A Southern blot transfers ______ t a nitrocellulose membrane. protein RNA DNA li

Question

A Southern blot transfers ______ t a nitrocellulose membrane. protein RNA DNA lipid Which of the following is true about cDNA? It is made from a DNA template. It is isolated from bacteria. Reverse transcriptase is used to synthesize cDNA. It has introns. The restriction endonucleases used in recombinant DNA work: always produce blunt ends (no unpaired bases) recognize sequences 4 - 6 bp long. cut the DNA outside the recognition sequence all of the above Alternative splicing of RNA: does NOT occur is thought to occur in only 0.1% of human genes can produce many different forms of a protein often occurs in bacteria At this time. it is _____ to determine a DNA sequence form a single DNA molecule. possible not possible DNA microarrays (DNA chips): can have sequences representing thousands of genes can be hybridized to fluorescently labeled DNA can be used to analyze transcript (mRNA) all of the above

Explanation / Answer

30. Plasmids are naturally occurring extrachromosomal pieces of (circular) DNA that are capable of self replicating.
They have multiple restriction sites but not cloning sites which can be cut by several restriction enzymes.
Therefore, this statement is false.

Hence, the correct option is (C).

31. Many steps cannot be automated in Sanger's dideoxy DNA sequencing protocol. Instead , the di-deoxynucleotidetriphosphates (ddNTPs) may be radioactively or fluorescently labeled for detection in automated sequencing machines.

Hence, the correct option is (D).

32. A Southern blot is a method used in molecular biology for detection of a specific DNA sequence in DNA samples.
Southern blotting combines transfer of electrophoresis-separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization.

Hence, the correct option is (C).

33.Complementary DNA (cDNA) is double-stranded DNA synthesized from a single stranded RNA (e.g., messenger RNA (mRNA) or microRNA) template in a reaction catalyzed by the enzyme reverse transcriptase. Therefore, the statement reverse transcriptase is used to synthesise cDNA is correct.

Hence, the ccorrect option is (C).

34.Restriction enzymes, also known as restriction endonucleases, are enzymes that cut a DNA molecule at a particular place.
They are essential tools for recombinant DNA technology. The enzyme scans a DNA molecule, looking for a particular sequence, usually of four to six nucleotides.
Once it finds this recognition sequence, it stops and cuts the strands. This is known as enzyme digestion. On double stranded DNA the recognition sequence is on both strands, but runs in opposite directions. This allows the enzyme to cut both strands. Sometimes the cut is blunt, sometimes the cut is uneven with dangling
nucleotides on one of the two strands. This uneven cut is known as sticky ends.

Hence, the correct option is (B).

35. Alternative splicing allows more than one protein to be produced from a gene and is an important regulatory step in determining
which functional proteins are produced from gene expression. Alternative splicing of RNA can produce many different forms of a protein.

Hence, the correct option is (C).

36.At this time it is possible to determine a DNA sequence from a single DNA molecule.

Hence, the correct option is (A).

37. The core principle behind microarrays is hybridization between two DNA strands, the property of complementary nucleic acid sequences
to specifically pair with each other by forming hydrogen bonds between complementary nucleotide base pairs.
A high number of complementary base pairs in a nucleotide sequence means tighter non-covalent bonding between the two strands.
After washing off non-specific bonding sequences, only strongly paired strands will remain hybridized.
Fluorescently labeled target sequences that bind to a probe sequence generate a signal that depends on the hybridization conditions such as temperature, and washing after hybridization.

DNA microarrays can be hybridized to fluorscently labeled DNA.

Hence, the correct option is (B).

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