For how many years has life existed on earth?
3.5 billion years
Why was the early surface of the earth hostile to modern life?
Extremely high temperatures, CO2-rich atmosphere, lots of UV radiation
First organisms on earth
Origins of oxygen gas
photosynthesis, breakdown of water, cyanobacteria
How much oxygen was in the earliest atmosphere?
very little or none at all
Kingdom that evolved into plants on the phylogenic tree
bacteria that break down nutrients in dead matter into simpler substances
Role of bacteria in the environment
Recycling nutrients, Bioremediation, fermentation, pasteurization, cleaning up oils pills
cause food poisoning
Why can giving antibiotics to patients at the first sign of symptoms cause more problems for the patients?
The overuse of antibiotics can select for antibiotic-resistant strains of bacteria.
a virus with single-stranded RNA that acts as a template for DNA synthesis
What does reverse transcriptase do (retroviruses)?
It uses viral RNA as a template for DNA synthesis.
RNA retrovirus, sexually transmitted disease, HIV causes AIDS, die from opportunistic infections
How does HIV cause AIDS?
By attacking and destroying helper T cells
method used to tell what kind of cell wall a prokaryote has
no cell wall, turn purple with Gram stain
cell wall, turn pink with Gram stain
Where are instructions for making new copies of a virus coded?
either RNA or DNA
What do all viruses need to replicate?
a host cell (obligate intracellular parasites)
allow bacteria to survive extreme conditions
outer protein coat of a virus
Viral structure outside of capsid ; made from host cell's membrane and has "spikes" embedded in it
Two ways viruses infect cells
Injection and Endocytosis
Immediately after infection new virions are made using the host cell's enzymes and ribosomes and released after the cell lyses; spread to other cells, infect and kill them
Viral DNA combines with host DNA to become a provirus and replicates, but does not produce virions; becomes dormant, then is activated and enters the lytic cycle
What happens when a person receives a vaccine?
Their body creates plasma cells that can produce antibodies against the specific pathogen.
Where does humoral immunity originate?
Germ Theory of Disease
Infectious diseases are caused by pathogens that spread disease from one organism to another
What causes infectious diseases?
process to identify a specific pathogen for a disease
How can an infectious disease by transmitted?
inhalation, physical contact, ingesting contaminated water or food, bite from an infected animal
Interferes with metabolism of pathogens, results from systemic inflammatory response, helpful in curing a disease, dangerous if it gets too high (protein denaturation)
Body's Defense Against Infections
Physical & chemical barriers, Internal non-specific defenses, Immunity
Physical & Chemical Barriers
skin, mucus membranes
ear wax, tears, saliva, sweat, stomach acid
Internal Non-specific Defenses
leukocytes, inflammatory response
pathogen-destroying white blood cells (neutrophils, macrophages, natural killer cells)
small, numerous, suicidal, phagocytic leukocytes
large, few, phagocytic leukocytes
Natural Killer Cells
non-phagocytic, destroy infected body cells by rupturing their membrane, act as cancer survaillance
resistance to a specific pathogen