Answer: RNAs are not processed before translation in prokaryotes, this process only takes place in eukaryotes.
Explanation:
Messenger RNA or mRNA is a single-straded ribonucleic acid that transfers the genetic information from the DNA (deoxyribonucleic acid) molecule of the cell nucleus to a ribosome (which are the machinery responsible for protein synthesis) in the cytoplasm. mRNA determines the order in which the amino acids of a protein will be joined and acts as a template or pattern for the synthesis of that protein. To accomplish this, the DNA molecule must be transcribed into an RNA molecule, which is used for protein synthesis.
The messenger RNA obtained after transcription is known as primary transcribed RNA or precursor RNA or pre-mRNA, which in most cases is not released from the transcription complex in a fully active form, but in eukaryotes it must undergo modifications before it can perform its function (RNA processing or maturation). These modifications include:
- Elimination of fragments (splicing): In most cases, the <u>mRNA undergoes the removal of internal, non-coding sequences called introns, and the connection of exons. This does not occur in prokaryotic cells</u>, as they do not have introns in their DNA.
- Protection by CAP: <u>Addition to the 5' end of the structure called "cap" or "capping"</u>, which is a modified guanine nucleotide, 7-methylguanosine triphosphate, via a 5'-5' triphosphate linkage, instead of the usual 3',5'-phosphodiester linkage. This cap is necessary for the normal RNA translation process and to maintain its stability.
- Polyadenylation signal: <u>Addition to the 3' end of a poly-A tail, a long polyadenylate sequence, whose bases are all adenine</u>. Its addition is mediated by a sequence or polyadenylation signal (AAAAAA), located 11-30 nucleotides upstream of the original 3' end. This tail protects the mRNA from degradation, and increases its half-life in the cytosol, so that more protein can be synthesized.
The mature mRNA (in eukaryotes) is transferred to the cytosol of the cell through pores in the nuclear envelope. Once in the cytoplasm, ribosomes are coupled to the mRNA. However, in prokaryotes, ribosome binding occurs while the mRNA strand is being synthesized. After a certain amount of time, the mRNA is degraded into its component nucleotides by ribonucleases. So, the transcription and translation processes are carried out in a similar way as in eukaryotic cells but they occur simultaneously. But, the fundamental difference is that, in prokaryotes, the messenger RNA does not undergo a maturation process and, therefore, no cap or tail is added and no introns are removed. Moreover, it does not have to leave the nucleus as in eukaryotes, because in prokaryotic cells there is no defined nucleus.
So, RNAs are not processed before translation in prokaryotes, this process only takes place in eukaryotes.
Our star—the Sun—is a bubbling, boiling ball of fire. See Picture 1 to the right. It constantly belches out great clouds of hot gas. This gas is all charged up with electricity, too. This stuff travels at astounding speeds, some of it right toward Earth! This means that Earth’s weather happens inside the Sun’s weather!
Thank goodness Earth’s magnetic field (see Picture 2) and atmosphere protect us from most of this blast. Otherwise, the Sun’s weather would be OUR weather. Yikes!
However, we are still affected by the Sun’s atmosphere and its violent activities. We call this part of our weather “space weather,” because it comes to us through space from the Sun.
Bacteria have either DNA or RNA as genetic material. This genetic material must be able to replicate efficiently and accurately in order to make sure that offspring inherit the same genotype as the parent organism. This is possible because of genetic information.
The statement is - True.
The five main factors that determine the weather at a certain place are the:
- geographic location/latitude
It determines the amount of sunlight, as well as the concentration of sun rays, which directly influences the temperature.
- altitude/height above sea level
The lower the place the warmer it is, the higher the place the colder it is, it is a simple rule that applies for all places on the planet, compared with places in their surroundings.
- ocean currents/large lakes
The ocean currents can bring cold and dry or warm and wet air masses, depending on what kind of an ocean current it is. The water also contributes to a more stable weather, with more moderate temperatures because of the thermal properties of the water to cool of and warm up slower than the land.
- winds
The air masses can bring cold and dry or warm and wet weather, so they influence the temperature and precipitation of a place.
- topography
Determines how much a place is exposed to the sunlight and the movement of the air masses.
