Why does DNA replication proceed continuously on the leading strand and discontinuously on the lagging strand?
a. because DNA polymerase synthesizes DNA in only one direction
b. because DNA ligase operates in only one direction
c. because DNA polymerase contains more than one subunit
d. because DNA polymerase synthesizes DNA in two directions
Ans: a. because DNA polymerase synthesizes DNA in only one direction
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Scientists examined the diversity of primary and secondary consumers from intertidal communities in four regions of the world:
Benguela along the coast of South Africa (BEN), California along the coast of North America (CAL), Humboldt along the coast of Chile in South America (HUM), and New Zealand (NZ). The number of organisms per square meter (mean density), which is a unit that represents total biomass of primary consumers (herbivores) and secondary consumers (carnivores), is plotted for each of these four regions on the graph below. Note: Image from Blanchette et al. (2009). Trophic structure and diversity in rocky intertidal upwelling ecosystems: A comparison of community patterns across California, Chile, South Africa and New Zealand. Progress in Oceanography 83: 107-116. After examining the graph, complete the following sentence. The black portion of each bar represents the percentage of [primary / secondary] consumers, whereas the gray portion of each bar designates the percentage of [primary / secondary] consumers from the four intertidal communities. What will be an ideal response?
What is the best way to investigate the effects of factors that influence populations?
What will be an ideal response?
Certain mutations in the regulator gene of the lac system in E. coli result in maximal synthesis of the Lac proteins (?-galactosidase, etc.) even in the absence of the inducer (lactose). Provide an explanation for this observation
What will be an ideal response?
"Sticky ends" are ________
A) single-stranded ends of fragments of double-stranded DNA B) regions of double-stranded DNA that can be cut by a restriction enzyme C) portions of DNA used as markers for STR analysis D) regions of DNA amplified in PCR