Answer: Glial cells called ASTROCYTES help maintain the blood-brain barrier, whereas SCHWANN CELLS create the myelin that envelopes axons
Explanation: Glial cells are specialized cell that are found in both central and peripheral nervous systems, that surrounds the neurones, providing them with support and insulation. There are different types of Glial cells these includes:
- Astrocytes: they maintain the blood brain barrier.
- Schwann cells: create the myelin that envelopes axons of the peripheral nervous system neurones.
- satellite cells: These cells help regulate the external chemical environment of neurones.
- Microglia: they clean up cellular debris through phagocytosis.
- Oligodendrocytes: create the myelin that envelopes axons of the central nervous system
Transcription factors are necessary for an initiation of transcription at a regulated gene but not sufficient.
Transcription is the first step of gene expression in which DNA molecule is copied (transcribed) into RNA (mRNA) by RNA polymerase. The process of transcription is divided into three phases:
1. Initiation
• RNA polymerase with transcriptional factors bind to gene promoter Transcription factors can enhance the interaction between RNA polymerase and a DNA sequence- promoter, encouraging the expression of the gene. Such transcription factors are called activators. Otherwise, when the gene expression is inhibited, factors are called repressors and they bind to sequence –operator.
• RNA polymerase unwinds DNA double helix (transcription bubble is formed)
2. Elongation
• RNA polymerases adds nucleotides complementary to DNA
3. Termination
• RNA polymerase gets to stop codon (transcribes a sequence of DNA known as a terminator)
• Formed complementary RNA strand is released from DNA-RNA complex
Answer:
Population is a collection of individuals of a species living in a defined area
Explanation:
Population:This is a collection of individuals of the same species occupying the same space and able to interbreed freely with one another when individuals of different sexes are brought together.
A species of animals may comprise a single cohesive population or may contain many geographical distinct populations.
Example:A population of Agama lizards in a Campus located in China.The whole human race, Homo sapiens comprising the black, Mongolian,red and white is a population.A population of <u>Cercopithe</u><u>c</u><u>us</u> <u>erythrogaster</u><u> </u>(Monkeys).
Answer:The placement of fossils throughout the sruface layers of earth
Explanation:
All of the Above
The urinary system carries out essential bodily function that help to maintain the body.
Apart from the obvious function of excreting <span>nitrogenous wastes, it helps to maintain an acid-base </span>homeostasis, regulate electrolyte balance and even helps to control blood volume and pressure