DNA replication occurs in the 5 prime (5') to 3 prime (3') direction. I'm sure you've heard this many times. I tutor in genetics, and all of my students can rattle that off. Less understand what it means.
First, understanding what 5' and 3' mean is important. DNA is composed of a ribose sugar, a phosphate group, and a base (A,T,G,C). The sugar has a phosphate group attached to its fifth carbon, and a hydroxyl group on its 3rd carbon. Nucleotides (separate components of DNA) are linked by the phosphate group and the hydroxyl group. So, every nucleotide is linked at the phosphate group and the hydroxyl group besides two - the two nucleotides at either end of the strand of DNA. The one that leaves a phosphate group exposed is called the 5' end of DNA, and the one that leaves a hydroxyl group exposed is called the 3' end of DNA.
<span>A problem with many students just memorizing that replication occurs in the 5' to 3' direction is that there are two strands of DNA involved in replication. DNA polymerase (the major enzyme responsible for replication) reads the already existing strand of DNA in the 3' to 5' direction, and creates the new strand of DNA in the 5' to 3' direction (meaning that it adds nucleotides to the 3' end of the new strand).</span>
DNA is always synthesized in the 5’ to 3’ direction.
Replication fork is form
within the nucleus during DNA replication and usually created by the enzyme
helicase. Helicase function by breaking the hydrogen bond that holds the DNA
strands together and the strands will serve as template for the leading and
lagging strands. Hence, DNA is always synthesized in the 5’ to 3’ direction.
If all species originated on the primitive Earth t the same time and did not change, which patterns would be expected in the geologic record? The upper rock strata would contain fossils of only more complex organisms.
C) maleness results from the minimal presence of one Y chromosome
Explanation:
From the given question, it can be clearly observed that in males irrespective of whichever syndrome they have a Y chromosome is always present whereas in females Y chromosome is not present.
Hence, one cal conclude that whenever the Y chromosome is present the individual acquires male characters.
The Y chromosome whenever present produces the hormones that leads to maleness, and the number of Y chromosomes in males can also be more than one such as in case of XYY Klinefelter syndrome.
