Answer:
E2F transcription factors
Explanation:
The E2F transcription factors (TFs) encode intracellular factors associated with the control of the cell cycle. E2F are TFs that bind to promoter consensus sequences in order to activate transcription. These TFs control the expression of target genes involved in cell proliferation including, among others, genes for DNA replication and mitotic activation. Moreover, the E2F proteins also may act as a link between cell fate and the cell cycle. The retinoblastoma (Rb) is a protein that modulates the activity of the E2F family of TFs, and it has been shown that the Rb/E2F pathway is a key molecular mechanism associated with cell proliferation.
Answer:
(B) resemble structures formed by bacterial communities that are found today in some shallow marine bays.
Explanation:
Extant stromatolites represent real "living fossils" for they are decendents of ancient forms that are associated with one of the first living forms on earth. Particularly, stromatolites are real bacteria communities where the autotrophic organism of the community are represented by cyanobacteria, which live along with heterotrophic bacteria. This clearly indicates that fossilized stromatolites points to bacteria (prokaryotes) as the first living things on earth (dated with not less than 3.5 billion year old)
Nowadays, stromatolites with cyanobacteria allows to reconstruct and understand fossilized forms. These current structures live in shallow marines ambients (e.g. Australia) but also in continental salt flats (e.g. Argentina) where few others bacteria can survive to these extreme conditions (high light exposure and salt concentration).
Answer:
The cytoplasm of the egg cell is same as like that of the ordinary cell's cytoplasm.
It has yolk in its center which contains nucleus, nucleolus and germinal spot.
The mammalian ova contains a small amount of nutritive yolk which provides the nourishment to the embryo for a time being.
The cytoplasm of the unfertilized egg contains some unevenly distributed proteins, specifically the cytoplasmic determinants.
These determinants are the substances that plays a major role in the oocyte formation and maturation. Sometimes they are clumped together and then divided heterogenitically.
Answer:
Conduction: This is a flow of heat by direct contact. Heat travels from a warmer object toward a colder object.
Convection: This is a transfer of heat by mixing a fluid. Convection occurs within liquids and gases. Examples include boiling water and when warm water mixes with cold water.
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Answer: the correct answer is A. ACTH
Explanation:
ACTH stands for Adrenocorticotropic hormone Adrenocorticotropic hormone (ACTH, also adrenocorticotropin, corticotropin) is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress (along with its precursor corticotropin-releasing hormone from the hypothalamus). Its principal effects are increased production and release of cortisol by the cortex of the adrenal gland. ACTH is also related to the circadian rhythm in many organisms.
