Answer:
Wheezing happens when the airways are tightened, blocked, or inflamed, making a person's breathing sound like whistling or squeaking. Common causes include a cold, asthma, allergies, or more serious conditions, such as chronic obstructive pulmonary disease (COPD).
Explanation:
Answer:
Cyclin-regulates the timing of the cell cycle. Normally, when cells touch, they stop growing. Growth factors-one of a group of external regulatory proteins that stimulate the growth and division of cells.
Explanation:
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Answer:
A special characteristic of one living creature is to grow, to do metabolic processes to react to adapt and to reproduce.
Explanation:
The purpose of human life is to be aware of the existence, to understand existence, to be responsible and to enjoy.
Why are we chosen to live in this world it is not known. There are theories that RNA plays an important part in this. The process that many forms of life developed through history by mutation and natural selection. And the most common answer to a question why are we here is the simple process of evolution.
<h2>DNA </h2>
Explanation:
1) Experiment done by Griffith:
- Griffith used two related strains of bacteria, known as R and S
- R bacteria were nonvirulent, meaning that they did not cause sickness when injected into a mouse whereas mice injected with live S bacteria developed pneumonia and died
- Griffith tried injecting mice with heat-killed S bacteria (that is, S bacteria that had been heated to high temperatures, causing the cells to die), the heat-killed S bacteria did not cause disease in mice
- When harmless R bacteria were combined with harmless heat-killed S bacteria and injected into a mouse, not only did the mouse developed disease and died, but when Griffith took a blood sample from the dead mouse, he found that it contained living S bacteria
- Griffith concluded that the R-strain bacteria must have taken up what he called a transforming principle from the heat-killed S bacteria, which allowed them to transform into smooth-coated bacteria and become virulent
2) Experiment done by Avery:
- Avery, McCarty and MacLeod set out to identify Griffith's transforming principle
- They began with large cultures of heat-killed S cells and, through a long series of biochemical steps progressively purified the transforming principle by washing away, separating out, or enzymatically destroying the other cellular components
- These results all pointed to DNA as the likely transforming principle but Avery was cautious in interpreting his results
- He realized that it was still possible that some contaminating substance present in small amounts, not DNA, was the actual transforming principle
3) Experiment done by Hershey and Chase:
- Hershey and Chase studied bacteriophage, or viruses that attack bacteria
- The phages they used were simple particles composed of protein and DNA, with the outer structures made of protein and the inner core consisting of DNA
- Hershey and Chase concluded that DNA, not protein, was injected into host cells and made up the genetic material of the phage
