error-prone DNA polymerasesUV radiationE. coliprokaryotic cellseukaryotic cellsRecent years have witnessed the emergence of a plethora of so-called novel DNA polymerases in both eukaryotic and prokaryotic cells. Many of these DNA polymerases are characterized by poor replicational fidelity and low ...
These organelles originated more than a billion years ago as single-celled organisms that were swallowed by larger cells. Since then the mitochondrial genome has shrunk, with many genes migrating to the cell nucleus. But that makes it all the more puzzling that mitochondria have retained any ...
Why do cells have organelles? Why does life use carbohydrates as signaling molecules, and proteins as enzymes? How do enzymes aid in cell regulation? How do most cells regulate the activity of enzymes? Why are endothelial cells important?
How do cells created through meiosis differ from somatic cells? Why does meiosis occur? Why must DNA be packed into chromosomes before mitosis can occur? A) During mitosis, the chromosomes are replicated, is the cell still diploid? B) After meiosis, the gametes only have 1/4 number of...
Eukaryotic cells are continuously threatened by unavoidable errors during normal DNA replication or various sources of genotoxic stresses that cause DNA damage or stalled replication. To maintain genomic integrity, cells have developed a coordinated signaling network, known as the DNA damage response (DDR...
Plants do not have skeletons to give them form. Plants rely on their cells to give them their form. Plant cells are regularly shaped and give plants rigidity. The cells do this through rigid cell walls, unlike the flexible cell walls in animals.
In more complex animals, the error rate in mitochondrial gene replication is relatively high. In that case, the best solution is to have a limited burst of cell division to form the female gamete precursors, giving many more germline cells than are needed, and then to cull most of them to...
It is even possible that loading sperm with policing RNA has ultimately been superseded in some instances by the production of sperm classes that do not contain the normal haploid DNA content and, hence, have limited ability to behave selfishly, instead serving their producer by helping brother ...
Interestingly, XYY karyotypes that do not present with a detectable phenotype have normal behavior and cognitive abilities, and normal serum testosterone levels, suggesting that, although the dosage of X-linked genes is important in normal development, this may not be the case for Y-linked genes....
Because many people with vitiligo also have stomach malfunction, they do not absorb vitamin B12 and folic acid very well. This may be part of the reason why these nutrients, along with vitamin C, are often successfully used as part of a vitiligo repigmentation program. Suggested doses are 5m...