Answer:
Because of homologous recombination
Explanation:
- When genes are establish on different DNAs or far apart on the same chromosome, they are classified self-sufficiently and are said to be unlinked.
- When genes are very close together on the same chromosome, they are said to be linked. That means that alleles, or genetic versions, that are already together on a chromosome will be inherited as a unit more often than not.
- We can see if two genes are linked, and how closely, by using data from genetic crosses to calculate the frequency of recombination.
- Using the technique of discovery recombination happenings for numerous gene pairs, we can make link maps that show the order and relative distances of the genes on the chromosome.
- When the genes are on the same chromosome but far apart, they are classified independently due to crossing (homologous recombination). This is a procedure that happens at the start of meiosis, in which homologous DNAs randomly exchange matching fragments. Crossing be able to connection new alleles in combination on the same chromosome, causing them to enter the same gamete. When the genes are far apart, the crossing occurs with sufficient frequency for all types of gametes to occur with 25% percentage frequency.
- When the genes are very close together on the same chromosome, the crossing still occurs, but the result (in terms of the types of gametes produced) is different. Instead of being classified independently, genes tend to "stay together" during meiosis. That is, alleles of genes that are already together on a chromosome will tend to pass as a unit to gametes. In this case, the genes are linked
The main difference between prokaryotes and eukaryotes is the presence of nucleus in eukaryotes and its absence in prokaryotes. Also, prokaryotes are unicellular, so one cell is a whole organism. On the other hand, eukaryotes are mainly multicellular, and thus more complex. More complex DNA is inside the nucleus in the eukaryotes which enables them to conduct a wider range of functions. Prokaryotes, as a single cell, have simple functions present.
Answer:
if the cell grows beyond a certain limit, not enough material will be able to cross the membrane fast enough to accommodate the increased cellular volume. When this happens, the cell must divide into smaller cells with favorable surface area/volume ratios, or cease to function. That is why cells are so small.
Explanation:
The study of fossils shows that the eukaryotic cells have been evolved from the prokaryotic cells. The endosymbiotic theory has been used to study the evolution of eukaryotic cells.
The endosymbiotic theory states that:
- Endosymbiotic theory is also referred to as the theory of symbiogenesis. The theory explains the evolution of eukaryotic cells from prokaryotic cells.
- The theory explains the presence of chloroplasts and mitochondria, and how these organelles form the eukaryotic cells. The theory explains the origin of mitochondria in animal cells and chloroplasts in plant cells.
Thus, the endosymbiotic theory defines the development of eukaryotic cells from the prokaryotic cells.
To know more about endosymbiotic theory, refer to the following link:
brainly.com/question/2957447
Answer:
The lac repressor is not bound to the operon.
Explanation:
The lac repressor is a protein encoded by the lac I gene. In absence of lactose, the lac repressor binds to the operator sequence of the lac operon and does not allow the RNA polymerase to express the operon. However, as lactose enters the cell from the medium, the beta-galactosidase enzyme converts it into allolactose which in turn serves as an inducer of the lac operon. Binding of allolactose to lac repressor trigger conformational changes in the protein and renders it unable to bind to the operator. The RNA polymerase is allowed to express the operon.
