Outline the three levels of defense of humans against the invasion of pathogens
What will be an ideal response?
In the course of an average day, we encounter pathogens (disease-causing agents) of many kinds: viruses, bacteria, fungi, and parasites. Fortunately, we possess several levels of defense against infection by pathogens. Each level brings an increasingly aggressive response. Humans have three levels of defense: (1) the skin and the organisms that inhabit it, (2) the innate immune system that uses nonspecific responses such as inflammation, and (3) the adaptive immune system, which mounts specific responses to infection.
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Which of the following is not true of the formation of a eukaryotic translation initiation complex?
A. eIF4F binds to the 5' cap of the mRNA. B. eIF2 binds to the A site to block the binding of the initiating tRNA. C. At least two GTP molecules are hydrolyzed per initiation event. D. eIF1, eIF1A, eIF2, and eIF3 are displaced before the 60S subunit joins the 40S subunit.
How do gene duplication and exon shuffling lead to new genes?
What will be an ideal response?
What name is given to a gene that is always expressed?
What will be an ideal response?
The atmosphere of early Earth is currently thought to have contained:a
methane, water, ammonia, nitrogen, and oxygen b. carbon dioxide, water, oxygen, nitrogen, and hydrogen c. carbon dioxide, ozone, nitric oxide, water, and hydrogen sulfide d. carbon dioxide, water, carbon monoxide, hydrogen, and nitrogen e. carbon dioxide, carbon monoxide, water, hydrogen, and nitric oxide