Answer:
Watson and Crick proposed the double helical model of DNA.
Explanation:
- This model says that DNA exist as double helix. It has two polynucelotide strands running in opposite direction i.e the strands are anti-parallel.
- Each polynucleotide strand is made up of several nucleotide liknked together by phophodiester bonds.
- The two strands are not coiled upon each other but the double strand is coiled upon itself around a common axis like the spiral stair case. Here base pairs forms the stairs and backbone of two strands form railing. Back bone contains sugar and phosphate.
- The base pairing is specific, adenine always pairs with thymine and guanine always pairs with cytosine. Thus if we see any base pair, it consists of one purine and one pyrimidine.
- The two strands of DNA thus show complementary base pairing.
- The strands are held together because of hydrogen bonding between the bases in opposite strand.
- One full helical turn involves ten base pairs and the base pairs are stacked 3.4 A apart.
- This form is called as B-form of DNA.
<span>Cocaine Preparations
-Coca leaves --> Coca Paste (60% pure): Not water soluble, so you can't inject it into the bloodstream -- you need an additional chemical step to turn the paste into crystal powder that can be injected or snorted
-Coca --> Cocaine Hydrochloride (99% pure): Doesn't hold up very well to heat, so you can't smoke cocaine hydrochloride
-Cocaine Hydrochloride (99% pure) --> Free-Base Cocaine or Crack Cocaine:
-Reconvert cocaine hydrochloride back to base state by removing hydrochloride from cocaine (that's why it's called free-base cocaine)
-Crack cocaine is a crystallized form, mixture of cocaine and baking soda
-75% pure
-Can be used at lower doses and is much cheaper than cocaine
-Can be smoked</span>
Answer:
D)
Explanation:
Because the independent variable stays the same for all the people in the experiment
Explanation:
the answer is c.= because meiosis is the reproduction of a germ cell with 60 chromosomes. involves splitting 60 chromosomes in half, so each cell will have 30 chromosomes in each cell..
Answer:
When the cell cycle is interrupted, apoptosis occurs.
Explanation:
Opoptosis is also known as programmed death of the abnormal cell. When cell DNA is damaged first it is repaired. If cell DNA cannot be repaired so the cell kill itself. If Opoptosis didn't occurs, then the cell divides with the damage DNA and transfer that damage DNA to the daughter cells which lead to cancer disease. Cancer also occurs when uncontrolled division of cells is done.
