Answer:
The correct answer is D
Explanation:
The cell membrane is essentially composed of the following:
- phospholipids
- cholesterol
- proteins
The phospholipid consists of a <em>hydrophilic </em>phosphate 'head' and the tail is the <em>hydrophobic</em> fatty acid chain.When cellular membranes form,phospholipids collect into two layers in light of these hydrophilic and hydrophobic properties. The phosphate heads in each layer face the fluid or watery condition on either side, and the tails conceal away from the water between the layers of heads, since they are hydrophobic.
There are 3 main factors that greatly influence the fluidity of the plasma membrane:
- temperature
- cholesterol
- saturated and unsaturated fatty acids
Answer: Missense mutation
Explanation:
Missense mutation is a type of point mutation where a single nucleotide is changed to cause substitution of a different amino acid. This in turns render the resulting protein non-functional.
In the case of sickle-cell disease, the sixth amino acid in the gene sequence, glutamate (GAG) is substituted with valine (GUA), due to Adenine nucleotide changed to Uracil nucleotide. Thus, missense mutation has occurred
Water evaporates from the ocean and land surfaces, is held temporarily as vapour in the atmosphere, and falls back to Earth's surface as precipitation. ... Water that infiltrates Earth's surface becomes groundwater, slowly seeping downward into extensive layers of porous soil and rock called aquifers.
