Chapter 16: Lessons 1-2

In the late nineteenth century, what did Dmitri Ivanovsky and Martinus Beijerinck discover?

They discovered that a virus was affecting tobacco plants, not bacteria, through a filtering device

Virus

Piece of genetic material covered by a protein coat

Pathogen

Virus that causes disease

What are viruses considered (cells)?

Acellular

What do viruses reproduce in?

A host cell

What are three things viruses do not have/do?

1. Have internal cell structures

2. Metabolize

3. Reproduce

What do all viruses contain?

Genetic material

Capsid

A protein coat surrounding viruses that protect genetic material

Envelope

A second outer structure outside a capsid

What are the four shapes of viruses?

Helical, spherical, polyhedral, or complex

Describe the virus found in the tobacco?

Tobacco mosaic virus: helical, coiled DNA in a spiral, capsid is a cylander

Describe adenovirus

The more protein subunits, the more faces of the polyhedral

Protein spikes

Stick out from capsid that aid in recognition and attachment to host cell

Bacteriophages

Viruses that specifically infect bacterial hosts

Lytic cycle

Virus binds to proteins on outer surface, then injects genetic material which interferes with the host’s cellular functions. Molecular machinery mass produces viral genome and proteins for replication. Many viruses are formed, causing the host cell to lyse.

Lysogenic cycle

Virus genome is merged into host cell and stays inactive for time. Protein synthesis does not occur and cell is not harmed, until virus is triggered to enter lytic phase.

Retrovirus

Virus with genome that must be converted to double stranded before copies can be made

Reverse transcriptase

Enzyme that makes a copy of DNA from RNA for retroviruses

Intergrase

Enzyme incorporating newly synthesized viral DNA into host cell for retroviruses

Viroid

Simpler version of virus that is composed only of a small loop of RNA (for plants)

How many nucleotides does a viroid have?

400 nucleotides

What does a viroid do to plants?

Disrupts protein synthesis, caused deceased or abnormal growth

Prion

Infectious protein that causes a host’s proteins to misfiled, taking on an abnormal shape disrupting function

Re-emerging disease

Virus appearing that was though to be eradicated

How many viral human diseases have been identified?

More than 200

Vaccine

Inactive or weakened parts of virus injected into a patient to improve immunity to that virus

Why is a new vaccine for influenza made every year?

The protein spikes on the virus change continuously due to mutations

Prokaryotes

Microscopic organisms that lack a nucleus, most abundant on Earth

What 2 things did Louis Pasteur prove?

1. Microorganisms cause disease

2. Bacteria do not do spontaneous generation

Germ Theory

Pathogens invade the body causing disease

What domains are prokaryotes classified into?

Domain Archaea and Domain Bacteria

What are archaea more similar to than bacteria?

Eukaryotic cells

Name three facts about Archaea

1. Do not contain peptidoglycan in cell walls

2. Have lipids in cell membrane

3. Found in extreme environments up to 300 degrees Celsius

What three shapes are bacteria found as?

Bacilli (bacillus) - long rod shaped

Cocci (coccus) - spherical

Spirilla (spirillus) - corkscrew/spiral-shaped

Where are bacteria’s DNA found?

Nucleoid

What does a bacterial genome exist as?

Circular chromosome

Plasmid

Smaller loop of extrachromosomal DNA

Name four structures bacteria have that cells also share?

1. Cell membrane

2. Cytoplasm

3. Ribosomes

4. Cell wall

Capsule

Made of carbohydrates, provides added defense against drying out

Endospore

Temporary resistant structure designed to provide protection during times of extreme stress

Flagella (flagellum)

Long whip-like projection used for motilityy

Binary fission

Asexual reproduction of bacteria resulting in two identical daughter cells

Conjugation

Bacteria release a part of their chromosome/plasmid through a surface projection called a pilus (pili) to exchange genetic information

How are prokaryotes producers?

Prokaryotes use photosynthesis or chemosynthesis to generate food, making themselves the basis of many food webs

What process to prokaryotes do the organic matter?

Decomposition

Nitrogen fixation

Prokaryotes create a usable form of nitrogen for plants

Obligate anaerobes

Prokaryotes that die in the precise of oxygen

Obligate aerobes

Prokaryotes that need oxygen to survive

Thermophiles

Prokaryotes that thrive in hot temperatures

Halophiles

Prokaryotes that thrive in salty environments

How can bacteria be transferred? Name 7 ways

1. Food

2. Water

3. Contaminated surfaces

4. Sexual contact

5. Water Vapor

6. Saliva

7. Air

Antibiotics

Treat bacterial infections

Name three ways to prevent bacterial illness

1. Hand washing

2. Careful food preparation

3. Proper hygiene

What are prokaryotes used by pharmaceutical companies for?

Vitamins, proteins, medicines

What is E. coli used for?

Producing insulin for people with diabetes

Bioremediation

Bacteria removing pollutants from soil/water