Which one of the following can lead to changes in chromatin structure and is often associated with activation of transcription?
A. methylation of RNA polymerase
B. addition of methyl or acetyl groups to
lysines located in the histone tail
C. methylation or acetylation of the
phosphodiester link between cytosine and
guanine
D. addition of lysine to CpG sites along the
histone tail
E. the presence of cytosine and guanine in a
repeating sequence in the histone tail
B
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The process of ____ describes cell specialization structure and gene activity
a. morphogenesis b. determination c. differentiation d. maturation e. growth
What structural element that is inserted into the major groove of DNA, where it recognizes specific DNA base pair sequences lining the groove, appears to be common to many DNA-binding motifs?
a) a ?-pleated sheet b) an ?-helix c) a double helix d) a random coil
A scientist is analyzing air bubbles trapped in ancient rocks that can be used to understand the ancient atmosphere. What do you expect the scientist will observe when comparing rocks younger than 3.8 billion years old to rocks older than 3.8 billion years?
A. The ratio of carbon-12 will be lower in the older rocks, because carbon-12 had to build up on earth before life could evolve. B. The amount of carbon will vary unpredictably in the younger rocks, because rock weathering added carbon dioxide to the atmosphere, and volcanic activity sequestered it. C. The younger rocks will have higher levels of carbon dioxide, because there was no carbon dioxide in the atmosphere before animals evolved and expelled it as waste. D. The ratio of the carbon-12 isotope will be lower in the younger rocks, because living organisms preferentially use carbon-12 over other isotopes.
What would cause you to believe that someone has a heart murmur?
A. irregular heart beats B. irregular heart sounds instead of sharp lub-dub sounds C. low blood pressure D. an irregular ECG