Chapter 18 Study Guide–Viruses and Prokaryotes

Bacteria
One-celled microorganisms that can cause infection

Viruses
-Infectious particle made only of a strand of DNA/RNA
-surrounded by a protein coat
-non-living

-Ability to reproduce
-Use nutrients and energy
-grow and develop
-respond to environments
All living things share 4 characteristics of life, what are they?

Viroid
-infectious particle that causes disease in plants
-has a single strand RNA
-without a protein coat

Prion
-Infectious particle made only of proteins
-no genetic material
-causes other proteins to fold incorrectly

capsid, nucleic acid, surface proteins
3 parts of the structure of a typical enveloped virus

They can only reproduce after infecting host cells.
What must viruses do before they can reproduce?

Fitting its surface proteins to receptor molecules on the surface of the host cell.
How does a virus identify its host?

Lytic Infection
infection where host cell bursts, relasing viral offspring

Lysogenic infection
infection where virus combines its DNA with host cell’s DNA there is no immediate harm

Bacteriophage
virus that infects bacteria

Prophage
viral DNA plus host cell DNA

Capsid
Protein shell of a virus

Bacteriophages pierce host cells
or
viruses of eukaryotes enter by endocytosis
or
fuse with outer membrane
How do viruses enter cells?

The body’s first defense against infection
The skin

-cuts and scrapes
-through mucous membranes and body openings
2 ways viruses enter the body:

Use surface proteins that match the cells receptor
How do some viruses trick cells into letting them in?

Surface proteins on capsid a of a flu virus have a high mutation rate
Why must a new flu vaccine be made every year?

Retrovirus
Contains RNA and used a special enzyme to make a DNA copy

Epidemic
Rapid outbreak of an infection that affects many people

Vaccine
Stimulates the body’s own immune response against invading microbes

Rabies
Disease caused by the bite of an infected animal

West nile
Disease caused by the bite ad an infected insect

Chicken pox
Disease caused by contact with a particular rash

Mumps
Disease that causes swelling in glands under a person’s jaw

Hepatitis A
Disease caused by contact with contaminated feces

-Common cold
-influenza
-SARS
-HIV
What are some examples of viral infections

Bacteria
Microscopic
single celled
prokaryotes
cell walls/membranes
Move with flagella diverse
3 common shapes

Archea
Microscopic
Single celled
Prokaryotes
Cell walls/membranes
Move with flagella
Extreme environments
Many shapes

Binary fission
Method of reproduction in prokaryotes, meaning division of half

Bacterium copies it’s chromosomes and produces a wall around the copy. Thick wall around bacterial DNA helps it survive harsh conditions
How is an endospore formed?

Facultative aerobe
Can survive whether oxygen is present or mot

Flagellum
Long whiplike structure used for movement

Obligate aerobe
Needs oxygen to survive

Endospore
Specialized prokaryotic cell that can withstand harsh conditions

Conjugation
Prokaryotic method of gene exchange

Obligate anerobe
Cannot live in the presence of oxygen

Plasmid
Separate circular piece of a prokaryote’s genetic material

Rod shaped
Bacilli

Spiral
Spirilla

Spherical
Cocci

Gram staining
Identifies bacteria

Gram positive
Purple

Gram negative
Pink

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