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