Final answer:
A culture with cells of only one species from a single progenitor is called a pure culture. This allows for the study of a single species' behavior accurately. Meanwhile, differences in characteristics among cells with the same DNA are due to gene expression, with environment playing a role in phenotype diversity.
Step-by-step explanation:
A culture that is composed of cells of only one species arising from a single progenitor is known as a pure culture. In microbial cultivation, when you take a single colony from a streak plate and transfer it to new media, you isolate a pure culture, as all cells in that culture are clones of the original single cell.
This purity is crucial for the accurate study of bacterial behavior and the effect of environmental conditions on a single species without interference from other microorganisms.
In multicellular organisms, despite having genetically identical cells, different characteristics are displayed in various parts of an organism's body due to differential gene expression.
This means that although all cells contain the same DNA, not all of this DNA is active at all times in every cell. Cells can turn on or express different sets of genes, which is why they can have varying functions and characteristics.
In the context of bacteria, even pure bacterial cultures inoculated from the same starting colony can demonstrate diversity in characteristics due to mutations and responses to different environmental stimuli.
This shows the importance of genetic regulation and environmental impact on phenotype expression, despite genetic uniformity at the baseline.