Histone Modification

question 127

Multiple Choice

Histone modification:

• A)is fixed; once a histone is modified, it stays that way and the genes with which it is associated are turned on or off permanently.
• B)is fixed, but this has no effect on whether genes are expressed.
• C)is random  sometimes the lysines are modified and sometimes they're not, but the state is independent of the environment or cell type.
• D)can change over time in response to environmental cues, allowing genes to be turned on or off as needed.
• E)can change over time in response to environmental cues, but this has no effect on gene expression.

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Definitions:

Denitrification

The microbial process of reducing nitrates or nitrites typically in soil, resulting in the escape of nitrogen gases back into the atmosphere.

Nitrate

A compound containing nitrogen and oxygen that is commonly found in fertilizers and can cause environmental issues in water systems.

Earth's Chemical Cycles

Natural processes that recycle chemicals such as carbon, nitrogen, and oxygen between the Earth's atmosphere, hydrosphere, lithosphere, and biosphere.

Usable Forms

Refers to resources or materials that have been converted into a state where they are ready for use by organisms or human technologies.