Senior 1 Biology Questions Genetic Engineering High School Biology Questions

Hello Explain a first. In genetic engineering, DNA ligases are indeed used to connect sticky ends, but instead of hydrogen bonds between bases, the phosphate group of DNA and the five-carbon sugar - phosphodiester bond (you can see the figure in the textbook). So A's statement is not quite right.

Option D, synthetic gene of interest, is reverse transcription through mRNA, or by pushing out the mRNA sequence through proteins, and then synthesizing DNA. Neither pathway requires restriction enzymes because there are no exogenous genes and there is no need to cleave exogenous genes.

The restriction enzyme is used in the "shotgun method", also known as the "shotgun method", which is not synthetic.

I'm a senior in high school, and although the textbooks I use are different, I can't go wrong with the general knowledge points Hehe, I personally understand, I hope it will help you!

dThe synthetic target gene is to reverse the mRNA sequence with the protein sequence, and reverse transcribed into DNA after the mRNA sequence is synthesized. Just synthesize!

b restriction enzyme cleaves the sticky end to obtain the gene of interest.

cOne is to use it as a delivery vehicle to transfer the target gene into the host cell; The second is to use it to make a large number of copies (called cloning) of the gene of interest in the host cell

A DNA ligase is the one that connects the DNA "handrail" (to generate phosphodiester bonds), and the phosphoric acid and five-carbon sugars upstairs form hydrogen bonds with each other, and have nothing to do with DNA ligase.

A: The role of DNA ligase is to catalyze the formation of phosphodiester bonds.

The hydrogen bonds linked by the bases are intermolecular forces, not chemical bonds, so the formation and breaking of hydrogen bonds are physical changes, not chemical changes, and of course there is no need for catalysts.

A is wrong with the chemical bonds of the enzyme's action.

DNA ligases act as chemical bonds between deoxyribose sugar and phosphoric acid, and hydrogen bonds between the bases, which are linked together without the enzyme itself.

D is right. The concept of artificial synthesis of the target gene is to put DNA together one by one like building blocks, and restriction enzymes can be understood as enzymes that take the building blocks apart, so they are not needed for artificial synthesis.

DNA ligase is attached to phosphoric acid and five-carbon sugar, and the base is linked by DNA polymerase.

Only restriction enzymes are required to obtain the gene of interest from the gene pool.

In fact, "2*2 3*1 3" is a problem of male and female: 2 3AA (female) x1 3 (male) + 2 3AA (male) x1 3 (female), in fact, this problem is quite difficult to understand. It is recommended that the landlord encounter such a problem with the latter approach, the aspect of the practice is sometimes very useful, make good use of it.

In addition, Royal Oak introduces a method that uses the method of genetic probability. Sometimes it's also useful.

Because the probability of aa is 1 3, the probability of aa is 2 3, so the probability of gene a is 1 3 + 2 3 * 1 2 = 2 3, and the probability of gene a is 2 3 * 1 2 = 1 3 (or 1-2 3 = 1 3) so the probability of a occurrence a is 1-1 3 * 1 3 = 8 9 (reverse approach); 2/3*2/3+2*2/3*1/3=8/9

DNA ligase is only a catalyst, and its amount cannot change the ratio of the cell.

To be honest, this question is not rigorous, and increasing the amount of enzyme may increase the amount of ligation product, because you can't determine the optimal amount of enzyme when doing experiments.

The amino acid order of hexapeptides: arginine--- valine--- glycine--- methionine--- histidine--- tryptophan.

Quite simply, the analysis is as follows:

1) Methionine--- Histidine--- Tryptophan, 2) Arginine--- Valine--- Glycine, 3) Glycine--- Methionine--- Histidine.

2 and 3, compare to know: arginine--- valine--- glycine--- methionine--- histidine.

Compare 1 again, and you can know the whole order: arginine--- valine--- glycine--- methionine--- histidine--- tryptophan.

== The codon information of the question stem is useless information! Didn't help with problem solving!

Arginine--- valine--- glycine--- methionine--- histidine--- tryptophan. Combine the clips together.

Arginine--- valine--- glycine.

Glycine--- methionine--- histidine.

Methionine--- histidine --- tryptophan.

So the amino acid order of hexapeptides: arginine--- valine--- glycine--- methionine--- histidine--- tryptophan.

means that there is no such gene.

Plasmid: A self-replicating circular double-stranded DNA molecule within a bacterial cell that can stably exist independently outside the chromosome and be passed on to the offspring, generally not integrating into the host chromosome. Most of the plasmids commonly used today are modified or artificially constructed, and "often contain antibiotic resistance genes", which are important tools in recombinant DNA technology.

Here, "often containing antibiotic resistance genes" is the marker gene.

The marker gene is located on the gene expression vector (plasmid) and not in the recipient cell.

If the recipient cell is E. coli, of course, the plasmid of E. coli cannot be used as a carrier, otherwise the marker gene will not play the role of marker identification.

No!!

The marker gene is not in the recipient cell.

Rather, in plasmids.

Some plasmids are naturally marked.

Some plasmids are synthetic.

The detection of the marker gene of the recipient cell is achieved through its expression. That is, if expression is not detected, it means that the recipient cell has no plasmid or no plasmid expression or plasmid without expression or plasmid without gene of interest.