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
<span>A cell can only grow so large in size because its
ability to exchange materials is affected by a growing surface-to-volume ratio.
Nature designed cells to be small in size because of the network of membranes
passing through it. If cells grow any bigger, membranes in it will not be able
to pass through its different parts and perform their purpose.
A cell is a network composed of many organelles (e.g. mitochondria, nucleus),
that communicate and work together to provide bodily functions. The cell is
small so that communication between organelles will be faster and much easier. When
cells are small they can be easily repaired when damaged and replicated when
needed.</span>
the main difference is that bacteria are free-living cells that can live inside or outside a body, while viruses are a non-living collection of molecules that need a host to survive.
Many bacteria help us: living in our gut digesting and helping absorption of our food, fixing nitrogen and decomposing organic materials in soil. Similarly, not all viruses are bad—we now know there are also beneficial viruses present in our gut, skin and blood that can kill undesirable bacteria and more dangerous viruses.
M1V1=M2V2
M1 * (650 ml) = 0.675 M *450 ml
M1= (0.675 M * 450 ml) / 650 ml
M1= 0.467 M
Answer:
La respuesta correcta es opción C. "Contar con organelos membranosos como los cloroplastos".
Explanation:
Una de las características que diferencia a las células procariontes de las eucariontes, es que las células eucariontes tienen organelos membranosos como los cloroplastos. Las células eucariontes son más complejas que las celulas procariontes, y tienen organelos rodeados por membranas donde efectúan sus distintas funciones celulares. Las células procariontes no tienen organelos y realizan la mayoría de sus funciones directamente en el citoplasma.
