Answer:
D.
Explanation:
Natural selection is the way that organisms adapt through adaptations to better survive and pass on the special genes which enable the offspring to survive. Saying an organism will always mutate to survive is wrong, as natural selection implies that not all organisms survive. With natural selection, nothing is "selected", so B and C are not correct. However, mutations DO make organisms "more fit" to survive their environments, so D is the answer.
Eukaryotes always have a cell membrane, but prokaryotes don't. Eukaryotic and Prokaryotic cells are both
building blocks of life in different organisms. The main difference of two is
in its structures. Eukaryotic cells contain organelles that are found
inside membranes, like the nucleus, which stores chromosomes and DNA.
Prokaryotic cells don't have a nucleus and no true chromosomes. Prokaryotic cells
are unicellular while eukaryotes are multicellular. The presence of
mitochondria, chloroplasts, and cell wall are all distinct to Eukaryotic cells.
Eukaryotic cells are found in animals and plants, while bacteria and archaea
have prokaryotic cells.<span>
<span>In terms of existence, prokaryotes have been on
Earth for millions of years; while eukrayotic cells have come to existence
through the process of evolution. </span></span>
These specialized interval structures found in the cell are organelles. They are crucial for the organisms survival.
Replication forkThe process by which DNA make copies of itself during cell
division is known as DNA replication. During DNA replication, the double helix
structure of DNA molecule is unzip by helicase enzyme which break the hydrogen
bond holding the complementary DNA base together. However, the separation of
the DNA strands will create Y shape called replication fork. Replication fork
will acts as template for creating new strands of DNA.
Answer:
The initial step in the formation of an aminoacyl-tRNA is activation of the amino acid by reaction with ATP
Explanation:
In protein synthesis, the first step involves the formation of an aminoacyl-tRNA. This reaction is catalyzed by the the Mg²⁺-dependent enzymes known as aminoacyl t-RNA synthetases and occurs in two steps.
The first step of the reaction of the formation of an aminoacyl-tRNA is the activation of the amino acid by the attachment of an AMP molecule formed from the hydrolysis of ATP to AMP and pyrophosphate. The aminoacyl adenylate intermediate is bound to the enzyme in this initial step. Subsequently, in the second step of the activation of the amino acid, the aminoacyl adenylate intermediate is then transferred to its specific tRNA. The pyrophosphate formed in the first step is hydrolyzed to 2 phosphate molecules by a pyrophosphatase.
The overall reaction step is illustrated below:
Amino acid + tRNA + ATP -----> aminoacyl-tRNA +AMP + 2Pi
