cell vulnerabilites - announcementskordella.weebly.com/uploads/8/6/0/4/8604167/cell...(swine flu,...
Post on 02-Jan-2021
3 Views
Preview:
TRANSCRIPT
Cell Vulnerabilites
1/24/2014
1
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
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
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
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
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
Reproduction
• The Earth’s environment is constantly changing
• For life to continue, living things must reproduce quickly enough to ensure survival
7
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
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
Viruses
1/27/2014
10
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
Lytic cycle
12
Lytic cycle
13
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
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
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
An introduction to some common viruses
You are not directly responsible for this – but I thought it would be
interesting!
17
Other viruses
• Influenza – a family of viruses that cause “flu-like” symptoms in humans
• Magnification here is 500,000 times!
18
Influenza – many versions of this
19
Influenza is spread by…
20
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
Herpes
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
These sores are an additional
VULNERABILITY because other bacteria/viruses
can invade through these openings
22
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
Ebola virus
A gruesome kiler, and a microbiologist’s nightmare! 24
Egyptian fruit bat – host for Ebola?
25
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
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
top related