10 Facts About Cells

Cells are the fundamental units of life. Whether they be unicellular or multicellular life forms, all living organisms are composed of and depend on cells to function normally. Scientists estimate that our bodies contain anywhere from 75 to 100 trillion cells. Cells do everything from providing structure and stability to providing energy and a means of reproduction for an organism. The following 10 facts about cells will provide you with well known and perhaps little known tidbits of information about cells.

1. Cells are too small to be seen without magnification. Cells range in size from 1 to 100 micrometers. The study of cells, also called cell biology, would not have been possible without the invention of the microscope. With the advance microscopes of today such as the Scanning Electron Microscope and Transmission Electron Microscope, cell biologists are able to obtain detailed images of the smallest of cell structures.

2. There are two primary types of cells. Eukaryotic and prokaryotic cells are the two main types of cells. Eukaryotic cells are called so because they have a true nucleus. Animals, plants, fungi and protists are examples of organisms that are composed of eukaryotic cells. Prokaryotes include bacteria and archaeans.

3. Prokaryotic single-celled organisms were the earliest and most primitive forms of life on earth. Prokaryotes can live in environments that would be deadly to most other organisms. They are able to live and thrive in various extreme habitats. Archaeans for example, live in areas such as hydrothermal vents, hot springs, swamps, wetlands, and even animal intestines.

4. There are more bacterial cells in the body than human cells. Scientists have estimated that about 95% of all the cells in the body are bacteria. The vast majority of these microbes can be found within the digetive tract.

5. Cells contain genetic material. Cells contain DNA (deoxyribonucleic acid), the genetic information necessary for directing cellular activities. DNA is a type of molecule known as a nucleic acid. In prokaryotic cells, the single bacterial DNA molecule is not separated from the rest of the cell but coiled up in a region of the cytoplasm called the nucleoid region. In eukaryotic cells, DNA molecules are located within the cell's nucleus. DNA and proteins are the major components of chromosomes. Human cells contain 23 pairs of chromosomes (for a total of 46). There are 22 pairs of autosomes (non-sex chromosomes) and one pair of sex chromosomes. The X and Y sex chromosomes determine gender.

6. Cells contain structures called organelles which carry out specific functions. Organelles have a wide range of responsibilities within a cell that include everything from providing energy to producing hormones and enzymes. Eukaryotic cells contain several types of organelles, while prokaryotic cells contain a few organelles (ribosomes) and none that are bound by a membrane. There are also differences between the kinds of organelles found within different eukaryotic cell types. Plant cells for example, contain structures such as a cell wall and chloroplasts that are not found in animal cells. Other examples of organelles include:

• Nucleus
• Mitochondria
• Endoplasmic Reticulum
• Golgi Complex
• Ribosomes

7. Different types of cells reproduce through different methods. Most prokaryotic cells reproduce by a process called binary fission. This is a type of cloning process in which two identical cells are derived from a single cell. Eukaryotic organisms have a similar type of reproductive method known as mitosis. Some eukaryotes also have the ability to reproduce sexually, which involves the fusion of sex cells or gametes. Gametes are produced by a process called meiosis.

8. Groups of similar cells form tissues. Tissues are groups of cells with both a shared structure and function. Cells that make up animal tissues are sometimes woven together with extracellular fibers and are occasionally held together by a sticky substance that coats the cells. Different types of tissues can also be arranged together to form organs. Groups of organs can in turn form organ systems.

9. Cells have varying life spans. Cells within the human body have different life spans based on the type and function of the cell. They can live anywhere from a few days to a year. Certain cells of the digestive tract live for only a few days, while some immune system cells can live for up to six weeks. Pancreatic cells can live for as long as a year.

10. Cells commit suicide. When a cell becomes damaged or undergoes some type of infection, it will self destruct by a process called apoptosis. Apoptosis works to ensure proper development and to keep the body's natural process of mitosis in check. A cell's inability to undergo apoptosis can result in the development of cancer.

Source: http://biology.about.com/od/cellbiology/a/cells-facts.htm

Bacteria: Friend or Foe?

Bacteria are all around us and most people only consider these prokaryotic organisms to be disease causing parasites. While it is true that bacteria are responsible for a large number of human diseases, they also make it possible for certain elements such as carbon, nitrogen, and oxygen to be returned to the atmosphere.

Life as we know it would not exist without bacteria to decompose waste and dead organisms. These bacteria ensure that the cycle of chemical exchange between organisms and their environment is continuous.

The decision as to whether bacteria are friend or foe becomes more difficult when both the positive and negative aspects of the relationship between humans and bacteria are considered. Let's discuss three types of symbiotic relationships: commensalism, mutualism, and parasitism.

Commensalism is a relationship that is beneficial to the bacteria which live off of the host, but does not help or harm the host. Most of the bacteria that reside within the bodies of humans are commensalistic.

In a mutualistic relationship, both the bacteria and the host benefit. For example, there are several kinds of bacteria which live inside the mouth, nose, throat, and intestines of humans and animals. These bacteria receive a place to live and feed while keeping other harmful microbes from taking up residence.

A parasitic relationship is one in which the bacteria benefit while the host is harmed. Pathogenic parasites, which cause disease, do so by resisting the host's defenses and growing at the expense of the host. These bacteria produce poisonous substances called endotoxins and exotoxins which are responsible for the symptoms that occur with an illness.

When all of the facts are considered, bacteria are more helpful than harmful. Humans have exploited bacteria for a wide variety of uses, such as: making cheese and butter, decomposing waste in sewage plants, and developing antibiotics. Bacteria have been able to survive without us, but we could never live without them.

source: http://biology.about.com/cs/bacteriology/a/aa032504a.htm

Tumbuhan Pemangsa Serangga..???

Selama ini kita sering mendengar hewan pemangsa, entah itu memangsa hewan lain ataupun bahkan memangsa manusia. Kita pun biasa mendengar istilah hewan pemakan tumbuhan. Tapi kalo tumbuhan pemakan atau pemangsa hewan…? Hmmm..masak siy bisa? Agak aneh ya?! Atau mungkin sebagian dari kita memang sudah ada yang mngenalnya. Yuks kita kupas lebih dalam tentang tumbuhan unik ini..

Tumbuhan yang satu ini disebut Venus. Nama latinnya adalah Dionaea muscipula. Ia merupakan tumbuhan pemangsa yang mengagumkan. Ia tak hanya memang serangga, ia akan memangsa siapa saja yang singgah ke kelopaknya, entah itu katak, kadal, atau cicak.

Tumbuhan ini mendapatkan mangsa dengan cara sebagai berikut. Seekor lalat yang sedang mencari makan tiba-tiba menemukan tumbuhan yang sangat memikat, yaitu Venus ini. Mengapa memikat? Tumbuhan ini bentuknya mirip sepasang tangan yang sedang memegang mangkuk. Yang membuatnya menarik bagi lalat adalah warnanya yang merah menyala dan baunya yang harum yang berasal dari kelenjar di sekitar kelopak. Lalat terpikat oleh bau harum ini dan mendarat di sekitar kelopak tanpa ragu. Ketika bergerak mencari makanan, tanpa sengaja lalat menyentuh bulu-bulu kelopak yang tampaknya tidak berbahaya. Beberapa saat kemudian, kelopak menutup dengan cepat. Lalat terjepit kuat diantara dua kelopak tersebut. Venus mulai mengeluarkan cairan pelarut daging sampai bentuk lalat berubah menjadi semacam gel. Gel ini kemudian diserap oleh Venus.

Hmm… glek!!! Ngeri juga yah..?!

Venus menangkap lalat dengan kecepatan tinggi. Coba kamu tangkap seekor lalat. Kemungkinan besar kamu gagal menangkapnya. Namun tumbuhan tanpa tulang dan otot ini mampu bergerak cepat. Subhanalloh…

Hasil penelitian menunjukkan adanya sistem listrik pada Venus. Gesekan serangga pada bulu kelopak diteruskan kepada reseptor yang terletak di bawah bulu. Bila gesekan mekanis ini cukup kuat, reseptor akan mengirimkan sinyal listrik ke seluruh permukaan kelopak. Sinyal ini diteruskan ke sel-sel penggerak agar kelopak menutup tiba-tiba. Tertangkaplah si lalat malang.

Selain system stimulus, Alloh Subhanahu Wata’ala juga menciptakan system mekanisme menutup kelopak dengan sempurna. Begitu sel-sel dalam Venus menerima stimulus listrik, terjadi perubahan konsentrasi air di dalam sel. Sel-sel kelopak mengeluarkan air dari tubuh mereka. Sebaliknya, sel-sel di luar kelopak menyerap kelebihan air dan kemudian mengembang. Proses menutupnya kelopak ini sama dengan saat manusia menggerakkan tangannya: satu otot berkontraksi, satu otot mengendur.

Lalat yang terjebak dalam kelopak sebenarnya menyentuh bulu-bulu kelopak berkali-kali. Ini menyebabkan sinyal listrik dilepaskan kembali sehingga kelopak menutup lebih rapat. Sementara itu, kelenjar pencernaan pada kelopak pun diaktifkan. Akibat stimulus ini, kelenjar-kelenjar itu membunuh dan melarutkan tubuh lalat perlahan-lahan.

Untuk menutup kelopak, bulu-bulu harus disentuh dua kali berturut-turut. Sentuhan pertama membangkitkan muatan listrik statis, namun tidak membuat kelopak menutup. Kelopak hanya menutup pada sentuhan kedua setelah muatan listrik statis mencapai batas tertentu dan dilepaskan. Dengan mekanisme ganda ini, kelopak tidak akan menutup tanpa kehadiran mangsa. Misal, kelopak tidak akan menutup saat terkena setetes air hujan.

Jika kita mau memikirkan, tumbuhan ini tentu tidak berpikir untuk melakukan semua mekanisme cari makan di atas. Alloh Subhanahu Wata’ala-lah yang Mahabesar untuk menciptakan mekanisme sistem yang mengagumkan ini. Subhanalloh!

Sumber: Majalah Elfata

Research #2

DAYA HAMBAT EKSTRAK KASAR SENYAWA DAUN KUMIS KUCING (Orthosiphon aristatus) TERHADAP PERTUMBUHAN Pseudomonas aeruginosa

Profita Oktavina Maharani, Biology Faculty, Jenderal Soudirman University

ABSTRACT

Pseudomonas aeruginosa is a kind of negative Gram bacteria with characteristic of opportunistic that could cause infection. Infection type that occurred among other things urine-duct infection, respiratory infection, dermatitis, smooth tissue infection, bone and joint infection, digestive infection, and vary of systemic duct infection. Orthosiphon aristatus is the one of plantation that contain chemical with characteristic of antibacterial to bacteria which could cause infection. It has been conducted an experiment to find out the class of active compound that contain in crude extract of O. aristatus leaf which able to inhibit P. aeruginosa and the Minimum Inhibition Concentration (MIC). This research was carried out at Microbiology Laboratory Biology Faculty of Jenderal Sudirman University on October 2008 – January 2009. The research used completely randomized design with 6 treatments and thrice replications. Each treatment used concentration of O. aristatus extract 0% (K₀), 2.5% (K₁), 5% (K₂), 7.5% (K₃), 10% (K₄) and 12.5% (K₅), respectively examined to P. aeruginosa. Examination was carried out by gel dilution method and calculation of total bacteria colony used Total Plate Count (TPC) method. The substance of antibacterial is alkaloid and flavonoid. MIC crude extract of O. aristatus to P. aeruginosa was equal to 2.5%.

Key words: O. aristatus, P. aeruginosa, infection, antibacterial, MIC

Research #1

PENGENDALIAN HAMA TANAMAN JERUK Toxoptera aurantii MENGGUNAKAN ENTOMOPATOGEN Verticillium sp.

Etiek Dwi W. S., Jenderal Soedirman University (2009)

ABSTRACT

Toxoptera aurantii is an insect and pest that is important to control the orange plantation because not only botch the plant, but also it can be the tristeza (CTV) and (CVEV) vector, and can help Capnodium sp. stimulation, which causes the sooty mold disease which reduces the production of oranges number. An entomopatogen Verticillium sp. which is one of the biological agency can be used at pest control inwrought (PHT) toward pests from Homoptera and Hemiptera ordo. One of them is T. aurantii. an insect pest research has been done based on what was mentioned a patogensitas Verticillium sp. toward imago T. aurantii. The aim from this research is to know effectivenes of Verticillium sp. toward imago T. aurantii. This research is done according to the experimental use of a complete random plan (RAL). Treatment uses Verticillium sp. suspension with concentration of 0g/100ml (K0), 2g/100ml (K1), 4g/100ml (K2), and 6g/100ml (K3). Each treatment use sample T. aurantii as many as ten and repeats as much as 6 times. Observation was done towards the death of imago T. aurantii, that given treatment using insect patogen. The result from the observation shows that Verticillium sp. influences the death of imago T. aurantii, although the highest mortality is achieved at only 28.3%. The death of T. aurantii in treatment use Verticillium sp. with concentration 2g/100ml, 4 g/100ml and 6g/100ml successive 13.3%, 28.3% and 20%, while controle doesn't show the death existence because Verticillium sp. infection.

Keyword: Entomopatogen, Verticillium sp. ,T. aurantii

Candida albicans dan Keputihan

Pernah dengar nama Candida albicans? Candida albicans adalah satu dari sekian banyak jenis yeast yang namanya cukup dikenal di bidang Mikrobiologi. Yeast sendiri merupakan fungi mikroskopis bersel tunggal yang bereproduksi secara vegetatif dengan membentuk sejenis kuncup (budding). Beberapa jenis yeast, termasuk Candida albicans, memiliki sifat dimorphic. Ketika berada di alam ia akan tumbuh sebagai miselium dan ketika berada di dalam tubuh ia akan tumbuh sebagai yeast yang bereproduksi dengan membentuk budding.

Candida albicans secara alami dapat ditemukan di dalam membran mukosa mulut dan juga di dalam vagina. Keberadaannya di dalam tubuh manusia ini dikenal dengan istilah “flora normal”. Sebagai flora normal vagina, Candida albicans tidak hidup sendirian melainkan hidup bersama dengan beberapa mikroorganisme lainnya.

Lalu apa hubungannya Candida albicans dengan keputihan?

Dalam kondisi normal, kehadiran Candida albicans dalam tubuh manusia tidak menimbulkan gangguan apapun. Gangguan hanya akan muncul apabila keseimbangan populasi flora normal ini mengalami perubahan. Entah itu jumlahnya meningkat dengan pesat ataupun menurun secara drastis. Perubahan keseimbangan flora normal dalam vagina dapat terjadi karena beberapa hal, antara lain:　

Penggunaan alat kontrasepsi oral. Penggunaan alat kontrasepsi oral ini dapat menyebabkan perubahan kondisi hormonal yang pada akhirnya akan mempengaruhi derajat keasaman (pH) vagina. Adanya perubahan pH ini akan mempengaruhi keseimbangan flora normal yang ada di dalamnya.

Mengkonsumsi antibiotik (dari golongan tetracycline) secara berlebihan akan mengganggu keseimbangan flora normal vagina dan berakibat lebih jauh akan meningkatkan pertumbuhanCandida albicans.

Terlalu sering membasuh vagina dengan cairan pembersih vagina juga akan mematikan flora normal tertentu dalam vagina, sehingga komposisi flora normal menjadi tidak seimbang.

Pemakaian celana dalam yang terlalu ketat dan penggunaan pembalut yang terlalu sering akan mengurangi aerasi di daerah vagina, sehingga akan meningkatkan suhu dan kelembaban di sana. Kondisi semacam ini memungkinkan yeast untuk berkembang biak dengan pesat.

Adanya perubahan keseimbangan flora normal dalam vagina tersebut akan mengakibatkan munculnya gangguan yang biasa disebut keputihan. Keputihan yang disebabkan oleh Candida albicans dikenal dengan nama “vulvovaginal candidiasis”. Gejala umum yang biasa muncul adalah rasa gatal yang teramat sangat pada vagina bagian luar, labia mayora (bibir vagina) menjadi kemerahan dan terkadang bengkak, keluar cairan vagina berwarna putih serupa keju berbau jamur.

Meskipun “vulvovaginal candidiasis” ini dapat diobati, ada baiknya kalau kita melakukan pencegahan agar tak dihinggapi gangguan yang satu ini. Caranya?

Jagalah kebersihan vagina dan sekitarnya, tapi usahakan untuk tidak terlalu sering menggunakan cairan pembasuh vagina.

Setiap selesai buang air sebaiknya membasuh vagina dari arah depan ke belakang (dari vagina ke anus).

Hindari penggunaan celana dalam yang ketat ataupun berbahan nylon, lebih baik gunakan celana dalam berbahan katun yang dapat menyerap keringat.

Jangan malas untuk mengganti pembalut sesering mungkin di saat menstruasi.

Apabila “vulvovaginal candidiasis” terlanjur menghampiri, segeralah berobat ke Spesialis Kulit dan Kelamin. Biasanya Dokter akan memberikan obat antifungi berbentuk cream untuk dioleskan atau berbentuk supositoria untuk dimasukkan ke dalam vagina ataupun berupa obat per oral (untuk diminum).

Sapporo 19012005, S. Gilangtresna

Referensi :

Cole, G. T. 1996. Basic Biology of Fungi. In Medical Microbiology4th edition, Baron, S. (eds). The University of Texas Medical Branch at Galveston, Texas.　

Marrazzo, J. 2003. Vulvovaginal candidiasis. British Medical Journal. Vol. 326 : p 993-994

Mc. Ginnis, M. R. and Tyring, S. K. 1996. General Concept of Mycology. In Medical Microbiology 4th edition, Baron, S. (eds). The University of Texas Medical Branch at Galveston, Texas

Walsh, T. J. and Dixon, D. M. 1996. Spectrum of Mycoses. In Medical Microbiology4th, Baron, S. (eds). The University of Texas Medical Branch at Galveston, Texas.

Sumber: www.kafemuslimah.com