(B) 142.
(C) 141.
(D) 429.
(E) 428.
An mRNA of 429 nucleotides will form a polypeptide chain with 143 amino acids, assuming each codon (set of 3 nucleotides) corresponds to an amino acid and the stop codon is not counted.
For the synthesis of protein in a process known as translation, each triplet set of nucleotides in the mRNA, called a codon, identifies a specific amino acid. Hence, an mRNA of 429 nucleotides would be segmented into a set of 3 to form the different codons for the amino acids. Since 429 divided by 3 is 143, the polypeptide chain resulting from this mRNA would have 143 amino acids.
In this case, the correct answer would be (A) 143. This calculation does not take into account the stop codon that does not correspond to an amino acid, but usually examination questions ignore the effect of the stop codon. To provide the most accurate answer, we would need to know if the mRNA sequence includes the stop codon or not.
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B) chloroplasts
C) mitochondria
D) endoplasmic reticulum
Answer: Ribosomes
Explanation:
Eukaryotic cells contain membrane-bound organelles, for example animal cells and plant cells. While prokaryotic cells don't, for example bacteria.
Since chloroplasts, mitochondria and endoplasmic reticulum are membrane-bound organelles, which meas that these organelles are surrounded by a phospholipid bilayer, they are only found in eukaryotes.
Endoplasmic reticulum is responsible for protein folding, modification and transport. Chloroplast is responsible for photosynthesis in plants, and mitochondria is responsible for cellular respiration. And, ribosomes is the organelle where protein synthesis takes place, and this happens in both Eukaryotic and Prokaryotic cells.
Answer: True
Explanation:
Unnatural occurences are those catastrophic events induced by humans which can exert drastic impact over the ecosystem. These may include deforestation, forest fire, intentional explosion, and others. This will result in loss of many species due to damage caused to the non-living physical environment.