Why does one strand of DNA replicate as a continuous strand and the other in fragments?
Because the two strands of a DNA double helix are complementary, each strand can act as a template for the synthesis of the other.
Why is the leading strand able to replicate continuously but the lagging strand isn t?
1. For the leading strand, the DNA polymerase can keep going because it always has a template. For the lagging strand, the DNA polymerase has to stop at some point because there is no template afterwards.
Why is it important that DNA replication takes place before cell division?
In order for all of the cells in your body to maintain a full genome, each cell must replicate its DNA before it divides so that a full genome can be allotted to each of its offspring cells. If DNA replication did not take place fully, or at all, the offspring cells would be missing some or all of the genome.
What disease does deletion mutation cause?
Deletions are responsible for an array of genetic disorders, including some cases of male infertility, two thirds of cases of Duchenne muscular dystrophy, and two thirds of cases of cystic fibrosis (those caused by ΔF508).
Why are base substitutions not always harmful?
However, base substitutions do not always cause a change in the sequence of amino acids. This is due to the degeneracy in the genetic code; the fact that there are 64 different possible triplets but only 20 different amino acids, some must code for the same amino acid.
Why is Auu AUC silent mutation?
Assume that a point mutation changes the codon AUU to AUC. Why is this a neutral mutation? Because they code for the same amino acids.
What happens when a chromosome undergoes a deletion mutation?
A deletion mutation can remove a single nucleotide, or entire sequences of nucleotides. If three or more nucleotides are lost in a gene, entire amino acids can be missing from protein created which can have serious functional effect. Losing a single nucleotide is often not better, as a frameshift mutation can occur.
What is the difference between a transition mutation and a transversion mutation?
DNA substitution mutations are of two types. Transitions are interchanges of two-ring purines (A G) or of one-ring pyrimidines (C T): they therefore involve bases of similar shape. Transversions are interchanges of purine for pyrimidine bases, which therefore involve exchange of one-ring and two-ring structures.
What happens when a nucleotide is deleted?
A DNA sequence is a chain of many smaller molecules called nucleotides. For instance, if just one nucleotide is deleted from the sequence, then all of the codons including and after the mutation will have a disrupted reading frame. This can result in the incorporation of many incorrect amino acids into the protein.
How does deletion affect protein synthesis?
A deletion changes the number of DNA bases by removing a piece of DNA. A reading frame consists of groups of 3 bases that each code for one amino acid. A frameshift mutation shifts the grouping of these bases and changes the code for amino acids. The resulting protein is usually nonfunctional.
Where does the 2nd step of protein synthesis occur?
The Process Of Translation Is the Second Step Of Protein Synthesis. As already mentioned, the process of translation happens in the cytoplasm, where mRNA binds with ribosomes, which are the exact protein synthesis sites.
What are the two stages of protein synthesis?
Protein synthesis can be divided broadly into two phases – transcription and translation. During transcription, a section of DNA encoding a protein, known as a gene, is converted into a template molecule called messenger RNA (mRNA).