Eukaryotic cells are theorized to have evolved from prokaryotes called the endosymbiotic theory. This explains that the most primitive eukaryotic cell engulfed a prokaryotic cell (by the process of phagocytosis) that is capable of cellular respiration and another prokaryotic cell that is capable of photosynthesis. These prokaryotic cells eventually became organelles and these organelles are the mitochondria and the chloroplast.
Answer:
c)Recruit the transcription factors and RNA Polymerase that compose the pre-initiation complex.
Explanation:
Transcription leads to formation of RNA from DNA. The process is carried out by RNA Polymerase which forms a RNA strand according to the template DNA strand.
It starts by the formation of pre-initiation complex. RNA Polymerase along with transcription factors binds to the promoter region of DNA and forms the pre-initiation complex. Generally the eukaryotic promoters have a sequence called as TATA box where the transcription factors bind first. Eventually RNA polymerase also binds to the region and the DNA strands separate starting the transcription process.
Answer:
The correct answer is "There are several mechanisms that explain why a hormone have different effects in different cells. These mechanisms include: multiple receptors for the same hormone, a single receptor coupled to different pathways and hormones interacting with receptors for other molecules".
Explanation:
Hormones are among the most versatile molecules of the body, responsible for different biological processes such as human growth, sex development and metabolisms. Hormones are responsible of these complex biological processes because they have drastically different effects in different cells. There are several mechanisms that explain why a hormone have different effects in different cells. These mechanisms include:
- Multiple receptors for the same hormone. For instance, there are multiple receptor for dopamine, a hormone and neurotransmitter responsible for different functions such as movement, memory, sleep and motivation.
- A single receptor coupled to different pathways. Most hormone receptors act with a cascade of signaling. This in consequence results in a single receptor interacting with different molecules having multiple effects.
- Hormones interacting with receptors for other molecules. One example is the action of one metabolite of progesterone named allopregnanolone. This metabolite interacts with GABA-A receptor, which gives it anxiolitic properties.
<span>Mammals
are type that feeds milk to its young and that usually has hair or fur covering
most of its skin. Living mammals classified into groups through method of
development. Mammals are warm-blooded higher vertebrates. E.g. Marsupials,
monotremes and humans.</span>
