is first transcribed (copied) to messenger RNA in a process similar to DNA replication. mRNA then leave the nucleus & enter the cytoplasm, where triplets of bases (codons) forming the genetic code specify the particular amino acids that make up an individual protein. This process, called tran
35、slation, is accomplished by that read the genetic code from the mRNA, and transfer RNAs (tRNAs) that transport amino acids to the ribosomes for attachment to the growing protein.NucleusCytoplasmFree amino acidsmRNAmRNAtRNA bindingamino acid toribosomeRibosome incorporating amino acids into the growi
36、ng protein chainGrowingprotein chainAmino acidRef. 4 Ref. 1 Nucleus CytoplasmDNAmRNATranscription (轉轉 錄錄)Translation (轉轉 譯譯)t RNARibosome(核醣體核醣體)Proteinbrings acidsaminotoRef. 12 Ref. 18 Ref. 13 Ref. 8 Summaries Knowing:1. Composition of chromosomes2. Purpose and procedures of mitosis3. Purpose and procedures of meiosis4. DNA, RNA, transcription, translation
