Question

1. Why is ATP synthase considered an active transporter?

2. Why is deleterious to a cell that DNA can be crosslinked, which forms covalent bonds between the two strands?

3. Describe all of the negative and positive controls used in the Pasteur experiment that disproved spontaneous generation, and briefly describe why each was included.

4. Why is a pH indicator used in cell culture media?

5. In biology we describe 10 important universal features of cells, #7 is that life requires free energy. Briefly describe where humans acquire this energy.

Answer 1

Answer 1: ATP synthase is considered an active transporter because of the fact that the ATP synthase uses the concentration gradient of protons formed during electron transport chain when some protein complex push the matrix out to the intermembrane space, and uses to power the synthesis of ATP.

Answer2: When there is formation of covalent bond within the same strand (intrastrand) or between two strands (interstrand) the crosslinked DNA will have hampered functioning in terms of DNA replication or transcirption, this hampered fiunctioning may produce some signal which lead to programmed cell death. Therefore, these kinds of crosslinking can be deleterious.

Answer 3: Positive control in Pasteur's experiment was, sample in a straight necked flsk, that he knew will get contaminated and the negative control sample in a sealed flask, that he knew will be uncontaminated. If spontaneous generation of microbe occurs upon exposure to air, then it was easily hypothesized that growth will be seen in both the open flask (straight necked flask and swan neck flask), but it was found that growth was found only in straight necked flask and not in closed or swan-neck flask and later concluded that air alone was not resposible for bacterial growth over the media, and hypothesized that the microbes are suspended in the air, which will get inside the straight necked flask via gravity.

Answer 4: pH indicator is used in a cell culture medium because the change in pH can make the cell growth difficult, and hence the pH indicator acts as a quick check on the condition of the cell culture media.

Answer 5: Human acquire energy by metabolizing the macromolecules into simpler form while generating ATP (Adenosine triphosphate), this ATP is produced after carbohydrate, lipid or protein metabolim. Most of the ATP is produced inside the mitochondira in cell, that's why mitochondria is called as the powerhouse of the cell.