Herpes

VIRUSES

Viruses – Viruses –

are particles that are NOT ALIVE.are particles that are NOT ALIVE.

Viruses reproduce ONLY Viruses reproduce ONLY inside a living CELL.inside a living CELL.

The Structure Of a VirusThe Structure Of a VirusInner core of Inner core of nucleic nucleic acidacid (This is the Viruses (This is the Viruses genetic material)genetic material)

Some contain Some contain DNADNA or or RNARNA but never both. but never both.

Surrounded by one or Surrounded by one or two protein coats called two protein coats called a a capsidcapsid. .

EXAMPLES OF THE MANY DIFFERENT EXAMPLES OF THE MANY DIFFERENT SHAPES OF VIRUSESSHAPES OF VIRUSES

A.Tobacco Mosaic Virus B.Polio Virus C.Human Immunodeficiency Virus (HIV)

D.Bacteriophage T4

E. Coli and the E. Coli and the BacteriophageBacteriophage

What it looks like in real lifeWhat it looks like in real life

T4 BacteriophageT4 Bacteriophage

Every virus has a specially shaped device Every virus has a specially shaped device called an called an attachment proteinattachment protein that can only that can only attach to a few kinds of cells.attach to a few kinds of cells.

Example of what Example of what bacteriophage (a type bacteriophage (a type of virus) does to a cell:of virus) does to a cell:

Step 1: Step 1: ATTACHMENTATTACHMENT

Step 2: Step 2: ENTRYENTRY: : Bacteriophage injects Bacteriophage injects nucelic acid into the nucelic acid into the bacterial cellbacterial cell

Step 3: Step 3: REPLICATIONREPLICATION: : Host’s metabolic Host’s metabolic machinery makes viral machinery makes viral nucleic acid and proteins nucleic acid and proteins

Step 4: Step 4: ASSEMBLYASSEMBLY: New : New Virus particles are Virus particles are assembledassembled

Step 5: Step 5: LYSIS AND LYSIS AND RELEASERELEASE: Host cell : Host cell breaks open and releases breaks open and releases new virus particlesnew virus particles

Receptor proteins are Receptor proteins are proteinsproteins embedded in embedded in the cell membrane that bind to a the cell membrane that bind to a signal signal molecule molecule enabling it to enabling it to respondrespond to the signal to the signal molecule. molecule.

Viruses are Viruses are segments of nucleic acids segments of nucleic acids contained in a protein coatcontained in a protein coat. They are . They are pathogenspathogens and and reproducereproduce by infecting cells by infecting cells and using the cell to make more viruses. and using the cell to make more viruses.

Are viruses living? Are viruses living? NONO

Viruses have a Viruses have a protein coat and nucleic protein coat and nucleic acidacid which are characteristics of living which are characteristics of living cells. cells.

Viruses also have characteristics of Viruses also have characteristics of nonliving cells which are: nonliving cells which are: viruses do not viruses do not respire, do not grow and CANNOT respire, do not grow and CANNOT reproduce outside a living cell.reproduce outside a living cell.

BECAUSE THEY DO NOT BECAUSE THEY DO NOT HAVE ALL THE HAVE ALL THE PROPERTIES OF LIVING PROPERTIES OF LIVING THINGS BIOLOGISTS DO THINGS BIOLOGISTS DO NOT CONSIDER THEM NOT CONSIDER THEM LIVING. LIVING.

Viruses reproduce using 2 different cycles:Viruses reproduce using 2 different cycles:

Lytic cycle Lytic cycle : Virus injects the cell with its : Virus injects the cell with its genetic informationgenetic information, the information is , the information is integratedintegrated with the host’s with the host’s DNA DNA , the host is , the host is now replicating now replicating viral viral genes assembles the genes assembles the new viruses, and host cell is new viruses, and host cell is broken broken to to release the new viruses. EX: release the new viruses. EX: cold & flucold & fluLysogenic cycleLysogenic cycle_: Virus infects the cell, _: Virus infects the cell, integrates its integrates its genetic informationgenetic information with the with the host’s host’s DNADNA, the host divides , the host divides normallynormally, and , and then provirus may enter the lytic cycle. EX: then provirus may enter the lytic cycle. EX: herpes & HIVherpes & HIV

attaches

DNA

Bacterial

viruses

Viruses

Lytic cycle

normally

DNA

HIVHIV is a virus that causes is a virus that causes AIDS.AIDS.

It has spikes on its surface that matches a It has spikes on its surface that matches a receptor protein on receptor protein on macrophagesmacrophages, which , which is an immune system cell that engulfs is an immune system cell that engulfs pathogens, and infections fighting cells pathogens, and infections fighting cells called called lymphocyteslymphocytes. .

AIDS is: AIDS is: a disease in which an a disease in which an individual is unable to defend the body individual is unable to defend the body against infections that do not normally against infections that do not normally occur in healthy individuals.occur in healthy individuals.

HIV infected people fell healthy for years HIV infected people fell healthy for years and can spread it to others without and can spread it to others without knowing they are infected. HIV is knowing they are infected. HIV is NOTNOT spread through spread through casualcasual contact but is contact but is transmitted in transmitted in body fluids.body fluids. This includes: This includes: sexual contact, blood, and breast milksexual contact, blood, and breast milk

Structure of HIV: Structure of HIV: envelopeenvelope composed of composed of lipid bilayer from host cell, lipid bilayer from host cell, capsidcapsid and and genetic material in the form of genetic material in the form of RNARNA. .

HIV attached to the cell at the HIV attached to the cell at the receptorsreceptors called called CD4CD4 which activates a which activates a co-receptorco-receptor that in turn starts that in turn starts endocytosisendocytosis. .

This process occurs for years after This process occurs for years after infection an eventually infection an eventually mutatesmutates to a point to a point it now recognizes a new cell surface it now recognizes a new cell surface receptor on receptor on T-CellsT-Cells. HIV reproduces in the . HIV reproduces in the T cells and T cells and destroysdestroys them. This them. This increasesincreases the amount of viral particles in the amount of viral particles in the blood. The destruction of T cells blocks the blood. The destruction of T cells blocks the body’s the body’s immune responseimmune response and signals and signals the onset of the onset of AIDSAIDS. .

EbolaEbola

HepatitisHepatitis

PolioPolio

RabiesRabies

SmallpoxSmallpox 30% Fatal30% Fatal

Vaccines Vaccines

Are used to PREVENT viral infections- Are used to PREVENT viral infections- What vaccines have you received in your What vaccines have you received in your lifetime?lifetime?

Viruses grown on chicken embryos are Viruses grown on chicken embryos are attenuated vaccinesattenuated vaccines

Another type of vaccine is made by heat Another type of vaccine is made by heat killing the virus killing the virus

BACTERIA (MONERANS)BACTERIA (MONERANS)Are the simplest of all living things and are Are the simplest of all living things and are prokaryotes (unicellular, Do NOT have a prokaryotes (unicellular, Do NOT have a nucleus, and NO membrane bound nucleus, and NO membrane bound organelles) Most are organelles) Most are heterotrophsheterotrophs (Feed (Feed on other organisms). on other organisms).

Characteristics of Bacteria: Characteristics of Bacteria:

Small Small Unicellular Unicellular Circular Circular DNA called a DNA called a

plasmidplasmid Can form Can form endosporesendospores under under

harsh conditions harsh conditions

2 types of reproduction: 2 types of reproduction:

Binary fission (Binary fission (Asexual)Asexual) – – Chromosomes replicate and the Chromosomes replicate and the cell divides cell divides

Conjugation (Conjugation (Sexual)Sexual) – Exchange – Exchange of genetic material through cell to of genetic material through cell to cell contact cell contact

2 Groups of Bacteria: 2 Groups of Bacteria:

Archaebacteria Archaebacteria (Ancient)(Ancient)

Methanogens – produce Methanogens – produce methanemethane

Thermophiles – live in Thermophiles – live in hothot water water

Halophiles – live in Halophiles – live in saltysalty conditions conditions (in the Dead Sea)(in the Dead Sea)

Eubacteria Eubacteria

ArchaebacteriaArchaebacteria

Methanogens- Methanogens- Produce methaneProduce methane

**Found in peat in marshes **Found in peat in marshes or hot springsor hot springs

**Responsible for **Responsible for flatulenceflatulence

ArchaebacteriaArchaebacteria

Thermophiles- live in Thermophiles- live in HOTHOT water water

Pompei worms survive with symbiotic relationship

with thermophilic archaebacteria

                                        

  

Thermophiles produce some of the bright colors of Grand Prismatic Spring, Yellowstone National Park

ArchaebacteriaArchaebacteria

Halophiles- Live in salty Halophiles- Live in salty conditions (Dead conditions (Dead Sea)Sea)

STRUCTURE OF BACTERIASTRUCTURE OF BACTERIA

Capsule: prevents bacteria from being easily Capsule: prevents bacteria from being easily engulfed by white blood cellsengulfed by white blood cells

Flagella: Long thread-like (whip-like) tail that Flagella: Long thread-like (whip-like) tail that enables the bacteria to moveenables the bacteria to move

Cell wall: gives the cell shape and prevents Cell wall: gives the cell shape and prevents osmosis from bursting the cell (Scientist use osmosis from bursting the cell (Scientist use Gram-StainingGram-Staining to reveal the cell wall structure) to reveal the cell wall structure)

Chromosomes (nuclear material): not Chromosomes (nuclear material): not enclosed in a nucleus; a single DNA enclosed in a nucleus; a single DNA molecule; arranged as a molecule; arranged as a CIRCULARCIRCULAR chromosomechromosome

Plasma Membrane: regulates what enters Plasma Membrane: regulates what enters and leaves the celland leaves the cell

STRUCTURE OF BACTERIASTRUCTURE OF BACTERIA

SHAPES OF BACTERIASHAPES OF BACTERIA

Bacilli,or rod-shaped

Spirilli, or spiralshaped

Cocci, or round

ANTIBIOTICSANTIBIOTICS

Are used to kill Are used to kill bacterialbacterial infections infections

DO NOT WORK AGAINST VIRUSESDO NOT WORK AGAINST VIRUSES

MutualismMutualism

Symbiosis in which Symbiosis in which two of the species live two of the species live together in such a together in such a way that both benefit way that both benefit from the relationshipfrom the relationship

Eg. E-coli Eg. E-coli