You should know...

Beta carotene : the yellow-orange pigment that gives foods such as carrots, rockmelons, apricots and mangoes their bright colour. It is one of the antioxidants that can contribute to long-term good health and provide protection against some of the effects of ageing and disease. Beta carotene may also be turned into vitamin A by the body as and when it is required.

Animal-like Protists

    Around 65,000 kinds of animal-like Protists have been known and studied. They are more usually called Protozoan (Greek: proto = first; zoa = animals). Their characteristics are unicellular and heterotrophic.

 

Body Characteristics

    Protozoan characteristics include size and shape, as well as body structure and function.

Size and shape

    Protozoans are microscopic in size, around 10 to 200 microns (µm). Their cell shape is quite variable; some are fixed, while others are changeable. Most Protozoan have some sort of motion appendage, such as pseudopodia (fake foot), cilia (soft hair), or flagella (whip-hair). Some also have a protective shell.

Structure and function

    Basically, Protozoa are composed of a cell membrane, cytoplasm, food vacuole, contractile vacuole, and nucleus. The cell membrane acts as a protective barrier and regulates food and gas exchange. A food vacuole is formed by ingesting or 'swallowing' molecules using the cell membrane or a spesific structure called cytostome (cell's mouth). The digested products of the food vacuole then enter the cytoplasm by diffusion. Food remains are exported through thr cell membrane by the vacuole. The contractile vacuole is a pump that excretes liquid food remains out of the cell by controlling and expanding, hence its name. The nucleus function is to control cell metabolic activity.

 

Life Styles

    Protozoans are heterotrophic. They prey on bacteria, other Protists, and organic waste. As a bacterial predator, Protozoa play important role in controlling bacteria population in the wild.

 

Habitat

    Protozoans are solitary or form colonies in a diverse range of habitats. Most of them live freely in ocean or freshwater, such as gutters, ponds, or rivers. Other live inside the soil. Some live symbiotically inside the bodies of animals or humans.     

 

Reproduction

    Most Protozoan reproduce asexually by binary fission. Cell division is started by karyokinesis (nuclear division) followed by cytokinesis (cytoplasm division). Those that reproduce sexually do so by combining gametes cells or vegetative. Sexual reproduction by the union of vegetative nuclear is called conjugation.

    In their life cycle, several Protozoans can produce inactive form of cells called a cyst. A cyst is covered by a polysaccharide capsule that protects the Protozoan from unfavorable environments, such as droughts. Once conditions are favorable again for example when food and water available, the cyst will break apart and new protozoa are alive again.

 

Classification

    There are more than 60,000 species of protozoan already identified. They are classified into four groups based on their method of motility; Rhizopoda, Ciliata, Flagellata, and Sporozoa.

Fungus-like Protists

    Fungus-like Protists are the group of water and slime molds. The fungus-like characteristics have structure to produce spores, heterotrophic, parsitic, or act as decomposers. As decomposers, they produce enzyms that break down or convert organic materials from dead organisms and absorb them in the form of inorganic materials.

Water Molds (Oomycota)

    There are 580 known kinds of water molds that act as decomposers in aquatic habitats. Most of them are free-living and obtain their nutrients from the remains of dead plants in ponds, lakes, and water streams. Some live inside dead tissue of plants, and some others are parasites of other aquatic organisms, for example Saprolegnia. It attaches itself to fish or other aquatic organisms. Saprolegnia has layers of membrane.

    There are also other water molds that are pathogenic to plants, for example white molds (Plasmopara viticola) that grow in colonies on grapes. Another example is the wilting and rotting potato plants and tomato plants that is caused by the water mold Phytophthora infestans.

    Water molds can reproduce sexually or asexually. It reproduce asexually by forming sporangium at the tip of their hyphae structures (filament or thread). Sporangium will be filled by flagellated spores (zoospores) that will be released when they mature. When spores fall on an optimal environment, they grow to become new mycelium.

    Sexual reproduction occurs by the meeting of male and female gametes. Gametes are produced by differenttiated hyphae. Male gametes are produced by antheridium, and female ones by oogonium. Fertilization between gametes produces diploid zygotes that grow into thick-walled spore which then will grow into new mycellium.

Slime Molds (Myxomycota)

    All slime molds produce free-living cells during part of their life cycle. These cells are called amoeboid because of their resemblance to Amoeba. Like the real Amoeba, slime molds are phagocytic predators because slime molds can ingest bacteria, pests, spores, and other organic components.

    During times of low food availability, hungry cells combine themselves together to form a slimy mass. This mass migrates to a new environment with more favorable conditions to support their growth. The mass motion is derived from the acculumulative force of contraction from each single cells. An example of a slime molds is Dictyostellium discoideum.

    

Protists

Protists are a group of eukaryotic organisms, either unicellular or multicellular, and have not yet shown real tissue differentiation. The member differ from one another in morphology and how they live. There are those with fungi, animal, or plant characteristic.

    Fungus-like Protists (molds) are parasitic molds or predatory molds that produce spores. Parasitic molds are unicellular, aquatic decomposers. Predatory molds or phagocytes are slime molds which are aggregates of migrating cells that form a spore-like structure.

    Animal-like Protists cover all non-photosynthetic Protozoan, for example Rhizopoda and Sporozoa. Protozoans are parasitic and unicellular predators.

    Plant-like Protists are unicellular and photosynthetic; some also have flagella (tail like cellular structure used for movement). Most of these Protists live freely or in a colonies in open seas and other aquatic regions. They are imortant members of Phytoplankton. Phytoplankton are the producers of the aquatic habitats. Other plant-like Protists are golden, red, green, and brown algae.

Protista

merupakan organisme eukariotik bersel satu atau banyak tetapi selnya sederhana dan tidak berdiferiensasi. Ada yang mirip hewan (protista), mirip tumbuhan, dan mirip jamur.

C. Sitoplasma

Sitoplasma (Greek: sito = sel, plasma = cairan/substansi) bukan merupakan substansi yang homogen dan terdiri dari bermacam-macam zat dan struktur yang berada dalam membran sel, kecuali materi nukleus (materi genetik). Dengan kata lain sitoplasma terdiri dari beraneka ragam mikrosom (Greek: mikro = kecil, soma = badan)/ organel-or ganel sel/ partikel subseluler yang sebagian besar adalah protein atau nukleoprotein dengan beberapa lipoprotein dan bahan-bahan lain. Beberapa dari partikel subseluler adalah:

1. Ribosom
   

   Semua sitoplasma sel tampak seperti bergranula. Hal ini disebabkan karena adanya sejumlah partikel halus yang tersebar secara baur. Pertikel-pertikel tersebut dinamakan ribosom. Ribosom cenderung membentuk kelompok-kelompok dari bermacam-macam ukuran yang disebut poliribosom dan poliosom. Ribosom sebagian besar terdiri atas rRNA (ribosom RNA) dengan sedikit protein (ribonukleoprotein). Sekurang-kurangnya sebagian dari RNA ribosom adalah mRNA (messenger RNA). Dengan demikian, ribosom bertanggung jawab atas sintesis protein spesifik dari protein dan semua enzim.
   

2. Nukleus
   

   Sel-sel prokariotik tidak mempunyai nukleus seperti pada eukariotik dengan membran nukleus yang jelas, yang ada adalah suatu daerah nukleus yang disebut nukleotid yang tidak ditutupi membran dan tidak mengadakan mitosis maupun meiosis. Pada bakteri DNA ekstrakromosom yang berbentuk seperti cincin kecil, dapat mengadakan replika secara autonom (tidak seirama dengan kromosom) dan dapat juga bertindak sebagai determinan genetik dan dinamakan episom atau plasmid.
   

3. Spora
   

   Spora pada bakteri adalah endospora, suatu badan yang refraktil terdapat dalam induk sel dan merupakan suatu stadium istirahat dari sel tersebut. Endospora memiliki tingkat metabolisme yang sangat rendah sehingga dapat bertahan hidup sampai bertahun-tahun tanpa memerlukan sumber makanan dari luar. Bila keadaan lingkungan memungkinkan, spora tersebut akan mengadakan germinasi dan menjadi sel vegetatif yang sanggup tumbuh dan bermultiplikasi seperti biasa. Kemampuan menghasilkan spora memberi keuntungan ekologis bagi bakteri, karena memungkinkan bakteri untuk hidup di lingkungan buruk. Hal ini penting bagi bakteri dalam tanah seperti Clostridium dan Bacillus yang sewaktu-waktu dapat menghadapi kekeringan. Pada saat itu, spora dapat terbawa oleh angin untuk berkembang biak di lingkungan yang baru.

B. Membran Sitoplasma

 

Membran sitoplasma disebut juga membran sel. Membran tersebut mempunyai 3 fungsi utama yaitu:

1. Memelihara tekanan osmosis.
   

   Artinya membran sel bertindak sebagai penyangga osmotik (osmotic barrier) dan tidak permeabel terhadap zat-zat yang mengion dan zat yang tidak mengion yang molekulnya tidak lebih besar dari gliserof.
   

2. Sistem transpor aktif.
   

   Berfungsi mengeluarkan enzim ekstraseluler dan zat-zat yang memelopori pembentukan dinding sel serta mengatur pemasukan garam-garam esensial, asam amino, dan gula-gula yang molekulnya lebih besar.
   

3. Menyediakan tempat untuk reaksi utama enzim.
   

   Menyediakan tempat untuk reaksi-reaksi utama enzim yang berhubungan dengan metabolisme energi. Jika membran sel tersebut diperiksa secara tersendiri akan tampak partikel-partikel kecil yang bergagang pendek melekat pada sel. Partikel-partikel ini menyerupai partikel yang ditemukan dalam mitokondria pada sel-sel eukariotik dan mengandung aktivitas ATP-ase.

Susunan Tubuh Bakteri

Bakteri tersusun atas dinding sel dan isi sel. Di luar dinding sel terdapat selubung. Sedangkan di dalam sel bakteri tidak terdapat membrane dalam (endomembran) dan organel bermembran seperti kloroplas dan mitokondria.

1. Dinding Sel
   

   Dinding sel dari suatu bakteri menentukan bentuk dari bakteri. Meskipun tidak mengandung enzim dan tidak bersifat semipermeabel, namun dinding ini banyak diperlukan agar sel dapat berfungsi secara normal. Dinding selnya kaku sehingga memungkinkan bakteri mengatasi konsentrasi osmosis yang sangat berbeda-beda dan agar sitoplasma tidak mengembang melampaui batas dinding yang kaku itu. Bila dinding sel tersebut disingkirkan atau terbuat dari lemak dengan suatu enzim, maka sel itu akan terbungkus hanya oleh membrane sel. Bentuknya akan menjadi bulat dan akan pecah jika diletakkan di lingkungan yang hipotonis.
   

   Kekakuan kekuatan dinding sel terutam dihasilkan dari serat yang kuat yang umumnya tersusun dari heteropolimer yang disebut peptidoglikan atau mukopeptida (disebut juga glikopeptida, muropeptida, glikosamino-peptida, mukokompleks, murein, dan sebagainya.) Serat-serat tersebut membentuk anyaman yang kuat. Anyaman tersebut bukan merupakan bahan yang solid, sehingga tidak menghalangi masuknya air, zat-zat makanan seperti glukosa, mineral, asam amino, dan bahkan molekul-molekul yang lebih besar.
   

   Hasil analisis dari dinding sel menunjukkan bahwa susunan dinding bakteri Gram positif dan Gram negative itu tidak sama.
   

No.	Gram Positif	Gram Negatif
1.	Komponen terbesar terdiri atas mukopeptida.	Terdiri dari 3 lapisan: Lapisan dalam: mukopeptida Lapisan luar:- Lipopolisakarida -Lipoprotein
2.	Pada beberapa bakteri terdapat asam teikhoik.	Tidak ada asam teikhoik.
3.	Mukopeptida mengalami lisis oleh lisozim.	Lisozim melunakkan dinding sel, deterjen mengadakan disorganisasi dinding dengan merusak lapisan lipida.
4.	Dinding sel tebal.	Dinding sel tipis.

 

 

 

 

 

 

 

 

Monera

Monera berasal dari bahasa Yunani, Moneres berarti tunggal. Monera meliputi organisme yang memiliki struktur tubuh amat sederhana, yaitu terdiri atas sel-sel primitive dan bersifat prokariotik. Sel prokariotik adalah sel yang inti selnya tidak memiliki membrane(pro=belum; kariot=selaput inti/membrane inti). Monera adalah salah satu dari kingdom yang ada saat ini. Yang termasuk ke dalam kingdom ini adalah Archaebacteria, Eubacteria, dan Cyanobacteria.

 

 

 

 

 

    

1. Archaebacteria
   

• Berasal dari kata Archaea yang artinya nenek moyang.
  
• Diduga sebagai makhluk hidup tertua yang hidup di bumi.
  
• Dinding sel tidak memiliki peptidolikan, yaitu polimer dari karbohidrat dan protein.
  
• Hidup di tempat ekstrem.
  
• Terbagi menjadi 3 jenis, yaitu: 1. Termofil—hidup pada lingkungan yang bersuhu sangat tinggi. Contoh: Pyrolobus fumarii
  

  
  2. Halofil—hidup pada lingkungan dengan kadar garam yang tingi, contoh: Halobacterium halobium
  

  3. Metanogen—hidup di lumpur dasar danau, rawa-rawa, dan saluran pencernaan hewan dan manusia, membebaskan
  

  gas metan sebagai hasil metabolisme.
  

1. Eubacteria
   

• Berasal dari kata bakterion (Yunani) yang artinya batang kecil.
  
• Ciri-ciri bakteri: -tubuhnya tersusun atas 1 sel (uniselular)
  

  -hidup sendiri-sendiri/ berkelompok
  

  -tidak memiliki kloroplas
  

  -berkembang biak secara paraseksual (secara generatif) dan aseksual (membelah diri)
  

  -ada yang bersifat parasit, ada yang bersifat saprofit
  

-hidup di mana-mana, mulai dari daerah tropis sampai daerah kutub

• Bentuk bakteri: kokus, basil dan spiril.
  

Perbedaan Antara Archaebacteria dengan Eubacteria:

Archaebacteria		Eubacteria
Tidak mempunyai peptidolikan pada dinding sel.		Mempunyai peptidolikan pada dinding sel.
Hidup di daerah ekstrem		Hidup di daerah di mana makhluk hidup tinggal.
Mempunyai membran sel yang bercabang.		Membran sel tidak bercabang.

Persamaan Antara Archaebacteria dengan Eubacteria:

Archaebacteria	Eubacteria
Bentuknya bervariasi.
Sama-sama prokariotik.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Bacteria

The bacteria are a large group of unicellular microorganisms without membrane-bound organelles in their cytoplasm(prokaryotes). They live at anywhere, include in the extreme area, growing in soil, acidic hot springs, radioactive waste, water, and deep in the Earth's crust, as well as in organic matter and the live bodies of plants and animals. Bacteria are one of the Monera groups. The study of bacteria is known as bacteriology, a branch of microbiology. The vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, and a few are beneficial. However, a few species of bacteria are pathogenic and cause infectious diseases. In developed countries, antibiotics are used to treat bacterial infections and in agriculture, so antibiotic resistance is becoming common. In industry, bacteria are important in sewage treatment, the production of cheese and yoghurt through fermentation, as well as in biotechnology, and the manufacture of antibiotics and other chemicals.

Things You Should Know About Viruses...

• it can cristalize.
• it does not affected by antibiotic.
• it's so small and can't be viewed without the help of electron microscope( it's smaller than bacteria.)
  
• it has characteristic of the parasite.
• it has no medicine to kill it, but has vaccine that can weaken it.
• it's only live at life creature.
• it does not do the metabolism.
  
• only consist by DNA/RNA.
• it can spread through air, water and soil.
• it can destroy the cell in lysis phase.
  

New, Faster Way To Diagnose, Fight Flu ScienceDaily (Aug. 18, 2009) —

Researchers at Emory University are using a new and faster method of rapidly producing highly targeted monoclonal antibodies for use in diagnostic tests as well as a temporary therapy to stave off infectious diseases such as the H1N1 (swine flu) virus.

Rafi Ahmed, PhD, director of the Emory Vaccine Center and a Georgia Research Alliance Eminent Scholar, and his collaborators generated high-affinity monoclonal antibodies against a strain of the influenza virus only a month after vaccinating human volunteers.

This new, timely technique allows researchers to quickly generate human antibodies against a pandemic flu strain as a stopgap therapy or to protect people from infection.

The antibodies, which can be isolated from a small amount of blood of humans infected with the virus, could be targeted against H1N1 and rapidly reproduced to detect or attack the virus. The monoclonal antibody technology was described last year in the journal Nature and is being developed in collaboration with scientists at the University of Chicago.

Not only is the new method quicker and less cumbersome, the researchers' new technique could be applied to almost any infectious disease, says Ahmed.