Answer:
All living things are made up of one or more cells.
Explanation:
The cell theory is a universal theory proposed by three scientists viz: Theodor Schwann, Mathias Scleiden, and Rudolf Virchow in the year 1838. These three scientists contributed to the cell theory and proposed the following:
1) All living things are composed of one or more cells
2) Cell is the basic and fundamental unit of life
3) New cells arise from pre-existing cells.
However, at an earlier date specifically 1665, an English scientist named Robert Hooke has discovered and coined the term "cells" in his published book by observing a piece of cork under a microscope. This Hooke's discovery of cells from a once living cork best supports the part of the cell theory that states that: All living things are made up of one or more cells.
The trp repressor blocks transcription of the trp operon (B) when the repressor binds to tryptophan.
trp operon or the tryptophan operon codes enzymes for the amino acid tryptophan. The operon is on when the tryptophan is low in amount whereas the operon is off when the tryptophan is low in amount. The operon is an assimilation of five genes.
Repressor is a small protein that is supposed to prevent the synthesis of proteins. It does so binding to the operator gene. Therefore, presence or absence of repressor is a determining factor for an operon to be on or off.
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Answer:
Restriction Enzymes
Explanation:
It is restriction enzymes specifically, which are used to cut DNA into fragments. Restriction enzymes can be regarded as biological scalpels which can produce either a blunt end or sticky end in DNA.
