Answer:
The correct answer is: d. REs activity is best preserved by freezing the RE and thawing it out for brief periods of time as needed.
Explanation:
- Restriction enzymes can be defined as endonucleases that can recognize specific nucleotide sequence in a DNA (Deoxyribonucleic acid) sequence and cause breakage of phosphodiester bond in the DNA at the target site. Hence, it has the capacity of cleaving a DNA sequence.
- These are made up of proteins which are required to be present in the accurately folded conformation in order to function.
- Any form of alteration in the three-dimensional structure of the protein induced due to physical, chemical, mechanical or physiological factors can cause denaturation of the protein which in turn can render the protein non-functional.
- Freezing of restriction enzymes (REs) directly without the use of glycerol will cause the movement of water molecules within the proteins as well layering of water molecules on the protein surface.
- At low temperature these water molecules change to ice crystals which can alter the conformation of the protein or can cause breakage of peptide bonds in the proteins by physical force.
- This can cause the protein to get denatured and hence non-functional.
- Hence, it is never advisable to preserve REs by freezing directly without glycerol.
- Glycerol forms a layer around the protein molecules and prevents the protein molecules from coming into direct contact with the water molecules and hence prevents protein denaturation.
A eukaryotic cell is classified this way if it B. contains a nucleus. In biology the definition of eukaryotic is "having a true nucleus" which is how to depict a prokaryotic cell from a eukaryotic cell.
Science can answer many questions for example the speed of light, the frequency of pitch or sound, dna tests
Answer:
4. Microorganism
Explanation:
Wind, Salinity, Soil moisture are abiotic factors, non living things.
Answer:
time; point
Explanation:
The complete question is as follows:
The shortest length of time required to kill all test microbes at a specified temperature is the thermal death __________ whereas the lowest temperature required to kill all microbes in a sample within 10 minutes is the thermal death _________.
time; point
window; point
point; time
time; temperature
- When a population of bacteria gets killed due to exposure to high temperatures then this is termed as thermal death.
- The time taken to kill a specific microbe at a specific temperature is termed as the thermal death time. The length of the time taken depends on the nature of the target microbe and hence, varies from one to another.
- The lowest temperature that will kill all the microbes in a sample within ten minutes is defined as the thermal death point. The temperature at which the microbes get killed within 10 minutes also varies from one microbe to another.
- Thermal death results in the disruption of the cell membranes of the microbes and hence can kill the microbes.
