D. Cyanobacteria one of the first beings
Answer:
D) Because sticky ends can be temporarily held together by hydrogen bonding between the two strands.
Explanation:
Restriction enzymes cut the DNA at specific restriction sites and by the mechanism of action they can form two types of ends:
- sticky ends-single-stranded overhangs are formed
- blunt ends-without overhangs.
The main advantage of sticky ends (their overhangs) is that they can complementary bind to another overhand formed by the same restriction enzyme. So, for example in cloning, if the DNA of interest and plasmid vector are cut with the same restriction enzyme, that forms sticky ends, fragment of DNA will fit into a bacterial plasmid in one direction.
On the other hand, blunt ends can be inserted into vector in both directions: head-to-tail or tail-to-head.
Answer:
A. Prions do not contain genetic information, which is affected by ionizing radiation.
B. Denaturants may affect the tertiary structure of prions.
C. Prions are proteins.
Explanation:
Prions are the proteinaceous infectious particles that cause many degenerative diseases of neurons in both animals and humans. They consist of only protein and no DNA or RNA. Due to the absence of DNA or RNA as genetic material, these infectious particles are resistant to ionizing radiation. Ionizing radiations affect nucleic acids of pathogens to destroy them.
Denaturation of proteins affects their secondary and tertiary structures and leave them non-functional. Denaturation may be caused by changes in temperature, pH, disturbance of hydrogen bonds, etc. Therefore, to destroy prions, they need to be denatured.
to give birth to youg one
Answer:
Biology is the study of living things and their processes of life. Both Hooke and Van Leeuwenhoek made major, early contributions to biology.
Robert Hooke
Robert Hooke is best known for the discovery of the cell. Using a microscope, Hooke looked at the makeup of a piece of cork. Through the microscope, he saw box-like structures. What he saw would later be known as cell walls. He discovered that these structures were cells, the building blocks of all life.
His discovery and future research contributed greatly to the cell theory.
Anton van Leeuwenhoek
Leeuwenhoek made his discovery after Hooke, but it was still important. He is best known for the discovery of bacteria. Unlike Hooke, Leeuwenhoek did not study plant cells; instead, he focused on protists (like amoebas) and prokaryotes (like bacteria). For his work with unicellular organisms, he is often called the "Father of Microbiology."
