Bio Chp. 19 #2
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What are the two types of autotrophs?
photoautotrophs and chemoautotrophs
What are photoautotrophs?
Organisms that use light energy to convert carbon dioxide and water to carbon compounds and oxygen
What are chemoautotrophs?
Organisms that make organic carbon molecules from carbon dioxide, use energy directly from chemical reactions involving ammonia, hydrogen sulfide, nitrites, sulfur and iron.
Where do some chemoautotrophs live and how do they obtain their energy?
Deep in the darkness of the ocean and obtain energy from hydrogen sulfide gas flowing from hydrothermal vents
What were the first organisms on earth?
What type of organisms were the first organsims on earth? (energy-wise)
What are the three types of organsims that obtain energy differently?
- obligate aerobes
- obligate anaerobes
- facultative anaerobes
What are obligate aerobes?
Organisms that require a constant supply of oxygen in order to live
What are obligate anaerobes?
Organisms that must live in the absence of oxygen
What are facultative anaerobes?
Organisms that can survive with or without oxygen
What is binary fission?
Type of reproducing where bacteria replicates DNA and divides in half, producing two identical daughter cells "clones"
What are the two types of reproduction that bacteria can undergo?
- Binary Fission
What is conjugation?
A type of reproduction where two bacterial cells exchange genetic information through a hollow bridge formed between them
What is spore formation and why does it occur?
When growth conditions become unfavorable, many bacteria form structures called endospores...? Occurs because bacteria would otherwise die in unfavorable conditions
Bacteria are ______ to ___________ the __________.
- living world
What are some bacteria?
Autotrophs (producers that capture energy by photosynthesis)
What are other bacteria?
Decomposers that break down the nutrients in dead matter and the atomosphere
Why are decomposers important?
Help ecosystem recycle nutrients and maintain equilibrium in the environment
What are nitrogen fixers?
Bacteria that chemically change nitrogen to ammonia or other usable nitrogen compounds
Why are nitrogen fixers important?
Because plants and humans cannot use nitrogen gas directly so it must be chemically changed so it can be used for amino acids
What percent of the earth's atmosphere does nitrogen approximately make up?
What are the human uses of bacteria?
- Used in the production of a wide variety of foods
- One type can digest petroleum so used to clean up small oil spills
- Used to mine minerals from ground
- Used to synthesize drugs and chemicals through genetic engineering
Where are nitrogen fixers found?
In root nodgles
What scientist obtained crystals of tobacco mosaic virus?
What was Stanley?
An American biochemist
What did Stanely do?
Obtained crystals of tobacco mosaic virus
What did Stanley infer and why?
That viruses were not alive since organisms do not crystalize
What are viruses?
Particles of nucleic acid, protein, and sometimes lipids
How can viruses ONLY reproduce?
By infecting living cells
How do viruses reproduce?
Enter living cells and inside use the infected cell's DNA to produce more viruses
How large are most viruses?
So small they can only be seen with electron microscope
What is a typical virus composed of?
A core of nucleic acids (DNA or RNA) surrounded by a protein coat
How many genes do viruses have?
A simple has only a few genes but ore complex may have more that a hundred
What is a capsid?
A virus' protein coat
What is a virus' protein coat?
What does the capsid contain?
Proteins that enable a virus to enter a host cell
How do capsid proteins of a typical virus get the virus inside?
Bind to receptors on the surface of a cell and "trick" it into allowing it inside
Once inside the cell, what happens to the virus?
The cell transcribes and translates the viral genetic information into viral capsid proteins
Why aren't we affected by all the viruses we breath in?
Because viruses are highly specific to the cells they infect
What are viruses that infect bacteria called?
What are bacteriophages?
Viruses that infect bacteria
What are the two ways a virus can infect a cell once inside?
- Replicate immediately killing the host cell
- Stay in cell up to 10 years before replicating
What happens in a lytic infection?
A virus enters a cell, makes copies of itself and causes the cell to burst
What is a bacteriophage T4 made up of and how is it activiated?
- A DNA core in an intricate protein capsid
- activated by contact with a host cell
Explain how a lytic infection is carried out.
- Injects its DNA directly into the cell
- Host cell can't tell the difference between its own DNA and the DNA of the virus
- Cell begins to make messenger RNA from the genes of the virus
- Virus makes thousands of copies of its own DNA molecule
- Viral DNA gets assembled into new virus particles
- The infected cell lyses (bursts) releasing hundreds of virus particles that can go infect other cells
In a _____________, a virus _________ its _______ into the ________ of the host cell, and the ________________ replicates along with ______________.
- Lysogenic infection
- viral genetic information
- host cell's DNA
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