Essay on particle theory

Submitted By Maliha360
Words: 2028
Pages: 9

There are 5 points in the particle theory

Matter is made up of particles

All particles move according to how much heat is added

All particles attract

All particles are made of different substances if they aren't alike

There are spaces between the particles

Cells organelles

Cell membrane-protects organelles

Cell wall- protects organelles

Mitochondrion- makes energy ATP

Lysosome- rids east and stores it

Nucleus- control centre

Nucleolus- makes ribosomes

Cytoplasm- holds organelles

Golgi apparatus- transports

Vacuole- stores

Endoplasmic Reticulum- transport protein

Ribosomes- make protein
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Science 6 December 2013:

Vol. 342 no. 6163 pp. 1185-1186

DOI: 10.1126/science.1247566
Essays on Science and Society
Science & SciLifeLab Prize
From Persistence to Cross-Species Emergence of a Viral Zoonosis

Daniel G. Streicker
Institute of Biodiversity, Animal Health, and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, Scotland, UK.
Emerging infectious diseases threaten all forms of life on Earth. Many pathogens of great historical and contemporary significance have originated from other species, triggering pandemics, disrupting agriculture, and challenging efforts to conserve endangered wildlife. Despite decades of research on species-jumping pathogens, the most central questions in the field remain major stumbling blocks for societies that seek to mitigate their impacts. These questions include which pathogens are most likely to emerge, which hosts are most likely to share pathogens, and what will be the long-term fate of newly emerged pathogens? Part of the challenge is that emergence, by nature, transcends scientific disciplines, occurring as the product of human behavior, environmental change, population, cellular and molecular biology, and evolution. Solutions therefore demand innovative pairing of theory and fundamental science with applied research and evidence-based policy-making.
My doctoral research used viral infections of bats to answer fundamental questions about pathogen emergence and to help guide control of a major zoonosis in the developing world. Working on bats was partly pragmatic—natural populations can easily be sampled in large numbers, and existing surveillance systems for reportable diseases, such as rabies, provide rich data sets. This choice was also driven by the fact that bats are a major source of highly pathogenic viruses, including severe acute respiratory syndrome (SARS), Nipah, Hendra, and Ebola viruses, which often emerge in the context of anthropogenic change with devastating outcomes for humans and animals (1). From an ecological and evolutionary perspective, the high species diversity of bats also presents a unique and fascinating system to test hypotheses on cross-species emergence in complex host communities.
Working with bat tissue samples from public health laboratories across the United States, I first constructed a data set of hundreds of rabies virus sequences from more than 20 bat species. Using ecological and molecular sequence data from both bats and viruses, I developed a novel population genetic framework to quantify transmission rates between species. This analysis (2) showed that, counter to the popular notion that rapid evolution in RNA viruses should make ecological overlap the best predictor of which host species share viruses, the genetic similarity of hosts constituted the strongest barrier to both initial infection and viral establishment in new