Explanation:
Scientists didnt belive that there are cells untill robert hooke (1665). He observed the cells in a cork slice with the help of a PRIMITIVE microscope
Leeuwenhoek (1674), with the help of an improved microscope, discovered free living cells in pound water for the first time.
It was robert brown in (1831) who discovered the nucleus in the cell.
Purkinjie in 1839 coined the term 'protoplasm' for the fluid substance of the cell.
THE CELL THEORY, that all plants and animals are composed of cells and that the cell is the basic unit of life, was presented by two biologists, schleiden (1838) and schwann(1839). The cell theory was fuether expanded by virchow (1855) by suggesting that all cells aris form PRE-EXISTING cells. With the discovery of the electron microscope in 1940,it was possible to observe and understand the complex structure of the cell and its various organelles.
Well, thats the history of the discovery of cells.
Answer:
Domain Eukarya
Explanation:
There are only three domains; the Archaea, Eukarya, and Bacteria. Domain Eukarya came from the first prokaryotic cells billions of years ago.
The answer is natural killer cells.
Natural killer cells are a type of lymphocytes and they are important for the innate immune system. They recognise stressed cells much faster than other immune cells. Their response is rapid and usually only a few days after a viral infection. They also respond to <span>cancer cell </span>formation. While other immune cells can detect only those harmful cells that have specific markers on the surface of the cell membrane, natural killer cells can even detect those cells that miss markers for apoptosis.
Answer:
A frameshift changes every codon past it. A base substitution only changes one codon.
Explanation:
DNA is comprised of nucleotides (A, C, T, G) that make up amino acids. Every three bases is called a codon and represents an amino acid.
In a frameshift mutation, a nucleotide is either added or deleted from the sequence. This offsets the entire sequence after it because the reading frame shifts. Here's an example:
ACTGCTATCGTCATC
If another T is added in between the first and second codons, then every codon after will be changed.
ACT>T<GCTATCGTCATC
A substitution mutation is usually less severe, as it only alters one codon in the sequence. These occur when one nucleotide is replaced by another one. Here's an example:
ACTGCTATCGTCATC
Let's say the first G is replaced by a T.
ACT>T<CTATCGTCATC
As you can see, none of the other codons changed.
Typically, a frameshift mutation is considered worse than a substitution mutation.
The correct answer is C, i.e., Passeur domesticus. According to binomial nomenclature, the name of the genus is started with a capital alphabet and name of the species is started with the lower alphabet. Further, it should also be in italics or alternatively may be underlined
