Answer:
The correct option is A. Steroid hormones exert their action by entering the nucleus of a cell and initiating or altering the expression of a gene.
Explanation:
Steroid hormones are derived from cholesterol and regulate multiple biological processes. All steroid hormones exert their action by crossing the plasma membrane and by binding with their respective intracellular receptors. They stimulate cell growth in a very different way, their lipophilic nature gives them the ability to cross lipid barriers, so, without the need for extracellular signals, these hormones can easily enter the cell, cross the cytoplasm and reach the nucleus. There they bind to specific receptors that are associated with DNA promoter regions, modifying their structure and promoting the expression of the genes under their control.
The thermodynamic barrier that must be overcome before products are formed in spontaneous reaction is activation energy.
The activation energy is the maximum amount of extra energy that is required by a reacting molecules to get converted into product. It is the minimum energy that is required or needed to activate or energize molecules or atoms.
It is needed in the reaction so that reactants can move together and overcome forces of repulsion and start bond breaking.
Reactant is the substance that takes part in and that undergoes change during a reaction.
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Answer:
Helicase
Explanation:
DNA replication is the process in which DNA makes copies of itself.
The process of DNA replication is supported by several enzymes.
The initial step of DNA replication is unwinding of double stranded DNA which is catalyzed by helicase enzyme. Helicase enzymes breaks the hydrogen bond between the DNA strands and prepare them for replication process.
Hence, the correct asnwer is "Helicase".
Answer:
From the years 1838-1839, the German scientist Matthias Schleiden proposed the first foundational belief about cells, that all plant tissues are composed of cells. ... The image above shows a drawing of the microscope set up used by Robert Hooke in 1665 in which he first saw cells in a thin slice of cork.
Answer: q:6
Explanation:
As they were looking for the strands for viruses they discovered DNA
