Cell Vulnerabilites 1/24/2014

Transcription

1 Cell Vulnerabilites 1/24/2014 1

2 Vulnerability What is vulnerability? Vulnerability means the inability to withstand the effects of a hostile environment All cells are exposed to the environment somehow 2

3 Living things Living things have certain basic characteristics/requirements Living things: Require energy Require water in its liquid form Require chemical nutrients Must be able to reproduce 3

4 Cellular life Most life on Earth is microbial, which means. Macro-life is easier to see, but makes up only a small portion of the total living mass of life on Earth! 4

5 Natural Selection Means that individuals that are best able to survive in an environment (because of their genetics) are the ones that are most likely to survive and thus pass on their genes Individuals that are weaker or MORE VULNERABLE - are less likely to survive and reproduce 5

6 Vulnerability Changes in the environment means a change in what most fit means This can be devastating to species Most species that have ever existed are extinct!! 6

7 Reproduction The Earth s environment is constantly changing For life to continue, living things must reproduce quickly enough to ensure survival 7

8 Other vulnerabilities Cells are vulnerable to environmental change and to attack by other livings Because Living things have to compete for resources, the competition is usually fatal 8

9 Cells and viruses Most life is in the oceans Every day, about 1 in 5 ocean microbes are killed by viruses Viruses require a host to reproduce, they cannot reproduce without taking over a living cell 9

10 Viruses 1/27/

11 Introduction - Cells Cells are like factories for making proteins DNA is the instructions for how to make these proteins What if the cell could be taken over, so instead of making the proteins it s supposed to make, it s tricked into making something else? That s what viruses do! 11

12 Lytic cycle 12

13 Lytic cycle 13

14 Where do viruses live? Many found free-living in the environment (oceans, soils, bodies of water, etc.) these are usually not harmful to humans, usually they just prey on bacteria Others are found in a host species For example, Swine-influenza viruses live in pigs Other viruses are found in bats, rodents, mosquitoes, ticks, etc. Every known species including humans are hosts to viruses 14

15 Where do Viruses live? Usually only able to infect one or two kinds of cells in their hosts (you have tens of thousands of cell types!) A virus is not vulnerable to the immune system of its host for example, Swine Influenza lives very happily inside of a pig But they often are highly vulnerable to the environments outside their hosts, so they are usually only found in their host 15

16 How viruses infect us Sometimes by accident they are able to cross the species barrier and survive in a new host Their new host may be highly vulnerable to the virus! (swine flu, bird flu, etc.) 16

17 An introduction to some common viruses You are not directly responsible for this but I thought it would be interesting! 17

18 Other viruses Influenza a family of viruses that cause flulike symptoms in humans Magnification here is 500,000 times! 18

19 Influenza many versions of this 19

20 Influenza is spread by 20

21 Rhinovirus Rhino = nose This is the virus that causes the common cold Colder temperatures INCREASE your vulnerability to this virus!! Spread just like influenza can be spread with influenza! An nm is a nanometer, and is a billionth of a meter! 21

22 Herpes These sores are an additional VULNERABILITY because other bacteria/viruses can invade through these openings Other versions of Herpes include the viruses that cause chicken pox, Epstein-Barr and Shingles. Nearly 2 in 3 people have these viruses! So we are a host species for these in a sense, since they live in us but *most* people are not vulnerable to them 22

23 Human Immunodeficiency Virus The Virus that causes AIDS Crossed species barrier to humans in c. 1915, possibly much earlier Destroys immune system, making humans totally vulnerable to all other kinds of infecting organisms False color green HIV virus particles emerging from a human immune system cell, a process which destroys the cell 23

24 Ebola virus A gruesome kiler, and a microbiologist s nightmare! 24

25 Egyptian fruit bat host for Ebola? 25

26 Viruses and where they infect Viruses can t attack all cells in a body only certain cells are actually vulnerable to any particular virus Rhinovirus attacks cells in lining of upper respiratory system Influenza attack cells in lining of respiratory tract Herpes attacks cells in and immediately below skin HIV attacks immune system cells in blood and lymph Ebola attacks and destroys the integument 26

27 Virus wrap-up With the exception of Ebola, none of the other viruses mentioned actually kill but they do make you more vulnerable to other diseases or other invading organisms Some scientists call some viruses smart or dumb based on how fast or if they kill their host A cure for these is a chemical that the virus is vulnerable to, but for most of these 27