viruses & prokaryotes · how do viruses reproduce? •viruses insert their genetic material...
TRANSCRIPT
![Page 1: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/1.jpg)
1
VIRUSES & Prokaryotes
Chapter 20
![Page 2: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/2.jpg)
2
![Page 3: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/3.jpg)
3
The Structure of Bacteria
• 3 basic shapes: rod, spherical & spiral-shaped
• No nucleus
• Cell wall
• Flagella or cilia for
movement
![Page 4: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/4.jpg)
4
How Bacteria Obtain Energy
• Some make their own food (like plants).
• Some obtain their food (like us).
These bacteria eat the nutrients in the agar.
![Page 5: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/5.jpg)
5
Reproduction in Bacteria• Most reproduce through
binary fission (asexual
reproduction), making clones.
![Page 6: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/6.jpg)
6
• Other bacteria exchange genetic information through conjugation (a.k.a. bacteria sex).• A hollow bridge
forms between the 2 bacteria & genes move from 1 bacterium to the other.
• The advantage- it increases genetic diversity.
![Page 7: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/7.jpg)
7
• Bacteria that causes illness and disease.Ex: diphtheria, tuberculosis, typhoid fever,
tetanus, syphilis, cholera, bubonic plague
• How are the diseases caused?– Bacteria damage the cells & tissues of an
organism by breaking them down for food.
or
– Bacteria release toxins (poisons) that travel through the organism’s body.
![Page 8: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/8.jpg)
8
•Bacteria that humans use and need in their everyday lives.
Escherichia coli (Esh-er-ish-e-ah coal-eye): one of many that live in your gut. Helps digest your food.
![Page 9: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/9.jpg)
9
Saccharomyces cerevisiae (sack-arrow-my-seas sair-uh-vis-ee-ay): a.k.a. baker's yeast. Makes bread rise.
Pseudomonas putida (sue-doe-moan-us poo-tea-dah): Cleans wastes from sewage water at water treatment plants.
Lactobacillus acidophilus (lack-toe-bah-sill-us acid-off-ill-us): Turns milk into yogurt.
![Page 10: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/10.jpg)
10
Arbuscular mycorrhizas (ar-bus-que-ler my-kuh-rye-zuh): one of a soil-living fungus family. Helps crops take up nutrients from the soil.
Streptomyces (strep-toe-my-seas): soil bacteria that makes streptomycin, an antibiotic.
Bacillus thuringiensis (bah-sill-us ther-in-gee-in-sis): a.k.a "Bt", a common soil bacterium. A natural pest-killer in gardens and on crops.
![Page 11: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/11.jpg)
Bacteria are Useful for:• Nitrogen Fixation
• Recycling of Nutrients
(decomposers)
• Foods & Medicines
• Producers
Ex: Prochlorococcus accounts for more ½ of photosynthesis in open oceans.
11
Antibiotics
![Page 12: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/12.jpg)
12
How Do You Treat a Bacterial Infection?
• If prevention fails, take antibiotics.• Antibiotics kill bacteria without harming
the cells of humans or animals.– They interfere with the cellular processes of
bacteria.
• Many antibiotics are produced naturally by living organisms.Ex: penicillin
• Others are synthetic (man-made).
![Page 13: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/13.jpg)
13
![Page 14: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/14.jpg)
14
Virus Facts
• NONLIVING: can’t grow, develop, or respire and cannot replicate on their own.
• ½ to 1/100 the size of the smallest bacterium.
![Page 15: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/15.jpg)
15
What do viruses look like?• Made of a core of genetic material
surrounded by a protein coat (capsid).
• Come in a variety shapes: rod or tadpole-shaped; helical; cube like
![Page 16: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/16.jpg)
16
How do viruses reproduce?
• Viruses insert their genetic material into a host cell.
– The capsid (outside protein) “tricks” the cell into allowing it inside.
• Once inside, the viral genes take over.
• The “hijacked” cell transcribes the viral genes, using the host cells own enzymes.
• Lytic or Lysogenic Cycles
![Page 17: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/17.jpg)
Viral Replication CyclesLytic cycle: Virus infects the cell, copies itself & causes the host cell to burst (lyse).• ex: influenza (flu), cold, rabies, AIDS
Lysogenic cycle: Virus infects the cell & inserts its genetic material into the hosts DNA. The host cell is not harmed.• ex: Herpes, Varicella (chicken pox),
HIV
http://www.youtube.com/watch?v=Rpj0emEGShQ
![Page 18: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/18.jpg)
• Because viruses bind precisely to proteins on the host cell’s surface & use it’s genetic system, most viruses infect very specific types of cells.
Ex: plant viruses infect plant cells, bacterial viruses infect bacteria (bacteriophages)
18
![Page 19: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/19.jpg)
19
RETROVIRUSES
• Contain RNA as their genetic material.Ex: HIV
• Retroviruses infect a cell and produce a DNA copy of their RNA. (retro = backward; RNA is copied in to DNA)
• This DNA is inserted into the host cell's DNA.
![Page 20: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/20.jpg)
20
How Can You Protect Yourself From Viral Infections?
• The best way: vaccines– Weakened or killed virus or viral
proteins.
– When injected, the vaccine stimulates the immune system.
– Sometimes produces permanent immunity.
• Protect yourself!– Stay away from known sick people.
– Wash your hands often.
![Page 21: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/21.jpg)
The Immune System and DiseaseChapter 35
![Page 22: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/22.jpg)
Infectious Disease
22
![Page 23: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/23.jpg)
infectious disease: changes to body physiology that disrupt normal body functions caused by microorganisms
pathogen: a disease-causing agent;
causes infection
-includes viruses, fungi, bacteria, protozoans & parasites
![Page 24: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/24.jpg)
How are Diseases Spread?
• Coughing, sneezing, physical contact
• Exchange in body fluids
• Contaminated food & water
• Animal contact (zoonosis)
– vector: animal carrier who
transmits the disease, but
doesn’t get sick themselves.
![Page 25: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/25.jpg)
Defense Against Infection
25
![Page 26: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/26.jpg)
Nonspecific Defenses
• General defense against many different pathogens.
• Include skin, tears & other secretions, inflammatory response, interferons & fever.
![Page 27: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/27.jpg)
First Line of Defense
● Include skin, saliva, mucus, & tears.
● As long as they remain intact, they can keep out many pathogens.
![Page 28: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/28.jpg)
Second Line of Defense
1.) interferons: chemicals released by virus-infected cells that slow down the progress of infection & buy time for the immune system to respond
2.) fever: higher body temperature slows down or stops the growth of some pathogens
![Page 29: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/29.jpg)
3) inflammatory response• A tissue response to injury or
infection, producing redness, swelling, heat & pain.
• Chemicals released by damaged tissues attract white blood cells to the site.
• The mass of white blood cells, bacterial cells & damaged tissue forms pus.
![Page 30: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/30.jpg)
Specific Defenses = the Immune System
• Very precise.
• Recognize “self” & “other” (& kill the “other”).
• Also known as immune response.
• Slower to respond than non-specific defenses.
![Page 31: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/31.jpg)
Antigens & Antibodiesantigen: specific foreign molecules that trigger an
immune response; usually located on a cell’s surface
antibodies: tag antigens for destruction by the immune system
– Shape allows it to bind to specific antigen. Body makes up to 10 billion different antibodies.
– Antibodies may be free floating or attached to B cells.
![Page 32: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/32.jpg)
Lymphocytes (White Blood Cells)
Two Types:
B cells
• Produced & mature in red bone marrow.
• Have embedded antibodies.
• Discover antigens in body fluids.
T cells
• Produced in bone marrow & mature in thymus.
• Must be presented with antigens by infected body cells or immune cells.
![Page 33: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/33.jpg)
The Immune System
• Two main types of specific immune response:
1.) humoral immunity
(pathogen is in fluids)
2.) cell-mediated
immunity (pathogen
has invaded a cell)
33
![Page 34: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/34.jpg)
Humoral Immunity1.) Antibodies on B cells bind to antigens in body fluids (like
blood & lymph).
2.) This stimulates rapid growth & division of B cells, both Plasma & Memory B cells.
3.) Plasma B cells make more antibodies that tag the antigens for destruction.
4.) Memory B cells remain
alive after infection ends
& quickly produce more
Plasma B cells if the
pathogen returns.
(Why vaccinations work!)
34
![Page 35: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/35.jpg)
Cell-mediated Immunity
• T cells destroy body cells containing viruses, fungi & cancer.
1.) Infected cell displays antigen on its outer surface.
2.) T cells are activated & kill infected cells.
3.) Memory T cells are
also produced to
respond quickly if the
pathogen returns.
• This is what causes
organ rejection.
35
![Page 36: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/36.jpg)
Fighting Infectious Disease & Health
36
![Page 37: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/37.jpg)
Vaccination
• Consists of pathogens that have been
weakened or killed so they cannot
cause a serious infection.
• Includes antigens that stimulate an immune response, but do not produce the severe symptoms of disease.
![Page 38: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/38.jpg)
![Page 39: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/39.jpg)
Acquired ImmunityActive Immunity: Person produces an
immune response to the antigen (including memory B & T cells) from either direct exposure (fighting the infection) or vaccination.
Passive Immunity: Antibodies produced against a pathogen by other individuals or animals produce temporary immunity.
Ex: rabies antibody serum, mother to fetus, breast milk
![Page 40: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/40.jpg)
Public Health Prevention of Diseases Spreading
1.) Regulating food and water supplies.
– Cholera, Typhoid, Guinea worm
![Page 41: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/41.jpg)
Public Health Prevention of Diseases Spreading
2.) Promoting vaccinations.• Herd Immunity
![Page 42: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/42.jpg)
Herd Immunity
![Page 43: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/43.jpg)
Public Health Prevention of Diseases Spreading
3.) Promoting behaviors that avoid spread of infection.
![Page 44: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/44.jpg)
New and Re-Emerging Diseases
• Many diseases were eliminated or were under control in the 1980s (e.g. polio & smallpox).
• Over the past decade, we have had a resurgence of old diseases and introduction of new diseases (Ebola, SARS, hantavirus).
• Why has this happened??
![Page 45: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/45.jpg)
Reasons for New and Re-Emerging Diseases
1.) Changing interactions with Animals:
– Human & animal habitats combine.
– Trade of exotic animals.
![Page 46: VIRUSES & Prokaryotes · How do viruses reproduce? •Viruses insert their genetic material into a host cell. –The capsid (outside protein) “tricks” the cell into allowing it](https://reader034.vdocument.in/reader034/viewer/2022051604/60049d4c8966990be21d6343/html5/thumbnails/46.jpg)
Reasons for New and Re-Emerging Diseases
2. ) Misuse of Antibiotics & medications:
– Not following instructions on medication.
– Overuse of antibiotics is causing resistance.
Pandemics