Answer:
DNA was discovered in 1869 by Swiss researcher Friedrich Miescher, who was originally trying to study the composition of lymphoid cells (white blood cells). Instead, he isolated a new molecule he called nuclein (DNA with associated proteins) from a cell nucleus.
Explanation:
Answer:
Viruses are like hijackers. They invade living, normal cells and use those cells to multiply and produce other viruses like themselves. This can kill, damage, or change the cells and make you sick. Different viruses attack certain cells in your body such as your liver, respiratory system, or blood.
Explanation:
Viruses tend to target specific tissues (cells) in the host.
For example, the influenza virus has a predilection for the respiratory tract, hepatitis viruses target the liver, polio virus targets the motor neurons of the spinal cord and rotavirus multiplies in the gut. Symptoms of a viral infection may be subtle and nonspecific or specific and suggestive of the causative agent.
Dengue virus, Ross river virus, measles and rubella infections are associated with fever and a widespread red rash, chicken pox and herpes simplex viruses are associated with blistering, often localized, rashes; and hepatitis viruses cause liver damage and jaundice.
Bacteria tend to be less tissue-specific and non-discriminatory than viruses and can cause a variety of infections once they have invaded the host.
These bacterial infections are often manifested by the presence of pus wherever the bacteria settle, and systemic symptoms such as fevers, chills, pain, swelling and loss of function occur when bacteria invade and multiply.
Answer:
A. diploid and C. somatic
Explanation:
Humans are diploid organisms and have 23 pair of chromosomes i.e. in total humans have 46 chromosomes.
There are 2 types of cells in humans (1) somatic cells and (2) germ cells.
Somatic cells are normal body cells which are diploid and have all 23 pairs of chromosomes. But, germ cells are special type of cells which are produced by gonads (sex organs). Germ cells are also known as gametes. In females, ovary is the sex organ which produces germ cells named as egg cells while in males testes is the sex organ which produces germ cells named as sperms. Germ cells (egg and sperm) are haploid cells which fuse to form a zygote which is the first cell of next generation. The process of fusion of egg and sperm is known as fertilization which is responsible for restoring diploidy in the progeny which receives half the genetic material from female parent and half the genetic material from male parent.
An abiotic factor is a non living thing
Answer:
The order must be K2→K1, since the permanently active K1 allele (K1a) is able to propagate the signal onward even when its upstream activator K2 is inactive (K2i). The reverse order would have resulted in a failure to signal (K1a→K2i), since the permanently active K1a kinase would be attempting to activate a dead K2i kinase.
Explanation:
- You characterize a double mutant cell that contains K2 with type I mutation and K1 with type II
mutation.
- You observe that the response is seen even when no extracellular signal is provided.
- In the normal pathway, i f K1 activat es K2, we expect t his combinat ion of two m utants to show no response with or without ext racell ular signal. This is because no matt er how active K1 i s, it would be unable to act ivate a mutant K2 that i s an activit y defi cient. If we reverse the order, K2 activating K1, the above observati on is valid. Therefore, in the normal signaling pathway, K2 activates K1.
