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taurus [48]
3 years ago
6

Which of these occurs first?

Biology
1 answer:
SpyIntel [72]3 years ago
7 0

Answer:

The correct answer is a.  Helicase unwinds DNA

Explanation:

DNA replication is a process in which DNA make it's own copy. There are several enzymes and factors which access the DNA replication process like helicase, primase, SSB protein, DNA polymerase etc.

The first step in DNA replication is the unwinding of double stranded DNA which is accomplished by an enzyme called Helicase. Helicase opens up the double stranded DNA at replication fork by breaking the hydrogen bond between the nucleotides of complementary strands.

This provides a single stranded template for DNA polymerase to form a new complementary strand. In <em>E. coli </em>Dna B is the primary helicase and in humans the primary helicase is MCM( minichromosome maintenance protein complex).

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If the initiating codon of a mRNA became mutated, what would the effect be on the transcript?
faltersainse [42]

Answer:

Translation will not occur.

Explanation:

The start codon is responsible for the initiation of translation in both prokaryotes and eukaryotes. AUG is the start codon in both which code for methionine in eukaryotes and formyl methionine and prokaryotes.

Therefore if the starts codon becomes mutated than the tRNA would not able to recognize the initiation codon and no methionine would be added as the first amino acid so the translation process might not start and no protein forms. Then the ribosome scans further for the next start codon to start translation.

7 0
3 years ago
What substances are returned to the blood before it leaves the kidneys?​
bekas [8.4K]

Answer:

The process is called reabsorption.

The substances that are returned are glucose, amino acids, water and salt. Hope this helped

6 0
3 years ago
How does the greenhouse effect keep the earth warm? The atmosphere
matrenka [14]
It creates great air
7 0
3 years ago
Read 2 more answers
Define the 3 signals for activation and the 3 outcomes of the complement system.\
sp2606 [1]
* More than 40 proteins and glycoproteins involved in the complement system are synthesized by the liver, macrophages, epithelial cells, they are present in the blood in plasmatic form, membrane, some have an enzymatic activity, regulator or membrane receptorThese are elements of the humoral innate immune response, they fight infections, purify immune complexes and apoptotic bodies.
<span>There are indeed three ways to activate the complement:</span>
Classical pathway: Activated by Immunoglobulins in immune complexes, aggregated Immunoglobulins, DNA, CRP, apoptotic bodies .......it involves nine fractions, starting with C1, then C4, C2, C3, to form a classical C5 convertase, then, activation of C5, C6, C7, C8, C9.

Alternative pathway: activated by polysaccharides (bacterial endotoxin), vascular wall poor in sialic acid, aggregated IgE ...C3b like is the first component in the alternate channel cascade, it will create an amplification loop, and form an alternative C5 convertase.

Lecithin pathway: Activated by mannose, fucose (carbohydrate of microorganisms)The first component is the complex MBL / MASP1 / MASP2: "mannose-binding protein": works according to the same principle as the complex C1 of the classical way (MASP2 cleaves the C4 and the rest of the cascade is equivalent to that of the classical way).

the three ways have the same outcome: A C5 convertase (formed by one of the pathways) cleaves C5 into C5a and C5b: C5b is deposited far from other fractions on the antigenic surface. The fixation of C5b in the cell is followed by that of C6, C7, C8, and C9 (9 molecules of C9): formation of the membrane attack complex (MAC) ==> Death of the cell by osmotic shock
8 0
3 years ago
the cell membrane of a red blood cell will allow water , carbon dioxide, oxygen and glucose to pass through. Because other subst
frosja888 [35]
Amino acids, sugars, and ions move<span> across </span><span>the cell membrane</span>
3 0
4 years ago
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