1. Bellwork: 2/4/15 Copy the question and the answer
Both euglena and cyanobacteria are photosynthetic unicellular organisms found in pond water. The feature that distinguishes euglena from cyanobacteria is the — A ability to maintain homeostasis B presence of ribosomes C ability to reproduce D presence of a nuclear membrane

2. Bellwork

3. Happy Tuesday Bellwork
Draw and Label the viruses above using the following terms: Capsid, DNA/RNA, Envelope.

4. Happy Tuesday Bellwork
DNA
RNA
CAPSID
RNA
CAPSID
CAPSID
ENVELOPE
Draw and Label the viruses above using the following terms: Capsid, DNA/RNA, Envelope.

5. Anticipation Guide: Discuss the following statements with a partner
Anticipation Guide: Discuss the following statements with a partner. Determine if you think they are true or false.
Viruses affect us just like bacteria.
Viruses have DNA.
Viruses can be cured by antibiotics.
Viruses are not alive.
Being a zombie is caused by a virus.

6. Viruses

7. OVERVIEW

8. Vocabulary Viruses: are noncellular or acellular infectious agents
Virology:
study of viruses
Virologists:
scientists who study viruses
Virion:
An intact viral particle

9. Cellular Organisms vs Acellular Particles
Eukaryotic Cell
Virus
Prokaryotic Cell
Prokaryotes
Eukaryotes
Viruses
Eukaryotic Nucleus
1 ųm (1000 nm)

10. Viruses range in size from 20 nanometers (nm) – 250 nanometers (nm)
1 nm = inches
If a cell was the size of your classroom, then an average virus would be the size of a softball.
proteins
animal
cells
atom
viruses
bacteria
0 m
10-6 m
10-5 m
10-7 m
10-8 m
10-9 m
Go five more feet!
10-10 m
A virus’ size helps it to reproduce. We’ll talk about this tomorrow.

11. Viral Size
20 nm to 1,000 nm
.02 u to 1 u

12. Viral components Spikes Nucleic acids DNA or RNA Capsid Protein
Envelope
Lipid
Spikes
Used to attach to cell
ONLY SOME VIRUSES

13. Generalized Structure of Viruses
virions having envelopes = enveloped viruses
virions lacking envelopes = naked viruses

14. Generalized Structure of Viruses

15. Helical Capsids
RNA
Helical capsids are rod-like structures with the RNA in the center of the helix. A helix is made by stacking repeating units in a spiral.
protein coat

16. Tobacco Mosaic Virus
Tobacco Mosaic Virus (TMV) is an example of a virus with a helical structure. Protein subunits wrap around the spiraling RNA strand.
This image taken using an Electron Microscope

17. Adenoviruses cause diseases like pink-eye or the common cold

18. Bacteriophage is a virus that infects bacteria.

19. Enveloped Viruses
Enveloped viruses are viruses which have a membrane coat surrounding the protein coat or capsid. These viruses are common in animal viruses, but are uncommon in plant viruses.
Herpes Simplex Virus.
A membrane (made of proteins) surrounds the capsid (also made of proteins) which surrounds the viral DNA.

23. Viruses are highly specific to the cells they infect. Examples:
Viruses are highly specific to the cells they infect Examples: 1) plant viruses infect plant cells 2) animal viruses infect only certain related species of animals 3) bacterial viruses (bacteriophage) infect only certain types of bacteria.
So, what about zombies?

24. Think-Pair-Share
Are viruses alive?
(Justify your answer)

25. Viruses have both living and nonliving characteristics.
Living characteristics of viruses:
They reproduce at a fantastic rate, but only in living host cells.
They can mutate.
They contain DNA or RNA

26. Nonliving characteristics of viruses:
They are acellular, they contain no cytoplasm or cellular organelles. They are not made of cells.
They carry out no metabolism on their own and must replicate using the host cell's metabolic machinery.
They do not grow or develop

27. Viruses are NOT alive because they DO NOT have ALL of the characteristics of life.

28. Virus Structure Activity
Create a model of a virus as instructed by your teacher
Label the model correctly
Summarize in 14 words how the structure of your virus is different than a cell.

29. http://www. dreamstime

31. http://www. dreamstime

32. Bellwork: 2/5/15
Virus Structure
Cell Structure

33. Viral Reproduction Cycles Essential Question: How do viruses reproduce?

34. Could viruses be helpful?

35. Since viruses can transport DNA and RNA
Since viruses can transport DNA and RNA into cells, scientists are exploring Gene Therapy
In Gene Therapy, viral genetic material is replaced with new DNA
In time, this could be used to cure genetic diseases. Currently we have no cure for these types of illnesses

36. Why are some viruses harmful?
Virus invades cell
When your cells make viruses instead of operating normally, YOU get sick
Virus forces cell to make copies of virus
Eventually so many copies are made, the cell explodes,
releasing all of the new viruses

37. Lysogenic Cycle

38. Characteristics of the virus
Icosahedral (20 sided), enveloped virus
Retroviruses transcribe RNA to DNA.
Two viral strands of RNA found in core surrounded by protein capsid.
Outer lipid envelop contains proteins (these knob-like structures responsible for binding to target cell)

39. HIV

40. HIV Replication
Reverse transcriptase (enzyme) produces viral DNA from RNA.
AZT is the HIV medication that blocks reverse transcriptase
Integrates into host DNA.
Period of latency occurs.

41. HIV (arrows) Infecting a T-lymphocyte

42. Transmission

43. Viral Replication
After a period of latency lasting up to 10 years viral replication is triggered and occurs at high rate.
White blood cells may be destroyed in the process, body attempts to replace lost cells, but over the course of many years body is unable to keep the count at a safe level.
Destruction of large numbers of white blood cause people to get sick from other diseases

44. Primary HIV Symptoms
Cold or flu-like symptoms may occur 6 to 12 weeks after infection.
fever
rash
headache
fatigue
diarrhea
sore throat
neurologic manifestations.
no symptoms may be present

45. LATER HIV Symptoms
HIV continues to reproduce, white blood count gradually declines from its normal value of
Once white blood count drops below 500, HIV infected person at risk for opportunistic infections.
The following diseases are predictive of the progression to AIDS:
persistent herpes-zoster infection (shingles)
oral candidiasis (thrush)
oral hairy leukoplakia
Kaposi’s sarcoma (KS)

46. Oral Candidiasis (thrush)

47. Oral Hairy Leukoplakia
Being that HIV reduces immunologic activity, the intraoral environment is a prime target for chronic secondary infections and inflammatory processes, including OHL, which is due to the Epstein-Barr virus under immunosuppressed conditions

48. Kaposi’s sarcoma (KS)
Kaposi’s sarcoma (shown) is a rare cancer of the blood vessels that is associated with HIV. It manifests as bluish-red oval-shaped patches that may eventually become thickened. Lesions may appear singly or in clusters.

49. AIDS
White blood count drops below 200 person is considered to have advanced HIV disease
Most deaths occur with a white blood count less than 50

50. Lysogenic Cycle
Hidden viruses “hide” for a while inside host cells before becoming active
Steps to the Lysogenic Cycle:
Attach to cell
Inject virus DNA/RNA
Integrate virus DNA/RNA into cell DNA
Wait (cell will grow, divide, etc.)
Remove from virus from cell DNA
Become active (lytic cycle)

51. Lysogenic Cycle
- Viruses

52. Lytic Cyle

53. When a virus invades…

54. Influenza A virus Properties of the virus
Enveloped virus with a segmented RNA genome
Infects a wide range of animals other than humans
Undergoes extensive antigenic variation (mutations)
Major cause of respiratory infections
Influenza A virus is the second acute infection to be discussed.
Myxovirus
Enveloped virus with a segmented RNA genome
Infects a wide range of animals other than humans
Undergoes extensive antigenic variation
Major cause of respiratory infections

55. Spread of influenza virus
Respiratory aerosoles can be generated from the respiratory tract by various means – from speaking to sneezing.
During a sneeze, millions of tiny droplets of water and mucus are expelled at about 200 miles per hour (100 metres per second). The droplets initially are about micrometres diameter, but they dry rapidly to droplet nuclei of 1-4 micrometres, containing virus particles or bacteria. This is a major means of transmission of several diseases of humans.

56. Respiratory Tract
There are various means by which the host is protected from infection by influenza virus.
The droplets containg the virus may be filtered by fines hairs and cilia in the nasal cavity.
Muco-cilliary cells lining the trachea can trap virus particles and sweep the virus to the back of the throat from where it is swallowed and excreted via the intestinal tract.
Alveolar macrophages can engulf the virus if it enteres as far as the lower reaches of the lung and alveolar sac.

57. Weekly consultation rates for influenza and influenza-like illness: Weekly
Returns Service of the Royal College of General Practitioners, 1988 to 1999
100
200
300
400
500
600
Epidemic activity
Higher than expected
seasonal activity
Baseline activity
Rate per population
Normal seasonal activity
Virus epidemiology
Infleunza A virus shows regular outbreaks during the winger months.
These are either
Eopidenics: widespread outbreaks within the coutry
Pandemics: Worldwide outbreaks of the virus affecting large numbers of people.
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Year
CDR Weekly Report: 5th November 1999

58. Lytic Cycle
Active viruses enter cells and immediately begin to multiply, leading to the quick death of the invaded cells.
Steps to the lytic cycle:
Attach to cell
Inject DNA/RNA
Produce (replicate) virus parts
Assemble new virons
Release viruses to infect other cells

59. - Viruses
Lytic Cycle

60. Which part of the lytic cycle is shown below?

61. Transmission of Viruses
Respiratory transmission
Influenza A virus
Faecal-oral transmission
Enterovirus
Blood-borne transmission
Hepatitis B virus
Sexual Transmission
HIV
Animal or insect vectors
Rabies virus
·         As with many infections viruses can be transmitted between susceptible individuals by a variety of means. The details provided related mainly to viruses infecting humans.
·         Many animal viruses do not remain infectious for very long outside the host.
Ø     Respiratory: Influenza A virus (and rhinovirus). Transmission in the form of aerosols during coughing and sneezing. The viruses are fairly sensitive to drying and their transmission is highest when individuals are in close contact.
Ø     Faecal-oral: Enteroviruses (e.g. poliovirus) A lot of viruses are excreted in faeces following high levels of replication in the gut.
Ø     Blood borne: Hepatitis B (and HIV). Transferred through contaminated blood products or via shared needles with drug abuse.
Ø     Sexual transmission: (HIV)
Animal/insect vector: Rabies. In many instances the virus infection is a specific pathogen of the animal and is not normally transmitted to humans by any other means.

62. Viral diseases result in cell death

63. Lytic or Lysogenic? Dengue Fever DISEASE VIRUSES AIDS HIV Wart
Herpes Simplex
Virus
Flu
Influenza
Measles
Morbillivirus .
Cancer
Hepatitis B
Dengue Fever

64. Lytic Cycle
Lysogenic Cycle

65. LYTIC VERSUS LYSOGENIC INFECTION
In a lytic infection, the host cells fills with virions and bursts.
The result is cell death.
Lysogenic infections are also known as latent infections.
The viral genome becomes incorporated into the host cell’s DNA.
It can remain this way for an extended period.
The host cell lives, until the lytic cycle begins

66. VIRUS Organisms that live on or near a host and cause harm.
Active Viruses
Hidden Viruses
Host
Parasite
VIRUS
Organisms that live on or near a host and cause harm.
A living thing that provides a source of energy for a virus or an organism
A tiny, nonliving structure that invades and then multiplies inside of a cell.
Some viruses hide for a while and become part of the cell’s genetic material. It may stay inactive and “hidden” for years. Then under certain conditions it becomes active and acts like an active virus. Ex – cold sores
A virus that immediately goes into action. It begins to take over cell functions and produce the virus’s proteins and genetic material. These parts then assemble into new viruses. The viruses multiply like a copy machine left on. When it is full the cell bursts open – releases the new viruses and dies.