Basidiomycota

• Introduction

The Basidiomycota contains about 30,000 described species, which is 37% of the described species of true Fungi (Kirk et al. 2001). The most conspicuous and familiar Basidiomycota are those that produce mushrooms, which are sexual reproductive structures. The Basidiomycota also includes yeasts (single-celled forms; Fell et al. 2001) and asexual species. Basidiomycota are found in virtually all terrestrial ecosystems, as well as freshwater and marine habitats (Kohlmeyer and Kohlmeyer, 1979; Hibbett and Binder, 2001).

Basidiomycota have a huge impact on human affairs and ecosystem functioning. Many Basidiomycota obtain nutrition by decaying dead organic matter, including wood and leaf litter. Thus, Basidiomycota play a significant role in the carbon cycle. Unfortunately, Basidiomycota frequently attack the wood in buildings and other structures, which has negative economic consequences for humans.

Symbiotic lifestyles (intimate associations with other living organisms) are well developed in the Basidiomycota. Symbiotic Basidiomycota include important plant pathogens, such as "rusts" (Uredinales) and "smuts" (Ustilaginales), which attack wheat and other crops. Other symbiotic Basidiomycota cause diseases in animals, including humans. Not all symbiotic Basidiomycota cause obvious harm to their partners, however. For example, some Basidiomycota, as well as a handful of Ascomycota, form ectomycorrhizae, which are associations with the roots of vascular plants (principally forest trees such as oaks, pines, dipterocarps, and eucalypts; Smith and Read, 1997). Ectomycorrhizal Basidiomycota help their plant partners obtain mineral nutrients from the soil, and in return they receive sugars that the plants produce through photosynthesis. Other symbiotic Basidiomycota form associations with insects, including leaf-cutter ants, termites, scale insects, woodwasps, and bark beetles (Wheeler and Blackwell, 1984; Mueller et al., 1998).

Humans have found diverse uses for Basidiomycota. Mushrooms, both cultivated and wild, are eaten in many countries. For the untrained, mushroom-hunting is a risky endeavor, because some Basidiomycota produce deadly toxins (Benjamin 1995). The basidiomycete toxin phalloidin (from the mushroom Amanita phalloides) binds actin, which is a component of microfilaments. Fluorescent stains that incorporate phalloidin are used by cell biologists to visualize the cytoskeleton. Other "toxins" produced by Basidiomycota include hallucinogens, which are produced by members of the genus Psilocybe (and other groups). Species of Psilocybe have traditionally been used in Central American indigenous cultures as a spiritual tool, and are now cultivated for the illicit drug trade. Other biochemical compounds of Basidiomycota that have practical uses include astaxanthin, a red pigment produced by the basidiomycetous yeast Phaffia (used to add color to farmed salmon), and certain enzymes from wood-decaying Basidiomycota that have potential applications in paper production and bioremediation (decontamination of polluted environments using biological agents).

• Characteristics

Basidiomycota are unicellular or multicellular, sexual or asexual, and terrestrial or aquatic. Indeed, Basidiomycota are so variable that it is impossible to identify any morphological characteristics that are both unique to the group and constant in the group. The most diagnostic feature is the production of basidia (sing. basidium), which are the cells on which sexual spores are produced, and from which the group takes its name. A long-lived dikaryon, in which each cell in the thallus contains two haploid nuclei resulting from a mating event, is another characteristic feature. Finally, clamp connections are a kind of hyphal outgrowth that is unique to Basidiomycota, although they are not present in all Basidiomycota. The following description of the characteristics of Basidiomycota traces the life cycle of a "typical" species, beginning at the site of meiosis.

The basidium is the cell in which karyogamy (nuclear fusion) and meiosis occur, and on which haploid basidiospores are formed (basidia are not produced by asexual Basidiomycota). Many Basidiomycota produce basidia on multicellular fruiting bodies (e.g., mushrooms), but basidia can also be formed directly from yeasts or other single cells. There is a great range of variation in morphology of the basidium, the number of spores formed, and how the spores are borne on the surface of the basidium (Ingold 1991). Typically, four spores are produced on each basidium, at the tips of minute stalks called sterigmata (Fig. 1). Each spore usually contains one or two of the haploid meiotic products.

Figure 1. SEM of the surface of a mushroom gill (Coprinus cinereus: Agaricomycotina) showing several basidia, some with four basidiospores attached.
(From McLaughlin, et al. 1985; used with permission © McLaughlin, Beckett and Yoon 1985.)

One of the most fascinating characteristics of Basidiomycota is the production of forcibly discharged ballistospores (Fig. 2), which are propelled into the air from the sterigma. Ballistospores may be sexual or asexual, and may be produced by basidia, hyphae, yeast cells, or even other ballistospores. This type of spore discharge must have evolved very early in the evolutionary history of the Basidiomycota as it is found in members of the earliest diverging lineages within the group. Ballistospory is associated with forms that disperse their spores directly into the air. Most aquatic Basidiomycota and forms that produce spores inside the fruiting body, such as puffballs, have lost ballistospory.

Ballistospory is associated with the production of a liquid filled "hilar droplet" that forms at the base of the spore, just above its attachment to the sterigma (Fig. 2). Resolving the mechanism of ballistospory has been a longstanding problem in mycology (Buller 1909, 1922; Ingold 1939; McLaughlin et al. 1985; Webster et al. 1984a, b; Yoon and McLaughlin 1986). In a series of studies, reviewed by Money (1998), it has been shown that spore discharge occurs when the hilar droplet fuses with a film of liquid on the surface of the spore. The rapid coalescence of the liquids causes a sudden shift in the center of mass of the spore and contributes to its release from the sterigma. This mechanism has been termed a "surface tension catapult" and it results in spores being discharged with a force of about 25,000 g (Money 1998, Pringle et al. 2005).

Figure 2. Scanning electron micrograph showing the hilar droplet at the base of a basidiospore (Coprinus cinereus: Agaricomycotina).(From McLaughlin et al. 1985)

Basidiospores germinate to form hyphae (filaments) or yeast cells that are typically haploid and uninucleate. The hyphae of Basidiomycota are septate. Ultrastructural features of the septa, visible with transmission electron microscopy, have been important in developing phylogenetic hypotheses in Basidiomycota (see the Agaricomycotina page).

Mating in Basidiomycota involves fusion of haploid cells, but fusion of the nuclei is usually delayed until the basidia are formed. Thus, the dominant phase of the life cycle in most Basidiomycota is a dikaryon, in which the two nuclei brought together in mating exist side-by-side in each cell (Fig. 3A). Sometimes a dikaryon can donate a nucleus to a uninucleate "monokaryon", resulting in a "di-mon" mating.

Clamp connections are hyphal outgrowths that form when cells in dikaryotic hyphae divide. One of the nuclei divides in the main axis of the hypha, while the other divides into the clamp (Fig. 3B). Septa are formed across each of the mitotic spindles. The apex of the backward-growing monokaryotic clamp cell fuses with the subapical cell, reestablishing the dikaryotic condition (Fig. 3C). All fungi that produce clamp connections are members of the Basidiomycota, but not all Basidiomycota produce clamp connections. The regular formation of clamp connections must have developed early in basidiomycete evolution, because they are found in all the major clades of Basidiomycota.

Sexually reproducing Ascomycota also form dikaryons, although they are not as long-lived as those of Basidiomycota. The clade that includes Ascomycota and Basidiomycota has been called the Dikaryomycotina, reflecting this presumably homologous similarity. Ascomycota produce clamp-like "croziers" at the bases of asci (cells in which meiosis occurs, homologous to basidia). Croziers may be homologous to clamp connections.

Figure 3. Diagram of clamp cell formation: A. Dikaryotic hypha, arrow shows direction of hyphal tip growth.
B. Clamp cell growing backward, nuclei undergoing synchronous division.
C. Mature clamp.
Illustrations © E. Swann 1997.

• Discussion of Phylogenetic Relationships

There is strong evidence that the Basidiomycota is monophyletic. Ballistospores, basidia, and clamp connections are present in the Agaricomycotina, Ustilaginomycotina, and Pucciniomycotina (although not in all species), suggesting that they have a common origin. Non-molecular characters that have been used to recognize major groups within the Basidiomycota include the form of the basidia (shape and septation), ultrastructure of hyphal septa and spindle pole bodies, presence or absence of yeast phases and "spore repetition" (production of spores directly from spores), and cellular carbohydrate composition (McLaughlin et al. 1995; Oberwinkler, 1987; Prillinger et al. 1990, 1991). Sequences of ribosomal RNA (rRNA) genes, recently supplemented by protein-coding genes, have played a major role in increasing our understanding of the relationships within Basidiomycota, and have demonstrated that some morphological attributes that have been emphasized in higher-level classification, such as the form of basidia, are subject to homoplasy (Swann and Taylor 1993, 1995, Swann et al. 1999).

Three major clades are strongly supported within the Basidiomycota: 1) Pucciniomycotina includes rusts (Pucciniales) and other taxa (Swann et al. 2001, Aime et al. 2006); 2) Ustilaginomycotina includes smuts (Ustilaginales) and others (Bauer et al. 2001, Begerow et al. 2006); and 3) Agaricomycotina includes mushrooms (Agaricomycetes), jelly fungi (Auriculariales, Dacrymycetales, Tremellales) and others (Hibbett and Thorn 2001, Swann and Taylor 1995, Wells and Bandoni 2001, Hibbett 2006). Monophyly of each of these groups has been supported in phylogenetic analyses of rRNA gene sequences and protein-coding genes (Hibbett et al. 2007). Similarities in the ultrastructure of septal pores and spindle pole bodies (McLaughlin et al. 1995) suggest that Ustilaginomycotina and Agaricomycotina could be sister groups, and some molecular phylogenies also support this topology. The placements of the Wallemiomycetes (a group of osmophilic molds) and Entorrhizomycetes (a group of root-inhabiting Fungi, previously classified in the Ustilaginomycotina [Bauer et al. 2001]) are particularly problematical (Matheny et al. 2006). At present, these are classified as "incertae sedis" within the Basidiomycota (Hibbett et al. 2007), but with the application of genome-scale datasets their placements may be resolved

perang vietnam

Masa Pra-dinasti

Pada tahun 214 SM, beberapa tahun setelah Kaisar Qin Shihuang mempersatukan Tiongkok, ia mengirim bala tentara ke selatan Tiongkok untuk menaklukkan wilayah yang sekarang adalah Guangdong, Guangxi, Fujian dan utara Vietnam. Penaklukkan itu disertai dengan penaklukkan suku kuno Bai Yue. Setelahnya, Dinasti Qin mendukung migrasi suku Han secara besar-besaran ke selatan dan membentuk 3 provinsi di selatan.

Selang puluhan tahun kemudian, tahun 203 SM, Dinasti Qin terpuruk ke dalam kekacauan. Pada saat ini, pemimpin militer Qin di Nanhai (sekarang Vietnam utara), Zhao Tuo mengambil kesempatan ini untuk membentuk negara sendiri, Nan Yue, dengan Raja Wu. Ibukota negara Nan Yue berada di daerah Guangzhou sekarang. Namun, Nan Yue kemudian ditaklukkan oleh Kaisar Han Wudi dari Dinasti Han pada tahun 111 SM. Untuk lebih 10 abad selanjutnya, Vietnam utara secara langsung dikuasai oleh Dinasti Han, Dong Wu, Dinasti Jin, Dinasti Selatan, Dinasti Sui dan Dinasti Tang).

[sunting]
Masa Dinasti-dinasti

Pada 939 CE, orang-orang Vietnam berhasil mengalahkan militer Tiongkok di Sungai Bach Dang dan mendapatkan kemerdekaan setelah 10 abad di bawah kontrol Tiongkok. Mereka mendapatkan otonomi secara lengkap satu abad kemudian. Pada masa pemerintahan Dinasti Tran, Dai Viet mengalahkan tiga usaha invasi Mongol di bawah Dinasti Yuan. Tiga kali dengan pasukan yang sangat besar juga dengan persipan yang hati-hati untuk serangan mereka, tetapi tiga kali berturut-turut orang-orang Mongol dikalahkan sama sekali oleh Dai Viet. Secara kebetulan, pertempuran terakhir dimana jendral Vietnam Tran Hung Dao mengalahkan kebanyakan militer Mongol diadakan lagi di Sungai Bach Dang seperti nenek moyangnya kurang lebih 300 tahun yang lalu. Feudalisme di Vietnam mencapai titik puncaknya saat Dinasti Le pada abad ke 15, khususnya selama masa pemerintahan Kaisar Le Thanh Tong. Antara abad ke 11 dan 15, Vietnam memperluas wilayahnya ke arah Sealatan dalam proses yang disebut Nam Tien (Perluasan ke Selatan). Mereka akhirnya menaklukan kerajaan Champa dan banyak kekaisaran Khmer.

[sunting]
Masa kolonialisme Perancis

Kemerdekaan Vietnam berakhir pada pertengahan abad 19 AD (Setelah Masehi), ketika Vietnam dikolonialisasikan oleh Kerajaan Perancis. Pemerintahan Perancis menanamkan perubahan signifikan dalam bidang politik dan kebudayaan pada masyarakat Vietnam. Sistem pendidikan modern gaya Barat dikembangkan dan agama Kristen diperkenalkan kepada masyarakat Vietnam. Pengembangan ekonomi perkebunan untuk mempromosikan ekspor tembakau, nila (indigo), teh dan kopi, Perancis mengabaikan permintaan akan pemerintahan sendiri (self-government) dan hak-hak sipil yang terus meningkat. Sebuah pergerakan politik nasionalis dengan cepat muncul, dan pemimpin muda Ho Chi Minh memimpin permintaan akan kemerdekaan kepada League of Nations (Liga Bangsa-Bangsa). Tetapi, Perancis memelihara dominasi kontrol terhadap koloni-koloninya hingga Perang Dunia II, ketika perang Jepang di Pasifik memicu penyerbuan ke Indochina. Sumber daya alam Vietnam dieksploitasi untuk kepentingan kampanye militer Jepang ke Burma, Semenanjung Malay dan India. Pada tahun terkahir perang, pemberontakan nasionalis berpasukan muncul di bawah Ho Chi Minh, melakukan kemerdekaan dan komunisme. Menyusul kekalahan Jepang, pasukan nasionalis melawan pasukan kolonial Perancis pada Perang Indochina Pertama yang dimulai pada tahun 1945 hingga 1954. Perancis mengalami kekalahan besar pada Pertempuran Dien Bien Phu dan dalam waktu singkat setelah itu ditarik dari Vietnam. Negara-negara yang berperang dalam Perang Vietnam membagi Vietnam pada 17th parallel menjadi Vietnam Utara dan Vietnam Selatan sesuai Perjanjian Geneva (Geneva Accords).

[sunting]
Perang Vietnam

Pemerintahan komunis atas Vietnam Utara ditolak oleh Amerika Serikat (A.S.) atas kemiripannya terhadap Uni Soviet dan Republik Rakyat Cina (RRC). Ketidaksetujuan dengan segera muncul atas ide pemilihan umum dan reunifikasi (Vietnam Utara dan Selatan), dan A.S. mulai meningkatkan kontribusi penasihat militer, bahkan Soviet menyuplai tentara dan persenjataan untuk memperkuat militer komunis. Serangan kontroversial atas kapal A.S. di Teluk Tonkin memicu serangan militer A.S. terhadap instalasi milter Vietnam Utara dan penempatan lebih dari 500.000 tentara di Vietnam Selatan. Pasukan A.S. dengan segera dibingungkan oleh sebuah perang gerilya yang buruk dengan Viet Cong, milisi komunis Vietnam Selatan. Pasukan Vietnam Utara gagal dalam usaha penyerbuan terhadap Selatan pada 1968 Tet Offensive dan perang dengan segera menyebar ke negara tetangga Laos dan Kamboja. Dengan korban yang menggunung, A.S. mulai memindahkan tugas perjuangan ke militer Vietnam Selatan dalam proses yang dikenal sebagai Vietnamisasi. Usaha tersebut membuahkan hasil yang campur aduk, tetapi dengan dukungan A.S., Vietnam Selatan mampu bertahan. Perjanjian Damai Paris (Paris Peace Accords) pada 27 Januari 1973 mengakui kekuasaan tertinggi kedua belah pihak. Di bawah perjanjian, seluruh pasukan perang Amerika ditarik pada 29 Maret 1973. Pertempuran kecil tetap berlanjut, tetapi semua pertempuran besar telah berakhir hingga sekali lagi, Utara menginvasi dan menundukkan Selatan pada 30 April 1975. Vietnam Selatan dengan singkat menjadi Republik Vietnam Selatan, sebuah negara boneka di bawah kekuasaan militer oleh Vietnam Utara, sebelum secara resmi disatukan dengan Utara di bawah pemerintahan Komunis sebagai Republik Sosialis Vietnam pada 2 July 1976.

[sunting]
Pasca perang Vietnam

Dampak dari pengambil-alihan kontrol, komunis Vietnam melarang partai politik lain, menahan tersangka yang dipercayai berkolaborasi dengan A.S. dan memulai kampanye masal tentang kolektifisasi pertanian dan pabrik-pabrik. Rekonstruksi negara yang porak poranda akibat perang terjadi sangat lambat dan masalah kemanusiaan serius dan masalah-masalah ekonomi menghadapi rezim komunis. Pada 1978, Militer Vietnam menginvasi Kamboja untuk melepaskan bekas rekan mereka, Khmer Rouge, dari penindasan. Aksi ini memperburuk hubungan dengan RRT, yang meluncurkan serangan mendadak kepada Vietnam Utara pada 1979. Konflik ini menyebabkan Vietnam lebih semakin bergantung terhadap bantuan ekonomi dan militer dari Soviet.Dalam sebuah perubahan sejarah pada 1986, Partai Komunis Vietnam mengimplementasikan reformasi pasar bebas (free-market) yang dikenal sebagai Doi Moi (Renovasi). Dengan kekuasaan negara tetap tak tertandingi, kepemilikan pribadi atas pertanian-pertanian dan perusahaan-perusahaan, deregulasi dan investasi asing dipicu. Namun demikian, kekuatan Partai Komunis Vietnam atas semua organ-organ pemerintahan tetap kuat.

[sunting]
Đổi Mới

Pada perubahan sejarah pada tahun 1986, Partai Komunis Vietnam menerapkan reformasi pasar bebas yang dikenal sebagai Đổi Mới(Renovasi). Dengan kekuasaan negara yang tetap tidak terlawankan, kepemilikan swasta atas pertanian dan perusahaan-perusahaan, deregulasi dan investasi asing dipacu. Ekonomi Vietnam mencapai pertumbuhan yang cepat dalam produksi bidang pertanian dan perindustrian, konstruksi dan perumahan, ekspor dan investasi asing. Vietnam sekarang adalah satu diantara negara dengan pertumbuhan ekonomi tercepat di dunia.

Secara politis, reformasi belum terjadi. Partai Komunis Vietnam mempertahankan kontrol atas semua organ-organ pemerintah.

biologi sel

ada awalnya sel digambarkan pada tahun 1665 oleh seorang ilmuwan Inggris Robert Hooke yang telah meneliti irisan tipis gabus melalui mikroskop yang dirancangnya sendiri. Kata sel berasal dari kata Latin cellulae yang berarti 'kamar-kamar kecil'. Anton van Leeuwenhoek melakukan banyak pengamatan terhadap benda-benda dan jasad-jasad renik dan menunjukkan pertama kali pada dunia ada "kehidupan di dunia lain" yang belum pernah dilihat oleh manusia. Karyanya menjadi dasar bagi cabang biologi yang penting saat ini: mikrobiologi.Perkembangan mikroskop selama hampir 200 tahun berikutnya telah memberikan kesempatan bagi para ahli untuk meneliti susunan tubuh makhluk hidup. Serangkaian penelitian telah dilakukan oleh 2 orang ilmuwan dari [[Jerman] yaitu Matthias Schleiden (ahli tumbuhan, 1804-1881) dan Theodor Schwann (ahli hewan, 1810-1882). Mereka menyimpulkan bahwa setiap mahluk hidup tersusun atas sel. Selanjutnya pada tahun 1885 seorang ilmuwan Jerman, Rudolf Virchow, mengamati bahwa sel dapat membelah diri dan membentuk sel-sel baru.

Biologi adalah suatu cabang ilmu yang mempelajari tentang makhluk hidup . makhluk hidup tersebut terdiri atas berjuta-juta sel dalam tubuhnya . Sel adalah satu unit dasar dari tubuh manusia dimana setiap organ merupakan penyatuan dari berbagai macam sel yang dipersatukan satu sama lain oleh struktur-struktur interselluler.
Sel juga merupakan sekumpulan materi yang paling sederhana yang dapat menjalankan proses hidup. Sel merupakan tingkatan struktur terendah yang mampu melakukan semua aktivitas kehidupan . Walaupun banyak sel yang berbeda satu sama lainnya, tetapi umumnya seluruh sel mempunyai sifar-sifat dasar yang mirip satu sama lain, misalnya :

oksigen akan terikat pada karbohidrat, lemak atau protein pada setiap sel untuk melepaskan energi .

mekanisme umum merubah makanan menjadi energi .

setiap sel melepaskan hasil akhir reaksinya ke cairan disekitarnya .

hampir semua sel mempunyai kemampuan mengadakan reproduksi dan jika sel tertentu mengalami kerusakan maka sel sejenis yang lain akan bergenerasi

Secara umum sel-sel yang menyusun tubuh manusia mempunyai struktur dasar yang terdiri dari membran sel, protoplasma dan inti sel (nukleus ) . Ketiganya mempunyai komposisi kimia yang terdiri dari air, elektrolit, protein, lemak dan karbohidrat .

a. Air
Medium cairan utama dari sel adalah air, yang terdapat dalam konsentrasi 70-85%. Banyak bahan-bahan kimia sel larut dalam air, sedang yang lain terdapat dalam bentuk suspensi atau membranous .

b. Elektrolit
Elektrolit terpenting dari sel adalah Kalium, Magnesium, Fosfat, Bikarbonat, Natrium, Klorida dan Kalsium. Elekrolit menyediakan bahan inorganis untuk reaksi selluler dan terlibat dalam mekanisme kontrol sel

c. Protein
Memegang peranan penting pada hampir semua proses fisiologis dan dapat diringkaskan sebagai
berikut :
1. Proses enzimatik
2. Proses transport dan penyimpanan
3. Proses pergerakan
4. Fungsi mekanik
5. Proses imunologis
6. Pencetus dan penghantar impuls pada sel saraf
7. Mengatur proses pertumbuhan dan regenerasi

d. Lemak
Asam lemak yang merupakan komponen membran sel adalah rantai hidrokarbon yang panjang, sedang asam lemak yang tersimpan dalam sel adalah triasilgliserol, merupakan molekul yang sangat hidrofobik. Karena molekul triasilgliserol ini tidak larut dalam air/larutan garam maka akan membentuk lipid droplet dalam sel lemak (sel adiposa) yang merupakan sumber energi. Molekul lemak yang menyusun membran sel mempunyai gugus hidroksil ( fosfolipid dan kolesterol) sehingga dapat berikatan dengan air, sedangkan gugus yang lainnya hidrofobik (tidak terikat air) sehingga disebut amfifatik.

e. Karbohidrat
Suatu karbohidrat tersusun atas atom C,H, dan O. Karbohidrat yang mempunyai 5 atom C disebut pentosa, 6 atom C disebut hexosa adalah karbohidrat-karbohidrat yang penting untuk fungsi sel.
Karbohidrat yang tersusun atas banyak unit disebut polisakarida. Polisakarida berperan sebagai sumber energi cadangan dan sebagai komponen yang menyusun permukaan luar membran sel. Karbohidrat yang berikatan dengan protein (glikoprotein) dan yang berikatan dengan lemak (glikolipid) merupakan struktur penting dari membran sel. Selain itu glikolipid dan glikoprotein menyusun struktur antigen golongan darah yang dapat menimbulkan reaksi imunologis.

Inti sel ( nukleus )

Inti sel merupakan pusat pengatur berbagai aktifitas sel. Nukleus mengandung DNA dalam jumlah besar yang disebut gen. Gen yang terdapat pada kromosom berfungsi untuk sintesa RNA yang mengatur karakteristik dari protein yang diperlukan untuk berbagai aktifitas enzimatik, serta mengatur reproduksi sel. Inti sel terdiri atas nukleolus, nukleoplasma dan membran inti sel.Membran dari inti sel terdiri 2 lapis, dimana lapisan luar berhubungan dengan membran retikulum endoplasma. Pada membran inti sel terdapat porus yang mempunyai diameter yang cukup besar sehingga dapat dilalui oleh molekul protein yang disintesa dalam inti sel.

DNA adalah sejenis asam nukleat yang tergolong biomolekul utama penyusun berat kering setiap organisme. Di dalam sel, DNA umumnya terletak di dalam inti sel.
Secara garis besar, peran DNA di dalam sebuah sel adalah sebagai materi genetik; artinya, DNA menyimpan cetak biru bagi segala aktivitas sel. Di antara perkecualian yang menonjol adalah beberapa jenis virus (dan virus tidak termasuk organisme) seperti HIV ( Human Immunodeficiency Virus ) .

DNA berbentuk seperti rantai panjang ganda yang terpilin (double helix); yang terdiri dari : 1) gugus posfat 2) gugus pentose (gula) yaitu deoksiribosa dan 3) basa nitrogen . RNA berbentuk seperti rantai pendek yang tunggal. basa nitrogen yang terdapat dalam DNA berupa timin,adenin,guanin,dan sitosin;RNA adenin,guanin,sitosin,urasil. kadar DNA tetap kadar RNA berubah sesuai dengan aktivitas sintesis protein. DNA berperan dalam sintesis protein dan pewarisan sifat;RNA hanya berperan dalam sintesis protein. DNA hanya terdapat dalam intisel yaitu dalam kromosom sedangkan RNA bisa ada di dalam inti sel maupun di luar inti sel yaitu di dalam ribosom. perbedaannya adalah DNA disebut double helix sehingga ia memiliki sepasang rantai genetik,sedangkan RNA hanya memiliki satu rantai saja . DNA sebagai pengatur segala aktivitas makhluk hidup dan penentu genetik,sdangkan RNA sebagai bentuk perintah DNA yang salah satu perintahnya yaitu membuat protein pada ribosom .

Struktur dasar RNA mirip dengan DNA. RNA merupakan polimer yang tersusun dari sejumlah nukleotida. Setiap nukleotida memiliki satu gugus fosfat, satu gugus gula ribosa, dan satu gugus basa nitrogen (basa N). Polimer tersusun dari ikatan berselang-seling antara gugus fosfat dari satu nukleotida dengan gugus gula ribosa dari nukleotida yang lain . Perbedaan RNA dengan DNA terletak pada satu gugus hidroksil tambahan pada cincin gula ribosa (sehingga dinamakan ribosa). Basa nitrogen pada RNA sama dengan DNA, kecuali basa timin pada DNA diganti dengan urasil pada RNA. Jadi tetap ada empat pilihan: adenin, guanin, sitosin, atau urasil untuk suatu nukleotida.
Selain itu, bentuk konformasi RNA tidak berupa pilin ganda sebagaimana DNA, tetapi bervariasi sesuai dengan tipe dan fungsinya . RNA lebih tidak stabil daripada DNA di dalam sel dan lebih rentan terhadap penguraian oleh enzim nuklease secara laboratorium . Terdapat 3 jenis RNA yang dibentuk oleh DNA, dimana tiap jenis RNA mempunyai fungsi yang berbeda, yaitu :

1.Messenger RNA (mRNA), berfungsi membawa kode genetik ke sitoplasma untuk mengatur sintesa protein

2.Transfer RNA (tRNA) untuk transport asam amino menuju ribosom untuk digunakan menyusun molekul protein

3.Ribosomal RNA (rRNA) untuk membentuk ribosom bersama dengan 75 protein lainnya.







Berikut ini adalah gambar sel tumbuhan:



Dan ini adalah gambar sel hewan:






Siklus Sel

Interfase (tidak aktif membelah atau stadium istirahat)

Periode interfase yaitu:

Periode saat sel istirahat setelah menjalani mitosis

Periode pada saat sel secara aktif membentuk protein, lemak, dan potongan-potongan RNA

Periode pada waktu penyalinan DNA

Fase ini memakan waktu 10 s.d 20 jam

Mitosis (pembelahan sel)

Stadium mitosis

Profase –> struktur protein yg tdp pd Sitoplasma sel bergerak kearah kutub yg berlawanan à pecah membran inti sel à kromosom diluar inti (sitoplama)

Metafase –> Kromosom 2 set pasangan yg berdampingan dibagian tengah sel

Anafase –> mikrotubulus mulai menarik pasangan kromosom agar terpisah

Telofase –> sel terbelah ditengahnya dan terbentuk membran inti yang baru

Fase ini memakan waktu 1 jam




MEIOSIS

Proses dimana sel-sel seks ovarium (oosit primer) atau testis (spermatosit primer)à sel telur atau sperma yang matang

Replikasi DNA dalam sel seks yg diikuti oleh pembelahan 2 sel –> terbtk 4 sel anak yg masing-masing hanya memilki 1 pasang kromosom yaitu 23 kromosom.

Selama fertilisasi informasi genetik yang terkandung dalam 23 kromosom telur akan manyatu dalam 23 kromosom sperma –> Embrio dg kromosom total 46

Hitsugaya Toushirou

Tōshirō Hitsugaya is very young by Soul Society standards. Born in Rukongai, [3] he became the youngest ever to reach captain rank. [3] Thus, he is called a "boy genius" or a "child prodigy" by many. Hitsugaya is very short and his height is comparable to Rukia Kuchiki's. He also has spiky silver-white hair (which tends to draw attention in the human world) and teal-emerald eyes, which evokes his ability of controlling ice and water. He wears standard captain's clothing, save for a green baldric around his shoulders which holds Hyōrinmaru, his zanpakutō.

Hitsugaya is generally mature and serious, in contrast to his free-spirited lieutenant, Rangiku Matsumoto, although he can sometimes be short-tempered and irritable. Despite their personality differences, he and Matsumoto seem to be very close. Hitsugaya is shown to also be easily irked by others goofing off or drawing unneeded attention to themselves, as shown when he led a team of Soul Reapers into Ichigo Kurosaki's school. He hates anything that he deems childish and hates being described as something close to a child, evident in a filler episode when he meets Ichigo's sister, Karin, who pats him over the head further angering him. [4] This is also shown more in the omake chapters, where he is repeatedly mistaken for a child, much to his annoyance. Fitting with the nature of his zanpakutō, Hitsugaya dislikes summer and warm weather in general.

Hitsugaya's intuition is extremely sharp, and he is the first person to correctly suspect Gin Ichimaru of foul play, though he understandibly did not suspect Sōsuke Aizen of the same. During his duel with Ichimaru in the anime, the latter remarks that Hitsugaya is the embodiment of a heavenly guardian that would be reincarnated once in a few centuries. This is attributed to his given name, which is a homonym for a casual Japanese term meaning "amateur" (藤四郎), possibly referring to Hitsugaya's young age and inexperience relative to the other captains of the Gotei 13. He is very protective of Momo Hinamori, due to the fact that they were old childhood friends, promising to kill those who harm her.

A running gag is Hitsugaya getting annoyed when anyone refers to him by anything other than his title, Captain Hitsugaya. Hinamori has called him by "Tōshirō," ("Hitsugaya-kun" in the Japanese manga and anime) and both she and Ukitake have occasionally used "Little Shiro" (シロちゃん Shiro-chan) — a nickname meaning "Whitey" (Snowy in the English manga) in reference to his hair — in both cases without repercussion, however. In the Shinigami Golden Picture Book sketches (omakes found at the end of episodes of Bleach), Jūshirō Ukitake comically gives Hitsugaya candy and other food because "Jūshirō" and "Tōshirō" sound similar and because they both have white hair, making them both "Shiro-chan." The first character in Hitsugaya's given name, Tōshirō, means "winter," which is appropriate given his white hair and ice type zanpakutō. Ichigo also calls Hitsugaya by his given name without the use of honorifics, much to his irritation, making him one of three captains Ichigo refers to in this manner (the others being Byakuya Kuchiki and Kenpachi Zaraki). In contrast, Orihime Inoue calls him "Tōshirō-kun".

[edit]
History

Hitsugaya's early life was spent in Junrinan, District 1 of Rukongai. There he lived with his grandmother and Momo Hinamori. He was also a friend of Jidanbō, the West Gate Keeper, whom he taught the "city rules."[5]

Hitsugaya meets Hyōrinmaru for the first time.

As a child, Hitsugaya had an icy demeanor that estranged himself from others, with the exception of his grandmother and Hinamori. She would call him "Shiro-chan" (Lil' Shiro in the English dub) and he would retort by calling her "Bed-wetter Momo." The three were very close, and Hitsugaya was irritated when Hinamori left to join the Soul Reaper academy. Throughout his childhood, he was always aware of what seemed to be an icy presence within himself and had continuous dreams about a plain of ice. He claims or believes he died on that plain. [6] Five years after Hinamori's departure, Hitsugaya encountered Rangiku Matsumoto, then a normal Soul Reaper, in a marketplace, when she stood up to a merchant who left his change on the counter, rather than handing it to him. The two got into an argument, and Rangiku noticed Hitsugaya's enormous latent spiritual power.

That night, Hitsugaya dreamt again of the icy plain and finally met Hyōrinmaru for the first time, though he could not hear the spirit's name. He woke up to find Rangiku admonishing him for not being able to control his power, which had been freezing his grandmother. She convinced him that power like his needed to be controlled, and convinced him to become a Soul Reaper.[7] With Hitsugaya's natural talent, he entered the Soul Reaper academy in spite of his age and became known as a prodigy, quickly ascending to captain of the 10th Division, ironically making him Rangiku's superior.

Hinamori has continued to call Hitsugaya "Shiro-chan" out of habit, and still feels protective of him. Because of a promise she had made, she only began to call him by name after he had achieved his zanpakutō's shikai and was recognized as a Soul Reaper. Highly capable and knowledgeable, he remains the youngest of the captains within the Gotei 13.

[edit]
Synopsis

Introduced along with the rest of the Gotei 13, Hitsugaya's sharp sense of intuition and keen sense of observation leads him to suspect 3rd Division captain Gin Ichimaru of foul play as the circumstances surrounding the coming execution of Rukia Kuchiki become more complicated. He warns Hinamori of these suspicions, which inspires her to attack Gin following Aizen's murder. When Izuru Kira steps forth to defend his captain against Hinamori, Hitsugaya breaks up the fight. He admonishes Hinamori for losing control of herself and forgetting her duty, and has her and Kira sent to prison. Hitsugaya also warns Gin that he knows he wanted to kill Hinamori, and that if he causes Hinamori to spill even a single drop of blood he will kill him. When Hinamori is manipulated into thinking that Hitsugaya killed Aizen, Hitsugaya knocks her out, and believing Gin responsible, attacks him. Hitsugaya manages to freeze Gin's arm, but Matsumoto interrupts and breaks it up after Gin threatens to kill Hinamori, distracting Hitsugaya and making him take a hit. Seeing how destructive Rukia's execution is becoming, Hitsugaya tries to stop the execution by appealing to the Chamber 46, only to discover all 46 members are dead and Aizen is responsible for murdering them, having faked his death. When Hitsugaya discovers Hinamori injured and interrogates Aizen, he angrily explains how Hinamori truly cared about him and how she worked so hard to be his lieutenant. Aizen replies that that's why it was easy to manipulate her and states that "admiration is a state furthest away from understanding". Hitsugaya tries to kill him with his bankai, but he charges at an illusion and is defeated with a single strike. Luckily, Retsu Unohana and Isane Kotetsu, who were also present to learn of Aizen's plan, rescued and healed them.

During the first anime filler arc, Hitsugaya later sends several Soul Reapers to fend off the Bount in Karakura Town. When the Bount infiltrate Soul Society, he, along with Renji and Matsumoto, investigate reports of Bount activity in a forest in Rukongai. The Bount, however, are gone by the time they reach the forest. Hitsugaya later has a battle with the Bount Koga Gō, whom he easily defeats thanks to the advantages his style of combat holds over Koga's. Though he assumes the Bount to be dead, Koga survives.

In a later arc, Hitsugaya leads a group of Soul Reapers assigned to defend Karakura Town against the arrancar threat. During the first attack, he battles Shawlong Koufang. Though heavily injured, he wins after being allowed to remove his power limit. Hitsugaya then has a conversation with Hinamori through video-conference. Hinamori apologizes to Hitsugaya for pointing her sword at him, Hitsugaya tells her not to worry about it. After bickering, they start talking about Aizen. Hinamori, who still cares for her former captain, begs Hitsugaya to save Aizen, thinking that Gin is manipulating him somehow. Angered by the fact that Hinamori is still devoted to Aizen, despite what he did to her, as a result of Aizen's conditioning her, Hitsugaya hopes for revenge. During the second arrancar attack, he fends off Luppi. Though Hitsugaya is initially unable to defend against Luppi's attacks and is knocked to the ground in a single hit, Luppi's inattentiveness and overconfidence gives him ample time to build up a finishing move. Luppi escapes death and promises to kill Hitsugaya in turn. Upon learning that Orihime has followed the arrancar back to Hueco Mundo, Hitsugaya and his team return to Soul Society to help in the preparation for war against Aizen, and he has recently been seen among the captains preparing to do battle. Currently, he is fighting against the Tres Espada, Halibel

[edit]
Hyōrinmaru

Hyōrinmaru's shikai.

Hitsugaya's zanpakutō is Hyōrinmaru (氷輪丸? literally "ice ring", idiomatically "full moon"). When sealed, Hyōrinmaru looks almost exactly like a normal zanpakutō with the exception of the guard, which is in the shape of a four-pointed star. The hilt is light-blue while the sheath is a deep blue. Hyōrinmaru's shikai command is translated in the English anime as "reign over the frozen sky" (霜天に坐せ sōten ni zase?). Hyōrinmaru is the strongest of all ice element zanpakutō in Soul Society.[8] Hyōrinmaru is one of the three zanpakutō spirits that have been seen, the others being Zangetsu and Zabimaru. Hyōrinmaru's spirit is a large, winged, Japanese dragon.

In its shikai, Hyōrinmaru itself remains the same, but gains a crescent-shaped blade attached to the hilt by a chain. Hyōrinmaru allows Hitsugaya to control water and ice. The slashes created by Hyōrinmaru gives off an immense amount of spirit power which overflows from the tip of the blade, creating a flow of ice vaguely shaped like Hyōrinmaru's dragon spirit. The dragon flies at opponents and instantly freezes anything it touches. The chain-blade also freezes anything Hitsugaya traps with it.

Hyōrinmaru's bankai.

Hyōrinmaru's bankai, named Daiguren Hyōrinmaru (大紅蓮氷輪丸? literally "great crimson lotus ice ring"), causes ice to flow from Hyōrinmaru onto Hitsugaya, forming into two large wings and a tail. Ice also forms into a dragon's head around his sword hand, encasing it up to the hilt; which is in the shape of an eight-pointed star. Additionally, his wings are capable of folding around him to serve as ice shields. During one of Hitsugaya's earlier battles, the arrancar Shawlong speculates that Hitsugaya's bankai will fade when all twelve petals disappear and that Hitsugaya's bankai is incomplete due to his young age. Later during his fight with Luppi, the petals no longer appear. Also during that fight, Hitsugaya states that "even if [Hyōrinmaru is] shattered, it will reform as long as there is water present."[9]

Hyōrinmaru's bankai has two known special techniques. The first is ryūsenka (竜霰花? literally "dragon hail flower"), which freezes any enemy Hitsugaya stabs, locking them into a cocoon of ice and freezing them to the core. Once frozen, Hitsugaya can shatter his opponent. The second is sennen hyōrō (千年氷牢? literally "thousand-year ice prison"),[10] which forms a multitude of ice pillars using the moisture in the atmosphere. These pillars hold the enemy prisoner for a thousand years, also freezing them.[11]

[edit]
Other media

Hitsugaya appears in the second Bleach movie, Bleach: The DiamondDust Rebellion, as one of the two main characters. When the "King's Seal," an ancient artifact, is stolen, Hitsugaya goes out in search of the thieves. After crossing paths with and fighting them, he goes missing, leading Seireitei to suspect him of treason. As Ichigo Kurosaki and others go out in search of Hitsugaya, Hitsugaya himself stumbles across a dark secret concerning a long-dead Soul Reaper named Kusaka Sōjirō, who was a close friend and rival of Hitsugaya's when he was younger. A one-shot manga chapter focusing on Histugaya's past was released to promote the film, revealing how Hitsugaya learned of his powers. In the movie DiamondDust Rebellion Kasuka was seen in a mask with eight for spider like holes. Apparently Kasuka uses the King's Seal to come back to life for revenge. In the end Kasuka ends up being killed by Toshiro his last words were "What if I..." and Toshiro's response was "If.."

Hitsugaya is featured in the Bleach 30 minute OVA, Sealed Sword Frenzy, in which he is part of the group of captains sent to the real world to seal away the escaped and notoriously dangerous shinigami criminal, Baishin. During their first encounter, he successfully fends off the criminal, though Baishin escapes.

Hitsugaya has been a playable character in every Bleach-related video game released so far, the only exception being Bleach: Heat the Soul. Often, he's playable in several different forms, such as his shikai and bankai and even in a gigai. He is also a playable character in the Nintendo DS game, Jump Ultimate Stars.

He is the only Bleach character to appear in two Bleach Beat Collection albums aside from Ichigo himself. The first one was a compilation album with Momo Hinamori and his lieutenant, Rangiku Matsumoto. The second one was also a compilation album, this time with the protagonist, Ichigo Kurosaki. His two songs are 'This Light I See' and 'Bleach the Limitation'. He is also portrayed by Takashi Nagayama in the Rock Bleach Musicals.

[edit]
Reception

Hitsugaya has been highly popular in the Weekly Shōnen Jump's Bleach! popularity polls ranking most of the times within the top ten.[12] In the latest poll Hitsugaya was voted the most popular character in the series, replacing Ichigo Kurosaki, who had previously held the position. He received 8278 votes, 383 votes more than Rukia Kuchiki, who finished second.[13] In the 2007 Japanese Newtype magazine character polls, he was voted the 7th most popular character in any anime.[citation needed] Carl Kimlinger from Anime News Network praised Steve Staley, Hitsugaya's English voice actor, for giving an interesting variation of his voice rather than "integrity-destroying abominations".[14] Various merchandise based on Hitsugaya's appearance has been created, including action figures,[15] plush toys[16], and key-chains.[17] In order to promote the second film of Bleach, the trailer had the line "Execute Hitsugaya!". Kubo admitted that it was his own idea to make everybody be surprised, but he and Masakazu Morita, the voice actor of Ichigo Kurosaki, received a lot of letters from worried fans, causing Kubo to apologize in response.[18]

genetics science

Genetics (from Ancient Greek γενετικός genetikos, “genitive” and that from γένεσις genesis, “origin”[1][2][3]), a discipline of biology, is the science of heredity and variation in living organisms.[4][5] The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding. However, the modern science of genetics, which seeks to understand the process of inheritance, only began with the work of Gregor Mendel in the mid-nineteenth century.[6] Although he did not know the physical basis for heredity, Mendel observed that organisms inherit traits in a discrete manner—these basic units of inheritance are now called genes.

DNA, the molecular basis for inheritance. Each strand of DNA is a chain of nucleotides, matching each other in the center to form what look like rungs on a twisted ladder.

Genes correspond to regions within DNA, a molecule composed of a chain of four different types of nucleotides—the sequence of these nucleotides is the genetic information organisms inherit. DNA naturally occurs in a double stranded form, with nucleotides on each strand complementary to each other. Each strand can act as a template for creating a new partner strand—this is the physical method for making copies of genes that can be inherited.

The sequence of nucleotides in a gene is translated by cells to produce a chain of amino acids, creating proteins—the order of amino acids in a protein corresponds to the order of nucleotides in the gene. This is known as the genetic code. The amino acids in a protein determine how it folds into a three-dimensional shape; this structure is, in turn, responsible for the protein's function. Proteins carry out almost all the functions needed for cells to live. A change to the DNA in a gene can change a protein's amino acids, changing its shape and function: this can have a dramatic effect in the cell and on the organism as a whole.

Although genetics plays a large role in the appearance and behavior of organisms, it is the combination of genetics with what an organism experiences that determines the ultimate outcome. For example, while genes play a role in determining a person's height, the nutrition and health that person experiences in childhood also have a large effect